Health News Digest

December 10, 2012

A Look at Omega-3, Omega-6, and Docosahexaenoic acid (DHA)


By  Michael D. Shaw

You’ve probably heard about omega-6 and omega-3 fatty acids, and their relative importance in your diet, and thus to your health. Let’s first demystify these terms.

Chemically, fatty acids are hydrocarbon chains, with one end being called “alpha” and the other “omega”—based on the first and last letters of the Greek alphabet. The carbon atoms in the chain can be linked to each other via a single bond (whereby two hydrogen atoms also appear) or via a double bond (whereby only one hydrogen atom appears). Yes, this is confusing. For those keeping score, the omega end is where the methyl group lies, and the alpha end is where the carboxyl group lies.

Inasmuch as the single bond requires more hydrogen atoms, it is considered to be “saturated,” while the double bond is said to be “unsaturated.” The omega designations (also referred to as n-3 and n-6) indicate the location of the first double bond, counting back from the “omega” end of the fatty acid. Both omega-3 and omega-6 fatty acids are considered essential, in that your body cannot synthesize them.

Three important omega-3 fatty acids are alpha-linolenic acid (ALA), which is found in some vegetable oils, such as soybean, canola, and flaxseed. ALA is also available from walnuts, Brussels sprouts, kale, spinach, and salad greens. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are found in fatty fish. Within the body a small amount of ALA converts to EPA and DHA. In men, this conversion efficiency is less than 5%, but is higher in women—presumably because of the importance of DHA to the fetus and neonate.

Research indicates that omega-3s reduce inflammation and might also lower the risk of heart disease, cancer, and arthritis. Owing to their concentration in the brain, they are important for cognitive and behavioral function, and babies deficient in omega-3s in utero appear to be at risk for vision and other neurological problems.

Omega-6s can be found in most vegetable oils and poultry and meat products, and many foods contain both omega-3 and omega-6 fatty acids—at various ratios. The typical American diet contains 14-25 times more omega-6s than omega-3s. This is worrisome since the heart-healthy Mediterranean diet has a much smaller ratio, and some authorities believe that the ratio in the diet of early man was closer to 1:1.

As such, there has been an interest in tweaking this ratio via supplementation. However, it is noted that both omega-3s and omega-6s are essential and healthy, and fluctuations in this ratio and any relationship to health effects could be coincidental. As Dr. Frank Sacks of the Harvard School of Public Health puts it, “While there is a theory that omega-3 fatty acids are better for our health than omega-6 fatty acids, this is not supported by the latest evidence. Thus the omega-6 to omega-3 ratio is basically the ‘good divided by the good,’ so it is of no value in evaluating diet quality or predicting disease.”

Notwithstanding the ratio, specific DHA supplementation has been shown to produce benefits in such conditions as:

  • Attention-Deficit Hyperactivity Disorder (ADHD)
  • Depression
  • Heart Disease
  • Lupus
  • Menstrual Pain
  • Raynaud’s Disease
  • Rheumatoid Arthritis

In addition to its importance in fetal brain development, studies have also suggested that DHA supplementation in pregnant women can reduce the number and duration of colds suffered by newborns. Walgreen’s Prenatal + DHA (Multivitamin/Mineral) is a popular product in this space.

Finally, since vegetarians and vegans may be reluctant to consume fish products, DHA can also be obtained directly from algae, and farm-raised algae does the trick, without upsetting the marine food balance. Suggested supplements include Spring Valley ALGAL-900 DHA, available at Walmart and other retailers.

Yes, there really are good fats.