Researchers find eating fish affects hormone levels in children

Scientists have indicated that eating more fish during childhood may alter hormone levels and increase chronic stress and immune responses, due to increased intake of mercury.

The US researchers compared the fish consumption of 100 children aged between 9 and 11 years old with levels of mercury and the hormone cortisol in their blood. They also examined the concentration of protective blood lipids, known to be a beneficial effect of eating fish, in an attempt to undertake a risk-benefit analysis of greater fish consumption.

The results showed that children who ate fish had significantly increased levels of mercury compared to those that did not, although this still fell well below levels considered a health risk by the US Environmental Protection Agency (EPA). Increased mercury was associated with reduced levels of cortisol, the hormone released in response to stress and involved in regulating metabolism, immune responses and blood pressure. However, subjects that ate fish also had higher levels of protective cholesterols within their body, which are associated with a decreased risk of heart disease.

The scientists highlight their study is the first to document a potential link between blood mercury and systemic inflammation and endocrine disruption in humans. However, they are unable to conclude whether increased fish consumption has a net beneficial or harmful effect on children, emphasising the need for further research.

The study is published in the journal Environmental Research.

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