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.

6 Responses to “Marion Nestle on Omega-3s”

  1. Igor Carron Says:

    Seth,

    It is interesting to see that we do not understand why this is happening and that there seems to be even more potentially compelling examples i.e.:

    http://scienceblogs.com/developingintelligence/2007/08/short_bowel_syndrome_and_the_p.php

    Igor.

  2. Timothy Beneke Says:

    “The single nutrients called vitamins produce miraculous improvements in vitamin-deficiency diseases.”

    My very casual impression is that the research findings that have been showing up in the press in the last year or two suggest that there is little evidence that taking vitamins helps people; and may in fact be harmful. Yes, Vitamin C was a major success with scurvy, but most of the other empirical evidence appears to be very disappointing for vitamins…

    That’s just my impression…

  3. seth Says:

    Igor, that’s a very interesting example, thanks for bringing it to my attention.

    Timothy, vitamins may not help when you are not deficient — e.g., don’t have scurvy. There is no doubt that vitamins produce miraculous recoveries from certain diseases (or to be more precise, certain symptom clusters).

  4. peter Says:

    i just got my blood test back and it shows that my HDL (good cholestrol) went from 48-50 to 58 since i’ve started taking flax seed oil on a daily basis.
    there were two subtypes of HDL measured, HDL-2 and HDL-3. Both were above the reference range. HDL-2 is better than HDL-3. (my hdl3 was way above ref. and my hdl2 was only slightly above the ref. ) The point of all this is that one measurement of the benefit of omega-3 is the effect on HDL. If Seth were to conduct a study, the measurements might include HDL2 and HDL3. It might be interesting to see if consuming DHA would increase the HDL3 more than flax seed oil.

  5. seth Says:

    Thanks for the info, Peter.

  6. asoff eracchi Says:

    Seth:

    Great stuff on your blog, I see that you have an interest in Omega oils, I was wondering whether you plan to cover Omega 5 oil.

    This is oil that is extracted from the seeds of pomegranates, usually by cold press methods.

    It has superb medicinal properties for men and women.

    Two California companies sell great Omega 5 oil products to include gel caps. I have been using the products of one of them for quite some time and simply adore the innovation.

    see: http://www.pomega5.com

    Please review and I am awaiting to hear your thoughts on this item.

    asoff