At first glance, nutrition seemed fairly straightforward to me. In the world of fitness training, it can be as simple as: calories in equal calories out for weight maintenance. That understanding is definitely important, but there’s a whole lot more going on between the calories in and the calories out. You might find, as I have, that an awareness of the finer details aids in a better understanding of the bigger picture. So, in order to make more educated choices about eating for our health, I've found it helpful to take a closer look at the foods I eat and how they affect me. This educational journey through fat nutrients was a veritable alphabet soup of acronyms and a few of the concepts required some critical thinking. Yet, in the end I found it was worth it. However, if you're less interested in the fascinating workings of fatty acids, just skip down to the bottom line section of the post.
Well, it's good to know that I'm not alone in my quest for nutritional knowledge. Let's journey on and get back to the topic of discussion in the last 2 posts: fats and specifically the polyunsaturated fatty acids (PUFA’s) known as omega-3 and 6.
Omega-3 and 6: Why are they important?
In case you missed the previous posts on fats, omega-3 and 6 are also known as essential fatty acids (EFA’s). This is because our bodies can’t make enough of them, so they must come from the foods we eat. EFA’s are extremely important in, among other things, cell membrane structure and function, cardiovascular health, vision, the regulation of gene expression and the proper working of our nervous system (Linus Pauling Institute).
Omega-3 and 6: What are they?
Omega-3 and omega-6 are terms which actually represent 2 families of fatty acids. In the omega-3 family the nutritionally important fatty acids include: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA can be made from ALA. However, the body doesn’t do this very efficiently (around 5% in men and slightly higher in women) (Wikipedia). The body can also convert EPA into hormone like substances called eicosanoids. Omega-3 eicosanoids are thought of as being less prone to cause inflammation. Unfortunately, since the body doesn’t convert EPA very efficiently, the rate at which these omega-3 eicosanoids are produced is much slower than that of omega-6.
In the omega-6 family there is linoleic acid (LA), gama-linoleic acid (GLA) and arachidonic acid (AA). Through a cascade of chemical reactions the body can make AA from LA. However, because of the excess of LA compared to ALA in the Western diet, the result is usually a greater formation of AA than that of the EPA that is made from omega-3. The body also converts AA into eicosanoids and because of the greater amounts of available AA more of the omega-6 eicosanoids are formed as a result.
The eicosanoids formed from the omega-6 AA are thought to be more "pro inflammatory" than the eicosanoids converted from ALA (AHRQ Evidence Report). If you're looking for more information on inflammation, this topic is discussed in another post. The important point here is that anything that promotes an inflammatory state in the body for long periods of time isn't good (Linus Pauling Institute).
Now we’re getting to the heart of the matter. Some experts believe that the current Western diet contains as much as anywhere from 10-25 times more omega-6 than omega-3. Compounding the situation is that omega-3 and omega-6 eicosinoids compete to use the same chemicals in order to be transformed. So the ratio of omega-3:omega-6 directly affects the type of eicosanoids formed and our Western diet encourages more production of omega-6. Remember that eicosanoids produced from the AA derived from omega-6 are considered to be pro-inflammatory.
Omega-3 and 6: Are their ratios important?
If you’ve been following the previous posts in this blog you know that studies have shown that there are definitely health benefits associated with including more omega-3’s in our diet. Table 2 below shows some of the benefits of omega-3's DHA and EPA (Lavie, et al).
Research suggests that an imbalance between omega-3 and omega-6 is an underlying cause in many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases (Simopoulos, A.P.). It's thought that omega-3 eicosanoids have regulating effect over omega-6 eicosanoids. When the two are totally out of balance, this regulating effect is removed and the eicosanoids from omega-6 exert a more "pro-inflammatory" state. It seems experts aren't in agreement yet on a specific ratio of omegas, however they do seem to recognize that more eicosanoids from omega-6 than from omega-3 contributes to inflammation, blood vessel constriction (which causes increases in blood pressure) and blood clotting (Linus Pauling).
Omega-3 and 6: How much to eat and from what foods?
So, aside from the ratios, how much of each omega is necessary for optimal health and what foods do we eat to get them? Well, as far as I can tell, at this point in time the US hasn’t assigned a Recommended Daily Allowance (RDA) for omegas. However, the Food and Nutrition Board of the U.S. Institute of Medicine has established adequate intake (AI) levels for both omega-6 and omega-3 fatty acids. You can view the AI’s here at the Linus Pauling Institute. An example of the AI's for adult males 19-50 years old is 17 grams per day and for females it's 12 grams per day. For males 51 years and older the AI for LA decreases to 14 grams per day and 11 grams per day for females. The Linus Pauling Institute also has a list of the best food sources for omega-3 and 6 and you can check that out here.
|Image from www.extension.org|
According to a report on EFA's by the Agency for Healthcare Research and Quality Evidence, Acceptable Macronutrient Distribution Ranges (AMDR’s) have been established for the essential fatty acids. You can view their table of sources and proportions of omega-3 foods and supplements here.
As you can see from the above information, knowing how much and what ratio of omegas to consume is a rather confusing and complicated subject. When it comes to the question of what to eat, I like how simply the Harvard School of Public Health puts it: “out with the bad and in with the good.” Here are their suggestions for how to eat better and also get more of the healthy fats:
- Try to eliminate trans fats from partially hydrogenated oils. Check food labels for trans fats; avoid fried fast foods.
- Limit your intake of saturated fats by cutting back on red meat and full-fat dairy foods. Try replacing red meat with beans, nuts, poultry, and fish whenever possible, and switching from whole milk and other full-fat dairy foods to lower fat versions.
- In place of butter, use liquid vegetable oils rich in polyunsaturated and monounsaturated fats in cooking and at the table.
- Eat one or more good sources of omega-3 fats every day—fish, walnuts, canola or soybean oil, ground flax seeds or flaxseed oil.
So, I’m no longer stuck in the old thinking that generic, low-fat eating is the way to go. From now on when it comes to fats it’s out with the bad and in with the good. Making educated choices about the foods we eat may seem complex at first, but with practice it becomes easier. Don't you think it's worth the effort to understand which food is healthier than another? When you consider how profoundly what we put into our bodies affects our health, we really owe it to ourselves and those we love to practice healthy nutrition habits!
Simopoulos, A.P., Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/17045449
Carl J. Lavie, MD, Richard V. Milani, MD, Mandeep R. Mehra, MD and Hector O. Ventura, MD, Omega-3 Polyunsaturated Fatty Acids and Cardiovascular Diseases, J Am Coll Cardiol, 2009; 54:585-594, doi:10.1016/j.jacc.2009.02.084, Retrieved from http://www.natap.org/2009/HIV/080509_04.htm
Linus Pauling Institute: http://lpi.oregonstate.edu/infocenter/othernuts/omega3fa/#intro
Edwards,T., Inflammation, pain, and chronic disease: an integrative approach to treatment and prevention.Retrieved fromhttp://www.ncbi.nlm.nih.gov/pubmed/16320856