Daily fruit consumption may lower type 2 diabetes risk
Adults who eat two servings of fruit per day are 36% less likely to develop type 2 diabetes during 5 years of follow-up compared with those who eat less than half a serving of fruit daily, data from an observational study show.
“We found a correlation between fruit intake and markers of insulin sensitivity, meaning people who consumed more fruit had to produce less insulin to lower their blood glucose levels,” Nicola Bondonno, PhD, a postdoctoral research fellow with the Danish Cancer Society Research Centre in Copenhagen, Denmark, and the Institute for Nutrition Research at Edith Cowan University, Australia, told Healio. “This is important because hyperinsulinemia can damage blood vessels and is not only related to diabetes, but also high blood pressure, obesity and heart disease.”
In an observational study, Bondonno and colleagues analyzed data from 7,675 adults recruited for the Australian Diabetes, Obesity and Lifestyle Study, a population-based survey of diabetes prevalence and associated risk factors, from 1999 to 2000 (45% men; mean age, 54 years). Participants completed an exam and food frequency questionnaires at baseline, including questions on fruit and fruit juice intake. Exposures of interest were intakes of total fruit, individual fruits commonly consumed by participants and fruit juice. Participants indicated their usual frequency of food items during the previous 12 months, with 10 frequency response options ranging from “never” to “three or more times per day.” Researchers stratified participants by median total daily fruit intake quartiles: 53 g to 75 g per day (quartile 1; n = 1,920); 109 g to 137 g per day (quartile 2; n = 1,920); 203 g to 253 g per day (quartile 3; n = 1,918); and 325 g to 448 g per day (quartile 4; n = 1,917). Associations between fruit and fruit juice intake and baseline fasting plasma glucose, 2-hour post-load plasma glucose, fasting insulin and insulin sensitivity and presence of diabetes at follow-up (5 and 12 years) were assessed using logistic and linear regression models. The findings were published in The Journal of Clinical Endocrinology & Metabolism.
Within the cohort, the most commonly consumed fruit was apples (23%), followed by bananas (20%), and oranges and other citrus fruits (18%). All other fruits contributed less than 8% each to total fruit intake. Median total fruit intake was 162 g per day.
Of 4,674 participants at 5-year follow-up, 179 had type 2 diabetes. Of 3,518 participants at 12-year follow-up, 247 had type 2 diabetes.
Researchers found that total fruit intakes were inversely associated with serum insulin and updated homeostasis model (HOMA2) of insulin assessment of beta-cell function, and positively associated with HOMA2 of insulin sensitivity at baseline. Compared with participants with the lowest fruit intakes (quartile 1), participants with moderate total fruit intakes (quartile 3) had 36% lower odds of having type 2 diabetes at 5 years, with an OR of 0.64 (95% CI, 0.44-0.92), after adjusting for dietary and lifestyle confounders.
Associations with 12-year outcomes were not statistically significant.
“Odds ratios indicate a lower odds of diabetes for moderate to high intakes of total fruit, apples, orange and other citrus fruits, and bananas, although confidence intervals were wide and associations were not statistically significant,” the researchers wrote of associations at 12-year follow-up.
Bondonno said the findings provide evidence that consuming fruit can reduce the risk for developing diabetes by preserving insulin sensitivity, but cautioned that it was an observational study.
“Interestingly, we did not see the same patterns for fruit juice, indicating that we should focus on consuming whole fruits,” Bondonno told Healio. “While we have some hypotheses, further research is required to confirm exactly what it is in fruit that is preserving insulin sensitivity. Diabetes is a huge public health burden and numbers are on the rise. A healthy diet and lifestyle that includes the consumption of whole fruits is a great strategy to lower your risk of developing type 2 diabetes.”