Certain nutrients in fish, including selenium, iodine, and sulfur-containing compounds, can lessen the harmful biological effects caused by exposure to heavy metals.

We analyzed the available evidence and found that 9 studies or assertions support the idea that selenium, iodine, and sulfur-containing compounds in fish may help reduce the harmful effects of heavy metal exposure, with no studies contradicting this. What we’ve found so far suggests these nutrients might interact with heavy metals in ways that lessen their biological impact, though the exact mechanisms aren’t fully detailed in the evidence we reviewed. Selenium, for example, is known to bind to certain metals like mercury, potentially limiting how much enters tissues. Iodine and sulfur compounds — such as those found in amino acids like cysteine — may also help the body process or eliminate toxins more effectively. These are natural components of many types of fish, which raises the possibility that eating fish could offer some protective benefit beyond its protein and omega-3 content. However, we did not find data showing whether this effect is strong enough to fully offset heavy metal risk, or how much fish would need to be eaten to see a difference. The evidence we’ve reviewed leans toward a protective role, but we cannot say how consistent or reliable this effect is across different people, fish types, or levels of exposure. Our current analysis shows this is an area where more research could clarify the relationship. For now, if you eat fish regularly, it’s possible these nutrients contribute to your body’s natural defenses — but they shouldn’t be relied on as a guaranteed shield against heavy metals.