Omega-3s and Mercury
In your article "The Omega-3 Connection" (Feb. '08 issue, p. 27), I was surprised to see the recommendation for eating more "heavy" fish (e.g., swordfish, tuna, mackerel). I have a 2-year-old son and had been warned not to feed a child too much of these fish due to the mercury content. There are other ways to enrich a child's diet with DHA or omega-3 such as enriched milk products, yogurt, and even infant formula. I would do just about anything to prevent type 1 diabetes in my child; however, I am not willing to risk mercury toxicity. Susan Stettler
Henry Rodriguez, MD, responds: There is no conclusive proof of the relationship between omega-3 fatty acid intake and reduced risk of type 1 diabetes—rather, the data that has been collected (including that cited in 'The Omega-3 Connection') shows an association between the two. We also have supportive data in animal models with type 1 diabetes.
Current studies, including the TrialNet NIP (Nutritional Intervention to Prevent Type 1 Diabetes) study, are investigating the question prospectively. There are potential risks of excess mercury, particularly with younger children. You are correct that there are alternative sources that can provide safer sources of omega-3s. Given our current level of knowledge, I recommend following current nutritional guidelines from the American Academy of Pediatrics, which is in accordance with the American Heart Association (AHA) in recommending adequate intake of omega-3 fatty acids, and with both AHA and the U.S. Food and Drug Administration (FDA) in designating seafood as an important component of a healthy diet. The FDA also recommends that young children avoid shark, swordfish, king mackerel, and tilefish, which are high in mercury.
Other kinds of fatty fish that are high in omega-3 include lake trout, salmon, and herring. Omega-3 supplements like DHA, and soybean products are also options. Stay tuned for results on currently ongoing trials.