Supplemental Science: Ich Bin Ein Fathead

We are all, quite literally, fatheads. The human brain is nearly 60 percent fat. Fatty acids are essential to both the structure and everyday function of the brain—critical components of brain cell membranes and many messenger molecules.

The most essential fatty acids for the brain are the omega-3s, notably docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which together make up 14 percent of the fatty acid in the brain. "DHA is the brain," says neurobiologist Norman Salem, discoverer of DHA and longtime researcher at the National Institutes of Health, now senior science fellow at DSM Nutritional Products Company.

So vital are omega-3s to the development of the nervous system that during the most rapid periods of human brain growth—gestation and infancy—mothers give their progeny first dibs on the fats even at the cost of depleting their own reserves. Throughout life, omega-3s contribute in multiple ways to the maintenance of brain health, from fostering the processing of information to stabilizing mood to staving off cognitive decline.

So it came as something of a surprise to many scientists when a National Institutes of Health study of omega-3 supplementation for macular degeneration of the eye recently found no neuroprotective effects on cognitive decline. The report, in JAMA, arrived on the heels of another recent study showing no effect on cardiac disease.

Scientists are quick to point out that, over the past decade, the nutritional baseline has improved so much for the most educated segments of the population, from which research subjects were drawn, that the studies wound up being ill-designed to show any effects at all. And for those with cardiac disease, the routine use of statin drugs over the past 10 years similarly raised the baseline level of protection. In both cases, it would now take much larger study populations to demonstrate any benefits of omega-3 supplementation. Moreover, observers say, the 350 mg daily dose of DHA was insufficient to produce effects in the brain.

In contrast, studying a general sample of the grade-school population, a team of Oxford researchers recently demonstrated the value of even short-term DHA supplementation, at a dose of 600 mg a day, for improving behavior and learning in children. In a randomized, double-blind, placebo-controlled study, reported in PLOS One, Alexandra Richardson and colleagues gave DHA or a sham pill to 362 healthy children ages 7 to 9 who were underperforming in reading. After four months, there was no effect of DHA on reading scores in the full sample—but "significant effects" among the 224 children who initially tested two years behind in reading level. Further, parents reported fewer ADHD-type behavior problems in their children.

The researchers suggest that DHA supplementation should be a "targeted intervention for the poorest readers." Reductions in ADHD-type behaviors, however, occurred across the board.

Researchers and nutritionists agree: It's important to get omega-3s from food, both those that are found primarily in vegetables and the DHA and EPA supplied by fatty fish and algae. The American Heart Association recommends an intake of 500 mg a day for cardiovascular health. Many neuroscientists believe that 500 mg a day of omega-3s, with an emphasis on DHA, is a minimum for supporting brain function. The mean intake of DHA in the United States is 80 mg a day; the median is 30 to 40 mg. The fact is, Salem observes, "people are not getting it in food."

Omega 3s in the Brain

• build nerve cell membranes (especially DHA)maintain fluidity of nerve cell membranes
• allow activation of receptor systems, including the visual receptor system
• make many bioactive compounds like the anti-inflammatory resolvins and other neuroprotectins
• support energy metabolism (especially EPA)
• modulate sodium, potassium, and calcium channels, affecting cell excitability in brain and heart
• modulate apoptosis, or programmed cell death
• provide vascular protection against stroke and dementia.

Support for Many Systems

• Lower blood triglyceride
• Reduce blood pressure
• Maintain heart function
• Regulate blood pressure
• Counter Inflammation
• Diminish back and joint pain
• Protect mood
• Preserve memory

Fatty Facts

• It takes four months to raise the level of omega-3 fats circulating in blood—the time required for red-cell turnover.
• Omega-3 levels increase faster in heart tissue than in blood.
• The brain is less sensitive to changes in omega-3 levels than is cardiac tissue.
• A major route of benefit to the brain may be that omega-3s in capillaries combat inflammatory molecules.
• Although omega-3s protect the heart by reducing levels of triglycerides, they do not lower levels of cholesterol.
• Omega-3s are thought to stabilize electrical signals in the brain as well as in the heart.
• Gut microbes may be involved in some benefits of omega-3s; animal studies show that diets rich in fish oil produce very different kinds of intestinal bacteria than do those rich in lard.