A new meta-analysis of data from more than 6 million participants found that consumption of processed meat, sugar-sweetened beverages, and trans fatty acids is associated with elevated risks of several chronic diseases, including type 2 diabetes, ischemic heart disease, and colorectal cancer.
Researchers used the Burden of Proof meta-regression framework to conservatively estimate dose–response associations based on 68 cohort studies and 1 case–control study, with follow-up periods ranging from 5 to 40 years.
The strongest association was observed between processed meat consumption and type 2 diabetes. Across intake levels of 0.6 to 57 g/day, the risk increased by at least 11%. A daily intake of 50 g (about the amount in 1 sausage or hot dog) was associated with a 30% higher risk of type 2 diabetes and a 26% increased risk of colorectal cancer. These associations followed a monotonic pattern, with risk increasing consistently with higher intake.
Sugar-sweetened beverage (SSB), consumption, including sodas, sweetened teas, and fruit drinks, was associated with an 8% increase in type 2 diabetes risk and a 2% increase in ischemic heart disease (IHD) risk. Risk was elevated even at relatively low intake levels such as 250 g/day, slightly less than one standard 12-oz can of soda.
Trans fatty acids (TFAs)—mainly from industrial sources such as partially hydrogenated oils in processed and fried foods—were associated with at least a 3% increase in IHD risk across a consumption range of 0.25% to 2.56% of daily energy intake. At 2% intake, the risk increased by 20%.
Each risk–outcome relationship was evaluated using a star-based scoring system derived from log-transformed risk estimates. Most received two stars, indicating weak but consistent evidence of association. The association between processed meat and IHD received a one-star rating due to greater inconsistency and a lack of statistically significant risk at higher consumption levels (e.g., RR 1.15; 95% UI, 0.97–1.36 at 50 g/day).
Despite low star ratings, all dose–response curves showed no apparent threshold for safe intake. Risk increased even at low consumption levels, with the steepest increases observed within the lower end of each intake range.
Most studies adjusted for potential confounders, including age, sex, body mass index, smoking, and energy intake. However, residual confounding, reliance on food frequency questionnaires, and variation in study design contributed to high between-study heterogeneity and influenced the strength-of-evidence ratings.
These findings support public health policies aimed at reducing intake of processed meat, SSBs, and industrial TFAs. The World Health Organization has recommended eliminating industrial trans fats and implementing sugar taxes to curb the burden of diet-related noncommunicable diseases.
Although the observed associations were modest, the widespread consumption of these foods and their contribution to disease burden suggest that even small reductions could have meaningful health impacts. Further research is needed to clarify these associations and inform dietary guidelines.
The authors reported no conflicts of interest.
Source: nature medicine