Controversy has arisen among the public and in the media regarding the health effects of fish intake in adults. Substantial evidence indicates that fish consumption reduces
coronary heart disease mortality, the leading cause of death in developed and most developing nations. Conversely, concerns have grown regarding potential effects of exposure to
mercury found in some fish. Seafood species are also rich in
selenium, an essential
trace element that may protect against both
cardiovascular disease and toxic effects of
mercury. Such protective effects would have direct implications for recommendations regarding optimal
selenium intake and for assessing the potential impact of
mercury exposure from fish intake in different populations. Because fish consumption appears to have important health benefits in adults, elucidating the relationships between fish intake,
mercury and
selenium exposure, and health risk is of considerable scientific and public health relevance. The evidence for health effects of fish consumption in adults is reviewed, focusing on the strength and consistency of evidence and relative magnitudes of effects of
omega-3 fatty acids,
mercury, and
selenium. Given the preponderance of evidence, the focus is on cardiovascular effects, but other potential health effects, as well as potential effects of
polychlorinated biphenyls and
dioxins in fish, are also briefly reviewed. The relevant current unanswered questions and directions of further research are summarized.