European researchers say that low doses of food contaminants such as BPA, phthalates, dioxins, and PCBs, could hasten or worsen certain metabolic problems caused by a high-fat diet.
In the study, the researchers fed mice a high-fat diet to which low doses of contaminants had been added. Two environmentally persistent contaminants (dioxin and PCB) and two non-persistent contaminants (phthalate and BPA) were used. Importantly, the doses were low and considered not to have any health impacts. In parallel, a control group of mice was fed with the same high-fat diet, but without the added contaminants.
The researchers then ran glucose tolerance and insulin sensitivity tests. They measured the livers for lipid accumulation and the expression of certain genes that play key roles in the metabolism of the adult mice.
The results showed that the effects are highly dependent on gender. In the females fed with a high-fat diet, the addition of contaminants worsened the glucose intolerance and altered the estrogen pathway. In males, it altered the cholesterol and lipid metabolism. There was no change in weight between the exposed mice and the unexposed mice.
The researchers say there is a connection between the observed glucose intolerance and the alteration in estrogen signaling in exposed females. Estrogens protect against metabolic disorders, but the findings suggest that in obese females, exposure to contaminants lowers the protection level that estrogens provide against metabolic disorders.
"With this study, we have succeeded in providing proof-of-concept that low doses of contaminants, even at levels normally considered to be without health impacts in humans, do in fact affect humans when subjected to chronic exposure, and when the contaminants are combined with a high-calorie diet," concluded researcher Brigitte Le Magueresse Battistoni.
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Source: FASEB Journal