Measurement of mercury levels in concentrated over-the-counter fish oil preparations: is fish oil healthier than fish?

CONTEXT Fish consumption has been associated with a decreased risk of coronary artery disease. Recent studies have illustrated that the high mercury content in cold-water fish may negate the cardiovascular benefits of fish meals. Fish oils have similar antiatherogenic properties to fish, and similar studies should be performed to determine the level of mercury in fish oils. OBJECTIVE To determine the concentration of mercury in 5 over-the-counter brands of fish oil. RESULTS The levels of mercury in the 5 different brands of fish oil ranged from nondetectable (<6 microg/L) to negligible (10-12 microg/L). The mercury content of fish oil was similar to the basal concentration normally found in human blood. CONCLUSIONS Fish are rich in omega-3 fatty acids, and their consumption is recommended to decrease the risk of coronary artery disease. However, fish such as swordfish and shark are also a source of exposure to the heavy metal toxin, mercury. The fish oil brands examined in this manuscript have negligible amounts of mercury and may provide a safer alternative to fish consumption.