Fat. It’s one of those nutritional words that has such negative connotations attached to it regardless of the fact that it is essential to our diet. Granted it’s not in the quantities regularly consumed by the average person, but it is necessary just the same. Although actual requirements for the two essential fatty acids are low, but there are some advantages to consuming fat-rich foods as long as they are the right kind of fats.
Long chain omega-3 fatty acids, EPA and DHA, are mainly found in cold water fish such as salmon. Because these fatty acids reduce blood clotting and inflammation they are thought to be important for the prevention of cardiovascular disease. DHA is also found in some nervous tissue and low levels have been linked to dementia and depression.
There is a crazy amount of research studies and literary reviews and meta-analyses that look at those research studies to try and figure out if omega-3s are beneficial or not. The research is pretty much split down the middle with half of the studies indicating that omega-3s are beneficial, the other half saying that it really didn’t make a difference at all. One Chilean study done in 1999 (D. Mezzano et.al, “Vegetarians and Cardiovascular Risk Factors”) found that vegetarians had significantly more platelets in their blood (the blood component that is part of the clotting process) and a shorter bleeding time than omnivores. When these vegetarians were supplemented for 8 weeks with omega-3s the bleeding time remained the same. Odd.
Plant foods don’t have EPA or DHA, but they do have alphalinolenic acid (ALA) which is a short chain omega-3 fatty acid and can be converted into EPA or DHA by the body. Some good sources of ALA are flax seeds (grind them to get the most out of them), hempseeds, chia seeds, canola oil, walnuts, soy oil and some soy foods. Linoleic Acid (LA) is also an essential fatty acid. This is an omega-6 fat which is found in a number of vegetables and oils. The issue? Large amounts of LA inhibit the conversion of ALA to EPA and DHA (how many more acronyms can I get in one sentence?). The recommended ratio of LA to ALA in your diet is 4:1; in vegans and vegetarians it is more like 15:1. It is this point where the research starts to lack; we don’t know what the long term effects of low EPA and DHA levels are in people. We do know that even with supplementation it is very difficult to raise DHA levels and only moderately successful to raise EPA levels.
What does this mean?
Large intakes of ALA may not be advisable, it is necessary to have an appropriate level within the body because it is essential to various different processes within the body (as mentioned before, cardiovascular health, neurological health, etc). The best source is the same source that the cold water fish use: algae. Supplementing with 200mg of DHA per day for three months raised vegan’s DHA blood levels by 50% (Z. Llyod-Wright et al, 2003, “Randomized Placebo Controlled Trial of a Daily Intake of 200mg Docasahexanoic Acid in Vegans”). This doesn’t mean that supplementing your diet is necessary, but it definitely doesn’t hurt (in the correct quantities, of course).