Lipoprotein(a) and the Fairies at the bottom of my garden

Just a brief giggle. You recall that a reduced fat diet, packed with plant antioxidants raises Lp(a). Without the plant toxins it works even better to raise Lp(a). This paradox is explained by the immense power of the low fat diet to physically tear Lp(a) out of atheromatous plaque and place it in to the circulation in antigenically recognisable form. It's healing. Snigger.

This is powerful medicine. I don't know how many covalent bonds the lysines and glutamines in apo(a) have made to the lysines and glutamines in fibronectin. Let's say quite a few. But the low fat diet appears to be able to tear several hundred of these covalent bonds apart and then it reassembles the apo(a) molecule in to its original shape in the plasma. Gasp in awe. Well that's incredible.

So incredible that anyone who believes it does not realise what incredible means.

Incredible means unbelievable. Better not to believe unbelievable things. These are the believers who published (just a little name and shame here):

Silaste ML, Rantala M, Alfthan G, Aro A, Witztum JL, Kesäniemi YA, Hörkkö S.

and the believers who editorialised:

Mohamad Navab; Srinivasa T. Reddy; Brian J. Van Lenten; Alan M. Fogelman


Even the Fairies at the bottom of my garden tell me not to believe stuff this stupid!

Peter

Lipoprotein(a) and tissue transglutaminase

"Lp(a) levels are low at birth and rise significantly between 0 and 7 days post partum; in this newborn population, a continuous rise of the mean Lp(a) levels was observed until 180 days"

Well, that's it. The smoking gun of arteriosclerosis. As we know, arteriosclerosis is essentially non existent for humans in-utero and it starts soon after birth (in the 1950s anyway, we may do better at damaging unborn children nowadays). Lp(a) starts low at birth and rises soon after. You only need to be a cardiologist to see the obvious cause and effect here.

OMG it must be so embarrassing to realise that LDL-C has nothing to do with the process, it's been that nasty Lp(a) all the time!

So the obvious explanation must be that Lp(a) worms its way through the arterial endothelium and rips and tears the elastin fibres of the intima to shreds. Simple and utterly plausible. Probably carries a flick-knife.

Except for the tissue transglutaminase (TTG) issue.

We have all heard of this enzyme as an antibody-ligand when testing for coeliac disease, but what does TTG actually do?

Well there is an awful lot of information in this paper. This is what they looked at:

"Because of its intimate interaction with fibrin and/or cell surface oriented structures, we asked whether Lp(a) could be a substrate for transglutaminases (e.g. Factor XIII, tissue transglutaminase). These enzymes catalyze cross-linking between endo-gamma-glutaminyl and endo-epsilon-lysyl residues of proteins (16) resulting in irreversible homo or heteropolymerization of susceptible proteins."

Note the heteropolymerization. Hetero means mixed. If TTG really acts on Lp(a), it doesn't just bind it to more Lp(a), it will bind it to other TTG substrate proteins too. Many of the other TTG substrates are physically part of the cement between cells. Molecules like fibronectin.

"First, substrate specificity was compared with known transglutaminase substrates including fibronectin (17) and alpha 2-plasmin inhibitor (30) and substrates of poor or unknown transglutaminase susceptibility including IgG, alpha 1-proteinase inhibitor, and albumin. This showed that Lp(a) had amine acceptor qualities comparable to that of fibronectin and alpha 2-plasmin inhibitor where as IgG, alpha 1-proteinase inhibitor and albumin failed to incorporate significant amounts of DSC."

So Lp(a) will heteropolymerise with fibronectin:

"FXIII or tissue transglutaminase may catalyze cross-linking and deposition of Lp(a) to surface oriented structures (e.g. connective tissue matrix proteins) and/or cell surfaces."

If you are wondering what fibronectin really does, from wiki:

"fibronectin also binds extracellular matrix components such as collagen, fibrin and heparan sulfate proteoglycans" (as well as intergins). Oh, look, proteoglycans...

And integrins, from wiki:

"Integrins are receptors that mediate attachment between a cell and the tissues surrounding it, which may be other cells or the extracellular matrix (ECM). They also play a role in cell signaling and thereby define cellular shape, mobility, and regulate the cell cycle."

So TTG binds Lp(a), almost certainly to fibronectin, one the main proteins which glue our tissues together. Lp(a) is not randomly sticky. It is enzymatically and specifically integrated in to the matrix of exposed extracellular material in the wall of a damaged artery.

If we reject the hypothesis that Lp(a) circulates with an elastin-targeted flick-knife in its pocket, we can look at the specific and deliberate incorporation of Lp(a) in to a cross-linked network of tissue proteins. This looks like an emergency repair kit to me. Elastin is broken by mechanical stress. Birth, growth, pulsation of arteries, hypertension, relative movement of the supply artery against fixed arteries like the intercostals, branch points in arteries etc are all mechanical stressors. Broken elastin implies stretching of the artery beyond what the elastin will tolerate. Damage to the elastin comes with damage to the endothelium. Disrupted endothelium exposes extracellular matrix and needs a clot to patch it and the clot needs strengthening. An area of damage intrinsically means that the location was too weak. Adding some fibrous tissue and a stronger muscle around damage is an adaptive stratagem in an injury-disrupted provenly-weak arterial area.

Looking at Lp(a) as a repair kit you can make certain predictions, especially if the repair kit is rather helpful.

First is that not having any Lp(a) is bad. Well, we know that's the case.

Next is that having some Lp(a) is good, we know that too from the same graph.

If you are genetically well endowed (with repair kits) they will not show up as repair patches on your arterial wall unless you are actively damaging that arterial wall. ie High Lp(a), (genetic low kringle IV repeat numbers) means nothing if you are not damaging your arteries. Thanks to Kurt for that anecdote!

If you do lots of damage, you will need lots of repair kits. Lp(a) goes up with carb intake and down with saturated fat intake. Check DELTA.

EDIT: Also from DELTA, your body anticipates damage, or detects actual damage, if you replace the saturated fat of the SAD with monounsaturated fat. So it makes more Lp(a). That's it. You liver is worried by MUFA. Extra virgin olive oil is heart healthy? Dump it for lard or, better still, beef dripping! Less plant antioxidants for your liver to eliminate too.

If you do some thing stupid, like pushing your carb intake beyond what is acceptable (even as a non industrialised form of carbs), your liver will make extra repair kits and they will be both needed and used on your arteries. Remember the vegetarian Bantu farmers getting nearly 90% of their calories from complex carbohydrate? Blood pressure rises with age. Not so at 70% from carbs in the Bantu fishermen.

The more damage, the more repair kits get made, the more repair kits get used. The more damage, the more blood pressure rises with age.

Lp(a) rises soon after birth because birth is when pressure induced damage starts. Life, especially being born, is a damaging process. Some lives are more damaging than others.

Are you going to blame the rising blood pressure on the repair kits? Have you forgotten to take your statin today? You may also have forgotten where you left your blood pressure tablets.

Peter

BTW, obviously these stable fibrous arteriosclerotic lesions have nothing to do with heart attacks. Heart attacks happen in the elderly, not in infants!

Intellectual honesty vs obfuscation

This papragraph is taken from Eric Westman's paper on LC for managing diabetes. Thanks to Valtsu for the heads up. Concise, accurate, comprehensive, numerical:

"Prior to the study intervention, the mean ± SD dietary intake for both groups was 2128 ± 993 kcal, 245 ± 136 g of carbohydrate (46% of daily energy intake), 86 ± 33 g of protein (18% of daily energy intake), 88 ± 57 g of fat (36% of daily energy intake). Over the 24-week duration of the intervention, the LCKD group consumed 1550 ± 440 kcal per day, 49 ± 33 g of carbohydrate (13% of daily energy intake), 108 ± 33 g of protein (28% of daily energy intake), 101 ± 35 g of fat (59% of daily energy intake). In comparison, the LGID group consumed 1335 ± 372 kcal per day, 149 ± 46 g of carbohydrate (44% of daily energy intake), 67 ± 20 g of protein (20% of daily energy intake), 55 ± 23 g of fat (36% of daily energy intake). There was no difference in self-reported exercise between the groups: the mean number of exercise sessions per week increased from 2.0 ± 2.0 to 3.0 ± 2.0 for the LCKD group and from 2.2 ± 2.2 to 3.8 ± 2.9 for the LGID group (p = 0.39 for comparison)."

For anyone who has slogged through the Ben-Gurion study, including the full text, looking for exactly this information, it simply is not there. You can stop hunting now. In a weight loss study there is NO REPORT of the absolute calories consumed! Either the DIRECT group does not include anyone who can present data or they are too scared of their own data to actually present it! But for people with a LC bias and honest data, there is no need for fear. Just generate the data, let the truth speak and and expect to be ignored! But not for ever....

A few IMT changes in a LCKD group over 6m would be nice too! I guess they are on their way if Dr Westman has anything to do with it.

Peter

Intimal wall volume reductions with weight loss

Thanks to Chris for the heads up on this one.

Just briefly: Low fat, Mediterranean and low carbohydrate: Statistically significant reductions in carotid vessel wall volume for all of them, with no significant differences between groups, so long as you lose weight:

"with no differences in the low-fat, Mediterranean, or low-carbohydrate groups (-60.69 mm(3), -37.69 mm(3), -84.33 mm(3), respectively; P=0.28"

But the LC group lost more intimal vessel wall volume than the other two groups, even if this wasn't statistically significant. I've also not got access the information about what they mean by low carbohydrate. As we know this could be anything up to 150g/d in some people's book!

2010 could be a good year for LC and honesty!

Peter

A tale of two abstracts

I've kindly re written the abstract for the high fat, low carbohydrate vs semi starvation paper by Eckel's group of clowns in Colorado. I've not attempted to re-title it as the current title needs to be discarded rather than corrected. Especially describing a non significant rise in LDL cholesterol as "hypercholesterolaemia" is not simply incorrect, it is completely dishonest. These people are, like Black's group in Belfast, not stupid. They're just bent.

The original:

Background: Little is known about the comparative effect of weight-loss diets on metabolic profiles during dieting. Objective: The purpose of this study was to compare the effect of a low-carbohydrate diet (<20 g/d) with a high-carbohydrate diet (55% of total energy intake) on fasting and hourly metabolic variables during active weight loss. Design: Healthy, obese adults (n = 32; 22 women, 10 men) were randomly assigned to receive either a carbohydrate-restricted diet [High Fat; mean +/- SD body mass index (BMI; in kg/m2): 35.8 +/- 2.9] or a calorie-restricted, low-fat diet (High Carb; BMI: 36.7 +/- 4.6) for 6 wk. A 24-h in-patient feeding study was performed at baseline and after 6 wk. Glucose, insulin, free fatty acids (FFAs), and triglycerides were measured hourly during meals, at regimented times. Remnant lipoprotein cholesterol was measured every 4 h. Results: Patients lost a similar amount of weight in both groups (P = 0.57). There was an absence of any diet treatment effect between groups on fasting triglycerides or on remnant lipoprotein cholesterol, which was the main outcome. Fasting insulin decreased (P = 0.03), and both fasting (P = 0.040) and 24-h FFAs (P < 0.0001) increased within the High Fat group. Twenty-four-hour insulin decreased (P < 0.05 for both groups). Fasting LDL cholesterol decreased in the High Carb group only (P = 0.003). In both groups, the differences in fasting and 24-h FFAs at 6 wk were significantly correlated with the change in LDL cholesterol (fasting FFA: r = 0.41, P = 0.02; 24-h FFA: r = 0.52, P = 0.002). Conclusions: Weight loss was similar between diets, but only the high-fat diet increased LDL-cholesterol concentrations. This effect was related to the lack of suppression of both fasting and 24-h FFAs.

Corrected version:

Background: Much is known about the comparative effect of weight-loss diets on metabolic profiles during dieting, though our research group seem peculiarly ignorant of the literature. Objective: The purpose of this study was to compare the effect of a low-carbohydrate diet (<20 g/d) with a high-carbohydrate diet (55% of total energy intake) on fasting and hourly metabolic variables during active weight loss. Design: Healthy, obese adults (n = 32; 22 women, 10 men) were randomly assigned to receive either a carbohydrate-restricted diet which was unrestricted in calories or fat and was consumed to satiation [High Fat; mean +/- SD body mass index (BMI; in kg/m2): 35.8 +/- 2.9] or a severely calorie-restricted, low-fat diet (High Carb; BMI: 36.7 +/- 4.6) for 6 wk. A 24-h in-patient feeding study was performed at baseline and after 6 wk. Glucose, insulin, free fatty acids (FFAs), and triglycerides were measured hourly during meals, at regimented times. Remnant lipoprotein cholesterol was measured every 4 h. Results: Patients lost a similar amount of weight in both groups (P = 0.57), the excess weight loss in the calorie and fat unrestricted High Fat diet not reaching statistical significance. There was an absence of any diet treatment effect between groups on fasting triglycerides or on remnant lipoprotein cholesterol, which was the main outcome. Fasting insulin decreased (P = 0.03) only in the High Fat diet, and both fasting (P = 0.040) and 24-h FFAs (P < 0.0001) increased within the High Fat group, as is appropriate for a fatty acid based metabolic profile. Twenty-four-hour insulin decreased (P < 0.05 for both groups), the decrease within the High Fat group being twice that seen in the High Carb group. Fasting LDL cholesterol decreased in the High Carb group only (P = 0.003), representing an increase in the atherogenic sdLDL particle subgroup. In both groups, the differences in fasting and 24-h FFAs at 6 wk were significantly correlated with the change in LDL cholesterol (fasting FFA: r = 0.41, P = 0.02; 24-h FFA: r = 0.52, P = 0.002). Conclusions: Weight loss was similar between diets despite unrestricted calories and fat intake in the High Fat group. The high-fat diet did not significantly increase LDL-cholesterol concentrations (P = 0.13). High Fat diets increase LDL lipoprotein size non significantly, potentially decreasing atherogenicity, which is possibly related to the increase in both fasting and 24h FFAs.


Peter

Arteriosclerosis images (2): Models

All of these images are taken from Dr John Duguid's monograph The Dynamics of Arterisclerosis. I'm not sure they are available elsewhere, so here come some horrible copyright infringements.

Duguid never uses the term mucopolysaccharide or GAGs, but it is pretty clear from the pictures that this is what the hyaline substance in Duguid's rabbit images represents. The body replaces the fibrin of blood clots with GAG, as it does in the healing process of fractures. Oddly enough the parallel goes on to calcification too but I think I might be stretching a point there...

Please bear in mind that the pulmonary emboli are a model. They are not arteriosclerosis, but just look at the vascular wall changes over the months after embolisation. Obviously they are in the pulmonary artery as this is where all emboli from peripheral veins end up!

Duguid has a whole series of picture of microthrombi in human arterial sections which produce similar changes to the model but in minute amounts. Hence in the previous post the clot over the frayed elastic membrane does not look like the large fibrin particle in the rabbit artery here.

Just for a giggle I've also included two of his images of the cholesterol fed rabbit. Classic.

The titles are self explanatory. The fibrin clot is huge and it's the lump on the lower left side in the lumen of the artery. The paler granular stuff is just blood in the artery. All of the stains are H and E and don't show elastin (not needed as the model does not use intimal trauma to produce the clots).



We now know that circulating endothelial progenitor cells rapidly coat thrombi, or other nasties (like foam cells), so finding a covering by six days is not surprising.



By two months the lesion is looking more like a typical childhood arteriosclerosis lesion:



By six months the lesions do look quite like the mature lesions seen in young children:



I would suggest that there is still a lump of what is probably GAG, but the bulk of the lesion (bottom of the section) is mostly just fibrous thickened intima.

It would have been lovely to have Prussian Blue stained sections and Sudan Red sections to confirm the presence of GAG and the near absence of cholesterol, but you don't get what's not in the book.

Don't forget this is a model!

Now, for the current prefered model in cardiovasciular research, fanfare please for the Cholesterol Fed (poisoned?) Rabbit:



All of the bubbly stuff is cholesterol. There is no GAG, there is no fibrin. EPCs coat these foam cells as well as they do fibrin clots, hence the layers of epithelial cells between the foam cells.

And, if your rabbit survives long enough, what does its aorta look like? Here's one (on the left) I prepared earlier:



Duguid does say quite explicitly that this particular rabbit was an exceptional example. Perhaps it has FH as well as cholesterol poisoning!

Now, did this rabbit die of a heart attack?

Hahahahahahaahahahahahahahahahahahahahaha

Peter

Arteriosclerosis in 1957

I was born in 1956, so I was an infant at the time these photographs were being taken. Each one records a personal tragedy. We should learn from them.

All illustrations are taken from Henry Moon's classic 1957 paper.

This is a normal coronary artery. It has been stained to emphasise elastic tissue. Note the continuous folded band of elastin with nothing visible between the elastic layer and the artery lumen (there is actually a single layer of epithelial cells here).



The thicker layer outside the thin black elastic layer is media and is made of muscle. The more granular layer outside the muscle layer is the adventitia. The slide comes from a 5 months gestation human foetus who died, without being born, in a tragic accident. Accidental death autopsies are where all of the pictures in this post come from. Non are cardiac patients.

Next is this picture of the coronary artery of an infant who was 4 days old. Note that most of the intima (dark red wavy layer) is normal and that all of the media is normal. But look at the lower right, there is an abnormal area of the elastic layer. It is shredded and there is fuzziness over the surface. This is the earliest stage of arteriosclerosis noted in this series.



If we next go on to look (slide below) at the coronary arteries from an infant of four months of age we can see a small section of normal intima, with intact elastic layer, on the upper left of the section of artery with normal muscle in the media outside it. Over the rest of the artery the elastic layer is grossly disrupted or absent, the intima is grossly thickened and the muscular media is still relatively normal, though it is a bit thickened at the lower area of the section:



And then we have this superb section actually through a branch of the coronary artery of a child of three years of age. There are some areas of elastic tissue intact but much of it is damaged and the intima has generally thickened wherever the elastic tissue is disrupted. The effect is most marked by the mouth of the branch. The smooth muscle layer (media) is still quite normal but somewhat thickened at the mouth of the branch too.



These last two high magnification images in one picture are stained to show the material of which the thickened intima is composed. In the lower image the changes extend in to the muscular media too.



Do you think it might be cholesterol?

You know, LDL-C, the stick-and-die stuff? Oddly enough if you do frozen sections and stain them with sudan red there are very occasional macrophages with a little lipid in their cytoplasm scattered thinly through this gunk.

But no, the wall to wall stuff stained with Prussian Blue is mucopolysaccharide, I think nowadays it's called glycosaminoglycans or GAG.

To me it's really weird how a cardiologist can think that LDL causes this, and that statins might stop it.

But then the world is a weird place!

Peter

It's Friday and we're heading south for the weekend so the blog will be quiet for a few days.

Saturated fat and sdLDL?

The post itself and the exchange of comments on Dr Davis' blog about genetic causes of sdLDL piqued the interest of many of us. You need to have read the post and comments to make sense of this particular post here. I'm not keen on decrying the concept of genetic sdLDL out of hand but, obviously, there is a great deal that can be thought about around the non genetic concept. My thoughts are down here as I don't want to go cluttering Dr D's post up with comments that are clearly mine, from my biased viewpoint, and very probably not congruent with those of Dr D. The situation is too interesting not to expand a little though...

I roughed out Stan and Ollie on Fitday, very crudely and making big guestimates.

Here they are:

Very crudely for Stan



I gave them both half a kilo of cabbage each, nuts as almonds, (slightly more for Stan as he is weight stable) and chicken, again slightly more for Stan to keep him weight stable. I also allowed Stan some cannola oil to make his total calories up to 2000kcal/d.


And here is a guess for Ollie


I assumed Ollie was burning 0.34lb/d of his own fat and entered this as lard. I allowed him a total (including the lard from his butt/belly) of 2,300kcal/d as he was carting a fair bit more weight around than Stan. Probably an underestimate.

Saturated fat "consumption" for Ollie (who near eliminated sdLDL) worked out as 67g/d, total fat was 83% of 2300kcal, MUFA 105g and PUFA 31g. Most of this fat was from belly-fat plus almonds.

Fat for Stan (who retained sdLDL) was from his diet only as he, quite correctly, lost very little weight over 6m. Results were saturated fat 17g/d, total fat 70% of 2000 calories eaten, MUFA 84g/d and PUFA 53g/d.

I find it hard to see that Stan's saturated fat is the reason for his sdLDL, unless one posits that 17g/d of saturated fat as chylomicrons (apoB48 labelled, gut produced) causes sdLDL in some way (sdLDL is apoB100 labelled and produced by the liver). While at the same time Ollie's 67g/d of saturated fat, available as FFAs after release by hormone sensitive lipase from his adipocytes, behaves differently to Stan's 17g/d saturated fat released from chylomicrons by lipoprotein lipase....

It's possible, but it seems implausible to me.

Dr Davis mentioned the tendency of this sub group of his patients to be borderline diabetic. This to me is far more interesting and makes my ears prick up. Both apoB100 and apoB48 have glycation-predisposed sites which, once glycated, inhibit their uptake by the LDL receptor (certainly for the apoB100 particles, probably something similar works for the apoB48 particle, I've not chased this).

If apoB100s are not taken up because they are glycated due to a borderline diabetes tendency we have a very plausible mechanism for "atherogenic" remnant particles both being formed and "remaining". It just needs a little sugar to get them there. And of course, some of us think sugar and arteriosclerosis might be linked anyway...

Peter

Physiological insulin resistance: Dolphins

This article was sent to me by Stan, and it's interesting on many levels. At the most basic is the gross error in the description of the management of diabetes. This is what the article says:

"In diabetic people, chronic insulin resistance means having to carefully control blood glucose, usually with a diet low in sugar, to avoid a variety of medical complications."

NO NO NO NO NO!

Human diabetes is managed by a diet low in FAT. Ask any diabetologist.

The experience of Dr Dahlqvist encapsulates the monstrous medical approach to the use of low carbohydrate diets in diabetes.

I'm feeling a bit polite tonight for some reason so I won't mention what I think about low fat diets and diabetets. Perhaps I need a glass of wine.



This marine mammal researcher can see physiological insulin resistance in dolphins and see that it is PHYSIOLOGICAL. The difference between a healthy dolphin and a healthy human is minimal (can she see that too?). We humans "do" physiological insulin resistance. But she and her collaborators cannot see that there is a difference between physiological insulin resistance and breaking your liver by living on soda and bagels to get pathological insulin resistance... As she says:

"If we started feeding dolphins Twinkies, they would have diabetes."

Not true. Their insulin resistance would go as they switched on carbohydrate metabolism in their muscles. It would take several years of Twinkies to cause diabetes. Like humans. We're fine for the first few hundred/thousand Twinkies. Then we break.

EDIT: Being in the UK I hadn't realised how small Twinkies are. Let's say 100,000 or so to break your liver...

But ultimately we humans need Twinkies to survive. We must eat them to remain happy and feel part of normal society. Imagine a teenager saying no to a Twinkie, just because they are diabetic! No, we must help people to eat Twinkies while diabetic, so we MUST research the "fasting gene" which is abnormally activated in human diabetes. And develop a drug to turn it off, of course.

BTW the activator of the fasting gene will turn out to be palmitic acid. What other messenger would you use to suggest that there is a fasting state? So we're back to using Palmitofake and a continuous supply of Twinkies.


The title says "Dolphins have diabetes off switch"

No, they do not. There is no off switch for a broken liver. Unbroken dolphins are just behaving like unbroken humans. They turn off physiological insulin resistance when carbohydrate becomes available, even if that carbohydrate come from fish via gluconeogenesis. It's simple and it's NOT diabetes.

Sigh.

Peter

There is potentially a whole load more posts from this link, follow up depends on all sorts of things...

John Hawks on Paleo in NY

I was looking for this report by scrolling back through John Hawks' weblog (it wasn't there, it was in Thinking Meat).

It had come to mind because I had made a bolognaise sauce for tonight's supper and had seared the mince and onions, quite deliberately, because I like the taste of seared meat. I guess like sweetness because it was rare before sucrose became widely available. But burned meat? AGEs and ALEs? Why? And is it bad for me? With quite well defined hearth use at 750,000 years ago I think I'm OK to eat seared meat. I'm not sure why I like it. It's not quite the same as feeding gamma irradiated "food" to cats (their brains fall to pieces) and I suspect it's something humans have been doing for a long time. A lot longer than the 10,000 years of growing grains, which Hawks rightly suggests some of us may be better adapted to than others, even on this brief time scale.

So AGEs and ALEs, yes. Unless, of course, those out-of-Africa-a long-time-ago people had stainless steel cooking pots for boiling meat in, which we've just not found yet...

Scrolling back through Arrested Adaptation, in a vain effort to find what wasn't there, I stumbled on his take about the Paleo in NY article which was discussed in "our" zone of the bloggosphere when it came out. I enjoyed it a lot. Though he has some gripes and beefs about "modern paleo" (with a particular BIG down on Crossfit), his article was generally enjoyable and informed. Being one of those weirdo's with strange dietary habits, even if not paleo, it's a good to get a bit of fun poked at me occasionally, provided it's not malicious...

You do tend to forget how strange you are.

Well, I do anyway.

Peter

Cholesterol: Near miss in Edinburgh

Just another brief post. This group were very, very, very lucky. Crucifiction is supposed to be unpleasant.

What did they do? Well it was more of the usual stuff but, back in the early years of this century, it was still considered ethical to include a placebo group in a statin trial! Gasp, horror, call the ethics committee.

Anyway, 54 people, all with known heart disesae, were allowed to go for 24 months without the benefit of atrovastatin. You wouldn't do this in the states! But here in Scotland, well, a few more heart attacks and no one will notice.

So what does a greater than 50% reduction of LDL-C and a near 50% reduction in C reactive protein do for CAC score progression?

Diddley squat, as you would expect. It's all the usual quotes:

"statin treatment does not have a major effect on the rate of progression of coronary artery calcification"

and

"Serum low density lipoprotein concentrations were not correlated with the rate of progression of coronary calcification (r = 0.05, p = 0.62)"

All utterly tedious.

What grabbed me was the near miss. The CAC score progression in the atrovastatin group was not significantly different to the placebo group.

The p value was 0.18

What would have happened if the p had cracked the mystical p<0.05, say with bigger groups or longer follow up?

In this study atrovastatin "allowed" or "facilitated" progesssion by 26% per year, placebo by only 18% per year.

As I say, p=0.18

A near miss for the careers of all involved.

Peter

Oh, and in the full text you can find that there were actually 2 diabetic patients and 10 current smokers in the placebo group vs no diabetics and only 5 current smokers in the statin group. Equalising these might have given catastrophe.

Cholesterol: Peto seeing some light?

Even Sir Richard Peto (second author) is seeing the light. Sir P is famous for stating (loosely remembered by me) that no individual study of the role of cholesterol in CVD is particularly convincing, but the overall weight of evidence was. I'm stuck with reading study after study and realising they are crap. A big heap of crap is no more convincing than a small heap, to me. But then I'll never get a knighthood.

Back to the Oxford abstract:

"Given usual apoB, lower LDL-C (consistent with smaller LDL particles) was associated with higher risk (P < 0.0001)."

Translation: at a given number of apoB100 particles, the lower the measured LDL the HIGHER the risk.

"The ratio apoB/apoA(1) was substantially more informative about risk (chi(1)(2) = 550) than were commonly used measures such as LDL-C/HDL-C, total/HDL cholesterol, non-HDL cholesterol, and total cholesterol"

Translation: Most of what we have measured in the past is bollocks. Our new ratio is slightly less bollocks.

Notice they didn't mention HDL/trigs. And they still believe sdLDL is out to get you. And no one has pointed out to them that sugar is a great generator of sdLDL.

I've not bothered down loading the free full text. The abstract says exactly what you would expect a real view of the world to say. That's enough to take notice of without working too hard.

Peter

Lipoprotein(a) and ascorbate

OK, ascorbate and Lp(a).

There are some posts which are quite hard to write. I really like the "Lp(a) is a surrogate for ascorbate" hypothesis. It's neat and elegant, so the more information I read which undermines it, the more depressing I find it.

We humans are members of the sub order haplorrini of the order primates. Haplorrhini, that is humans and apes, Old World Monkeys and New World monkeys, have all lost function of that gene for the last enzyme in the formation of ascorbate from glucose.

Of course the crucial species are the tarsiers.

Tarsiers are quite interesting as they have been batted back and forth from the haplorrhini, ie us lot, to the prosimians, ie the rest of the primates. It's a very very close call genetically as to whether tarsiers are haplorrini or not.

There is one isolated report that tarsiers cannot make vitamin C. This should put them firmly in to the haplorrini but geneticists still argue the exact grouping.

It matters because the loss of ascorbate synthesis appears to have occurred in haplorrhini very soon after the split between our sub order and the rest of the primates.

Now, there is this concept that humans lost the ability to synthesise ascobate because a common ancestor to all of us haplorrini sat around all day eating melons and nectarines. Of course it's quite hard to say exactly what the ancestor of the tarsiers actually ate, but it's quite simple to say what current tarsiers eat. They eat insects, lizards and small snakes. I've seen at least one textbook entry which suggest that tarsiers are about as close to anything resembling the common ancestor of we haplorrhini as anything alive today.


Perhaps tarsiers use Lp(a) as an ascorbate replacement? No one has checked this, but what they have checked is whether the New World monkeys make Lp(a). They don't. Or, if they do, it is unrecognisable using human Lp(a) sensing antibodies. If tarsiers can make an Lp(a) like substance it puts them firmly down with the Old World monkeys and apes. They're certainly not an Old World monkey or an ape.

To summarise: Only Old World monkeys and apes make recognisable Lp(a). All haplorrhini have lost ascorbate. The haplorrhini are probably derived from an ascorbate-less near carnivore. New World monkeys are doing fine without Lp(a) or ascorbate. Modern tarsiers are doing fine as pure carnivores without ascorbate....

Of course the guinea pig is a fascinating little beast too. As far as I am aware, it does not make Lp(a) (Pauling and Rath appear to have made a mistake here), it doesn't make ascorbate and it doesn't eat much fruit either. OK, guinea pigs never ever, ever eat fruit in the wild. They live in the high Andes where the year round fruit availability is probably as good as it is in Antarctica.

They eat grass. And guinea pig pooh. That puts ascorbate intake down at very low, but not zero, levels. Like rabbits, they actually live primarily on volatiile fatty acids produced by hind gut fermentaion of cellulose. The minute you feed them cr@pinabag they will immediately become either hyperglycaemic, hyperinsulinaemic or both compared to living on short chain saturated fats. That's not exactly how they are designed to run and their ascorbate requirement rockets. BTW they become obese too. Feed them rabbit cr@pinabag and they die. It's a bit like feeding sailors or tarsiers on dried salt beef and ships biscuits, but probably doesn't taste as good. Doesn't have the weevils either.

Then there is that fruit bat which has also lost its ability to synthesise ascorbate because, well, it eats fruit. This sounds quite convincing as a reason for losing ascorbate until you realise that it seems as if all bats have lost their ability to synthesise ascorbate. Most ascorbate-less bats are pure carnivores. Insects are where it's at. Insects don't synthesise or supply much ascorbate. Fruitbats are the oddballs among bats and it's probably not why they don't make ascorbate. That's just a bat-thing.

Now, I hate to mention hedgehogs again but, here I go, we all know that they not only do make ascorbate, but they also make an Lp(a)-like substance too. As an aside to pointing out that this doesn't go along with Lp(a) as a surrogate for ascorbate, I'd just like to mention kringles III and IV to clear up a minor point:

Humans repeat kringle IV from plasminogen in their Lp(a). Hedgehogs repeat kringle III. How convergent is that? Not very. But in hedgehogs it is kringle III of plasminogen which binds to fibrin, in humans it is kringle IV. So hedgehog Lp(a) seems to be markedly convergent with human Lp(a). This makes me happy as it suggests Lp(a) is not some idiotic mistake only made by humans and their kin. It's worth evolving by non related species. That just leaves the big unknown of whether hedgehogs are also using Lp(a) to deliver oxidised lipids to where they are most needed (guess yes!).... And what we are both doing with those lipids. And their kringles in addition to binding to fibrin.

Anyway, the simple concept that humans and guinea pigs make Lp(a) as an ascorbate substitute seems to be so full of holes that I can't see it. Sigh.

Mega dosing on C in the attempt to put the clock back 40 million years and so reduce Lp(a) and heart disease does not hold water. Whether there is a pharmacological benefit of mega dosing ascorbate, along the lines of using niacin to mimic beta hydroxyburytate, seems possible. But if this is the case it's an accidental benefit derived from faulty logic...

Oh, a last comment on bats. None of them make ascorbate. Some, but not all, are VERY long lifespan species. Not in the league of Naked Mole rats of course, but some certainly live far longer than the same sized mouse.

Never mind mega dosing on ascorbate, that's without making any ascorbate and living on insects.

Peter

Lipoprotein(a): 7-ketocholesterol and cancer

This group did lots and lots and lots and lots of very, very, very clever things. So many, so complex and so clever that I'm not going to try and discuss them all. I was stuck with having to read them all because of the big lump of truth that they tripped over without apparently commenting and I had to look for any justification of the actual conclusions they came to! It's one of those papers where you can't tie the discussion to the results...

This is the executive summary to let me get to the holes in the study.

They found that oxLDL acts on cancer cells in tissue culture to induce two specific changes. The first was the induction of autophagy. This is the housekeeping process of clearing out the odds and sods of damaged and non functional proteins which accumulate with aging. This is a Good Thing, classically induced by ketosis. Good old beta hydroxybutyrate is the classic trigger. So, apparently, is oxLDL!

Obviously, if you are certain that oxLDL causes cancer, you have to consider that any Good Thing happening in bad cancer cells is a Bad Thing for the organism in general. There is no doubt that oxLDL does induce autophagy in cancer cells. This is purported to encourage super cancer cells to develop. These are what I was looking for in the results.

The second thing which oxLDL does is to induce apoptosis in cancer cells. Generally, death is considered to be a Bad Thing from a cancer's perspective. For the organism affected by cancer cells, apoptosis of those cancer cells might be considered a Good Thing.

I dunno.

Perhaps you could say that oxLDL is really Good all round, the cancer cells can die with the happy satisfaction that they had dusted the cupboard under the stairs and emptied the rubbish bins before they committed suicide and the organism is happy to lose the cancer?

There is an unspeakable amount of detail about cell pathways involved but the bottom line is free radicals, ROS. Some ROS equals autophagy, lots equals apoptosis.

OxLDL causes lots of ROS.

Now, if you ignore the discussion and introduction, both of which are exercises in cognitive dissonance, and go to the results you can play hunt the super squeaky clean autophagic cancer cells. Until you are blue in the face. They're not there because they are all either dead or looking VERY sick. No one mentioned finding sleek autophagous cancer cells. Just dead ones.

The action of oxLDL on cancer cells is to kill them. There was no other finding noted on the cellular level, using a microscope. OxLDL, especially the 7-ketocholesterol component, is a potent apoptosis inducer in cancer cells. Quite how this can be a Bad Thing, as expressed throughout this paper, is beyond me.

But there are a series of snags.

OxLDL also induces apoptosis in cultured human umbilical vein endothelial cells. This is undoubtedly a Bad Thing from the CVD point of view. Like Really Bad.

So perhaps oxLDL is really the cause of arteriosclerosis?

It's a nice idea but there really isn't a lot of oxLDL in the blood of any species. In humans it's bound to Lp(a) and in all other species it is present at the lower limits of detectbility. Let's just go back to the Bergman/Krauss/Tsimikas paper and recap:

"In individuals with low Lp[a] levels, there is a corresponding low level of OxPL/apoB, suggesting that in the absence of Lp[a], these OxPLs do not accumulate on plasma apoB-containing lipoproteins other than to a minor degree. A similar situation exists with most animals that we have studied (32, 33). For example, in mice with marked hypercholesterolemia, a situation in which OxPLs recognized by E06 are abundant in the arterial tissues (and probably elsewhere as well), the levels of OxPL/apoB in plasma are very low, and often just at the level of detection of our assay (33). In contrast, Lp[a]-transgenic mice have very high OxPL/apoB levels, even in a C57BL/6 background without obvious atherosclerosis (34). Presumably, this reflects the generation of such OxPLs as a component of normal physiological processes. Lp[a]-transgenic mice express both human apoB-100 and apo[a] and thus can form a true covalent Lp[a] similar to that found in humans (34). Mice expressing high levels of human apoB-100 alone, or apo[a] alone, nevertheless have very low levels of OxPL/apoB (34), suggesting the need for an intact Lp[a] to enable preferential binding of OxPL."

So when you take some native LDL, cook it with copper sulphate and then pour the resulting mess of goo on to cultured cells on a petridish you are really getting a handle on what is happening in the real world of human cardiovascular disease aren't you? Like yeah.

In the real world the oxidised lipids of oxLDL rapidly transfer to Lp(a) (in humans, apes and transgenic Lp[a] mice) or (in all other species) they are excreted, presumably by the liver. Either way, they don't hang around.


Lp(a) has a large sticky moiety which binds to fibrin and proteoglycans. It's not going to see either of these in healthy vascular tissue. Delivering 7-ketcholesterol to the damaged tissue around a cancer cell might be a bit of a magic bullet. It's hardly surprising the body makes lots of apo(a) when the liver picks up markers that you have cancer.

Delivering it to damaged vascular tissue, where fibrin or proteoglycans are exposed, might be good or bad. Probably good in view of a number of other oxidised lipid products present in Lp(a). But if the damage is on going and severe it seems a little unfair to blame the sticking plaster for the damage.

But I would maintain that circulating Lp(a) through healthy tissue has NOTHING in common with pouring copper-oxidised LDL on to cultured vascular smooth muscle cells or endothelial cells.

I suppose at some stage we have to talk about the natural arteriosclerosis which occurs in aged rats and rabbits, but there is so much more of interest about Lp(a) and so little research published to work from...

Peter

BTW Barry Groves has an interesting article by Wayne Martin on the role of Dipyridamole in cancer management. It has a nice description of cancers and fibrin which fits neatly with Lp(a) being a potential anticancer stratagem based on targeting blood clot with an apoptosis inducing agent.

Lipoprotein(a) and oxidised lipids: What's your mimium requirement?

Just briefly, from this paper:




The paper was written before the Lp(a) is oxLDL paper, so the authors are showing the two seperate plots, one is the amount of oxidised phospholipid per unit LDL and the other is Lp(a).

I like the similarities in the curves! Life should be logical.

From the practical point of view, at what level of Lp(a) do you need to hurry in making out your will? Look at graph B.

Obviously there is a "least risk" value for Lp(a), but if you had null genes for apo(a), and so come out with zero Lp(a), you would still be in exactly the same risk category as the sextiles 3 and 4 but wouldn't be worrying about it! So, in this study, using this Lp(a) assay, for people eating modern food, anything below 24mg/dl has the same risk as zero Lp(a). Perhaps lower if you are lucky.

Note also from graph A that having undetectable oxidised lipids per unit LDL in your blood DOUBLES your risk of incident CVD. That's it. No oxLDL [ie no Lp(a), whichever you please] DOUBLES your risk of heart disease.

EDIT: I guess "is observationally associated with" would be a better phrase. Don't want to sound like the AHA about cholesterol here!

And you thought your genes evolved apo(a) to kill you!

Wrong.

Peter

Lipoprotein(a) is oxidised cholesterol

If you want someone with serious expertise on the separation of plasma lipids using an ultracentrifuge then Krauss, obviously, is your man. Author number nine out of twelve on this next paper. He was, obviously, their man too.

If you want to look at oxidised lipids in lipoproteins you need an antibody which locks on to oxidised lipids but not to undamaged lipids. This is called E06. It is quite specific and only binds to the phosphocholine residue of an oxidised phospholpid. It's probably the most commonly used antibody for detecting oxLDL. Or what people thought was oxLDL until this paper came out.


What did this group do? All sorts of things, most of them very clever in deed.

Let's scream through the results. First they took an antibody to Lp(a) and pulled the Lp(a) out of plasma with it. E06 reactivity was pulled out along side Lp(a).

They got Krauss to spin some lipids and found, lo and behold, E06 reactivity separated out ONLY with the Lp(a) fraction.

They took some LDL and oxidised it artificially with copper ions. Then they offered it a choice of Lp(a) or native LDL to share lipids with. Not only did E06 reactivity jump out of the oxLDL and in to Lp(a), it ONLY jumped in to the Lp(a). None jumped from copper oxidised LDL to native LDL. None would leave its Lp(a), even to go to another Lp(a).

They went on to check if Lp(a) is just susceptible to oxidation in its own right, by looking for malondialdehyde-lysine residues. It's not oxidised itself. It just collects oxidised lipids. The antibody for malondialdehyde-lysine is E14. It ignores Lp(a). However the E06 antibody to oxidised phospholipid not only recognised Lp(a) but also apo(a) alone, presumably both from sources where they have had access to oxidised lipids.

The implication from this is that while some of the oxidised phospholipids are in the lipid particle of the Lp(a), a big chunk are also bound to the apo(a) protein.

The group feel that apo(a) initially captures oxidised phospholipids from the aqueous plasma phase and they are then transfer over several hours to the lipid droplet.

EDIT: I miss read this, the lipid drop captures the oxidised phospholipds and then they get arranged on the apo(a) glycoprotein. This may have some relevance to apo(a) isoforms, Lp(a) levels and vascular injury.

They doubt that Lp(a) really goes around stealing oxidised lipids from oxLDL particles. What they suspect is happening is that whenever oxidised lipids are released from damaged tissues, Lp(a) is the mop which mops them up. They probably never get as far as native LDL.

As far as they are concerned Lp(a) IS oxLDL. And oxLDL IS Lp(a).

Do tissue damage, the liver makes a sponge for oxidised tissue lipids. Probably many more oxidised lipids than E06 recognises.

You have to wonder whether the liver senses free oxidised lipids in the bloodstream and makes apo(a) in response to them (almost certainly the case, because Lp(a) spikes after injuries such as percutaneous cardiac procedures, where everyone expects oxidised lipids to be mechanically released without dietary warning). Or whether, as in the Finland intervention, volunteers do something grossly stupid such as reducing the fat content of their diet. And the liver pre-empts...

Probably a bit of both.

So, Beth, you asked in the comments section of the last Lp(a) post:

What does Lp(a) actually do?

It preferentially accumulates oxidised lipids and binds them in a form where they cannot be immediately excreted from the plasma. It also puts a great big sticky label on them that allows them to firmly bind to damaged tissue.

Only Lp(a) does this.

Only in humans and related apes. Oh, and in mice genetically engineered with both human apoB100 and apo(a) in combination. Of course.

Why?

That too is an interesting question.

Peter

Lipoprotein(a) Bantu recap 2

More from the Lugalawa study in Tanzania.

We all get two copies of any particular gene, one from our mother and one from our father. The gene coding for the number of kringle IV repeats on apo(a) is exactly like this. Some people get apo(a) of the same size from both parents, others get a pair of different apo(a)s, one size from each parent.

If you are trying to compare the effect of apo(a) size on Lp(a) concentration, and the confounding effects of diet, it would be really helpful to have everyone in the study with just one size of apo(a) each. They're not actually that rare and in the Bantu study Pauletto found quite a number of individuals with only one apo(a) size who could be pair matched with someone similar from the neighbouring village.

The effect is shown here in Table 2



Just in case the table is not 100% clear on a casual glance (it wasn't to me!!) here is the section we need, just copied from the middle section of the table.



We can see that the median in the fishermen is half that of the vegetarians with a p value < 0.001

Just imagine a drug had been found to halve Lp(a) level. Eric Topol would wet himself!

But it gets more interesting. Pauletto went on to plot isoform size against Lp(a) concentration. Here are the data from the matched apo(a) size:



Look especially at apo(a) with less than 15 kringle IV repeats. Lp(a) is 55mg/dl in the vegetarians and less than 20 in the fishermen. Same genes. Now this is not statistically significant, but that comes from trying to compare 6 farmers with 4 fishermen!

So Pauletto cheated a little to bump his numbers up and went on to do the same plot but included anyone with more than 85% of their expressed apo(a) size in a given bracket. This gave more people and significant p values across all ranges.



I don't find the differences very biologically convincing at the right hand end of the plot with the long apo(a) kringle IV repeats. With long apo(a) you can eat what you like and still have low Lp(a), within these cultures. But it seems likely, if you believe Lp(a) furs up arteries, that the short apo(a) repeat farmers are in a lot more trouble than the similarly gifted fishermen... Lp(a) 60mg/dl vs 20mg/dl.

But it gets worse for the farmers! They are significantly more likely as a group to have short form apo(a). Here is the isoform distribution between the groups:



The bottom section clearly shows that the vegetarian farmers are more likely to have killer apo(a) isoforms, as well as making more Lp(a) than they should for a given apo(a) size. A double whammy.

Why should this be?

Pauletto thinks it's a founder effect:

"...even though the 2 populations are racially homogeneous, we have found a significant difference in apo(a) isoform size distribution between the inhabitants of the 2 villages, probably due to differences between the founders of the 2 villages."


This seems implausible to me. Founder effects would certainly be likely to persist in isolated populations but these populations intermarry commonly.

What seems far more likely is that there is an on-going positive selection pressure for short apo(a) isoforms in the vegetarian farmers. Intermarriage dilutes this effect but doesn't eliminate it. Of course you could argue the converse, that fishermen are selected to have longer apo(a) isoforms but this seems less likely when you consider what Lp(a) might actually be doing, other than keeping Eric Topol off of the streets.

You have to ask whether the farmers benefit from high Lp(a) levels.

Peter

Lipoprotein(a) Bantu recap

Just to recap from a few years ago, there are two well studied villages in Tanzania. One has a diet which is subsistence agriculture and so complex starch based, the other is also mostly starch based but supplemented with half a kilo of fish a day. Their daily food intake is approximately described in this Lancet paper:

"Daily energy intake was similar in the two populations (2196 kcal [9·19 MJ] in the fish-diet group vs 2109 kcal [8·82 MJ]). There was no difference in salt intake (4·4 vs 4·0 g daily). In the fish-diet group, 23% of energy intake was from fish with consumption of 300-600 g daily (three to four fish meals per day). Among the vegetarians, most energy was derived from complex carbohydrates (82% compared with 70% in the fish-diet group) such as maize and rice. The proportions of energy derived from protein were 11% and 18%, respectively, and those from fats 7% and 12%. "

The vegetarians are as close to an ideal version of a low fat vegetarian diet as you can get. I don't know much about Ornish's ideas but I'm guessing this comes as close to doing it "correctly" as you can. Exercise too!

The fishermen on the lake shore seem closer to the Kitavans in their macronutrient intake. Still high carb, but not quite up at the 82% of calories mark eaten by the vegetarian farmers...

Using blood pressure as a surrogate for CV health, the fish eaters appear to beat the complex carb group quite convincingly:




So, if you are on an extremly low fat vegetarian diet and your blood pressure isn't doing what it's supposed to do, don't blame yourself. Eat some animals.

Pauletto's group think it is specifically the omega three lipids which have the beneficial effects on BP, but I'm not so sure. If you eat a diet based on fish and seal alone, and virtually zero carbs, you still get this increase in blood pressure with age. Despite the omega three fatty acid intake being very high.

The comparison comes from Paal Røiri's 2005 discussion paper "Eskimo-kostholdets betydning for dødeligheten av hjerteog karsykdommer". We have this table of blood pressure changes with age, rising from just over 100mmHg systolic in childhood to around 150mmHg over the age of 60.




Either extreme does not appear to be ideal. It looks like the upper tolerable limit of unrefined complex carbs seems to be some where above 70% of calories but below 80%. Living down at 4% might not be perfect either. But I digress.

The striking difference between the two Bantu groups is in Lp(a) level. Obviously the vegetarians have higher Lp(a) levels than the fish eaters, as you would expect from their slowly rising blood pressure with age.

You can see that the vegetarians have a median value for Lp(a) of 27mg/dl where as the fishermen have a median of 14mg/dl.




The assumption is that the high Lp(a) is bad and is furring up their arteries and putting up their blood pressure as they age.

Probably genetic. Bad genes mean the farmers have short kringle IV repeats and so their high Lp(a) sets about giving them their just desserts.

Maybe.

Peter

Lipoprotein(a) Oxford abstract

This is Watkins, one of the senior authors of this paper on Lp(a) and heart disease:

"This is the most convincing evidence so far that this protein [Lp(a)] is directly part of the pathway that causes heart disease rather than a bystander. If we can target it through treatment, we might expect to lower the risk of disease," coauthor Dr Hugh Watkins (University of Oxford) told heartwire.

OK, we have known for quite a long time that Lp(a) is associated with heart disease. We also know that genetics has a big influence on the level of Lp(a) in the bloodstream. The basic rule is that if you have a small number of kringle IV repeats from your apo(a) genes you will have a large amount of Lp(a) in your blood stream. All of this is old news.

How many repeats of kringle IV you have is a genetic trait. The people at Oxford have used a very sophisticated search technique to locate a couple of changes, each involving a single base pair, in the region of the DNA which makes up the chromosome area coding for apo(a). Either of them affects the number of kringle IV repeats you have in your apo(a). Hence the amount of Lp(a) in your blood.

Finding two single point DNA variations which influence kringle IV repeats is a huge achievement. We now have a piece of genetic mechanism information. What puzzles me is how this is any different from simply counting the number of kringle IV repeats in apo(a) extracted from an ordinary blood sample, which we have been doing for years, without knowing exactly which change in the DNA affected the count.

What is assumed in this paper and the inferences drawn from it is that Lp(a) is intrinsically bad and that genes are the sole control of the level of Lp(a).

Both assumptions are probably wrong. We have to back to Tanzania to see what might actually influence Lp(a) in people with identical apo(a) kringle IV repeats. Hint, its not atrovastatin or ezetimbe.

But one thing came out of the abstract which is actually quite interesting. There is an association between these gene changes, "a small Lp(a) lipoprotein size" and heart disease.

I'm just wondering if a small Lp(a) particle is also a dense Lp(a) particle..........

Back to the Bantu next.

Peter

Lipoprotein(a) genetics press release

Richard over at Free the Animal discussed this press release, relating to this paper, delivered a day early from the NEJM, by Santa, to cardiologists all over the world.

The paper itself is a piece of trivia (next post) but it is useful personally as it has me back to thinking about Lp(a), arteriosclerosis and genetics. Before I start talking about the abstract there are a couple of laughs/cries to be had from the press release itself.

First is Eric Topol. When you read a technical paper and you see the word "Atkins™" in the discussion, you know you are sitting on a garbage heap. When you see Eric "rent a quote" Topol in a press release you know you are in for a laugh too. Just how funny Eric is requires that you read Malcolm Kendrick's superb essay on Treating to New Targets, the TNT study, which obviously went like a bomb. Or bombed.


You really must read the original essay if you haven't already, but always remember the statistical significance and the biological significance of being dead are two quite different things, unless you sell a statin of course. Eric is owned by statin pushers.

Now, for another giggle, down at the end of the press release there is the section which is as predictable as the musings from dear Eric. This time Kathiresan gets the idiot award:

"Finally," adds Kathiresan, "the genetic data suggest the hypothesis that lowering the plasma Lp(a) lipoprotein level by pharmacologic means will lower the risk of coronary disease."

That sounds perfectly reasonable, if you have Kathiresan's outlook, until you get to the follow on, added by the pharmaceutical company which owns Heartwire's tame author, Lisa Nainggolan:

"Another group of drugs in development that lower Lp(a) are the cholesteryl-ester transfer protein (CETP) inhibitors (such as anacetrapib), which also raises HDL..."

Now if anyone out there thinks that anacetrapib is going to turn out to be remotely different from torcetrapib or the genetic defects giving low CETP activity in Japanese or non-Japanese USA citizens, all of which raise HDL while killing people of heart disease, well you must be on a statin.

Equally, if you think a pure Lp(a) reducing pharmaceutical agent is going to stop heart disease, you're probably wrong. As Dr BG says, Lp(a) has some seriously good effects but you shouldn't run with scissors...

Now, reducing the need for the body to make Lp(a), that's a different approach to lowering it pharmacologically!

Peter

Who pays the piper: Disturbed earth

I hope this is going to be the last post on Bradley and Hunter. Once again Table 5, but now the HbA1c line.




An HbA1c of 5.2, 5.3, 5.4 or 5.5 is normal. Any variation within these limits is virtually irrelevant clinically. Moving a tenth of a percentage point in this region is utterly insignificant. The changes in HbA1c don't even get a mention in the discussion. But perhaps they should do.

The low fat group dropped their HbA1c from 5.4 to 5.3, shrug. The low carb group dropped their HbA1c from 5.3 to 5.2. Mega shrug. Sound just about identical, don't they?

There are two very strange things about this. The first is that the drop for the low fat group does not reach statistical significance. The p value is 0.4 for within LF group change.

But the drop from 5.3 to 5.2 in the low carbohydrate group is statistically very significant, p=0.01. How can this be?

The second strange thing is that, in the whole of Table 5, there is only one value expressed to three decimal places. That is the standard deviation of the HbA1c of the post diet low carbohydrate group. This sd has to use three decimal places because it is so small. Having zero would not look good.

What does an sd of +/- 0.003 mean? Because three standard deviations around a mean include 99% of the population we know that 99% of the values lie within the 5.2 +/- 0.009 range. But HbA1c is only reported to one decimal place and you can only ever deal with a whole number of people. So, by the end of the eight week study, 11/12 subjects on the low carbohydrate diet will have had an HbA1c of 5.2 and the 12th person will either have been 5.3 or 5.1, there is no other way of looking at the data.

This is what happens when you take a group of people eating anywhere between 190g/d and 275g/d of carbs and drop them all to close on 104g/d. Everyone's post prandial glucose drops and the range of HbA1c both drops and tightens up.

Not so the low fat diet people.

Before the study they started with carbohydrate intakes of about 120-240g/d and tightened in to a minimal spread round 226g/d on the low fat diet. So some individuals increased their carbs, some decreased them, some didn't change them that much.

The changes in glycaemia will have been all over the place following changes in individual carb intake. Some will have risen, some dropped. There was a spread to begin with and a spread at the end. The overall effect is a small and insignificant drop because the carb intake variation is blunted by a 500kcal energy deficit being made up of zero-carb butt fat!

Had this diet not included weight loss the low fat people would have really come out badly on an HbA1c basis as they would have been eating glucose instead of burning butt fat!

In terms of glycaemia, everyone benefited in the LC group. Some benefited and some were injured, ever so slightly, in the low fat group. This is hidden in the average but shows through the standard deviations!

Overall this aspect is more of interest for looking at how information gets buried, rather than any genuine clinical effect. Information gets buried all right. Luckily you can see the disturbed earth in the results tables.

That's it. I've had enough of Hunter and will give it a rest.

Peter

Who pays the piper: Other lipids

About lipids, quote from the discussion in the Bradley and Hunter paper, related to Table 5:



"As expected, the low-fat diet decreased both LDL and HDL cholesterol. Although the low-carbohydrate diet did not decrease LDL cholesterol, it was not associated with a significant decline in HDL cholesterol. Given the established evidence that LDL lowering reduces the risk of coronary heart disease, the lack of a decrease may be of concern. In contrast to the lack of a change in LDL and HDL in response to the low-carbohydrate diet, there was a significant reduction in triglycerides within this group compared with no significant change within the low-fat group. This response has been consistently reported in other studies comparing a low-carbohydrate and low-fat weight reduction diet (12). It has been speculated that this result is due to a combination of a decrease in the VLDL production rate and an increase in triglyceride removal from the blood (31). Previous studies (32,33) indicate that increased triglycerides are an independent risk factor for cardiovascular disease, although it is impossible to predict the overall effect of the lipid changes with the lowcarbohydrate diet. Further examination of the lipid subfraction profile may help elucidate the effects of the dietary regimens on lipid metabolism. Indeed, previous studies have suggested that low-carbohydrate diets increase LDL particle size and decrease small dense LDL particles (34)"

This is a load of mealy mouthed beating around the bush. My translation (couched in terms of the lipid hypothesis, for believers such as Bardley and Hunter):

The low carbohydrate diet did no harm to LDL, this is really good. Low fat diet converted any bouyant LDL around from the pre study diet to sdLDL during the study. This is really bad, it just improved a lab number while actually injuring the participants. The low carbohydrate reduced triglycerides, this is really good. The low fat diet didn't. This is cr@p.

Executive summary: The low carbohydrate beat the low fat diet on lipids, hands down.

Peter

Who pays the piper. High fat diet drops HDL!

From the discussion of Bradley and Hunter's 2009 paper:

"A major concern associated with low-carbohydrate diets is that the reciprocal increase in dietary fat intake, particularly if this includes saturated and trans fat, may have detrimental effects on cardiovascular risk"

Who mentioned trans fats? To find out what the diets were actually like we need to look at Table 1:




Hard to say, but there are a few rather commercial sounding foods listed where we might find trans fat. How about the nutrient breakdown on the diet, that's here:




It looks like 60% of calories from fat in the LC group, 21% saturated, 21% monounsaturated and 13% polyunsaturated.

Now hang on, 21+21+13 does not equal 60. What was the other 5%? This was a study in which university nutritionists were providing the food. They should be able to make three numbers add up. It's not as if we are working with food frequency questionnaires or dietary recall from a year ago. As they say in the methods:

"Volunteers attended on alternate days throughout the study and were supplied with all appropriate foodstuffs (preweighed into daily portions) for their particular diet"

So 5% of the fat in the LC diet was not supplied in a form which could be listed comfortably in Table 4. Anyone for trans fats?

So lets go and look to see if there is any other evidence of trans fats as 5% of calories. We can try looking in Table 5.




Hands up who knows what saturated fat does to your HDL level? OK, go to the top of the class. The LC arm increased their saturated fat intake from 15% to 20% of a few less calories, with a similar increase in monounsats too, yet they DROPPED their HDL from 1.47mmol/l to 1.35mmol/l. Not catastrophic, just bad (if you believe in lipids being good or bad, all this means to me is that they fed trans fats as well as a little extra saturated fat). In just 12 people this is not STATISTICALLY significant. At a population level it would be biologically significant.

Of course the low fat folks dropped their HDL from 1.40mmol/l to 1.15mmol/l. Statistically (p=0.01) and biologically significant. Just what anyone would expect from a low fat diet, except that the drop seems even worse than you would expect from an ordinary university designed low fat diet! Table 4 suggests 4% unlistable fats for the low fat group too.

Trans fats shared equally? I don't know.

At this point I would just like to suggest that in NO WAY should ANYONE ever let a Belfast nutritionist design their diet. Just say NO.

Stick to eating Food.

Peter

Who pays the piper. Ignorant or bent?

Let's go back to 2006. Black and Hunter produced this paper with this as the final line of the abstract:

"In this study, a high-sucrose intake as part of an eucaloric, weight-maintaining diet had no detrimental effect on insulin sensitivity, glycemic profiles, or measures of vascular compliance in healthy nondiabetic subjects"

This statement is incorrect. The victims started with a fasting blood glucose of 4.8mmol/l, normal, and ended up as pre-diabetics with a FBG of 5.6mmol/l (discussed here). The glycaemic profile was NOT free of detrimental effect of either intervention diet. The only mystery was whether Hunter's group was ignorant of the concept of pre diabetes or bent. Now, if we go to the results section of the 2009 paper by Bradley and Hunter, currently under discussion, we can find this line:

"Although glucose tolerance tests were not performed, the mean fasting plasma glucose of 5.6 mmol/l was in the pre-diabetes range, consistent with an increased risk for development of diabetes."

Which seems to nicely answer that question. I particularly like both studies having exactly 5.6mmol/l as the value cited. A pure fluke, but so informative....

Ignorant or bent? You decide!

Peter

Who pays the piper for arterial stiffness? Now for Table 7...

First the problem: TABLE 7



OK, first the easy bits. Both diets dropped systolic and diastolic blood pressures by the same amount. I'll come back to the pulse pressure (systolic - diastolic) later, but it didn't change by any significant amount either.

The last line, brachial pulse wave velocity, didn't change and was the same on both diets. This is a marker of how stiff the brachial artery is, a muscular artery which doesn't store blood in the same way as the elastic arteries such as the aorta. You can say muscular arteries didn't change with diet or weight loss.

There are then a set of numbers derived from the aortic arterial waveform, this waveform, deep in the aorta, is estimated from a peripheral pulse (illustration stolen from some random Nature paper where folks probably knew what they were talking about):




The time-to-wave reflection is the time from the start of contraction to a very early reflected wave from the periphery. It comes much sooner than the wave described in the previous post and just shows as a "bumping up" of the pressure in the aorta.

The sooner this wave arrives the more rigid the aorta. To find it you look for an inflection point on the upswing of the pulse pressure. It's marked as Tr in the diagram. It's probably similar in the information it carries as aortic pulse wave velocity in the last post but requires much more sophisticated software to extract.

This marker of aortic health improved by twice as much in the low fat diet as the low carbohydrate diet. That's interesting, but note that both groups improved.

The amount that the blood pressure gets "bumped up" by using this wave is the augmentation pressure, recorded as "augmentation" in the table. To get the augmentation index you should just divide the augmentation pressure by the pulse pressure and multiply by 100 to get a percentage. ie how much of your pulse pressure is from augmentation due to early reflection... The numbers don't add up exactly as the machine seems to be doing something slightly different and describing the end result as aortic augmentation index as compared to the usual augmentation index... That's just inside the box of tricks used and I can't tell exactly what they've done.

So, because pulse pressure didn't really change, augmentation and augmenation index should change together. They do, but only approximately. The difference has, again, to be within the machine and how it looks at the waveforms and does its calculations.

What's bad is that, as reported by Hunter, AI got worse in the low carb group and got better in the low fat group. Oh no! So Hunter can say in the discussion:

"It is possible that the high fat content of a low-carbohydrate diet exerts detrimental effects on endothelial function, which raises concerns regarding the long-term safety and efficacy of low-carbohydrate diets"


But when you look at the numbers the low carbohydrate group started with an augmentation of 7.4 mmHg and this increased to 8.4 mmHg.

The low fat group started with a higher value of 9.2 mmHg and this dropped to 8.3 mmHg.

So the low carbohydrate group started 1 mmHg of augmentation below the end result of 8.4 mmHg. The low fat group started at 1mmHg of augmentation above the end result of 8.3mmHg.

I defy anyone to claim 8.4 is different from 8.3 with SDs of 5.4 and 7.8 respectively.

The end values were the same.


So there are two insoluble mysteries. First is how the "aortic" augmentation index, the only value which made p<0.05, is different for the simply calculated augmentation index percentage, which probably didn't reach p=0.04.

The second is how come a group of 12 people can improve one measure of aortic stiffness (time-to-wave reflection) and worsen another (augmentation index), when both parameters are derived from the same 12 cardiovascular systems! Dunno on either of those.

But I would also add that augmentation should never be zero! You're pushing blood down a pipe. Some augmentation is essential and normal and a quick look around pubmed has some poor folks with augmentation indices of >40%, to put things in perspective... It's not like cholesterol (jk), the lower the better blah blah blah !

This comes down to clinical vs statistical significance. Both groups ended up with the same augmentation, neither change was significant, biologically or statistically, but a machine derived variant made p=0.04 in favour of low fat diet, but with dubious biological significance.

There is a huge goldmine of information in the results which need talking about but I think that's enough for now. It's all pro LC and anti LF, as you would expect.

Peter

BTW I've just calculated the AI% from changes in pulse-pressure and reported augmentation and, using the simple percentage technique [of AP/PP X 100], the end of study AI% for LC (17.14%) actually ends up slightly lower, compared to the end value for the LF group (17.29%). Hunter no doubt would argue the direction of change being awful despite LC end result beating LF etc etc but still, it's pleasant pedantry to look at the numbers...