This prospective cohort study evaluated the association between ultra-processed food (UPF) intake and the risk of incident type 2 diabetes in three large cohorts of healthcare professionals in the USA. A total of 198 636 participants were evaluated, with recruitment beginning between 1976 and 1989. All cohorts were followed up every 2 years until June 2017, including validated food frequency questionnaires every 2–4 years. According to NOVA classification, foods were categorised as unprocessed/minimally processed foods; processed culinary ingredients; processed foods; or UPFs.
Over 5 187 678 person-years of follow-up, 19 503 cases of incident type 2 diabetes were documented. After adjustment for non-dietary risk factors for type 2 diabetes, but not BMI, the hazard ratio (HR) for type 2 diabetes, comparing the highest and lowest quintiles of UPF intake, was 1.56 (95% CI, 1.47–1.65). Each one-serving increment per day was associated with a 5% increase in type 2 diabetes risk. Further adjustment for BMI at baseline attenuated the association (BMI was estimated to account for 67.4% of the correlation); however, the increased risk remained significant (HR 1.28).
There was high heterogeneity in the link between different UPF subgroups and type 2 diabetes risk, with significant increases associated with sauces, spreads, and condiments; artificially and sugar-sweetened beverages; animal-based products; ready meals; and other UPFs. In contrast, ultra-processed breads (dark and whole-grain, but not white) and cereals; packaged snacks; and yogurt and dairy-based desserts were associated with lower risk.
The authors also conducted a systematic review and meta-analysis, which included four studies as well as the present data. The pooled relative risk for type 2 diabetes in the highest versus lowest UPF quintiles was 1.40 (95% CI, 1.23–1.59). Notably, UPF intake was higher in these US cohorts (36.1% of total intake, by weight) than in the UK Biobank (22.1%) and in the French NutriNet Santé cohort (15.4%).
The authors acknowledge the limitations of cohort studies, and that the participants in this study, as well as the others included in the meta-analysis, were predominantly of white ethnicity. Nonetheless, their results support the current recommendations of limiting total UPF consumption.
Attempts to achieve remission, or at least a substantial improvement in glycaemic control, should be the initial focus at type 2 diabetes diagnosis.
9 May 2024