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.
Vinod Patel highlights the growing evidence base that lifestyle interventions are effective, and encourages persistence even though they can be difficult.
25 May 2023