Thursday, February 25, 2010

Corn Oil and Cancer?

The benefits of corn oil keep rolling in. In a new study by Stephen Freedland's group at Duke, feeding mice a diet rich in butter and lard didn't promote the growth of transplanted human prostate cancer cells any more than a low-fat diet (1).

Why do we care? Because other studies, including one from the same investigators, show that corn oil and other industrial seed oils strongly promote prostate cancer cell growth and increase mortality in similar models (2, 3).

From the discussion section:
Current results combined with our prior results suggest that lowering the fat content of a primarily saturated fat diet offers little survival benefit in an intact or castrated LAPC-4 xenograft model. In contrast to the findings when omega-6 fats are used, these results raise the possibility that fat type may be as important as fat amount or perhaps even more important.
There's a large body of evidence implicating excess omega-6 fat in a number of cancer models. Reducing omega-6 to below 4% of calories has a dramatic effect on cancer incidence and progression*. In fact, there have even been several experiments showing that butter and other animal fats promote cancer growth to a lesser degree than margarine and omega-6-rich seed oils. I discussed that here.

* The average American eats 7-8% omega-6 by calories. This means it will be difficult to see a relationship between omega-6 intake and cancer (or heart disease, or most things) in observational studies in the US or other industrial nations, because we virtually all eat more than 4% of calories as omega-6. Until the 20th century, omega-6 intake was below 4%, and usually closer to 2%, in some traditional societies. That's where it remains in contemporary traditional societies unaffected by industrial food habits, such as Kitava.


Greta from said...

I am going to go check the data I have at fitday and see what my 3-6-9 breakdown has been over the last year (at least for the days I entered my food). This is quite interesting.

Ok. Fat is 35% of my calories. Saturated is 11% of total calories. Poly is 5%. Mono is 13%.

Should I tweak anything?

Daniel said...

And in your (and mine) favorite study, the Lyon Diet Heart study, they got 12 cancers in the control group vs. 2 in in the low-omega 6 group. Note that the study was a bit underpowered to detect cancers.

Inflammatory eicosanoids is one theory and the authors mention it. They also mention that the low omega 6 group had higher serum vitamin E (despite consuming less vitamin E) and seemed to postulate that such low vit E serum level might have had an anti-cancer effect. They note that PUFAs are the main substate for vit E (so it makes sense for the low PUFA group to have higher serum vit E levels).

Unknown said...

Lard is the animal fat richest in Omega-6. 10% of lard calories are O-6 so a very high-fat diet consisting mostly of lard could put you over the 4% of total calories mark I imagine. I'd be interested in seeing a mouse study that looked at that (not that I expect there to be one).

The reason I ask is because I want to know if unprocessed Omega-6 is as dangerous as the highly processed corn oils. Perhaps unadulterated O-6 isn't as bad? I'd just like to know.

Unknown said...

Hi Stephan -

Another great post. Just wondered if you consume eggs and chicken on a regular basis given that the majority of the feed here in the USA is either corn or soy (whether organic or not). Wouldn't this type of feed result in high omega-6 levels in the chicken and thus promote inflammation in one consuming either the chicken eggs or meat? Can I assume that flax seed would be the ideal feed for chickens given its higher omega-3 content? Thanks.


Unknown said...

Even Joel Salatin feeds his pigs corn. What pigs eat matters a lot in how much omega 6 their fat contains.

This 1971 study shows differing omega 6 concentrations depending on diet.

Feeding pigs sugar and soybean meal resulted in 3% omega 6. Feeding pigs corn and soybean meal resulted in 16% omega 6. Feeding pigs corn, soybean meal and soybean oil resulted in 37% omega 6. The highest was feeding pigs molasses and soybean oil which got up to 47% omega 6.

Soybean meal contains about 1% oil, so a diet low in fat means the pigs won't store omega 6. Instead they make the carbohydrates into saturated fat. But if the pigs get to eat omega 6, they store it.

Julot said...

Hi Stefan,

Thank you for another great post. But concluding from the nocivity of corn oil to taht of omega-6 looks problematic to me. In the case of corn oil, just like in most industrial vegetable oils, there are many other suspects than omega 6 -- from trans to rancidity to chemicals used for extraction and growing. There seems to be an underlying hypothesis that the thing that matters most is the composition of the fat in terms of saturated, mono-insaturated, o6 and o3, but it would be just an hypothesis after all, just like the underlying hypothesis that long prevailed in nutrition that the macro-composition of the diet (carbs, proteins and lipids) is the only factor we'd focus on.

I guess my question then is: do we have any data comparing good quality PUFA (organic, fresh, cold press, etc...) with industrial quality PUFAs, in particular omega-6? After all, the conclusions you and others come to, that saturated fats are basically healthier than omega-6s, could very well be explained simply by how fragile the omega-6 are. The o6 we eat are much more likely to be adulterated in some way than the saturated fats are. I guess my question is pretty muck the same as Cusick's here.

One anecdoctical fact I have in mind here is the benefice many people report from switching to high quality oils in their diets. I for one suspect that this is the major factor in the good results of, say, Kousmine.

Robert Andrew Brown said...
This comment has been removed by the author.
Robert Andrew Brown said...

Cuisik and Julot

Yes oxidised fats in food end up in the body, and add to the effects of Omega 6.

But the primary problem is the excess of Omega 6 and lack of Omega 3s.

This thread, which is largely mine, contains a significant number of trial summaries, which taken in the round provide strong evidence that Omega 6 in its unadulterated form significantly adds to the risk of breast and other cancers.

v/vmary said...

i have some info for you that is off topic, but i wasn't sure you would see it in the other posts about teeth.

my husband was born in 1963 in taiwan during a time when the people there still ate a traditional diet (except for the brain-washing of the population to believe bottle-feeding was better than breast-feeding). he, his three brothers, and half-sister all have beautiful teeth. this is the thing: they were all bottle-fed and the sister sucked on a pacifer until she was 5 years old. BUT, their family ate lots of fish, pork fat mixed into rice, organ meats, sweet potatoes and rice, bone broths etc. unfortunately i ate this way only partially while pregnant (i was living in taiwan at the time in the 90s). i have two daughers- one who i breast fed for 2 weeks and then switched to formula, and the other i almost exclusively breast fed for 10 months. both daughters required palate expanders. that was enough for the first daughter, and she didn't need braces. the second on did.

so- based on my husband's and my experience, i feel that the use of pacifiers isn't important. my older daughter's teeth are better, and that may be because i ate a more traditional chinese diet when i was pregnant with her. with the second child, i moved back to the US at 4 months of pregnancy and ate the SAD diet. so if the mom has a bad diet, breast feeding doesn't make a difference. since all the siblings in my husband's family got bottle-fed, maternal nutrition while pregnant, and eating well as children seem to be the most important factors.

Nigel Kinbrum said...

I got a copy of "Incidence of cancer in men on a diet high in polyunsaturated fat - The Lancet March 6 1971.pdf" off Eddie Vos. I don't know whether you've linked to it anywhere in your blog. If not, click HERE.

Unknown said...

I recently emailed Walter Willet about his views on omega-6, as his research leads him to believe there is an INVERSE relationship between nut consumption and disease. Lotta 6 in those nuts. Here's what he emailed back to me.

"The anti omega-6 people are the nuts. There is a huge body of evidence of benefits for these fatty might find my book, Eat, Drink, and Be Healthy useful on this point,


So I gotta wonder if there are substances in whole foods like nuts that would offset their high omega-6 content? And if comparing an industrially refined oil like corn oil, that's been stripped away and fractionated from the whole food is a fair comparison?

Matt Stone said...

That is the question Deb. I would kill to see the results of corn oil vs. whole Brazil nuts in a trial - Brazil nuts having the greatest omega 6 to omega 3 ratio of any food.... 1,144 to 1

I wanna know how much can be contributed to omega 6 consumption, and how much is due to free radical poisoning in the development of PUFA-associated diseases.

Mark said...

Matt, I think you're thinking the same thing as I. Is it just any excess omega-6 or is it ok/necessary to get some from unadultered/organic/cold-pressed seeds? Robert, have you had work in this? If you are wondering, my questions drive from the work done by Brain Peskin.

Chris Kresser said...

I've wondered why Salatin feeds his chickens and pigs corn. That's some pretty scary data Kaw presented re: n-6 content in soy/corn-fed pigs. I imagine it's similar for chickens and eggs.

We get our meat from a local farm that doesn't feed any grain at all. We get our eggs from chickens we have in the backyard. There isn't enough pasture, worms, etc. for them to meet their dietary requirements so we do give them a feed. Unfortunately it has both soy and corn. I've been trying (in vain) to find a feed that doesn't have soy or corn. We've considered mixing up our own feed, but it's prohibitively expensive - it would be cheaper to buy pasture-raised eggs from the farmer's market.

Anonymous said...

@ Stephan

They should be required to use the term "animal fat" or maybe "sat/mono" fat or "non - PUFA". As you point out, apart from coconut we always get sat and mono in roughly similar amounts.


That is why I cook with ghee, butter or coconut rather than lard. It's not the processing- 100% natural virgin linoleic acid is just fine as a poison.


Your argument reminds me of the one that sugar addicts make for natural, raw honey. You might be right, but I think "cold pressed" LA is still poisonous in SAD amounts. I do think that when one eats lard or pork, the 10% or whatever PUFA content is mitigated simply by all the good SF and neutral or good Monounsaturates. But if you got half your fat as lard, and the other half as butter and ate 60% of calories as fat, your PUFA as kcal fraction would be close to 4% but not lower. That is why I eat grass fed ruminants and grass fed butter. Total PUFAs under 3% and minimal need for n-3 supplements.

Julot said...

No offense, but while I see how these trials demonstrate that corn oil etc are bad in excess, I don't see any comparative study of industrial vs quality oils, so I remain doubtful and maintain my initial point.

I see your point about sugar vs honey, Kurt, but I think it's pretty different -- in one case, we know that the physiological processes are the same for honey and sugar. In the other, we have serious reasons to believe that there are big differences between intact LA and adulterated o6. And I'm not only talking about oxydation, which is an obvious culprit, but also about other adulterations of those very fragile substances. When we're talking about sugar or honey, we're mostly not, as far as I know, talking about components of cell membranes. So I think this is pretty different.

While I recognise the trials, whose conclusions is clearly that industrial vegetable oils are bad, I am also troubled by the lack of a proposed mechanism as to why those o6 would be so bad. The only one I'm aware of is precisely oxydation, so it makes sense to differentiate between PUFA qualities, which once again I don't see happening anywhere.

And once again, there are anecdotical evidence that high quality oils make a significance difference in degenerative diseases.

Steve said...

The effect of the saturated fat diet (which I understand is an Isocaloric diet and hence not high fat by my standard) still neglects the effect of saturated fats on hormones! I mean how can you compare the effect of two diets when the model is castrated. Saturated fats , especially in a high fat diet, will have significant impacts on testosterone, IGF-1, IGFBP3, SHBG, ... You all know that. Making that conclusion from this model and extending it to humans is not necessarily a just argument.

Anna said...

I'll look over my Joel Salatin books to refresh my memory, but the corn I remember his pigs eating was a small amount of whole kernals scattered within the composting wood shavings (used as bedding in the cow barn during the winter). The corn ferments ("corn mash" or Jack Daniels for pigs). Unless he also feeds corn to the pigs in quantity in another way of which I am unaware, the corn is merely a pittance of a "bribe" to get the pigs to turn the compost for him (encouraging them to express their "pigness", as he describes it), similar to the way wild hogs root through forest litter looking for acorns.

Did I miss something about the pig feed?

Anna said...

I just recently heard that some local people (North San Diego area) who keep chickens make a co-op purchase (to keep the cost lower) of chicken feed that comes from Tennessee - it doesn't contain corn or soy. Apparently it has peas, alfalfa and other content. I can try to get more info, if the chicken keepers who read WHS are interested.

One of the local feed stores apparently stocked this feed for a time, but stopped because it was so "unusually" attractive to bugs and rodents compared to the conventional chicken feed (the feed stores I checked stocked Purina only). Hmmm, what does that tell you?

Chris Kresser said...

Hi Anna,

Thanks for your reply. I actually found that feed online a while back.

Unfortunately it still has corn in it. I wonder what the omega-6 implications of that are (without soy, but still with corn).

I'm still trying to find a local supplier that will carry it. It's far too costly to ship it - the shipping is actually more expensive than the product!

Chris Kresser said...

Oops! I just noticed you said a feed that doesn't contain corn and soy, and comes from Tennessee. This one comes from North Virginia and has corn. Yes, please do send me the information about their feed if you can.

Please send me a message through my blog here.


Chris Kresser said...

That is the question Deb. I would kill to see the results of corn oil vs. whole Brazil nuts in a trial - Brazil nuts having the greatest omega 6 to omega 3 ratio of any food.... 1,144 to 1

Brazil nuts are the #1 dietary source of selenium, with 544 mcg per ounce. Selenium is incorporated into proteins to make selenoproteins, which are antioxidants.

I find it very interesting that a food so high in omega-6 is also extremely high in antioxidants. Coincidence? Probably not.

This is one of many reasons why I always recommend getting nutrients from whole foods.

Stephan Guyenet said...

Hi Daniel,

I thought that was pretty remarkable as well.


Actually chicken and turkey fat have much more omega-6 than lard. If you buy leaf lard and render it yourself, it's only 6% omega-6.

Hi Jeff,

I have a pastured egg every morning. The total amount of omega-6 in an egg or a piece of chicken isn't that much.

Hi Julot,

It's not just corn oil. Any oil that's rich in omega-6 increases cancer in rodent models. I will say that the oils that are used in these experiments are industrially processed oils. But keep in mind that there's no such thing as corn oil or soybean oil that aren't industrially processed. You can't get the fat out without machines and solvents.

There are some experiments that have compared refined vs. unrefined oils on various diseases. The result depends on the oil and the disease. Unrefined peanut oil causes atherosclerosis more than refined peanut oil. Unrefined coconut and red palm oil are protective against atherosclerosis. I haven't seen any studies on cancer specifically.

I'm not convinced of the idea that oxidation in refined oils is the relevant factor. Oxidation in oils used for deep frying, I could believe, but I'm not convinced there's enough oxidized fat in a bottle of store-bought corn oil to make a difference. Even extra-virgin olive oil is partially oxidized when you buy it.

I'm somewhat familiar with Kousmine. It's hard to say that people feel better because of the oils she recommends though-- she suggest many other diet changes that should improve nutritional status.

Stephan Guyenet said...

Hi Julot,

There are very straightforward mechanisms to explain the negative effect of excessive omega-6 on health. I've written about it quite a bit on this blog if you want to take a look through the archives. It centers around their effect on eicosanoids, although there are a number of other proposed mechanisms that also probably contribute (susceptibility to oxidation, direct actions on PPARs, etc).

Hi Steve,

Excess omega-6, compared to animal fats, promotes cancer in a number of models regardless of whether or not they're castrated.

Hi Anna,

I've been to Polyface, and the pigs eat mostly feed. It's probably mostly corn and soybeans just like other pig feeds.

Unknown said...

Well Stephan, you certainly put Willett's take on nuts into perspective.

Interestingly, he's also kinda anti-milk, because he thinks it increases risk of certain cancers. I would've assumed it was due to milk raising IGF, if that's the case...but his theory is that excess calcium sort of "deactivates" vitamin D, and that's how he thinks milk may increase cancer risk.

Chris Kresser said...

I think roasted nuts are probably OK in reasonable quantities, but it's probably best to de-emphasize the ones that are high in omega-6.


Are you recommending roasted over raw, soaked? I doubt it but just curious why you said roasted.

I still wonder about brazil nuts. I have patients with thyroid issues, and selenium has been shown to increase conversion of T4 to T3. Sure, they could take a selenium supplement but in almost every case I prefer whole foods as nutrient sources.

But one ounce of brazil nuts has 5.8 grams of n-6 PUFA. That's quite a high amount. Maybe a supplement is better in this case.

Chris Kresser said...

I have a pastured egg every morning. The total amount of omega-6 in an egg or a piece of chicken isn't that much.

I guess that's good to keep in mind for people that, for whatever reason, don't have access to pastured eggs.

According to, a medium raw egg has 4.4g total fat, with 1.4 saturated, 1.4 mono and 0.6 pufa. Of the PUFA, the vast majority is n-6 (505 mg vs. 36 mg of n-3). 0.5g of n-6 is not a huge amount.

On the other hand, I've seen studies suggesting that commercial eggs have 19x more n-6 than free-range eggs. If true, that means the n-6:n-3 ratio must be almost completely reversed, i.e. 500 mg of n-3 and 35 mg of n-6). So pastured eggs are obviously a better choice, especially if someone eats a lot of eggs.

Robert Andrew Brown said...


Mark maybe you are wondering about plant based v long chain Omega 3 and 6 fats, and our ability to convert the plant based fats to the long chain fats.

The ability to convert can be blocked by a host of factors, including some mineral and vitamin deficiencies, some medical conditions, excess Omega 6, and there is increasing evidence that some population groups with a shoreline origin like the Innuit, and Celts may have genetic variations that makes them poor converters.

Women convert much better than men.

Many medical and neurological conditions are associated with fats imbalance that relate to conversion imbalances.

I have difficulty with the premise that everybody has the ability to convert the plants fats to the long chain fats in the amounts required.

Some trials in young and old men show the rate of conversion of Omega 3 linolenic to DHA was in the groups selected a fraction of 1%.

Trials in pregnant women also show conversion can be poor.

DHA and EPA are essential to health, and trials suggest that for a least some people the only way to get a sufficient intake is to include DHA and EPA in the diet.

Many factors in western diet conspire to disrupt the fat conversion pathways.

Stephan Guyenet said...

Hi Switters,

I know for a fact that roasting nuts reduces anti-nutrients including phytic acid and makes them more digestible. I haven't seen any data on soaking and dehydrating nuts so I can't comment on it. I would expect it to make them more digestible, and my anecdotal subjective evidence is that it does make them feel more digestible. Some traditional groups soaked nuts, but I think most just roasted them before eating unless they were very high in tannins such as acorns.

I'd be very surprised if pastured eggs had 19X less omega-6 than commercial eggs. Especially considering most of their food is still corn and soybeans.

Anonymous said...

The relationship between corn oil and cancer brings to mind an interesting article in which it was hypothesized that the prime cause of cancer is chronic cellular hypoxia which results from adulterated and improper ratios of polyunsaturated acids when incorporated into cell membranes.

Quoting from the abstract:

--"no single unifying cause of cancer has been established. Although it is well known that tumors are hypoxic, and that there is a correlation between the level of hypoxia and prognosis, with the exception of Warburg's studies, little work has been done to investigate the relationship between hypoxia and cancer. Over 70 years ago, Warburg showed that cells could always be made cancerous by subjecting them to periods of hypoxia. Moreover, he demonstrated that once cells had converted to a cancerous state, reversion could not occur.----It is our hypothesis that long term hypoxia of cells in the body--is the primary cause for cancer. We believe that hypoxia, which has to meet Warburg's findings of a critical 35% reduction in intracellular oxygen levels to initiate cancer, is linked to the incorporation of adulterated, non-oxygenating, or inappropriate polyunsaturated fatty acids PUFAs) into the mitochondrial membranes. Such incorporation causes changes in membrane properties that impair oxygen transmission into the cell. Trans fats, partially oxidized PUFA entities, and inappropriate omega-6:omega-3 ratios are all potential sources of unsaturated fatty acids that can disrupt the normal membrane structure."

Refined vegetable oils such as corn oil that are high in linoleic acid seem to fit the description of cancer causing fatty acids perfectly as they often have significant levels of trans fats in them, they are readily oxidized,
and, of course, they effect the omega-6:omega-3 ratio of mitochondrial membranes. The hypothesis makes sense to me.

Robert Andrew Brown said...


You said

"On the other hand, I've seen studies suggesting that commercial eggs have 19x more n-6 than free-range eggs. If true, that means the n-6:n-3 ratio must be almost completely reversed, i.e. 500 mg of n-3 and 35 mg of n-6). So pastured eggs are obviously a better choice, especially if someone eats a lot of eggs."

I suspect this is not what you meant. High n6 would not reverse the Omega 3 6 balance - that would need high n3 and low n6.

Commercial eggs are generally high in Omega 6 but feeding with flax can improve ratios.

Anonymous said...

The link to the preceding post on chronic cellular hypoxia and the prime cause of cancer is:

Stephan Guyenet said...

Hi J,

Sorry I keep forgetting to respond. Yes, chicken feed does shift the balance toward omega-6 in the eggs and meat, including increasing long-chain omega-6 like arachidonic acid.

Flax is a good supplement for chicken feed, but it shouldn't be the only source of fat. Chickens need a balance of omega-6:3 just like we do.

Chris Kresser said...

Completely range-fed chickens that don't eat corn or soy at all should have eggs low in n-6 and high in n-3. They'd be eating mostly greens and grubs, worms, insects, etc.

I did manage to find a soy/corn-free feed online, which also has flax. If I had the equipment I'd do a test of the n-3/n-6 content of my chickens now on the soy/corn feed and after a few months on the soy/corn-free feed. Would be interesting to find out.

Here's the link to the study I was thinking of. The authors say that the n-6:n-3 ratio for pasture-raised Greek eggs was 1.3 whereas it was 19.9 in US supermarket eggs.

That's almost 19 times more n:6 in a supermarket egg than a pastured egg.

Stephan Guyenet said...

Jack and Mark,

I'm familiar with Peskin. I just read his paper in Medical Hypotheses. It's time for me to put this thing to rest. He states that the fact that tumors have low oxygen supports his claim that low oxygen is behind cancer. Tumors have low oxygen because blood vessel growth doesn't keep up with tumor growth. That happens after the tumor has already developed, not beforehand.

His basic hypothesis is that polyunsaturated fats in the membrane determine the cell's permeability to oxygen. He implies that PUFA transport oxygen across the cell membrane. The problem is that oxygen doesn't require PUFA or any other fatty acid to get across the membrane. Molecular oxygen is a non-charged small molecule that diffuses across the membrane freely. His claim that PUFAs influence its transport across the membrane has no support I'm aware of. I followed his reference for that statement, which was this study:

And it didn't support his claims. As far as I can tell, the study has nothing to do with oxygen transport across the cell membrane. It's about fatty acid composition and lipid peroxidation in cancer cell lines. Grossly misquoting papers that are supposed to support your central argument is a characteristic of science abusers. A nice way to put it is that Peskin has a vivid imagination.

Hi Switters,

The Greek eggs had 38% less omega-6. Check out table 1. What was very different was the ratio, but that was mostly due to the omega-3 content.

Stephan Guyenet said...

Here's a reference showing that oxygen diffuses across the cell membrane quite readily (half as fast as through pure water, which is very fast):

From the abstract:

"It is concluded that oxygen permeation across the cell plasma membrane cannot be a rate-limiting step for cellular respiration."

Jeffrey of Troy said...

The healthy sources of fat for humans are : animal fat, nut fat, & fruit fat. All other sources of fat must be strictly minimized (eliminated if possible).

The public should not be taught to think in terms of "saturated" or "monounsaturated" or "polyunsaturated"; it has only increased confusion.

sandra said...

Am I reading the chart from the
n6 vs n3 egg study incorrectly, or do the fish meal eggs have a huge amount of n6 compared to the others? I know the n6:n3 ratio is OK, but still.

I just got my first pastured egg from my backyard chickens yesterday, but I'll still need to supplement some with store bought... if I ate just one egg per day like you Stefan, I wouldn't worry. But should big egg eaters avoid the fish meal eggs because of large amounts of n6 in spite of the ratio? Or am I way off track?

Chris Kresser said...

It looks to me like you're reading that correctly, Sandra. I don't have an explanation, though. My understanding is that fish meal is simply the bones, offal and whole fish ground together. I can't see how fish meal fed chickens would have twice the amount of n-6 than supermarket chickens. ??

I'd like to figure this out because the corn/soy-free feed I found today for our backyard chickens has fish meal as a source of protein. That's the issue when you remove soy - how to replace the protein.

Bevan said...

I had no idea that corn oil could have so many benefits. Your blog has been very helpful for me in understanding about whole food supplements. This will also help a lot of other people who are looking for advice.

Anna said...


I'll try to find out that TN source of chicken feed for you.

But I just had a wild thought - perhaps way off base - what about raising your own protein for the girls? Grubs, crickets, worms, etc? Lots of reptile keepers breed crickets. I'm also thinking about vermiculture - I have two very efficient and super easy to use Worm Factory composting boxes that produce gobs of worms - I'll bet laying hens would find worms very tasty. I wonder if the protein quality and content would be desirable.

Robert Andrew Brown said...


The egg composition would depend on the overall food of the chicken and it is likely the balance of their food was high in Omega 6. The producers were probably worrying about Omega 3 and not Omega 6.

Jeffrey of Troy

Large quantities of Omega 6 are only found in plant reproductive material, and to a lesser extent in animal fat. Omega 6 levels in wild animals fluctuate seasonally in line with plant reproductive materials which include grass seed both fully formed and in formation.

Pre the invention of agriculture access to plant reproductive material and high Omega 6 animal fat would have been seasonal subject to limited storage ability.

Heather Lackey said...

Anna - That's what I was thinking when I read switters' last comment, that original chickens (OC ;)) didn't get their protein from soy or fish meal, so why not feed them what they did get it from? Looks like it's definitely doable: Attract and feed flies to your chickens

Unknown said...

You mean that Peskin guy has duped me? His YouTube video on the evils of fish oil supplements caused me to throw mine in the trash. )<:

Here it is in two parts, for anyone who'd like to attempt a good debunking of his claims - since he's having quite an impact on a lot of folks.

What's Wrong with Fish Oil: Part1

What's Wrong With Fish Oil: Part2

Unknown said...

One quick reading of Peskin's webpage was enough to convince me that he's a nut job. And those videos don't help. I don't even listen to the arguments - just him. He's doesn't have a stable worldview, and therefore his beliefs are instantly in question. He has the same chance of being correct as a broken pocket watch.

I have sort of an off-topic question: Does anyone know a web resource that can give me portion sizes of various foods given a desired amount of protein? For instance, if I tell it "28 g of protein" it will say "124 g of sirloin" or "80 g of salmon".

Lots of web resources will tell you the reverse (e.g., how much protein is in X lbs of beef), but I'm trying to get it other way around.

Robert Andrew Brown said...

Hi Deb,

I have just watched these videos and am feeling slightly shell shocked.

I was horrified by the suggestion/ implication that the supplementation of formula feed with Omega 3 EPA and DHA is harmful. Breast milk of women on non western diets contains about 1/2% - 1% DHA. DHA is essential to the development of the brain nervous system and eyesight. It is the special functional properties of DHA that allowed the development of nervous systems, and there is no substitute for it. Levels of Omega 3 DHA in western women are often frighteningly low, and hence the argument for supplementation.

PLEASE SEE NEXT POST for this section which links to a paper called "Health Benefits of docosahexaenoic acid (DHA)" which was too large to include here.

He says Omega 3 does not affect CRP. Type CRP and DHA into pubmed
and read the results.

For example

Fish oil supplementation lowers C-reactive protein levels independent of triglyceride reduction in patients with end-stage renal disease.

Put DHA and cardiovascular disease into pubmed.

Here is a sample

Effects of dietary fish oil and trans fat on rat aorta histopathology and cardiovascular risk markers.

There is a vast amount of evidence that Omega 3 is essential to human health that he fails to even acknowledge. Omega 3s are essential to neural function.

The American National Institute of Health the former Surgeon General, and some of the most respected researchers in the field in the world would strongly differ with Professor Peskin.

Robert Andrew Brown said...


There is a mass of evidence on the importance of Omega 3 to health.



"Docosahexaenoic acid (DHA) is essential for the growth and functional development of the brain in infants. DHA is also required for maintenance of normal brain function in adults. The inclusion of plentiful DHA in the diet improves learning ability, whereas deficiencies of DHA are associated with deficits in learning. DHA is taken up by the brain in preference to other fatty acids. The turnover of DHA in the brain is very fast, more so than is generally realized. The visual acuity of healthy, full-term, formula-fed infants is increased when their formula includes DHA. During the last 50 years, many infants have been fed formula diets lacking DHA and other omega-3 fatty acids. DHA deficiencies are associated with foetal alcohol syndrome, attention deficit hyperactivity disorder, cystic fibrosis, phenylketonuria, unipolar depression, aggressive hostility, and adrenoleukodystrophy. Decreases in DHA in the brain are associated with cognitive decline during aging and with onset of sporadic Alzheimer disease. The leading cause of death in western nations is cardiovascular disease. Epidemiological studies have shown a strong correlation between fish consumption and reduction in sudden death from myocardial infarction. The reduction is approximately 50% with 200 mg day−1of DHA from fish. DHA is the active component in fish. Not only does fish oil reduce triglycerides in the blood and decrease thrombosis, but it also prevents cardiac arrhythmias. The association of DHA deficiency with depression is the reason for the robust positive correlation between depression and myocardial infarction. Patients with cardiovascular disease or Type II diabetes are often advised to adopt a low-fat diet with a high proportion of carbohydrate. A study with women shows that this type of diet increases plasma triglycerides and the severity of Type II diabetes and coronary heart disease. DHA is present in fatty fish (salmon, tuna, mackerel) and mother's milk. DHA is present at low levels in meat and eggs, but is not usually present in infant formulas. EPA, another long-chain n-3 fatty acid, is also present in fatty fish. The shorter chain n-3 fatty acid, α-linolenic acid, is not converted very well to DHA in man. These longchain n-3 fatty acids (also known as omega-3 fatty acids) are now becoming available in some foods, especially infant formula and eggs in Europe and Japan. Fish oil decreases the proliferation of tumour cells, whereas arachidonic acid, a longchain n-6 fatty acid, increases their proliferation. These opposite effects are also seen with inflammation, particularly with rheumatoid arthritis, and with asthma. DHA has a positive effect on diseases such as hypertension, arthritis, atherosclerosis, depression, adult-onset diabetes mellitus, myocardial infarction, thrombosis, and some cancers."

Chris Kresser said...


We do some vermiculture already, and you're right, the hens do love worms. However, with nine birds they'd require a lot of worms to meet their protein requirement. I'm also uncertain as to whether worms alone as a protein source would be sufficient.

I love the idea about catching flies for them! Maybe flies + worms would be enough for protein. It strikes me that one of the main reasons for getting backyard chickens is sustainable food production, and yet their feed is being shipped from who knows where. I'd much rather it come from our house (kitchen scraps, flies, worms, etc.) so I hope we can make this work.


Anna said...


The amounts you need might be prohibitive, but you might consider raising a variety of insects the way some other animal keepers do, though obviously on a much larger scale:

I'm sure there is a lot of info on the lizard forums. Right now I'm wishing I had a few chickens to help me sift through the tray of worm castings that need harvesting. A year or so ago I was preparing our fairly large suburban garden for a few chickens (new fences, etc.) when my HOA updated and revised the CCRs specifically prohibiting poultry. Bummer.

Robert Andrew Brown said...


Re my posts above in response to the Peskin videos.

This is a power-point from the Research and Development Associates from the US Army looking back at the conference called "Nutritional Armor
for the Warfighter" to which I gave the link above and repeat. It shows the military are taking the Omega 3:6 issue very seriously; and fish is on the menu (-:

Powerpoint link

Quotes from Surgeon General Carmona.

"Dr. Carmona noted that while the military uses cutting edge technology in every other realm, and U.S. Special Forces are very nutritionally savvy, with web sites devoted to the subject, the standard MRE (meals-ready-to-eat) field ration does not reflect the latest nutritional knowledge.

These were some of the comments by former Surgeon General Carmona:

“I thought I had all the answers until I talked to Joe Hibbeln … he showed me how he had been able to correlate low levels of omega-3s to depression suicide, and a whole bunch of other mental health problems.”
“Obviously this is not the magic bullet … but it is an extraordinarily important component of comprehensive soldier health, fitness, and wellness that needs to be incorporated as quickly as possible, and we cannot afford to wait another decade or two before this knowledge percolates through the [Pentagon bureaucracy] pipeline.”
“In the last quarter century and especially the last decade, there has been a very compelling accumulation of scientific evidence base for the consideration of the use of omega-3 fatty acids and possibly enhancing other foods with omega-3s.”
“The current uptake of omega-3s in military diets is probably subpar. Soldiers may be at increased risk from stress and physical or mental injury because of this dietary insufficiency. Our troops have need for this nutrition armor, for they are tactical athletes.”

Dr. Carmona went on to note that while omega-3s linked to better mood and reduced tendency toward violent or impulsive behavior, strong evidence indicates that omega-3s reduce the effects of traumatic brain injury and enhance surgical outcomes. As he said, “… the idea of IV [intravenous] omega-3s in the field at time of injury … certainly has merit.”"

Anonymous said...


Thank you for setting me straight on Peskin's hypoxia/cancer hypothesis which obviously is in the same category as the "lipid hypothesis" which has been described as "simple, easily understood, and wrong."

Regarding your response to Julot concerning information on the negative effects of excessive omega-6 on health, I noticed that an abundance of information on the subject has been published by Bernard Hennig of the University of Kentucky. A search on Pubmed for the words "linoleic" and Hennig B" yields 47 hits of studies published between 1985 and 2009. These publications may not cover every aspect of the adverse effects of linoleic acid on health, but there is enough information in that one place to convince most people that consumption of linoleic acid should be minimized.

Gary Wu said...

For your scientifically minded readers, Paleo for Life has set up a page that collects the research articles relevant to the Paleo diet in one place:

Paleo diet Research Articles

We would love to hear your thoughts on how we can make this page even more useful.

Julot said...

I'm familiar with Peskin too and I don't question that he looks very much like a nut job. I don't think it follows that he can't be right more often than a broken watch. If quoting papers that don't clearly support your view is characteristic of science abusers, like Stephan says, grossly mischaracterising what your opponents have to say, like Robert does with Peskin, is not particularly rigorous or fair. Peskin's point is not that there's not benefit to o3, since he's recommending them. His point is that overdosing on fish oil is every bit as bad as overdosing on o6, and this, at least, matches many people's experience. His point is also that the conversion rate is sufficient in human beings, and that DHA can't be converted back into LA. No one, not even Peskin, questions the problems of overdosing on o6. I for one don't recommend fish oil supplements and am very happy I got off them.

Julot said...

About Kousmine: the reason I'm putting forward the effects of oils among her nutritional recommendations because they seem to be the most effective. The other dietary recommendations from Kousmine are to use lots of nuts (so, more omega 6s); lots of whole grain, sometimes raw (and we have reasons to believe those are not major health factors beyond the extent to which they keep patients away from processed food and possibly help regulate appetite); very limited dairy and meat. That's about it for the Kousmine diet, which therefore is rich in high quality omega 6s, as well as in short chain omega 3 (since she recommends one teaspoon of flaxseed every morning in her breakfast mix).

Julot said...

About o6 mechanism: I did not find it in the archives. I found claims that o6, particularly AA, play a major role in inflammatory processes, but I still have no idea why they're supposed to be so inflammatory in and of themselves. In fact, it looks a bit like the cholesterol argument to me, blaming the bandage for the wound, or the fireman for the fire.

Robert Andrew Brown said...
This comment has been removed by the author.
Robert Andrew Brown said...


Have you watched the Peskin videos referred to? I am guessing from your comments you have not.

I have responded rigorously and fairly to the video. I am not anti Peskin, I just feel the strong anti fish oil message is unbalanced, in some instances inaccurate, and so misleading.

I would not brand Peskin as a nut. I do feel his comments on the EFAs fail to fairly represent the general consensus of current research by those who specialise in the subject and understand it best.

From my recollection the video does not have a good word to say about Omega 3.

It does not say too much fish oil is bad for you, it implies fish oil in any amount is bad for you, and implies fish is of no benefit which clearly flies in the face of the wider evidence.

He does not try and make an argument DHA converted from vegetable sources is good and DHA from fish oil is bad, which maybe from a quick look at some of his other material is what he meant to try and argue.(and I would argue in an untenable position as from the body's perspective DHA is DHA whether it was made in the body or eaten in the diet)

The video is not a balanced discussion as to whether fish oil in excess may have positive and negative health effects. The reaction of a viewer in throwing their fish oil in the bin highlights how the message in the video is interpreted by a general public who are not informed about the Omega 3 6 debate.

If it were I would have acknowledged there are issues, and explained why I believe that fish oil supplementation within sensible limits is for the vast majority beneficial.

If this video does not represent Professor Peskin's position, and it may not, I invite him to remake it so it does and provides a more balanced argument.

On your comment that humans can make the DHA they need, there is a mass of evidence that some human beings are very poor converters, as I have discussed above.

There is a mass of evidence that Omega 6 products are linked to inflammation. A whole segment of the drugs industry, including the design of many pain killers and anti-inflammatories is founded on blocking the Omega 6 downstream pathways.

Finally the Omega 3 and 6 families are entirely separate and humans and animals cannot inter-convert the two. Plants can make Omega 6 LA into Omega 3 ALA, humans can't. Omega 3 DHA cannot be made from Omega 6 LA or converted back to it.

I looked up Catherine Kousmine

Thank you for that reference.
Catherine was clearly a long way ahead of her time. Had Catherine been aware of the latest research on the poor ability of some to convert the plant based to long chain fats, I am sure Catherine would have modified her position to take account of this.

Dr Kousmine's concerns as to the impact of foods on the permeability of the intestinal membrane were well founded. Recent trials have shown a number of factors including a lack of vitamin D and oxidised Omega 6 fats increase the permeability of the intestinal membrane.

Chris Kresser said...

Dr Kousmine's concerns as to the impact of foods on the permeability of the intestinal membrane were well founded. Recent trials have shown a number of factors including a lack of vitamin D and oxidised Omega 6 fats increase the permeability of the intestinal membrane.


If you could point me to some of the studies suggesting that vitamin D deficiency and n-6 fats increase intestinal permeability, I'd appreciate it.

I've seen one recent study linking n-6 fats to IBD, but I'd love to see the papers you're referring to.

Unknown said...


You might want to read this post by Stephan:

He discusses a study in rats which shows directly that eicosanoids derived from omega-6 fatty acids cause insulin resistance, leptin resistance and fatty liver. Blocking an enzyme in the pathway that converts n-6 to eicosanoids keeps most of the damage from happening.

You might also want to read these posts:

In those posts Stephan discusses eicosanoids further. The amount of n6 in tissues is proportional to intake of n6, enzymes don't discriminate between n-6 and n-3 when making eicosanoids, therefore increased n-6 will lead to increased inflammatory eicosanoids, which play their role in insulin and leptin resistance.

Unknown said...

In think Tropical Traditions makes a chicken feed w/ coconut and no soy/corn called cocofeed

Chris Kresser said...

In think Tropical Traditions makes a chicken feed w/ coconut and no soy/corn called cocofeed

I see that on their website, but it looks like they don't sell it. If you click "purchase" on the Cocofeed page, it takes you to a screen where you can buy chickens they've raised on Cocofeed. I don't see any place to buy the feed itself. Do you know differently?

Anonymous said...

Julot, Robert,

Regarding the need for DHA and AA, a number of recent studies have found that DHA and AA are the only two polyunsaturated fatty acids that are "essential". Both are converted from ALA and La in only negligible amounts according to link below:

The question then becomes, how much DHA and AA is needed? Another study found that while it commonly thought that about 1% of energy intake should be omega-6 when provided by linoleic acid, less than half that amount of omega-6 may be needed when some AA is in diet. DHA needs also about 0.5% of energy intake.

Anonymous said...

Julot noted that arachidonic acid is often unfairly and unwisely demonized. AA is essential for muscle repair and growth and is vital for brain function. Humans convert only negligible amounts of LA to AA, so it is important to get preformed AA from animal fat. Eggs provide a fair amount of AA relative to their fat content.

A recent study found that fish oil alone can provide sufficient omega-6, as shown in the following link:

The study found omega-6 requirements (rats) to be 0.3 to .56% of energy intake when provided by fish oil.

Anonymous said...

Julot noted that arachidonic acid is often unfairly and unwisely demonized. AA is essential for muscle repair and growth and is vital for brain function. Humans convert only negligible amounts of LA to AA, so it is important to get preformed AA from animal fat. Eggs provide a fair amount of AA relative to their fat content.

A recent study found that fish oil alone can provide sufficient omega-6, as shown in the following link:

The study found omega-6 requirements (rats) to be 0.3 to .56% of energy intake when provided by fish oil.

Robert Andrew Brown said...

Hi Jack

Was your post done in a bit of a rush, it seemed less thorough than usual?

Essentiality - A huge topic and the source of much debate.

Generally Omega 6 LA and Omega ALA are the only two fats that are considered to be essential - BUT that is based on the premise people can convert the plant fats to the long chain fats. Some with medical conditions cannot eg Zellwegers, many as discussed below are poor converters.

The trial you cited said "We established a total omega-6 fatty acid requirement of between 0.30% and 0.56% of dietary energy," which fits in with the work of Lands and others, and is within the range of LA found in the natural diet.


- Women can convert better than men, up to 10% of ALA to DHA - But MANY have defective conversion for a host of reasons, dietary excess and deficiencies, medical condition, and there is emerging evidence that some are genetically poor converters.

- Men convert at best about 1% of ALA to DHA many convert very little, a fraction of 1%.

Re Fish oil providing adequate Omega 6 the trial you cited said "Fatty acid profiles for the 1% fish oil group displayed clear essential fatty acid deficiency, 5% fish oil appeared marginal, and 10% and soybean oil diets were found to prevent essential fatty acid deficiency."

Some whales and dolphins may actually seek out high Omega 6 marine foods to allow them to breed.

Both Omega 3 and 6 and their derivatives are essential to optimal health and body function.

It is incorrect to say "Humans convert only negligible amounts of LA to AA, so it is important to get preformed AA from animal fat."

Humans in general terms seem to convert Omega 6 better that they convert Omega 3s, and can make more than adequate AA from LA.

Stephan looked at Lands work on conversion in a previous post.

Excess Omega 6 is a problem and a multimillion dollar industry. The drugs in the NSAIDS work by blocking the downstream Omega 6 pathways


I will try and dig out those refs tomorrow.

Unknown said...


That appears to be the case now, but I know that in the past they did offer it for sale

Sadiqanaeem said...

An informative article ! I must appreciate.I also use corn oil and I 'll continue this use.

Jonathan Byron said...

@ Kurt and Julot:

Honey contains sugar, but the effects on the body of honey can be significantly different from the effects of a comparable dose of refined sugar. The research on honey suggests that we cannot always predict the effects of a human diet based simply on grams of sugar or other linear, reductionist assumptions. The question of whether preparation methods for oils contributes some of the negative effects is a valid one.

Natural honey and cardiovascular risk factors; effects on blood glucose, cholesterol, triacylglycerole, CRP, and body weight compared with sucrose:

Natural honey modulates physiological glycemic response compared to simulated honey and D-glucose:

Effects of basswood honey, honey-comparable glucose-fructose solution, and oral glucose tolerance test solution on serum insulin, glucose, and C-peptide concentrations in healthy subjects:

David said...

" I would certainly not take at face value the observational studies by Willett and colleagues that suggest that eating nuts regularly will cut your heart attack risk in half. Show me a controlled trial and I'll be on board."

I think you don't give Willet enough credit by dismissing his findings as observational. Even if his findings on nuts are due to a healthy user bias, given that they show that nut-eaters have half the mortality (in some of the studies) as non-nut-eaters, it certainly sugests nuts aren't very harmful. Also, he parses his observations of the effect of nuts on disease by different sub-groups, finding similar effects among vegans (who are ostensibly "healthy-conscious") and non-vegans, young and old, etc. etcl. and finds similar results across all subgroups. Obviously, a controlled trial would be nice, but we don't have many useful controlled trials when it comes to nutrition, and overall his evidence, supplemented by that of other observational trials from throughout the world, are pretty convincing of a benefit of nuts. In any cas, you should know that mouse studies aren't necessarily relevant to people, and thus are not necessarily more informative than observational studies.

Stephan Guyenet said...

Hi David,

I'm not dismissing Willett's findings on nuts, I just think they need independent confirmation from controlled studies before they turn into diet advice (which they already have).

If the association represents causation, it would suggest that simply snacking on nuts will cut your risk of heart attack in half. I find that very hard to believe, given the multi-factorial nature of CVD. I'm OK with nuts, I just think the claim that they're the cure for heart disease in is a little premature.

Willett and his team sliced and diced the HRT data every which way, and still got it backwards. So I can't take the nut thing at face value, even though it looks pretty solid for an observational result.

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Robert Andrew Brown said...


Here is a link to a study on vitamin D and gut integrity.

"Novel role of the vitamin D receptor in maintaining the integrity of the intestinal mucosal barrier"

Don Matesz said...

I caution against concluding that omega-6 is carcinogenic. Cancer cells like normal cells require linoleic acid for growth. Butter or lard would supply less linoleic acid per calorie than corn oil, so they would set limits on rate of cancer growth compared to corn oil which is something like 70% linoleic acid.

Also, a diet rich in n-6 might appear harmful in an environment with abundant carcinogens (modern civilization) but less harmful in an environment where people have less exposure to carcinogens (e.g. the Khalahari, mongongo nuts).

I also tend to question reductionistic approaches which equate foods with nutrients. Nuts e.g. are very different as foods from corn oil, corn oil is also very different from corn. The nuts contain many factors (VT-E, minerals, phenols, etc.) which could negate the effects of isolated linoleic acid rich oil. For a H-G example, the mongongo nuts eaten by !Kung have a high n-6 content, but also very high VT-E (565 mg/100g), unlike corn oil.

Stephan Guyenet said...

Hi Don,

I agree that nuts are more than just bags of linoleic acid. I think they can be a part of a healthy diet.

As far as the !Kung however... they do eat a ton of LA-rich mongongo nuts, but they're also possibly the least healthy HG tribe I know of. Body composition is often poor (undermuscled) and I believe they have a measurable incidence of heart attack.

Anonymous said...

@jonathan Byron

I don't find any of those studies convincing in the same way that studies showing that fructose raises your sBG and insulin less after a meal does not convince me that fructose is healthier than glucose.

"The research on honey suggests that we cannot always predict the effects of a human diet based simply on grams of sugar or other linear, reductionist assumptions."

Would you agree that alcohol consumed in the form of both beer and wine at large intakes will both put you at risk of cirrhosis - this is the same kind of "linear, reductionist assumption" and it makes perfect sense. No one would deny that the form of delivery can modulate the effects of either fructose or alcohol short term, or even mitigate some of the damage long term - but the point is how big is that effect in comparison to the long term effects on your liver. Basic knowledge of biochemistry makes it unlikely that say, 75 g /day of fructose from any source is good for you over the long term -unless you think there is some kind of magic going on.

"The question of whether preparation methods for oils contributes some of the negative effects is a valid one."

It may be of interest, but as Stephan has pointed out:
1) we already have plenty of evidence that excess n-6 is harmful and outside our evolutionary experience and
2) There is really no such thing as getting large amounts of n-6 without these preaparation methods - so the question of whether they would be harmless without them is in that sense meaningless

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Gentle Dental said...

Thank you for another great post. Its really interesting to know about benefits of corn oil.

MangoManDan said...

Omega-6 lipids seem to be so much more common in animal and vegetable foods than omega-3 lipids.
Has anyone come across any reading that would help me with a common-sense approach to achieving a healthful balance between the two?

David said...

According to this source, among the !Kung, researchers found that blood pressure did not rise with age, and did not find any hypertension or coronary heart disease at any age (p.83):

Don Matesz said...


It seems that David's link disputes any claim that !Kung have a measurable rate of CHD.

It does mention cataracts as a common problem among the !Kung, but I would find it difficult to sort out the effect of diet from the effect of spending one's entire life exposed to the blinding sunlight of the desert (which would stress the lense).

IN the same book (p.82), the author reports that Howell entered a !Kung camp one day to find 4 females playing jump rope. Their ages were 8, 11. 15, and 66. The older woman "was at least as active and enthusiastic as the children." This casts doubt on the "undermuscled" comment also.

What exactly is your definition of "undermuscled"? If you mean they don't look like modern athletes or the people on the covers of Men's Health or Oxygen I would agree.

However I would call a person "undermuscled" only if s/he did not have enough functional musculature to carry out required activities and play. Since !Kung not only succeed at hunting and gathering but also engage in vigorous play even at advanced ages I’d say they have plenty of muscle.

Further, degree of muscularity is primarily determined by intensity of activity and exertion against resistance, only secondarily by protein content of diet. So if !Kung have less muscle than, say Plains bison hunters, it would be primarily because they engage in less high intensity activity, not because they eat mongongos.

For example, !Kung hunt primarily medium size game like wildebeest and Kuru. Lifting these does not require as much muscle as team lifting small herds of 1500-2000 lb. bison out of ravines the way Plains Indians did. If Plains Indians had more muscle it was because they lifted heavier things, not because they ate more bison and less nuts.

As for protein, it may be that contemporary !Kung have a less than optimum intake of animal protein, but that is not the fault of eating mongongos. That is a result of being confined to the Khalahari.

Which also means the contemporary !Kung diet is NOT the ideal. It probably has too little n-3, iodide, and other nutrients best provided by marine and lacustrine ecosystems exploited by prehistoric ancestors. I use them as a model, but keep in mind modern research and their diplacement from optimum ecosystem.

Robert Andrew Brown said...

Re !Kung

My impression was that the intake of mongongos was seasonal and the nuts only were a staple in famine.

Has any body seen anything on the amount of these nuts that were eaten year round, year on year.

I looked and did not find much that definitively answered this question.

What ever their state of musculature, from the photos the !Kung are very lean.

Stephan Guyenet said...

Hi Don etc,

I thought I had read a while back that actual ischemic heart attacks have been recorded among !Kung, but I haven't been able to find the reference. So maybe it was internet BS or my imagination.

Check out the picture of the !Kung man in this paper to see what I mean by undermuscled (check out his thighs and calves):

Unknown said...

Hi Stephan,

I don't find it surprising that you would find cardio vascular diseases among the !Kung; since it is highly implicated, if not proved, that it is also caused by chronic infectious diseases.

Two very recent papers.
Elkind, M. S. V. et al. Infectious burden and
risk of stroke: The Northern Manhattan Study. Arch. Neurol.
67, 33–38 (2010)

Elkind, M. S. V. et al. Infectious burden and carotid plaque thickness: The Northern Manhattan Study.
Stroke doi.10.1161/STROKEAHA.109.571299

Stephan Guyenet said...

I was looking through my copy of the book "The !Kung San" and I take back what I said about them being undermuscled. They weren't muscular, but their body comp looked fine to me. The picture of the guy in the paper I linked to must have been an exception.

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Joe said...

Can you please explain what an omega fat is? Also what's the difference between omega-3 and omega 6 fats? Is there such thing as omegas 1,2,4,5 and 7?

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