Eating fresh fruit every day was linked with a lower risk for diabetes and diabetes-related vascular complications in a Chinese epidemiological study that included half a million people.
Among individuals without diabetes at baseline, daily fruit consumption was associated with a 12% lower risk for getting diabetes compared to never or rarely eating fresh fruit (hazard ratio 0.88; 95% CI 0.83-0.93; P<0.001); this corresponded to a difference of 0.2 percentage points in 5-year absolute risk, said a research team led by Huaidong Du, MD, PhD, of Oxford University in England.
The study found a dose-response relationship between fresh fruit and diabetes risk, with each daily portion of fruit consumed linked to a 12% reduction in risk (HR 0.88; 95% CI 0.81-0.95; P=0.01 for trend). This association was not significantly modified by sex, age, region, survey season, or a range of other factors including smoking, alcohol consumption, physical activity, body-mass index, and family history of diabetes, Du and colleagues reported online in PLOS Medicine.
Among individuals with diabetes at baseline, eating 100 grams per day of fresh fruit was associated with lower risks of all-cause mortality (HR 0.83; 95% CI 0.74-0.93), microvascular complications (HR 0.72; 95% CI 0.61-0.87), and macrovascular complications (HR 0.87; 95% CI 0.82-0.93) (P<0.001 for trend), the study found.
“To our knowledge, this is the first large prospective study demonstrating similar inverse associations of fruit consumption with both incident diabetes and diabetic complications. These findings suggest that a higher intake of fresh fruit is potentially beneficial for primary and secondary prevention of diabetes,” Du and colleagues wrote.
Previous studies of fruit intake and diabetes risk “were conducted primarily among Western populations and tended to combine fresh fruit with processed fruit (sometimes including also fruit juice), in contrast to focusing only on fresh fruit, as in our study. This may partly explain the much stronger linear association observed in our study. In addition, the stronger association we observed might also be due to the very low level of fruit consumption among Chinese people … ” they added.
Chinese patients with diabetes tend to avoiding eating fresh fruit because of a mistaken belief that any sweet-tasting food will raise their blood sugar, Du and colleagues said. However, the study found an overall weak inverse association of fruit consumption with blood sugar, and blood glucose was very slightly lower on average among daily consumers versus non-consumers.
For clinicians, the study “reinforces the power of nutrition,” said Lauri Wright, PhD, of the University of South Florida in Tampa, in an email to MedPage Today. Wright, who was not involved in the study, is a spokesperson for the Academy of Nutrition and Dietetics.
“This may be very motivating to patients with diabetes or at risk of diabetes to know that just 1-3 servings of fruit each day may decrease the risk of developing diabetes or life-threatening complications from diabetes,” she said. “A great example of food as medicine!”
From 2004 to 2008, the investigators recruited approximately 510,000 adults ages 30-79 for inclusion in the China Kadoorie Biobank study. During about 7 years of follow up, 9,504 new cases of diabetes were recorded among the more than 480,000 participants without diabetes. Among the approximately 30,000 individuals with diabetes at baseline, 3,389 deaths, 9,746 cases of macrovascular disease, and 1,345 cases of microvascular disease were recorded. The investigators used Cox regression analysis to explore connections between these outcomes and self-reported fruit consumption.
As for the possible mechanisms underlying the study’s findings, the natural sugars in fruit may not be metabolized in the same way as refined sugars, Du and colleagues said.
In addition, fruit is a good source of dietary fiber, minerals, and antioxidants, “which may work synergistically to confer several benefits on metabolism — including anti-oxidative, anti-inflammatory, anti-proliferative, anti-platelet, anti-hypertensive, anti-dyslipidaemic, anti-hyperglycaemic, and antiatherogenic effects — and modulation of the composition and metabolic activity of gut microbiota, which could reduce the risk of diabetes as well as of vascular complications among those who have already developed diabetes,” they suggested.
Limitations of the study included that its dietary questionnaire was not validated against another reference method, and that it did not distinguish among different types of fruit the participants consumed.
The study provides “strong evidence in support of current dietary guidelines that fresh fruit consumption should be recommended for all, including those with diabetes,” the investigators concluded.
