Wednesday, February 28, 2018

More on drinking varnish

This paper is a gem.

Reducing the Dietary Omega-6:Omega-3 Utilizing α-Linolenic Acid; Not a Sufficient Therapy for Attenuating High-Fat-Diet-Induced Obesity Development Nor Related Detrimental Metabolic and Adipose Tissue Inflammatory Outcomes

What did they do? They fed rats chow or they fed them on one of four other diets enriched in PUFA. The extra PUFA were based around various mixtures of linoleic acid with alpha-linolenic acid, some  were mostly corn oil, some were slanted towards varnish (flax/linseed oil). Total 18-C PUFA made up 9.4% of calories, ie was obesogenic, and this was identical for all of the high fat diets. Overall macros were identical in all of the high fat diets too. There was no sucrose. The rats were fed ad lib.

Here is the link to Table 1 which lists the compositions, it's too big for putting it up as a jpeg. Just look at how utterly fair the composition of the high fat diets were. Even if the absolute amount of linoleic acid in the lard is not accurate, there will be a consistent error across the diets and the results stay plausible. My only complaint is that there was no group where the omega-3 lipids predominated in the diet PUFA, a 50:50 mix was the maximum. Whereas the maximum omega-6 fed group got essentially all of their PUFA from omega-6 PUFA.

The second excellent feature is that the rats were neither semi-starved nor forcibly overfed. Rats are not people. They cannot be verbally asked to overeat to maintain a stable bodyweight nor to calorie restrict to lose weight. They will simply eat until they are no longer feeling hungry. If that happens while they are svelte or not until they are morbidly obese, the rats don't care.

What happened?

Almost nothing. The chow fed rats, with around 3.5% of calories as PUFA, stayed at a reasonable weight. The obesogenic high fat diets (ie nearly 10% of total calories as PUFA) each caused almost exactly the same progression of obesity:

Why almost?

Can you see that the open squares group gain weight slightly more slowly than the other PUFA diet groups? This shows between week six and week 17. The two hashtags mark out a couple of time points where this achieved statistical significance. This slightly less obese group of rats is the group which ate the least alpha-linolenic acid, the most linoleic acid. This suggests that omega-6 PUFA are less fattening than omega-3 PUFA. I like that. Protons likes that.

The effect was fairly small and only shows as an early facilitation of weight gain. By the end of the study the rats and their adipocytes were all about as fat as they were going to get on 9.4% of calories from any family of PUFA.

You can easily hide this effect by under feeding (pair feeding to the same calories as a chow fed group or arbitrarily reducing overall caloric availability) or overfeeding (paid humans or intragastric cannula over-fed rats). If you are an omega-3 lover this can be necessary. But, given a decent study, it shows.

Consuming the 18-C omega-3 rich linseed oil/flax oil/varnish may not make you terribly much fatter than corn oil will eventually make you, but it should get you there quicker. The situation for EPA and DHA is different. Oxidising these will increase the cytoplasmic NADH:NAD+ ratio via peroxisomal oxidation (bad) and give reasonable mitochondrial function from oxidising the residual saturated caprylic acid C-8 (good), which is the normal fate of very long chain fatty acids of any ilk.

Executive summary: Omega-3 18-C fatty acids are more obesogenic than omega-6 18-C fatty acids. The effect is small but real, it might show better if all of the PUFA were alpha-linolenic acid rather than to 50:50 mixture used. It still makes me happy.


The Protons view (skip this if you're fed up with hearing it over and over again)...

I consider that the mitochondrial oxidation of PUFA will always show as increased peak insulin sensitivity. The cost of that increased insulin sensitivity is fat gain. The fat gain eventually eliminates any benefit from the initial increase in insulin sensitivity. Forced manipulations of the food intake downwards will preserve the intrinsic insulin sensitivity at the cost of chronic hunger. So when high PUFA-fed lab-rats are "pair fed with the chow group" the PUFA rats will look really good, metabolically. The converse, encouragement to overeat, based on avoiding "accidental" weight loss (weight loss is a huge confounder in studies of hepatic lipid accumulation from almost any intervention, PUFA included) by weekly weighing to maintain weight will mask any benefits from saturated fat induced adipocyte insulin resistance. Stacking the deck is crucial to the result you want to get.


Eric said...

My, have you been prodigous. I guess we're all overwhelmed which is why there haven't been any comments posted.

Just to show some mercy: I'll post a link to something that is at most tangentially related -- bacon:

nitrates and nitrites in cured meat:

The article teases out nitrates and nitrites in cured meat as the danger, makes the case that big meat has been acting like big sugar and tobacco and blames the WHO for putting cured meat and red meat in the same bin in its quasi-vegetarian agenda, thereby obscuring the danger from cured meats.

I am curious, is there an alternative view?

Also, do observational studies bear this out, as in Brits eat more bacon than anyone else and have the highest rates of colon cancer? I am not aware of any such data.

Zoran Markovich said...

Hello Peter,
Again, something very interesting for me, related to Linolenic acid vs. EPA and DHA. My two pennies added from this study:
Their conclusion (probably wrong) aside, this sentence is importat: "In contrast, no changes were observed in the content of mitochondrial electron transport chain proteins or carnitine palmitoyl transferase-1 in the liver indicating little direct effect of fish oil on mitochondrial metabolism." Further in this study, authors name some studies as a proof. Maybe it's interesting for you.
Best regards,
Zoran Markovich

Peter said...

Eric, my children have bacon and scrambled eggs for breakfast almost every day, obviously fried in butter to offset the PUFA in the bacon. I have a rambling anecdote about how beneficial dietary nitrates are (conversion to nitric oxide in the stomach, antibacterial, especially against helicobacter spp plus other good effects). And the nitrosamine-cancer idea seems very unlikely to me compared to glucose/insulin/IGF-1...

Zoran, just read the abstract but the concept seems to fit perfectly with Protons concept. Some benefit from the C-8 in mitochondria seems likely and we should never forget that they (omega-3 VLCFA) really are high level signalling molecules. But not get carried away with any idea of superiority to beef dripping.


Eric said...

It is not like one can either have bacon or sugar. I assume if you feed your kids lots of bacon, either they like it very much or you have looked at the science and decided the danger was not too high.

That is exactly what I have been looking for. Nitrosamines have been known to be carcinogenic in animals for a long, long time (to the point that my parents were queasy about making toast hawaii, i.e. pineappe, bacon, cheese) back in the early 70s. The question really is does it translate into a measurable risk in humans eating normal amounts of the stuff.

Then again, while we do not avoid cured meat actively, our normal amount is a lot lower than what you describe.

Anonymous said...

The Eades' - in Protein Power - talked about plant n3 PUFAs being extra proinflamatory via the eicosanoid pathway - blocking delta 6 desaturase enzyme, which works with plant n6(which are fine in amounts found in real food). This doesn't occur with EPA/DHA, which does the opposite. They also said exessive AA in some sensitive people cause a similar proinflammatory effect. The book is 20 years old, as you know. It does make sense for why most nuts and seeds are n6 dominant in their PUFA fraction, while flax, soy, hemp, chia etc are rare exceptions.

Peter said...

Interesting, Mike was ahead of the game!


Peter said...


Effect of meat (beef, chicken, and bacon) on rat colon carcinogenesis

In contrast, compared with lard- and casein-fed controls, the ACF multiplicity was reduced by 12% in rats fed a diet with 30% bacon and by 20% in rats fed a diet with 60% bacon (p less than 0.001)

Mmmmmmm, bacon.......


Eric said...
This comment has been removed by the author.
Eric said...


I have no beef with bacon, just trying to figure out how bad the nitrite reaction products are quantitively. And I worry more about the "cocoa" powder (marketed as low sugar, but it is mostly maltodextrin) and sweets that my kids eat, and the heated salami on the pizza is probably far down the list of harmful things in the pizza :)

On the rats, I was going to write that surely, the rats didn't eat cured bacon, but they did (Herta is probably the market leader in France for Wieners, known as sauccison the strasbourg and lots of ham products). They actually went into a supermarked and bought the stuff real people eat. That's what I call applied science!

I wouldn't vouch for the olive oil, though. The quality you get in French supermarkets is probably even worse than elsewhere in Europe.

I am also pretty sure that the "dry powdered cooked meat" used in the standard chow was worse than some of the supermarket stuff. Just like the rabbits that were fed cholesterol which in all likelyhood was highly oxidized, this stuff might be nasty.

The hundred F344 rats were randomized to ten groups after initiation, and fed on dry powdered diets, based on a modified AIN 76 formula (UAR, Villemoisson, France). Five groups received a relatively “low fat” diet containing 14% fat and 23.5% protein. Five other groups received a very high fat diet containing 28% fat and 40% protein. Fat represented 32% of calories in “low fat” diets, and 51.5% in high fat diet. These values are below and above the average human intake in affluent countries (40%). Fat and protein were provided either by dry powdered cooked meat, making 30 or 60% of the diet, or with olive oil (Carrefour, France) and vitamin-free casein, or with lard and vitamin-free casein (UAR, Villemoisson, France) (Table 1). Two sources of fat were used to make two control diets: olive oil and lard. Olive oil was chosen because it is “neutral” in colon carcinogenesis studies, since it does not enhance or reduce tumor incidence. Lard was chosen because its fatty acids composition is the same as bacon, and is halfway between beef and chicken. Beef (hamburger Carrefour), chicken (with skin, Gastronome) and bacon (Herta) were obtained from a local supermarket (Carrefour Purpan, France). The 3 types of meat were cooked in an oven for 15 min at 180–185°C. Each dish contained 500 g of meat on a thickness of 1 cm. These cooking conditions may generate 1–15 ng/g of heterocyclic amines in beef, 15–65 ng/g in bacon, and 40 ng/g in chicken (17). After cooling, there were minced, frozen for 24h at −20°C, then freeze dried. After the analysis of fat and protein contents in each type of meat (see values in Table 1, notesb–d), meat diets were supplemented with casein to reach the 23.5 or 40% protein targets. The percentage of fat was adjusted with lard for beef diets and with chicken fat for chicken diets (Table 1).

Eric said...

About Mike Eades and plant n-3, interestingly, pastured beef and free range chicken seem to have more n-3 from various analyses, which are almost guarantueed to be plant n-3. I seem to remember there is even a brand of high Omega3 butter in NZ, and they specifically plant things for the cows to eat.

Fish n-3 are not necessarily benign either:

Eric said...

re rats eating cured bacon: apparently they did not adjust the diets for salt content, and the rats eating the salty bacon ended up drinking way more water, so the authors are assuming it is not some mysterious protective effect of bacon rather than that of plain old water we are seeing here. They go on to cite observational studies on humans showing that drinking plenty of water protects against colon and breast cancer.

Who ever knew water was a panacea? Now can we talk calvados?

Peter said...

Ad hoc hypothesis number 2388 methinks. Maybe nitrates/nitrites generate NO which is protective against just about anything/everything... As an anaesthetist I recall when there was a time when simply saying "NO" was the correct answer to most viva questions. It would get a grin from your examiner even if it was incorrect.


Eric said...

who was jumping to an ad hoc hypothesis, you or the autors? we know after all some nasty things happen if we feed rats nitrosamines without the extra salt. they also cite some papers about the beneficial effects of drinking water, although it is beyond me what the mechanism could be with breast cancer. even the dilluted feces make only limited sense, as extra water gets mostly peed out, and the consistency of the feces is probably more a function of fiber content and bacteria.

though if your hypothesis is corrrect, we should be eating ham and spinach sandwiches....

Eric said...

again, from the rats that did their shopping at Carrefour's:

Reddy and colleagues reported that the incidence of colon tumors was the same in F344 rats given a diet containing 60% beef meat, and in rats given a diet similarly balanced with 40% soybean protein and 25% corn oil (tumor incidence beef/soy ratio =1.1, p=0.79) (10). Clinton and colleagues have also shown that the incidence of adenocarcinoma was the same in Sprague Dawley rats given balanced diets containing 20% beef or 20% soybean protein (tumor incidence beef/soy ratio=1.1, p=0.96) (11).

What strikes me as interesting is that beef did not turn out better than the nasty PUFA concoction!

Peter said...

Eric, my own personal feeling is that these models have very little to do with real life. If eating bacon in epidemiology had a relative risk of cancer greater than 10 maybe, then I might be interested. In general I think the people who feed their kids on hot dogs have a lot of confounders they're not going to tell some Harvard dietitian about.

Ad hoc could be either me or them!


Eric said...

Peter, that's probably a sensible approach, to look only for order of magnitude harmful effects.

There's this guy who is a science journalist with a major in biology who had a hard attack at 40 while jogging and still reasonably thin. He set out to learn "all" about nutrition and is now promoting his book. Unfortunately, he did not turn out a German Gary Taubes. From his pitch,

it's a terrible rehash of mediterranean diet rules, Walt Willett is god and the adventists teach us that vegan with the odd fish is best. He also does not mention differences between fats other than olive oil rulez.

The interesting part is on page 3 of his pitch. He summarizes studies on CR, protein restriction and live extension thusly:
1. CR extends life, mainly because cell go from growth mode to cleanup mode
2. the same is true of protein restriction
3. especially true of restriction of essential amino acids which are primarily found in animal producs
4. proposed mechanism of action: essential amino acids acitivate mTOR, no mention at all of fats...

He cites a paper

that according to his summary claims order of magnitude effects from eating 20% of calories animal protein in middle age (50 -65) such as 1.74 mortality 4.0 cancer risk. I smell rat of the kind that does not go shopping but haven't had time to read the paper.

Peter said...

Well, what can you say? None of us get out of here alive. We all have to make our own decisions. I have to say I'm not a protein freak myself but I like to try and be logical in what I do. The paper is epidemiology and shows protein will kill you, until it flips at 65, at which point it makes you live for ever. De Longo strikes me as a hybrid of diet salesman and politician! I may be misjudging him, but if he has seen a market for packaged eating-less at $$$$$ I suppose I really should just say good for him.


Robert Andrew Brown said...

Study uses Male C57BL/6 mice

A stain with peroxisomal defects ? (see below) - given importance of peroxisomes to metabolism of LA and ALA is this an appropriate model to use to run this study - i respectfully suggest not . . .

2.5. Thiolase deficiency

Consistent with the redundancy of thiolases, mice lacking isoform B of ACAA1 (strain C57BL/6 J) [46] exhibit no detectable phenotype. No compensatory upregulation of other thiolases (isoform A; SCPx) was found. Further analysis (but in Sv129 strain) showed a drop in the hepatic triglyceride content and increased levels of C20:3, C20:5 and C22:5, both in liver and plasma [47]. Upon treatment with Wy14,643, induction of peroxisomal β-oxidation was less than in wild type mice and liver triglyceride levels increased although expression of PPARα-targets including the peroxisomal β-oxidation enzymes ACOX1 and MFP1, was increased. Furthermore, upregulation of FAS and SCD1 by WY14,643 was higher in the mutants than in the controls. In contrast, enzymes involved in cholesterol biosynthesis were upregulated in wild type but not in Acaa1 knockout mice. The latter was not due to a defective SREBP2 signaling [48]. It is unclear however how ACAA1 isoform B controls these processes.