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United States Department of Agriculture

Agricultural Research Service

Keep healthy fatty acid ratios with N.D. seed oil
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Dr. Wesley Canfield

In a column in 2008, I attempted to shed some light on the omega-3 fatty acid story. About 96 percent of all omega-3 fatty acid in the U.S. food supply comes from alpha-linolenic acid found in canola, soy and flax.

Although most people think first of fish oil when omega-3’s are mentioned, the oils from seeds grown in North Dakota are rich sources of ALA, which is an essential fat for humans. Even the meat from animals, especially those allowed to graze on range grass, is a significant source of ALA.

In February, the American Heart Association announced a science advisory in the journal Circulation, and the story was picked up by several media outlets. The gist of the advisory statement is that the AHA is concerned—in light of the recommendations to consume more omega-3’s — about reduced intake of omega-6 fatty acids in the U.S. population. Both types of fatty acids are members of the polyunsaturated fatty acid family.

Linoleic acid, an essential fatty acid for humans, is an omega-6 fatty acid and accounts for most of the omega-6 content of the U.S. diet. Currently, the ratio of omega-3 to omega-6 fats in the U.S. diet averages 1 to 10. This means that for every 1 gram (9 calories) of omega-3 fats consumed, 10 grams (90 calories) of omega-6 is consumed. Since this is an average, this also means that some people are consuming diets with higher ratios, such as 1 to 25, as well lower ratios.

In the 1970s, the importance of PUFAs — as essential fatty acids — began to get media attention. Now, we know about the individual PUFAs and their ability to reduce the risk of heart disease and improve other chronic conditions such as high blood pressure, diabetes, some cancers and asthma.

More recent evidence suggests that the omega-3’s may help in the battle of the bulge — namely obesity prevention. In a 2002 issue of Circulation, the AHA advised Americans to eat more omega-3’s, and even greater amounts if heart disease is already present.

So, why the advisory about omega-6’s in 2009? After reviewing the science advisory statement, it was evident that the advice is well-intentioned.

But the manner in which it was presented to the public left some confusion, at least in my mind. Here is my take on the advice to eat more omega-6’s. The advice can be considered from two separate but related issues.

The absolute amounts of omega-3 and omega-6 fatty acids consumed each day in the average American diet, as well as the balance (or ratio) between the two PUFAs are both important.

The effect of this ratio on the risk for heart disease and other chronic conditions has been the subject of much scientific investigation as well as speculation. Simply put, the evidence suggests greater risk when populations consume diets with higher ratios, such as 1 to 25 as noted above. One theory to explain this states that when more omega-6 is consumed, greater quantities of pro-inflammatory chemicals are formed. Chemicals from omega-3 metabolism are less inflammatory. The balance between these chemicals is thought to influence chronic disease risk.

How can the average person increase their omega-3 intake easily?

Add flax oil, which is about 50 percent ALA and has an ALA to A ratio of about 10 to 3. Only about 7 to 8 grams (½ tablespoon) of flax oil (containing 3½ to 4 grams of ALA) would be necessary to triple your omega-3 intake each day. This amount would increase the LA content only by about 1 gram, or 9 calories. Adding canola oil, which is about 12 percent ALA, with an ALA to LA ratio of 1 to 2, requires a greater volume of oil each day, about 2 tablespoons. This contains nearly seven times the LA as one-half tablespoon of flax oil.

Consuming any of the seed oils produced from North Dakota crops such as corn, sunflower, safflower, soybean, canola and flax will provide omega-6 fats. Consuming more canola and flax oils will make the ratio between omega-3 and omega-6 fats more favorable, while still providing adequate amounts of omega-6 fats. Salad dressings, spreads and other omega-3 fortified foods are readily available in your grocery stores.

So, the Heart Association’s latest advice can be clarified a bit: eat enough omega-3 and omega-6 fats and keep your ratio low!


Last Modified: 4/8/2009