Kan eksponering for persistente organiske miljøgifter øke risiko for metabolsk syndrom? En litteraturgjennomgang av eksisterende forskning på sammenhengen mellom miljøgifter og metabolsk syndrom

Abstract

Metabolic syndrome (MetS) is a clustering of abdominal obesity, elevated blood pressure, insulin resistance, dyslipidemia, and is associated with diabetes mellitus type 2 and cardiovascular disease. The prevalence of MetS is continuously increasing worldwide. Several hypotheses have been proposed for the etiology of MetS, including dietary factors, obesity and sedentary lifestyles. Persistent organic pollutants (POPs) such as dioxins (PCDDs) and dioxin-like polychlorinated biphenyls (PCBs) might also contribute to the etiology of MetS and its augmented incidence in recent years. Human exposure to POPs primarily derives from food, particularly from fatty fish consumption. This project thesis provides a review of relevant scientific literature regarding POPs and their potential role in the development of MetS. Twenty-two epidemiological studies and nineteen experimental studies on the relationship between both dioxin-like and non-dioxin-like POPs and MetS components are included in this project thesis. Depending on the MetS definition, a few epidemiological studies have shown significant correlations between POP exposure and MetS components. However, because of uncertainties stemming from confounding factors and lack of randomization, causality cannot be determined. Although experimental animal studies have suggested a cause-and-effect relationship between single components of MetS and POPs, the results are not reliable enough in terms of establishing maximum tolerated doses or a causal conclusion. Additionally, the findings may not be applicable to humans due to species-specific differences. Even given these factors, dietary guidelines should still take the precautionary principle into account as existing associations between POP exposure and MetS may ultimately prove correlative. Further investigations are needed to demonstrate causality and the underlying mechanisms.