medwireNews: Two prospective studies published in The BMJ add to the evidence that higher intake of fruit, vegetables, and wholegrain foods is associated with a decreased risk for developing type 2 diabetes.
The first study, by Nita Forouhi (University of Cambridge, UK) and colleagues, showed that each standard deviation (SD) increase in plasma vitamin C – used as a marker for fruit and vegetable intake – was associated with a significant 18% reduction in the risk for diabetes after adjustment for confounding factors.
The risk reduction was a significant 25% when total carotenoid levels were used to indicate fruit and vegetable intake among the 22,833 European Prospective Investigation into Cancer and Nutrition EPIC-InterAct participants studied. This included 9754 participants with verified type 2 diabetes and a randomly selected subcohort of 13,662 individuals, from an original cohort of 340,234 participants (583 individuals overlapped both groups), with an average follow-up of 9.7 years.
The researchers also created a composite score based on vitamin C and individual carotenoid levels. They found that those in the highest quintile, which corresponded to a median self-reported fruit and vegetable intake of 508 g/day, had a significant 50% lower risk for type 2 diabetes than those in the lowest quintile, corresponding to a median intake of 274 g/day.
Furthermore, each SD increase in the composite biomarker score, equivalent to a 66 g/day difference in total fruit and vegetable intake, was associated with a significant 25% reduction in the risk for type 2 diabetes.
Forouhi and co-authors say: “This would be equivalent to an absolute risk reduction of 0.95 per 1000 person years of follow up if achieved across an entire population with the characteristics of the eight European countries included in this analysis.”
They conclude that “even modestly higher fruit and vegetable consumption could help to prevent development of type 2 diabetes.”
The second report was based on data for 158,259 women and 36,525 men who participated in the Nurses’ Health Study (1984–2014), Nurses’ Health Study II (1991–2017), or Health Professionals Follow-Up Study (1986–2016).
Of these, 18,629 developed type 2 diabetes during 4,618,796 person–years of follow-up.
In this study, individuals in the highest quintile of total wholegrain consumption (median 1.9–2.8 servings/day) had a significant 29% lower risk for type 2 diabetes than those in the lowest quintile (median 0.1–0.3 servings/day).
However, Qi Sun (Harvard TH Chan School of Public Health, Boston, Massachusetts, USA) and co-investigators note that the association was non-linear and the risk reduction “slightly plateaued” at more than two servings per day.
The researchers also found that the association was stronger among lean individuals relative to those who were overweight or obese, but there was no significant difference across levels of physical activity, family history of diabetes, or smoking status.
Sun et al conclude: “These findings provide further support for the current recommendations of increasing wholegrain consumption as part of a healthy diet for the prevention of type 2 diabetes.”
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