HealthDay News — Consuming more whole fruits, specifically apples, grapes and blueberries, is associated with lower type 2 diabetes risk, findings from a longitudinal observational study indicate.

Each additional three servings of whole fruit per week was significantly associated with a 2% lower odds of type 2 diabetes incidence after adjusting for dietary, lifestyle and personal risk factors, Isao Muraki, MD, PhD, from the Harvard School of Public Health in Boston, and colleagues reported in BMJ.

The benefit was greatest with blueberries, at 26% lower odds per three servings a week, according to the researchers.

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The opposite correlation was observed for the same amount of fruit juice, which significantly elevated diabetes risk 8%, and cantaloupe which correlated with a 10% higher risk.

A possible explanation for this variation may be differences in fiber content, antioxidants and phytochemicals, the researchers suggested. They added that mixed results in previous studies regarding the benefits of eating more fruit for diabetes may be because researchers did not analyze the effect of different fruits separately.

For the current study Muraki and colleagues analyzed the risk of type 2 diabetes based on fruit consumption among 66,105 women from the Nurses’ Health Study, another 85,104 from the Nurses’ Health Study II, and 36,173 men from the Health Professionals Follow-up Study. They collected data on how often participants ate various foods, as well as diabetes status using questionnaires every four years.

All participants were free of chronic diseases at baseline. During follow-up, 6.5% developed diabetes. Adjusted hazard ratios pooled across the three studies for diabetes risk per three whole fruit servings per week were as follows:

  • 0.74 for blueberries (95% confidence interval 0.66-0.83)
  • 0.88 for grapes and raisins (95% CI 0.83-0.93)
  • 0.93 for apples and pears (95% CI 0.90-0.96)
  • 0.95 for bananas (95% CI 0.91-0.98)
  • 0.95 for grapefruit (95% CI 0.91-0.99)
  • 1.10 for cantaloupe (95% CI 1.02-1.18)

Diabetes risk was neutral for peaches, plums, apricots, prunes, oranges and strawberries.

When participants substituted three servings per week of whole fruit for fruit juice, pooled results indicated an even greater benefit, with a 7% lower overall risk for any whole fruit and as much as 33% lower risk for blueberries, the researchers found.

“Greater consumption of specific whole fruits, particularly blueberries, grapes, and apples, is significantly associated with a lower risk of type 2 diabetes, whereas greater consumption of fruit juice is associated with a higher risk,” the researchers concluded.

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