Statut redox, inflammatoire et métabolique chez une population inuit : effets d'une alimentation traditionnelle riche en acides gras omega-3 et en sélénium, mais contaminée par du mercure et des biphényles polychlorés

Authors: Bélanger, Marie-Claire
Abstract: The Inuit of Nunavik are exposed by their traditional diet to environmental contaminants including methylmercury (MeHg) and polychlorinated biphenyls (PCBs), at levels potentially noxious for health. Nevertheless, this diet is rich in omega-3 fatty acids and selenium. We formulated the hypothesis that these dietary factors could have beneficial effects counteracting the potentially pro-oxidant effects of contaminants. An epidemiological study conducted in 1992 retrieved a relatively low prevalence of ischemic heart diseases and type 2 diabetes in these Inuit, maybe because of their high consumption of omega-3 fatty acids. The initiation of research on the Inuit and environmental contaminants to which they are exposed to revealed another factor that might affect their health: a high prevalence of obesity. In fact, the observation that several participants suffered from obesity lead us to carry out relevant measurements in order to assess metabolic syndrome components, the inflammatory status and endothelial function in this population, in an attempt to distinguish the potentially harmful effects linked to obesity from those linked to contaminants. The potential effects of omega-3 fatty acids on the components of the metabolic syndrome have therefore also been investigated. Our results indicate, firstly, that the observed levels of contaminants had no evident oxidant effect detectable at the level of the redox couples of vitamin E and coenzyme Q10 in these Inuit. The contaminants were nevertheless associated with an increase of low-density lipoprotein oxidation, and a stimulation of the antioxidant defenses. Besides, a positive association between omega-3 fatty acids and fasting blood glucose suggests that the introduction of a western diet rich in refined sugars could induce the expression of hyperglycemia and hyperinsulinemia phenotypes without concomitant dyslipidemia usually reported for Caucasians. In fact, the lipid profile of the Inuit remained favourable, characterized by low levels of triglycerides and free fatty acids, and high levels of HDL cholesterol. Moreover, close to half of the studied subjects presented a fasting hyperinsulinemia, without evidence of peripheral inflammation or endothelial dysfunction, which are conditions usually met in hyperinsulinemic and obese Caucasians.
Document Type: Thèse de doctorat
Issue Date: 2007
Open Access Date: 12 April 2018
Permalink: http://hdl.handle.net/20.500.11794/19071
Grantor: Université Laval
Collection:Thèses et mémoires

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