Finally, a reputable source, the Harvard School of Public Health has put to rest the great fish debate. We have long known that fish is good, especially oil fish rich in omega-3 fatty acids. The problem is that recent analysis has shown that these fish are also high in PCBs, mercury and other toxic compounds. This study (Link via ScienceDaily) shows that overall, the benefits outweigh the risks, but that pretty much everyone should avoid tilefish (golden bass), king mackerel, shark and swordfish (my personal favourite).
The evidence was suggestive that mercury may have subtle effects on brain development for a child exposed in the womb, or in early childhood. To obtain the benefits of omega-3 fatty acids for brain development and minimize the potential risk of mercury, the investigators' findings agreed with the recommendations of the Environmental Protection Agency and Food and Drug Administration that women of childbearing age, nursing mothers and young children should eat up to two servings per week of a variety of fish (for example, salmon, light tuna, shrimp, mackerel, and up to 6 oz. per week of albacore tuna) and avoid only four species of fish--golden bass (also known as tilefish), king mackerel, shark and swordfish--larger, predatory fish that have higher levels of mercury. The researchers emphasized that this advisory is only for women of childbearing age, nursing mothers and young children, not the general population. Importantly, the evidence suggests that, for those women, it is as important for their health and for the brain development of their infants that they eat a variety of other types of fish as it is to avoid the four fish species higher in mercury.