Fruits, Vegetables and Whole Grains Reduce Type 2 Diabetes Risk

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Higher consumption of fruit and vegetables and whole-grain foods is associated with a lower risk of type 2 diabetes, according to a pair of studies in the British Medical Journal.

A prospective study of fruit and vegetable intake included 9754 individuals with incident type 2 diabetes, as well as a subcohort of 13,662 participants from the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct study. The study included measurement of plasma biomarkers—vitamin C and carotenoids—of fruit and vegetable intake.

In a multivariable adjusted model, participants with higher plasma vitamin C had a lower risk of type 2 diabetes: hazard ratio (HR) 0.82 per standard deviation. Higher total carotenoids were also associated with a lower risk of type 2 diabetes: HR 0.75 per SD. For a composite biomarker including vitamin C plus individual carotenoids, risk of type 2 diabetes was reduced by half (HR 0.50) for participants in the highest versus lowest quintile.

One SD difference in the composite biomarker score was associated with a 66 g/d difference in self-reported total fruit and vegetable consumption, along with a one-fourth reduction (HR 0.75) in type 2 diabetes. From a public health standpoint, the investigators conclude, “[C]onsumption of even a moderately increased amount of fruit and vegetables among populations who typically consume low levels could help to prevent type 2 diabetes.”

The second study included data on 158,259 women and 36,525 men from two Nurses’ Health Study cohorts and from the Health Professionals’ Follow-Up Study. Consumption of whole-grain foods was assessed using food frequency questionnaires. In more than 4.6 million years of follow-up, 18,629 incident cases of type 2 diabetes were identified.

With adjustment for lifestyle and dietary risk factors, participants with higher total whole-grain consumption had a consistently lower risk of type 2 diabetes. On pooled analysis, the HR for type 2 diabetes was 0.71 for participants with the highest intake of whole-grain foods, compared to the lowest level. For those consuming one or more servings of whole-grain breakfast cereal per day, the HR was 0.81. For other whole-grain foods at two or more servings per week, HRs were 0.79 for oatmeal, 0.88 for brown rice, 0.85 for added bran, and 0.88 for wheat germ.

The protective effects of whole-grain consumption were greater in participants who were lean, rather than overweight or obese. “These findings provide further support for the current recommendations that promote increased consumption of whole grain as part of a healthy diet for the prevention of type 2 diabetes,” the researchers write [Zheng J-S, et al. Association of plasma biomarkers of fruit and vegetable intake with incident type 2 diabetes: EPIC-InterAct case-cohort study in eight European countries. BMJ. 2020; 370:m2194, doi: 10.1136/bmj.m2194;; Hu Y, et al. Intake of whole grain foods and risk of type 2 diabetes: results from three prospective cohort studies. BMJ. 2020; 370: m2206, doi: 10.1136/bmj.m2206].