Link between ultra-processed foods and cancer not explained by body fat: Study

Mediation analysis by European Prospective Investigation into Cancer and Nutrition (EPIC) researchers found that adiposity (body fat) explained only a small part of the association. The researchers suggested the need for further research to investigate other mechanisms that may be at play (if there is indeed any causal effect of UPF consumption on these cancers).

Among the largest prospective cohort studies in Europe, EPIC recruited half a million participants across 23 centres between 1992 and 2000. The current finding of a positive association between UPF and the two cancers noted above confirms earlier work by EPIC researchers. Ultra-processed foods are industrial formulations that use ingredients not ordinarily found in kitchens and include soft drinks, packaged snacks, reconstituted meat products, and packaged buns and breads.

The current analysis of the EPIC cohort dismisses adiposity as an explanation for how ultra-processed foods may lead to cancer.

The study was conducted by Fernanda Morales-Berstein, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK, and colleagues to investigate the role of adiposity in the associations between ultra-processed food consumption and head and neck cancer and oesophageal adenocarcinoma in the EPIC cohort.

The study included 450,111 EPIC participants. Cox regressions were used to investigate the associations between UPF consumption and the risk of HNC and OAC. Mediation analysis was performed to evaluate the role of BMI and waist-to-hip ratio (WHR) in these associations. Accidental death was investigated as a negative control outcome in sensitivity analyses.

Based on the study, the researchers reported the following findings:

· During a mean follow-up of 14.13 ± 3.98 years, 910 and 215 participants developed HNC and OAC, respectively.

· A 10% g/d higher consumption of UPFs was associated with an increased risk of HNC (hazard ratio [HR] = 1.23) and OAC (HR = 1.24).

· WHR mediated 5% of the association between the consumption of UPFs and HNC risk, while BMI and WHR, respectively, mediated 13% and 15% of the association between the consumption of UPFs and OAC risk.

· UPF consumption was positively associated with accidental death in the negative control analysis.

"We reaffirmed that intake of ultra-processed foods is associated with an increased risk of oesophageal adenocarcinoma and head and neck cancer in the EPCI Study," the researchers wrote. "Since body mass index and waist-to-hip ratio explain little of the associations between UPF consumption and upper-aerodigestive tract cancers, there is a need for further research to investigate other mechanisms that may be at play."

According to the authors, the findings are likely influenced by residual confounding, as indicated by the negative control analysis.

"Therefore, our findings should be regarded with caution until their replication in other settings (i.e. in populations with different underlying confounding structures) or triangulation with evidence obtained using other methodological approaches," they concluded.

Reference:

Morales-Berstein, F., Biessy, C., Viallon, V. et al. Ultra-processed foods, adiposity and risk of head and neck cancer and oesophageal adenocarcinoma in the European Prospective Investigation into Cancer and Nutrition study: a mediation analysis. Eur J Nutr (2023). https://doi.org/10.1007/s00394-023-03270-1