Researchers have developed a new model that could significantly enhance public health guidelines by providing more nuanced advice about fish consumption, particularly during pregnancy. The findings, detailed in a paper published in The American Journal of Epidemiology, were a collaborative effort by scientists from Brigham and Women’s Hospital—a founding member of Mass General Brigham—Harvard T.H. Chan School of Public Health, University of Rochester Medical Center, and Cornell University. The study introduces a novel framework that assesses the average mercury content in fish consumed, offering a balanced view of the harmful effects of mercury and the beneficial impacts of nutrients found in fish. This model was applied to a population in Massachusetts, where researchers observed that eating more fish with low mercury levels during pregnancy generally supported neurodevelopment while consuming fish with higher mercury levels proved detrimental.
Senior author Susan Korrick, MD, of Brigham’s Channing Division of Network Medicine and Division of Pulmonary and Critical Care Medicine, noted that public advisories about fish intake can be ambiguous, often leading to reduced consumption. Dr. Korrick, affiliated with the Harvard Chan-NIEHS Center for Environmental Health, highlighted fish consumption guidelines’ confusion. Lead author Sally Thurston, PhD, of the University of Rochester Medical Center, echoed these sentiments, emphasising the importance of considering the type of fish consumed rather than merely reducing fish intake. She pointed out that low mercury fish intake benefits neurodevelopment during pregnancy, whereas high mercury levels can be harmful.
The study also delves into the neurodevelopmental risks associated with Methylmercury (MeHg) exposure, contrasting them with the neurodevelopmental benefits of essential nutrients found in fish, such as polyunsaturated fatty acids, selenium, iodine, and vitamin D. Traditional studies often measure mercury exposure through hair samples, which does not allow for differentiation between the effects of mercury and the benefits of nutrient intake. By using a more sophisticated statistical approach and considering the estimated average mercury content in the fish consumed, the researchers aimed to overcome these limitations. Data for the study were gathered from the New Bedford Cohort (NBC), which has been tracking the neurodevelopment of children born to mothers living near the New Bedford Harbor Superfund site in Massachusetts. Alongside analysing hair samples, the researchers utilised survey data from food frequency questionnaires completed by the mothers shortly after childbirth.
The findings reveal that children whose mothers consumed more fish with lower levels of mercury exhibited better neurodevelopmental outcomes, including in areas such as IQ, language, memory, and attention. Conversely, higher mercury levels in fish consumed during pregnancy were linked to poorer neurodevelopmental outcomes. However, the authors acknowledged several limitations to their study, such as the imprecise estimates of mercury levels in fish and the dietary survey measures. Additionally, the study was confined to participants from the New Bedford area and focused solely on neurodevelopmental outcomes without considering variations in the nutrient content of the consumed fish.
Dr. Korrick expressed hope that this study would improve the estimation of the risks and benefits of fish consumption, which is crucial for informed dietary choices in many health-conscious diets. The team anticipates that future research will refine this model by incorporating both the average mercury content and the nutritional profile of fish, thereby enabling more accurate public health recommendations.
More information: Sally W Thurston et al, A Novel Approach to Assessing the Joint Effects of Mercury and Fish Consumption on Neurodevelopment in the New Bedford Cohort, American Journal of Epidemiology. DOI: 10.1093/aje/kwae149
Journal information: American Journal of Epidemiology Provided by Brigham and Women’s Hospital
