OnePhatMan

Docosahexaenoic acid, or DHA, is one of the wonderful dietary fats known as omega-3 fatty acids. If you’ve been reading me for a while, you know I can wax poetic about the omega-3 fatties because they’re so dang good for you. DHA has the nifty ability to not only lower LDL and triglyceride levels in your blood, but to also raise HDL levels.

Pretty good for one of those evil fats, huh? Wait’ll you read the rest of the article, though.

DHA is one of two important acids (the other is eicosapentaenoic acid (EPA), which I’ll talk about in another article) found primarily in fish, particularly in coldwater fish like salmon, sardines, mackerel, tuna, anchovies, and halibut. Shrimp, flounder, and swordfish also have DHA (and EPA), but not in levels as high as the first list. Wild fish tend to have more DHA than farmed fish, because they get it from algae and seaweed they consume. Whole eggs, red meat, and organ meat also have DHA—particularly if the chickens were free range and the cattle was grass (not grain) fed. Seaweed is a good source of vegetable DHA.

Now, the lowdown:

DHA is not an essential fatty acid, because your body is able to synthesize it from EPA. It can’t do that very well, though, so it makes the most sense to just eat thingswhich contain it. Interestingly, DHA is the most unsaturated fat there is, having six double bonds.

The human brain is 60% fat. Care to guess which fatty acid is most prevalent in brain material? If you guessed DHA, you’d be absolutely correct. Mothers provide DHA to developing embryos and newborns via their blood and milk, respectively. Premature infants who missed the vital brain developmental stage at the end of pregnancy scored an average of 15 points lower on IQ tests (tested later in life) than infants who did not miss this stage. Double-blind testing did, however, show that DHA supplementation in premature infants led to improved brain function.

Bottle-fed babies scored an average of 9 points lower than breast-fed babies, affected greatly by the fact that baby formulas in the US do not yet have added DHA.

Interesting side note: DHA levels in the breast milk of American women has declined considerably over the last few decades, corresponding more or less to our obsession with dietary fat. In the same time frame, standardized test scores of American children have dropped overall, relative to the rest of the world. Interestingly, Asian women eat a diet high in fish and seaweed, and Asian children now top the world list on intelligence tests. Coincidence? I don’t know, it’s just something that clicked in my head while I was preparing this article.

In addition to being the chief ingredient in the human brain, DHA is also the chief building block in our retinas. The development of the retina and the visual cortex in infants are dependent, like the brain, on DHA. Studies have shown that infants fed formula without DHA have vision worse than infants fed formula with DHA. The difference in visual acuity was roughly equivalent to one line on a standard eye chart. The U.S. Food and Drug Administration is currently reviewing a proposal that DHA be required in formula.

Brain cells and retinal cells (and indeed, nerve cells in general) use DHA in their myelin sheaths (and in the phosphlipid layer surrounding them, but to be honest, I don’t want to go into that much detail) and in the synaptic areas between the nerve cells. DHA keeps the nerve cells flexible—

Side note: Think about it for a second. This stuff comes from fatty coldwater fish, primarily. The whole idea of flexibility makes sense—imagine the fish having some of the more saturated fats in the cold water. I’m seeing a bunch of stiff fish swimming around.

—and helps carry the electrical charge between the cells. Additionally, the brain uses DHA for energy (along with glucose) because it’s such a good source (it’s a LONG molecule, with 22 carbon atoms and 16 hydrogen pairs).

Alcohol—even a little—affects DHA levels in your body, because it immediately leaches it from your cells. The National Institutes of Health report that rats (and cats and monkeys) fed a low-fat diet for a year maintained their levels of DHA, but after a single drink, DHA levels dropped within an hour. Heavy drinkers and alcoholics are generally found to be chronically deficient in DHA. They’re also prone to other mental problems like depression.

Ah, depression. Several studies have shown that societies which have a diet not providing adequate supplies of DHA have increased rates of depression. In America, land of of the lowfat and fat free, over 25,000,000 adults are now classified as “depressed”, and the number keeps climbing every year. As a matter of fact, researchers at the University of Michigan now report that 2% of children in North Carolina aged 6 to 14 are on anti-depressants.

Another interesting note, in light of current US headlines: birth lowers DHA levels in the body of the mother, and is thought to be a factor in postpartum depression. Somebody call Tom Cruise.

Speaking of children and DHA, preliminary evidence shows children with attention deficit disorder (ADD) also have low DHA levels, though no empirical evidence indicates supplementation improves symptoms (unless you look on alternative health sites, which do indicate via anecdotal evidence that DHA supplements improve ADD symptoms. I tried to stick to pure studies for this article). In 1995, the most recent year for which I could find statistics, there were 7,000,000 Ritalin prescriptions written in the US.

Victims of Alzheimer’s also show (are you surprised?) lower levels of DHA in the brain. Like the ADD information, no studies have linked supplementation to improvements in symptoms, but anecdotal evidence from doctors gives some encouragement, linking DHA supplements to improved mental capacity in Alzheimer’s sufferers.

Until very recently, the human diet had an omega-6 to omega-3 ratio of 1:1 or 2:1. With the advent of modern food processing—and the addition of all those hyrogenated oils—that ratio is now estimated to be between 10:1 and 25:1. Recent evidence indicates the higher that ratio is in women, the higher their chances are of getting breast cancer. The traditional diet of Japanese women (known for low incidences of breast cancer) has a ratio of 4:1. And, if I may generalize, it looks to me like the progression of all the common “Western” diseases—heart disease, diabetes, cancer, etc—have risen in a linear fashion as the ratio of omega-fats in our diet has risen.

I could go on and on about the benefits of DHA, and the dangers of not getting enough, but I’m going to stop here, because I think you get the point and I suspect your eyes may be rolling back in your head by now.

Eat more fish - it’s good for you!