Tuesday, December 14, 2004

A Fat We Can't Live Without

Some of my work as a graduate student focused on the importance of a particular fat in our diet. It's a fat that our ancestors consumed a lot more of than what you or I consume, for reasons that have to do mostly with how our livestock are farmed and fed. This particular fat decreases inflammation. You can guess that if we don't get enough of it, we'd have difficulty with diseases of inflammation ... like arthritis and heart disease. This fat is even linked to brain function, it can reduce depression and aggression, and it's absolutely vital for the development of the fetal brain. (Are you pregnant? Make sure you're getting some.)

What is this fat? Well, even though I alluded to us getting it from animal food, it's not a saturated fat. In fact it's polyunsaturated. We can't live without it, yet our bodies can't make it, so we have to eat it, making it what nutrition textbook writers call an "essential fat". Can you guess yet? I'll give you the best hint ... it's found in fish oil. It isn't fish oil, but it's found in it, and it's the reason sales of fish oil are through the roof. The fat I'm referring to is of a type called omega-3. If you're someone who takes fish oil, you may know this fat by the abbreviations EPA (EicosaPentaenoic Acid) and DHA (DocosaHexaenoic Acid), which are often listed on the bottle's "Supplement Facts" label.

EPA and DHA are the important forms of omega-3, and you can only find them in foods of animal origin1. You may have read about the omega-3 in non-animal foods like walnuts and flax seed. Unfortunately, that vegetable form (alpha-linolenic acid) has to be converted in our body to the more active EPA and DHA before it can do much of its anti-inflammatory work. And only a tiny bit gets converted.2 So, if you want to make sure you're getting enough of the active forms of omega-3, it's best to eat an animal that has done the conversion for you.

For animals to do the conversion, you have to supply them the raw materials. Animals that graze, that is, whose diets are not heavily supplemented with grain3 (as are most of today's livestock), do a lot of converting. Fish, because many of them still graze and are not grain-fed, do a lot of converting (and also eat a lot of smaller fish that did a lot of converting). It follows then that fish (and fish oil) or the flesh of grazing animals are the best natural sources for EPA and DHA.4

That's one reason why last weekend I served lamb (in the form of Braised Lamb Shanks - recipe listed). Lamb is one of the few meats commonly available that comes from an animal still left to graze, at least for part of its life. You may be fortunate to live near a specialty market or health food store that sells free-range beef or buffalo5. But most meat in grocery stores, unless otherwise labeled, came from an animal that was raised in relatively close quarters with other animals, was grain-fed, and was likely the recipient of antibiotics, growth hormones, and animal by-products in its feed (although this last addition has been somewhat curtailed in light of the spread of mad-cow disease ... which propagates through a herd when animals are fed brain and nervous tissue from their fellow animals. Yuk.)


1 Purslane, a plant that grows near the Mediterranean, is a rare exception.
2 That's a post unto itself!
3 Diets based on grains such as corn, soy, millet, etc. do not provide good raw materials. This applies to humans too.
4 This is one reason I do not support diets that completely eradicate foods of animals origin.
5 Organic meat is not the same as free-range or range-fed meat. Organic usually refers to the quality of grain, in this case organic, fed to the animal.

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