The links between diet and multiple disease processes are getting stronger. Of the many nutrients now getting attention for their ability to preserve cognitive function, perhaps none has more potential for brain-saving than omega-3 fatty acids. That may be because these natural components of fat-rich fish are superb multitaskers, exerting a variety of biological effects through multiple pathways. "The strongest evidence is for omega-3s," observes neuroscientist Greg Cole, whose UCLA laboratory is investigating the neuroprotective effects of the marine compound. But oily fish, such as sardines, salmon, and mackerel, it turns out, are more than just brain food.
Supplements of the omega-3 fat docosahexaenoic acid (DHA) may save premature infants from developmental delays. Given to lactating mothers, DHA—a component of nerve-cell membranes and the myelin sheaths protecting nerve-cell communication—improved babies' performance on tests of memory, problem- solving, early number concepts, and language. But only girls benefited. Boy babies may need higher doses of DHA.
A Bonus for Boys
Swedish researchers have found that adolescent boys who eat fish at least once a week have something to show for it—gains in verbal and visuospatial intelligence. Among 15-year-olds who ate fish once weekly, scores rose 6 percent by the time they were 18. Teen boys who ate fish more than once a week wound up with an 11 percent increase in intelligence.
It may be possible to prevent Alzheimer's disease and other forms of dementia with a fish-rich diet or fish-oil supplements. DHA, researchers now find, stimulates production of a nerve-cell protein, LR11, that blocks the buildup of toxic substances long associated with the disorder. DHA-rich fish oil increased levels of LR11 both in vitro and in the brains of rats specifically bred to develop Alzheimer's disease, and in human nerve cells.
Genes in the Balance
Omega-3s may temper what's written in the DNA. A diet that provides a more healthful balance of fatty acids than most Americans get—with more omega-3s versus omega-6s—significantly inhibits the expression of genes that promote inflammation. Rebalancing the diet with more fish may curtail the development of autoimmune diseases.
While many studies suggest the benefits of omega-3s against cancer, heart disease, stroke, and cognitive decline, only now will the nutrient get a true test—in 20,000 healthy people across the U.S. The huge study, run by Harvard and the National Institutes of Health, is expected to prove whether omega-3s, along with vitamin D—"the most promising nutrients we know of," says the lead researcher—can prevent an array of chronic diseases.