An unsolved puzzle: the complex interplay between methylmercury and fish oil-derived fatty acids within the cardiovascular system

Methylmercury (MeHg), a toxic pollutant generated by the methylation of inorganic mercury in the aquatic environment, is bioaccumulated and biomagnified through the aquatic food chain, reaching high concentrations in certain fish species. Accordingly, human exposure to MeHg mainly occurs due to the ingestion of contaminated fish. Although it is well known that the central nervous system represents an important target of the deleterious effects of MeHg, both experimental and epidemiological evidence indicates that MeHg exposure can also lead to cardiovascular dysfunction. Nevertheless, fish-derived n-3 polyunsaturated fatty acids (n-3 PUFAs), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have been reported to decrease the risk of cardiovascular disease development. In this scenario, although there seems to be antagonism between MeHg and fish-derived n-3 PUFAs concerning the cardiovascular system, the benefits and risks related to seafood consumption remain under debate, and the available (basic and epidemiological) literature does not provide a quantitative assessment of the benefit-risk relationship of n-3 PUFA intake and MeHg exposure. This review delves into the intricate interplay between MeHg and fish-derived n-3 PUFAs, pointing to specific research topics that deserve additional attention to improve the knowledge concerning the benefits and risks of fish consumption on the cardiovascular system.