Summary:
Obesity is a major global health concern, affecting a large proportion of adults and contributing to increased risk of chronic diseases such as cardiovascular disease and cancer. Environmental factors are increasingly recognised as potential contributors to obesity, including exposure to persistent organic pollutants such as dioxins and polychlorinated biphenyls (PCBs). These chemicals are widespread, accumulate in the food chain, and are primarily ingested through animal-based foods. Despite regulatory restrictions, they remain detectable in the environment and human body due to their persistence. Dioxins and PCBs can disrupt metabolic processes through multiple biological pathways. They act as endocrine-disrupting chemicals, influencing fat storage, energy balance, and hormone regulation. Some compounds interfere with fat cell development and promote abnormal fat accumulation, while others impair metabolic signalling pathways involved in appetite and energy use. Although these mechanisms suggest a potential role in obesity, findings from human studies have been inconsistent. This study is a large prospective cohort study that investigated the association between dietary exposure to dioxins and PCBs and changes in body weight and waist circumference over five years in more than 215,000 adults. Dietary exposure was estimated using food questionnaires and contamination data. The results showed that higher dietary intake of both dioxins and PCBs was associated with increases in body weight over time. Overall, the results were consistent across multiple analyses, supporting the observed relationship with weight gain. These findings suggest that ongoing exposure to environmental pollutants through the diet may contribute to weight gain, even at relatively low levels. While the observed effects were modest and subject to potential limitations, this study highlights the continued presence of these substances in the food supply and supports the need for strategies to reduce exposure as part of broader efforts to prevent obesity and related chronic diseases.
Abstract:
Background: Obesity is a growing global health concern. Some evidence suggests that exposure to polychlorinated biphenyls (PCBs) and dioxins, may play a role in weight gain, but human prospective data are limited and have shown inconsistent results. Therefore, this study investigate the association between dietary exposure to dioxins and PCBs and changes in weight and in waist circumference after 5 years of follow-up in a large prospective cohort. Method: We included 215,556 participants recruited between 1992 and 2000; of whom 99,046 provided data on waist circumference. Body weight or waist circumference were measured at recruitment and self-reported at follow-up. Intakes of dioxins and PCBs were estimated using country-specific dietary questionnaires collected at baseline, and food contamination concentrations based on a European Food Safety Authority database. Associations were estimated using multilevel mixed linear regression models. Results: Higher intake of both dioxins and dioxin-like PCBs (dioxins + DL-PCBs) (Q4vsQ1 = 0.07kg/5-years (95%CI 0.01, 0.13)), and non-dioxin like PCBs (NDL-PCBs) (Q4vsQ1 = 0.27kg/5-years (95%CI 0.20, 0.35), p-trend<0.001)) were associated with weight gain. Inverse associations were observed between dietary intake of dioxins + DL-PCBs and NDL-PCBs and waist circumference change (Q4vsQ1 = −0.44cm/5-years (95%CI -0.56, −0.31), p-trend<0.001 and Q4vsQ1 = −0.21cm/5-years (95%CI -0.34, −0.07), p-trend<0.001, respectively). These inverse associations were primarily caused by a subset of participants from one country who provided most of the waist circumference data. Results were consistent across stratified and sensitivity analyses. Conclusion: Results obtained in this large prospective study show a positive association between dietary intake of both dioxins + DL-PCBs and NDL- PCBs and weight gain. Although the observed associations were small and there may be measurement errors, the consistency of these associations across multiple stratified analyses and sensitivity analyses strengthens the validity of the findings. The findings suggest that the effect of dioxins and PCBs are still present in the food chain despite regulatory bans. Efforts should be strengthened to reduce the exposure levels in the general population not only to lower the risk of obesity, but also to prevent various chronic conditions.
Article Publication Date: 03/03/2026
DOI: 10.1016/j.clnu.2026.106619
