Marion Nestle on Omega-3s

In a January 2007 New York Times article about adding omega-3s to food, Marion Nestle, the NYU nutrition professor, said this:

My experience in nutrition is that single nutrients rarely produce miracles. But it’s also been my experience that companies will put anything in their food if they think the extra marketing hype will help them sell more of it.

I was critical. The single nutrients called vitamins produce miraculous improvements in vitamin-deficiency diseases. In the current issue of Scientific American, Nestle is more accurate:

In the early 1970s Danish investigators observed surprisingly low frequencies of heart disease among indigenous populations in Greenland that typically ate fatty fish, seals and whales. The re­searchers attributed the protective effect to the foods’ content of omega-3 fatty acids. Some subsequent studies—but by no means all—confirm this idea.

Because large, fatty fish are likely to have accumulated methylmercury and other toxins through predation, however, eating them raises questions about the balance between benefits and risks. Understandably, the fish industry is eager to prove that the health benefits of omega-3s outweigh any risks from eating fish. [A mysterious sentence. Perhaps something was lost in the editing.]

Even independent studies on omega-3 fats can be interpreted differently. In 2004 the National Oceanic and Atmospheric Administration—for fish, the agency equivalent to the USDA—asked the Institute of Medicine (IOM) to review studies of the benefits and risks of consuming seafood. The ensuing review of the research on heart disease risk illustrates the challenge such work poses for interpretation.

The IOM’s October 2006 report concluded that eating seafood reduces the risk of heart disease but judged the studies too inconsistent to decide if omega-3 fats were responsible. In contrast, investigators from the Harvard School of Public Health published a much more positive report in the Journal of the American Medical Association that same month. Even modest consumption of fish omega-3s, they stated, would cut coronary deaths by 36 percent and total mortality by 17 percent, meaning that not eating fish would constitute a health risk.

Differences in interpretation explain how distinguished scientists could arrive at such different conclusions after considering the same studies. The two groups, for example, had conflicting views of earlier work published in March 2006 in the British Medical Journal. That study found no overall effect of omega-3s on heart disease risk or mortality, although a subset of the original studies displayed a 14 percent reduction in total mortality that did not reach statistical significance. The IOM team interpreted the “nonsignificant” result as evidence for the need for caution, whereas the Harvard group saw the data as consistent with studies reporting the benefits of omega-3s.

I would have described benefits of omega-3 for which the evidence is clearer, as is done in the cover story about omega-3 in the current issue of Ode. Nabokov called Salvador Dali “Norman Rockwell’s twin brother, kidnapped by gypsies in babyhood.” I think of Ode, which put a Dali lookalike on its July/August 2005 cover, and Spy as linked like that.