After a month off to take care of some very important VitalSigns tasks, I’m ready to complete the series on fats. Having attempted to clear up some negative myths about saturated fats and considering the virtues of monounsaturated fats, I now move to the third and final category of natural fatty acids, polyunsaturated.
What’s the latest word on polyunsaturated fatty acids (PUFA’s)? Following is the typical story told by most enlightened nutrition scientists, bloggers and practitioners who are guided by basic science and a careful reading of existing studies and shun traditional guidelines. It’s the way I have understood the truth about PUFA’s and have written about them in this blog. Anyway, here’s the standard teaching and then will present some new ideas.
Polyunsaturated fatty acids contain 2 or more double bonds (contrasted with monounsaturated fats with contain 1 and saturated fats which have none)
The two classes of PUFA’s are omega 6 (linoleic acid) and omega 3 (alpha linolenic acid). They are considered essential because they are not produced in our bodies and thus must be consumed in our diets. These fatty acids play an important role in cell membranes and lead to the production of messengers called eicosanoids which initiate many important functions in our bodies. Omega 6 fatty acids produce eicosanoids which cause blood to clot, induce smooth muscle cell contraction, cause inflammation and pain and much more. Omega 3 related eicosanoids thin blood, relax smooth muscles, reduce inflammation – generally the opposite of the omega 6 eicosanoids. When these two are balanced everything should work just fine. The problem is that omega 6’s are found in vegetable oils, processed foods, nuts and even in excess in grain fed beef and thus are way over consumed in modern diets.
Due to their under-consumption, Omega 3’s tend to be nutrition stars leading to the inclusion of salmon in every “superfoods” list. I have a book on my shelf about omega 3’s called “The Queen of Fats”. They are divided between docosahexanoic acid (DHA) and eicosapentanoic acid (EFA) both of which have long been considered good for arteries and the brain. Being considered heart healthy, Omega 3’s are supplemented in fish oil capsules and have even been approved by the FDA in high dose to lower triglycerides.
Current diets often contain a 20:1 or higher ratio of omega 6:omega 3 while it is thought that 4:1 or less is healthy with many experts saying a 2:1 ratio is ideal. Many studies have shown an excess of omega 6 to be associated with an increased incidence of heart disease, cancer and other degenerative diseases. We have therefore recommended greatly reducing omega 6 and increasing omega 3. This has led to recommendations to frequently consume fatty fish such as salmon. It has also prompted fish oil supplementation as mentioned above and a great reduction in the use of vegetable oils, margarine and other “foods” produced in a chemistry lab. While all of this is basically true, next time I will discuss some subtle changes in my understanding which may results in altered recommendations.