A study appeared in this month’s American Journal of Clinical Nutrition that I’m sure vegetarians of every stripe will hate to see.
Researchers compared the long-chain omega-3 levels (LCPUFA) of 463 vegetarians to that of 196 meat eaters and found that the vegetarians had substantially lower levels of these important fatty acids. The interesting part of this studyâ€”to me, at leastâ€”is that it didn’t matter how long people had been vegetarians, one year or twenty years, they still had lowered LCPUFA levels. Typically, with long term exposure to either a deficit or an abundance of a particular nutrient, the body adapts over time. Not so with these long chain omega-3 fats, apparently. The researchers report that although the levels of these fats are lower in vegetarians, they are stable.
Vegetarians get a fair amount of alpha linolenic acid, which is the main omega-3 fatty acid in plants. Many people take flax oil, a rich source of alpha linolenic acid, to boost their levels of LCPUFA. MD and I were criticized for writing in Protein Power that flax oil was not an optimum source of LCPUFA, and that people should eat sardines or other fatty fish to get these fats. This study presents data that the conversion of alpha linolenic acid to the longer chained omega-3 fatty acids EPA and DHA is fairly inefficient, at least in vegetarians.
In the introduction to the article, the authors do a good job of succinctly describing these long chain fatty acids and their health benefits:
Apart from being a source of energy, fatty acids have a wide range of physiologic functions. Many fatty acids can be produced endogenously; however, nâ€”3 and nâ€”6 polyunsaturated fatty acids are essential fatty acids that must be provided in the diet. The long-chain metabolites of these essential fatty acids are needed for cellular membrane functions and the production of eicosanoids, which play a role in inflammatory reactions, blood pressure control, and platelet aggregation. These essential fatty acids also influence gene regulation; for example, they act as ligands of peroxisome proliferator-activated receptors that are involved in growth and development. Of particular interest are the long-chain nâ€”3 fatty acids eicosapentaenoic acid (20:5nâ€”3; EPA) and docosahexaenoic acid (22:6nâ€”3; DHA), which are abundant in oily fish and therefore are also referred to as the marine fatty acids. Although their action is not fully understood, these fatty acids probably account for the inverse relation between fish consumption and the risk of developing coronary heart disease and stroke that has been observed in epidemiologic studies (1â€”4). Apart from its probable cardioprotective effects, DHA is, with arachidonic acid, one of the 2 most prevalent polyunsaturated fatty acids in brain and retinal phospholipids and plays a role in normal neurotransmission and visual function.
Sounds to me like something one would rather have more of than less.
With all the hype about vegetarian diets being more healthful, it should be remembered that along with lowered levels of LCPUFA these diets are deficient in a number of other nutrients as well. For example, vegetarians typically have higher homocysteine levels thanks to their non-existent intake of vitamin B-12 other than in supplement form. Most people, thanks to the anti-meat lobby, think only of folate as being the nutrient necessary to reduce homocysteine. Au contraire, it takes vitamin B-12 as well, which meat eaters have in abundance, keeping their homocysteine levels lower than those of their vegetarian brethren.
In PPLP, you wrote that grain-fed beef has a 15:1 omega-6/3 ratio. How did you get that number? This link at Cal-Chico says 4:1. I went to the USDA nutrient database and picked a few random cuts. I got as low as 2:1 and as high as 10:1. Granted, I didn’t go through every cut, but I’m wondering what accounts for the discrepancy?
I don’t know where I got the info, but 15:1 sounds high. I’m sitting in the airport at Dallas right now trying to catch up on all these comments. I’ll check it out when I get back to my references.
I think I forgot to give the link to the Chico website.
Thanks, AOE. It’s an interesting site.
I think grass-fed beef is overrated.
Most of the polyunsaturated fats are saturated within its rumen, so the omega 3/6 content of the food doesn’t matter that much. I think the microorganisms produce the required long chain polyunsaturated fatty acids themselves.
I have no doubt that grass-fed beef is healthier, but not as much as the sellers want us to believe. It is also much more expensive. Grass-fed meat is usually way too lean, and we know that too much protein without fat is bad (rabbit starvation). The claims that grass-fed beef has less saturated fats should not convince us of anything. The “studies” they show usually compare the least omega 3 rich part of grain-fed beef with the richest part of grass-fed beef.
I think organic beef has the best of both worlds, at least here; the animal has to have a minimal % of grass, then its diet is completed with grains.
““Animals eat and store fat, but unfortunately
the digestion process of ruminants converts
healthy polyunsaturated dietary fats into less
healthy saturated ones which then appear in
ruminant meat and dairy products. This means
that even if we find a way of feeding sheep
or cattle lipids like long chain omega-3, their rumen microbes will automatically saturate
them. Hence the second step in this research
project is to find a way of protecting the
polyunsaturated fats as they travel through the
rumen, so that they can then be absorbed into
the animals’ bodies making them available for
incorporation into meat and milk.”
I’ve just found this specific quote on this page: http://www.agresearch.co.nz/publications/intouch/AgResearch_News_Dec2005.pdf .
Thanks for the comment. I happen to like grass-fed beef a lot, but we all have our different tastes. Organic beef is fine, too, but I prefer grass fed.
Appreciate the link.
Would it not make more sense to eat the grass fed beef which may be more expensive but is much better for the environment, and supplement the meal with some healthy nonsaturated plant based oil if it is too low fat?
That would work in terms of providing fat, but I don’t know if it would make up for it taste-wise.