Meta-analysis on the health effects of processed foods

In a systematic review and meta-analysis, a higher intake of processed meat, sugar-sweetened beverages and trans fatty acids was associated with increased risk of major chronic disease such as T2D, IHD and colorectal cancer.

This summary is based on the publication of Haile D, Harding KL, McLaughlin SA, et al. - Health effects associated with consumption of processed meat, sugar-sweetened beverages and trans fatty acids: a Burden of Proof study. Nat Med. 2025 Jul;31(7):2244-2254. doi: 10.1038/s41591-025-03775-8.

Introduction and methods

Background

Consumption of ultra-processed foods, such as processed meat, sugar-sweetened beverages (SSBs) and trans fatty acids (TFAs), has been associated with an increased risk of chronic diseases [1-2]. However, uncertainty remains regarding the strength, consistency and dose–response relationships of these associations, largely due to heterogeneity across observational studies.

Aim of the study

In this systematic review and meta-analysis, the authors evaluated the associations between consumption of processed meat, SSBs and TFAs and the risk of T2D, ischemic heart disease (IHD) and colorectal cancer.

Methods

This study used the Burden of Proof methods to examine the association between processed meat and the risk of T2D, IHD and colorectal cancer; between SSBs and T2D and IHD; and between TFAs and IHD.

The number of studies and participants included for each risk-outcome association were as follows:

• Processed meat:
  • T2D: 15 prospective cohort studies and 1 nested case-control study, including 1,115,885 participants and 64,607 T2D events.
  • IHD: 11 prospective cohort studies, including 1,173,821 participants and 31,549 IHD events.
  • Colorectal cancer: 18 prospective cohort studies, including 2,678,052 participants and 30,259 colorectal cancer events.
• SSBs:
  • T2D: 18 prospective cohort studies and 1 nested case-control study, including 563,444 participants and 39,505 T2D events.
  • IHD: 8 studies, including 961,176 participants and 24,542 IHD events.
• TFAs:
  • IHD: 6 prospective cohort studies, including 26,509 individuals and 12,548 IHD events.

Nonlinear dose–response relationships were modeled using spline-based meta-regression, accounting for between-study heterogeneity and bias covariates. Conservative effect estimates were summarized using the Burden of Proof risk function (BPRF) and translated into a star-rating system reflecting evidence strength.

Main results

• Compared with no intake, consumption of processed meat (0.6–57 g/day) was associated with a ≥11% higher risk of T2D, while intake levels of 0.78–55 g/day were associated with a ≥7% higher risk of colorectal cancer.
• After accounting for between-study heterogeneity, the association between processed meat consumption and IHD was weak.
• Intake of SSBs (1.5–390 g/day) was associated with a ≥8% higher risk of T2D and, at 0–365 g/day, with a ≥2% higher risk of IHD, compared with no consumption.
• TFA consumption at 0.25–2.56% of daily energy intake was associated with ≥3% higher risk of IHD.
• Across all associations, risk increased monotonically with intake, with the steepest increases observed at low consumption levels, approximately equivalent to one serving per day or less. Most associations received two-star ratings, indicating weak or inconsistent evidence; processed meat and IHD received a one-star rating.

Conclusion

Using conservative Burden of Proof methods, this study showed that higher consumption of processed meat, SSBs and TFAs was associated with increased risk of major chronic diseases. According to the authors, “our observation that the greatest increases in disease risk occurred at low intake levels suggests that even lower levels of habitual consumption of these dietary risk factors are not safe.”

Find this article online at Nat Med.

References

1. Mendoza, K. et al. Ultra-processed foods and cardiovascular disease: analysis of three large US prospective cohorts and a systematic review and meta-analysis of prospective cohort studies. Lancet Reg. Health Am. 37, 100859 (2024).
2. Srour, B. et al. Ultra-processed food intake and risk of cardiovascular disease: prospective cohort study (NutriNet-Santé). Br. Med. J. https://doi.org/10.1136/bmj.l1451 (2019).