The effect of a vegetarian versus conventional hypocaloric diet on serum concentrations of persistent organic pollutants in patients with type 2 diabetes

• A randomized trial was conducted in patients with type 2 diabetes (T2D).
• The study compared vegetarian versus conventional antidiabetic diet with the same energy restriction (12 weeks).
• The β-cell function and serum levels of 24 persistent organic pollutants (POPs) were assessed.
• The change in serum concentrations of total POPs was correlated to changes in HbA1c, fasting plasma glucose level, and β-cell function.
• The correlations were independent of changes in body weight and volume of visceral fat.

Background and aimsThe aim of this study was to explore the effect of a vegetarian versus conventional diet on the serum levels of persistent organic pollutants (POPs) in patients with T2D after 12 weeks of dietary intervention and to assess their relationships with metabolic parameters.Methods and resultsMen and women with T2D were randomly assigned to follow either a vegetarian diet without fish or meat (n = 37) or an isocaloric conventional antidiabetic diet (n = 37). Both diets were energy restricted (minus 500 kcal/day). All foods were provided to the participants. At randomization (week 0) and 12 weeks, the meal test was performed to assess the β-cell function and serum levels of 24 POPs. Dioxins and dioxin-like POPs were analyzed by isotope dilution high-resolution gas chromatography (HRGC) and mass spectrometry after cleanup of the silica and carbon columns. Non-dioxin-like POPs were analyzed by gas chromatography with an electron capture detector (GC–ECD). Statistical analyses used were repeated-measures analysis of variance (ANOVA), a multivariate regression model, and Pearson's correlations.We observed a statistically nonsignificant trend toward increases in the serum levels of most POPs in response to both hypocaloric diets with no differences between groups. In the groups combined, the change in serum concentrations of total POPs was correlated to changes in HbA1c (r = +0.34; p < 0.01), fasting plasma glucose (r = +0.41; p < 0.01) levels, and β-cell function measured as insulin secretion at a reference glucose level (r = −0.37; p < 0.01), independent of the changes in body weight and volume of visceral fat.ConclusionShort-term hypocaloric vegetarian and conventional diets did not reduce the POP levels, possibly due to mobilization of fat stores. Our findings support the relationship between POPs and diabetes, especially β-cell function.Trial registrationClinicalTrials.gov number, NCT00883038, completed.