Lots of packaged foods now promote their omega-3 content, as interest in the essential fatty acid has made it the latest hot nutrient but less commonly understood is the importance of the ratio of omega-3 to omega-6 consumption for overall health.
It appears that humans used to consume roughly equal amounts of omega-3s and omega-6s (a 1:1 ratio) before the advent of processed foods, but western diets now have a ratio closer to 1:15. Omega-3s are anti-inflammatory, whereas omega-6s are primarily inflammatory. (See “The Skinny of Fatty Acids.”) When balanced, these substances ensure our immune system functions optimally. Since our bodies cannot produce essential fatty acids, we have to obtain them from our diet. There are few sources of omega-3s besides the flesh of coldwater fish such as salmon, mackerel, and sardines. Omega-6s are abundant in refined vegetable oils, such as soy oil, and omnipresent in processed foods in part because of their long shelf life. Diets high in omega-6s can cause inflammation that can lead to diseases such as asthma, coronary heart disease, forms of cancer, plus autoimmune, and neurodegenerative diseases. The imbalance between omega-3 and omega-6 fatty acids may also contribute to obesity, depression, dyslexia, hyperactivity, and even a tendency toward violence, according to Dr. Andrew Weil.
So how did this imbalance arise? Omega-3s are produced by leaves and algae (fish get theirs from eating algae-consuming creatures). Omega-6s come from seeds. During the past century, both human and farm animal diets have shifted away from leaves and become more dependent on seeds. For example, corn oil has an omega-6 to omega-3 ratio of 46 to 1, whereas canola and olive oils are 3 to 1. Omega-3 fats spoil much more readily than omega-6, thus the scarcity of olive and canola oils in junk food. Partially hydrogenating fats increases their stability, but eliminates any omega-3 fatty acids. As livestock diets have shifted from pasture to corn-based grain, levels of omega-6s in meat have also climbed steeply as omega-3s have declined.
In short, the Western, or American, diet is high in omega-6s and low in omega-3s, especially when compared to traditional Mediterranean or Japanese diets. Yet the diets in all wealthy countries are becoming more American. The answer? Michael Pollan states it simply in his book In Defense of Food: “Eat food (not edible foodlike products). Not too much. Mostly plants. It is time to stop worrying about our intake of individual nutrients, and simply use our common sense. Those oven-roasted red potatoes with rosemary and olive oil actually do taste better than potato chips, and contribute to our health more than we could have imagined.
- Rebecca Taggart