This blog is about the intersection between evolutionary biology and food. But also about practical applications, sustainable agriculture, and general tasty things.
Some readers have wondered: what's the big deal about these omega-3 fatty acids you have been talking about? So here is a list of important facts and why you should care about them.
Omega-3 fatty acids and omega-6 fatty acids are essential fatty acids that both have important roles to play. The scientific evidence shows that omega-3 fatty acids play an important role in the health of the heart and the brain as discussed in this post from Mark's Daily Apple on Fats.
The standard American diet is very very high in omega-6 fatty acids primarily from vegetable oils and grains and fairly low in omega-3 fatty acids. Why is this bad? From an evolutionary perspective it's inappropriate- we evolved on a diet with a ratio of omega-6 to omega-3 that was 2:1- 1:1. There is strong evidence excess omega–6 intake prevents the body from utilizing omega-3 and even depletes it from our body.
Of course we can have a brain without adequete omega-3s, but for optimal mental development omega-3s play a huge role. This post at Whole Health Source talks about research showing that deficient children suffered various effects ranging from low verbal intelligence to poor social behavior.
In another post he talks about how omega-3s play a huge role in the risk for heart disease.Omega-6s oils are often considered heart-healthy, but this is based on outdated and misinterpreted research. The unfortunate connsquences of a high-omega 6 diet are evident in the Israeli Paradox: people in Israeli consume tons of "heart healthy" oils like soybean oil, yet have very high rates of heart disease.
Seafood is the primary source of omega-3s that are readily utilized by the body. Flax and some other plant sources have small amounts, but their conversion to the usable form is low, though this can be increased by decreasing intake of omega-6 as I discussed in my post about seeds. The most interesting evidence, which Susan Allport talks about in The Queen of Fats, comes from a study that compared Africans eating no fish compared to Minnesotans eating some fish, but also lots of Western high omega-6 foods. The Africans had more optimal omega-3 levels! Their low omega-6 intake allows them to utilize more of the omega-3s found in plants.
The role of the ratio is controversial. Some believe that as long as your ratio of omega-6 to omega-3 is 10:1-1:1, you are in the clear, but Stephen from Whole Health source presented some good evidence that the total amount of omega-6 is more important. His conclusion is that you should get no more than 4% of our calories from omega-6 fats. The sad fact is that eating lots of fish and fish oil might help with preventing heart disease, but it's like putting a bandaid on a severed arm if omega-6 intake continues to be high. Acculturated Inuit still eat plenty of fish, but that so far hasn't protected them from getting obesity and diabetes from consuming too much omega-6.
The bottom line is that omega-3s are important and too much omega-6 is damaging. Ditch the high-omega 6 oils (safflower, sunflower, soybean, corn, canola) and anything with them (store-bought mayo and sauces unfortunately). All the omega-6s you need can be obtained by consuming nuts and fruit oils like olive oil..though not too much of course! It's also probably wise to consume some seafood or fish oil, but the lower the consumption of omega-6s is, the lower that need is. I personally don't take fish oil anymore because it does have some side effects (burping, bleeding more when cut) that I found unpleasant and it's hard to find a fresh and environmentally friendly source.
I hope Stephen from Whole Health Source writes a book about this someday! The only book I can recommend right now is Susan Allport's The Queen of Fats, which is an interesting primer, though unfortunately it focuses too much on the ratio theory.