Insights from global studies

The findings of Nanri et al. diverge from much of the existing literature, which has consistently demonstrated a positive association between red and processed meat consumption and T2D risk. A large cohort study from the Harvard T.H. Chan School of Public Health found that the percentage lower risk of T2D associated with substituting 1 serving/d of nuts and legumes for total red meat was 30 % (HR = 0·70; 95 % CI 0·66, 0·74), for processed red meat was 41 % (HR = 0·59; 95 % CI 0·55, 0·64) and for unprocessed red meat was 29 % (HR = 0·71; 95 % CI 0·67, 0·75). Substituting 1 serving/d of dairy products for total, processed or unprocessed red meat was also associated with a significantly lower risk of T2D^{(Reference Gu, Drouin-Chartier and Sacks2)}. In an individual-participant federated meta-analysis involving data from 31 cohorts and 1·97 million adults with 100 000 incident cases, the cohorts were from the region of the Americas (n 12) and the Eastern Mediterranean (n 2), European (n 9), South-East Asia (n 1) and Western Pacific (n 7) regions. Greater consumption of each of the three types of meat (unprocessed red meat, 0–49 g/d for processed meat and 0–72 g/d for poultry) was associated with increased incidence of T2D, with HR of 1·10 (95 % CI 1·06, 1·15) per 100 g/d of unprocessed red meat (I ² = 61 %), 1·15 (1·11, 1·20) per 50 g/d of processed meat (I ² = 59 %) and 1·08 (1·02, 1·14) per 100 g/d of poultry (I ² = 68 %)^{(Reference Li, Bishop and Imamura3)}.

It is also worth noting that the study by Nanri et al. had a relatively small sample size (2709 participants) and a modest number of T2D cases (135), which may have limited the statistical power to detect significant associations. Larger cohort studies or meta-analyses specific to Asian populations might provide more conclusive evidence.

Methodological considerations and regional dietary patterns

Nanri et al.’s study focuses on a Japanese population, where traditional dietary patterns differ markedly from those in Western countries. The lack of a significant association between meat consumption and T2D in this cohort may reflect the relatively low baseline consumption of red meat in Japanese diets, as well as the high intake of fish and plant-based foods such as soya compared with Western populations. High intake of fish and plant-based food might mitigate some of the negative metabolic effects observed with high red meat consumption in Western diets. Additionally, the study population’s baseline health status, lifestyle factors such as physical activity and genetic predispositions could also play a role in influencing the outcomes.

A systematic review on red meat and T2D risk noted that dietary context and population-specific factors, such as genetic predispositions and overall lifestyle, can substantially influence study outcomes^{(Reference Derbyshire and Ruxton4)}.

A prospective study on French women similarly highlighted that processed red meat, but not unprocessed red meat, was associated with incident T2D, further suggesting that the specific type of meat consumed and its preparation method may be important risk modifiers^{(Reference Lajous, Tondeur and Fagherazzi5)}.

Substitution effects and preventive strategies

While Nanri et al. did not find a significant association between meat consumption and T2D risk, evidence from other regions suggests that substituting red and processed meat with plant-based proteins can reduce T2D risk. A study from the European Prospective Investigation into Cancer and Nutrition (EPIC) project reported that replacing red meat with foods like nuts, legumes or dairy products could prevent up to 8·8 % of new diabetes cases^{(Reference Ibsen, Steur and Imamura6)}. These findings underscore the potential benefits of dietary interventions that prioritise plant-based foods, which is a strategy that could be explored further in Asian populations.