Researchers have recently discovered that tuna contains the mineral selenium in an unusual form called selenoneine. This form of selenium plays an important role in the health of the fish by serving as an antioxidant and protecting the fish's red blood cells from free radical damage. Interestingly, it is also able to bind together with mercury compounds in the fish's body (including methyl mercury, or MeHg) and lower their risk of mercury-related problems. Because there are approximately 20-30 micrograms of selenoneine in a 4-ounce serving of tuna, we are likely to get some of this same antioxidant protection when we eat tuna. Equally interesting, perhaps tuna will turn out to be a fish that—even when contaminated with mercury—might pose less of a mercury risk than might otherwise be expected due to the presence of selenoneine. There is some evidence to show that lower concentrations of both selenoneine and selenium itself may be present in fresh tuna that lacks its characteristic reddish color and is more watery and softer in texture at the time of purchase. However, further research is needed to determine exactly how the selenium content of tuna is related both to its appearance and also to its potential mercury risk.
Written by whfoods.org
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