Sunday, February 10, 2008

Lipoprotein(a) and DELTA

This has got to be one of the strangest abstracts I've read. Because it's only an abstract most of the really interesting information, like insulin levels, lies hidden in the American Journal of Clinical Nutrition.

It's a crossover design so all people acted as their own control group. The study participants were chosen as having low HDL cholesterol and/or elevated triglycerides, two classic markers of insulin resistance. The purpose of the study was to see which of two interventions decreased the participants "risk factors" for heart disease (ie it was a short study with no body count). Both interventions reduced some of the dreaded saturated fat from the of 35% of total fat in the Average American Diet (usually termed the Standard American Diet or SAD, but...). Excellent move to improve lipids wouldn't you think? Except replacing the saturated fat with carbohydrate decreased HDL by 7.2% and using monounsaturated fat decreased HDL by a mere 4.3%.

How about triglycerides? Well the MUFA substitution did nothing to triglycerides (the phrase used is "tended to be lower", meaning no change unless viewed through rose tinted spectacles. I hope their statistician resigned over this phrase, or has since been sacked). The use of carbohydrate cranked up triglycerides, but by how much it doesn't say, just "significantly".

But the best results were lipoprotein(a). You know, that BAD lipoprotein with the genetically pre programmed blood level. It got un-genetically reprogramed upward by 20% in the increased carbohydrate period. The MUFA feeding did far better on this front, MUFA replacing saturated fat only increased lipoprotein(a) by 11%.

In the murky world of lipid belief these changes are, I understand, considered to be BAD. All of them, except perhaps that non-changed triglyceride value in the MUFA feeding period.

Luckily the calculated LDL-C went down, although goodness knows what happened to lipid particle size and numbers (actually you can pretty well assume they got worse, especially the small dense LDL during the carbohydrate period). The abstract certainly makes no suggestion the researchers considered anything other than calculated LDL. It was enough that this reduced a little to allow the DELTA researchers to claim improved CV risk for both interventions.

Actually they claim that MUFA "improved" cardiac "risk" more than carbs. Even if you believe their LDL stupidity, can anyone really believe that a 6.3% reduction is either statistically or biologically "better" than a 7.0% reduction? In your dreams, cardiologist.

What came out rather well was the Average American Diet, SAD or not.

Peter

9 comments:

Chainey said...

Marvelous Blog. Thanks so much for all the effort you put into it. I'm working my way through all the back postings.

I wish I had the knowledge and experience to decipher research reports as you do. I downloaded one [1] that purports to show that pretty much any food boosts insulin. I don't see how that can be so.

I found it via the anti-Atkins book Carbophobia, by Dr Michael Greger. Before I dive in to low carb fully I wanted to see if the other side had any compelling argument.

If it's really true that foods such as eggs provoke nearly the insulin response of high carb foods, then a basic support of LC eating would seem to be shaky.

Erik said...

Interesting book you've found, Chainey. I must check it out also. And as always, good blog, Peter.

Peter said...

Hi Chainey,

I followed your link to the Holt, Miller and Petocz paper. Of the 38 test foods I would only really recognise four as edible; beef, eggs, fish and cheese! These have almost the lowest AUC for both insulin and glucose compared to the rest of the "foods" tested. They definitely come out tops if you want to control both blood insulin and blood glucose. The investigators muddied the water by including lentils and baked beans in the high protein group, then only talking about groups. Look at the response to baked beans in Table 4. They as bad as white bread, but are classed as a "protein" food. This approach, presumably deliberate, stops the high protein group showing well. You notice they didn't include a group with 1000kcal of butter or lard. Wonder why? These give a flat line insulin and glucose response.

Basically, except those four, this study doesn't look at anything other than Mars Bars and croissasants. I'd have hoped that Dr Gerger could do better than this! Can he?

If you real want information look at Dandona's papers in this post, he gives data for glucose in another paper (unimportant, behaves as you'd expect) but here he looks at cream and casein. Particularly see this paper, look at table 1.

Cream is a flatline insulin and glucose response. Casein is unusual as it contains insulinogenic amino acids. Note that although there is an insulin spike there is a FALL in glucose. That's just casein for you.

For a more normal protein see chicken here. Oh, this used to be free access, now you have to pay. Better take my word that there is neither an insulin or glucose spike for chicken.

Good luck with your decisions. Personally I wouldn't trust my life to Dr Gerger unless he can up with much better data, any more than I would trust Dr Campbell. You HAVE to read the data and understand what you are doing. Taking someone's word for what comprises a healthy diet is very risky. DON'T TAKE MY WORD! Let the data speak. They have a lot to say.

I think it has come up in comments before that I strongly feel that we should not have diet gurus. I KNOW that everyone must be wrong some of the time, particularly me. I have no problem with this. Show me data and I'll assess how it fits with my world view. If needed I'll change my view.

My interest in data is to see if I'm wrong! Doing OKish so far.

Peter

Sasquatch said...

Hi Peter,

I have a question and a comment. Is there a reason you focus on dairy fat? Is it because of the vitamins? The flavor?

Also, I'd like to outline my strategy for thinking about lifestyle and health that I feel helps me stay grounded amidst all the confusing science.

I read as much of the science as I can, but I put everything into the context of how we evolved and what has worked in the past. There's plenty of archaeological/anthropological data on how we lived and what we ate when we were generally healthier than today. I am skeptical of anything that doesn't square with this.

Well I'm going to go finish rendering this pork lard, see you later.

Chainey said...

Hi Peter

Thanks very much for the references. I'll follow up on them right away.

I've done my own review of Carbophobia, which you can find here

Eric, the above review includes a link to the full book on-line (He's giving it away!)

I'm going to get hold of Dr K's book as soon as I can. Also I'll read Gary Taubes.

I agree on the "No Gurus" advice. My Skeptidrenaline glands are pumping at all times.

Thanks again.

Peter said...

Hi Chainey,

Thanks for the link to your review of the book, I enjoyed the review and it certainly does not make me wish to have the book on my hard drive. I guess you could imagine that might be my viewpoint! The comparison of four diets trial has been discussed extensively on the net. It was a while ago it all happened and I'll have to have a think where I could get a summary.

Found one, it's here on Michael Eades' Blog. The graphs, tables and interpretation are all there. You asked in your review whether the studies actually say what Dr Greger claims:

No they don't, not this one.

Enjoy Eades' page. I absolutely agree with your comment that Dr Atkins was prickly. I know he upset Prof Yudkin, the UK's main LC teacher at the time, not because Atkins was wrong (he wasn't), he was just "ornery". Is that the right word?

Peter

Peter said...

Hi sasquatch,

I did 3 weeks full paleo, no dairy, no chocolate and obviously no grains. This was the time I was buying the fattiest pork or lamb chops cutting much of the meat off (the cats did well) and getting my animal fat up while keeping protein low. Doing that low protein bit was the hard part. So I find it possible but difficult on a practicality basis.

I fully agree we should have an eye on evolution all the time. The dairy is a compromise of convenience and, I have to admit, taste. Eggs in butter vs eggs in lard.......

I bend this way as I cannot see a cow evolving to damage her calf. My main concern re dairy is all of the very short chain fatty acids which are not present in meat or fat. But SCFA in coconuts do not seem to harm humans, so maybe they're not so bad. Using butter/cream removes the lactose and most of the protein, so it's just the lipids to consider.

Definitely a compromise and I admire people who go fully paleo. Not for me at this stage. On the thought agenda.

Peter

Erik said...

Chainey, thanks for the review. The book gave me some thoughts, but I still keep my feet on the low(er) carbohydrate side of things. Also, going through all those references and verifying the data of a good portion of them seems like a monumental task.

Peter, you have perhaps seen this upcoming study. Could be one to watch.

Sasquatch said...

For the record, I eat a lot of dairy too. I figure it can't be that unnatural for a human, given we all consume it at some point. I'm lucky enough to be lactose tolerant. Still, I buy whole, unpasteurized milk and ferment it myself.

Although I do have to say, human milk has a different macronutrient composition than cow's milk.