The skinny on omega-3 fatty acids

Originally published in The Ottawa Citizen September 28, 2005
Our diet has radically changed over the past century, and with it the balance between two essential omega fatty acids, omega-3 (linolenic acid) and omega-6 (linoleic acid). An essential nutrient is one that the body cannot make for itself or cannot manufacture enough of on its own.

We now consume more grain-fed fish and animals, vegetable oils (corn, safflower, sunflower and cottonseed) high in omega-6 fatty acids, and fewer vegetables and eggs. Most margarine and many packaged baked goods contain trans-fatty acids or hydrogenated oils that block the body’s ability to convert the omega fatty acids into other important nutrients.

Our dietary balance of omega-6 to omega-3 fatty acids has shifted from an estimated 1-3:1 a century ago to approximately 10-14:1 in the typical North American diet today. In other words, instead of consuming equal amounts of omega-6 and omega-3, we are now consuming between 10 to 14 times more omega-6. This imbalance can cause health problems.

Why are people paying more attention to omega fatty acids and the dietary balance shift? The omega-3 fatty acids seem to have several important properties: they reduce inflammation, prevent heart arrhythmias, dilate blood vessels and have anti-clotting capabilities.

Omega-6 fatty acids do just the opposite; they promote an inflammatory response and encourage clotting.

The human body requires all of these processes to function well but the dietary balance now favours the omega-6’s. Food scientists continue their research studying the effects this might have on heart and inflammatory diseases, among others.

We know that breast milk rich in nutrients like arachidonic acid (ARA) and decosahexanoic acid (DHA), derived from the omega-6 and omega-3 fatty acids, respectively, accumulate in every organ and cell in the body and promote infant brain and eye development. Indeed, at specific nutrient levels, babies have better co-ordination, problem-solving skills and sharper vision.

A worldwide study looking at the breast milk concentration of DHA and ARA found a wide range of values. Women in societies consuming large quantities of fish had the greatest concentration of these breast milk nutrients.

A growing body of scientific research seems to implicate omega-3 fatty acid deficiency with an increased incidence of common diseases such as heart disease, Crohn’s disease, asthma, Alzheimer and certain kidney diseases, among others.

Observational studies that looked at the health outcomes of a Mediterranean diet seemed to point to a lower risk of coronary artery disease and certain cancers. Although many countries border the Mediterranean Sea, each with populations that have varied diets, there are common dietary threads: use of olive oil, raw fruits and vegetables, bread and cereals, potatoes, nuts and seeds, little to no red meat or eggs, low to moderate consumption of fish, chicken and wine.
This geocultural difference is important when one considers it is a diet lower in saturated and trans-fats than our North American “super-size” menu. It goes the heart of how it alters the body’s ability to processes these nutrients.

The granddaddy of the omega-3 fatty acids is a compound called alpha-linolenic acid (ALA). It is found in oils (canola, walnut, fish and flaxseed), green leafy vegetables, nuts, seeds and beans.

The body uses specific enzymes to convert ALA into eicosapentaenoic acid (EPA) and DHA. Research indicates that EPA and DHA confer the health benefits associated with the omega-3 fatty acids.

Consider these enzymes as a series of assembly lines bringing the product from processing station to processing station. ALA and linoleic acid use the same initial assembly line before they split up and travel down their own manufacturing line.

When more linoleic acid is consumed than ALA, the former prevents the ALA from being processed. This common assembly line or enzyme is the rate-limiting step in production. This emphasizes the concern about the current imbalance of omega-6 to omega-3 in our diets and its possible deleterious health consequences.

How should our society correct the balance?

Changing our diet is certainly the primary goal. Certain foods are a better source of omega-3 fatty acids than others. The reason is based on the type of omega-3 fatty acid present within it.

Bypassing the first assembly line is another way around this problem.

Flaxseed, although a great source of omega-3 fatty acids, contains the greatest concentration of ALA and must compete with linoleic acid to be processed.

Consuming seafood (shrimp, canned light tuna, salmon, pollock, and catfish) and fish oil is a good source of EPA and DHA and bypasses the enzyme needed to convert ALA to EPA and DHA.

This avoids the competition for the first assembly line stage.

Before we accept the health benefit claims from the makers of omega fatty acid supplements, more research into omega fatty acids is required. Besides, eating foods rich in omega-3’s provides a greater array of nutrients than any supplement can.

Later, we will cover the omega-3 dietary recommendations, the food quantities required to meet them and cover the most common and well-researched treatment uses.


© Dr. Barry Dworkin 2005

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