An Australian study of more than 7000 adults suggests 2 servings of whole fruit per day helps preserve insulin sensitivity and mitigate risk for type 2 diabetes.
Consuming 2 or more servings of fruit daily vs consuming a half a serving or less reduced by 36% the odds of developing type 2 diabetes (T2D) diabetes in the next 5 years among more than 7500 Australians, according to a study published in the Journal of Clinical Endocrinology and Metabolism,
"We found an association between fruit intake and markers of insulin sensitivity, suggesting that people who consumed more fruit had to produce less insulin to lower their blood glucose levels," said Nicola Bondonno, PhD, lead investigator and adjunct lecturer at Edith Cowan University's Institute for Nutrition Research in Perth, Australia, in a statement. Maintaining low levels of circulating insulin, she added, mitigates risk for blood vessel damage and for hypertension, obesity, and heart disease, in addition to diabetes.
Although previous research has demonstrated an inverse relationship between fruit consumption and incidence of T2D, Bondonno and colleagues noted that a more specific relationship between fruit intake and measures of insulin resistance and β-cell dysfunction is not yet understood. To help characterize mechanisms by which higher fruit intake may reduce T2DM risk, the team examined associations between intake of total fruit, individual fruits commonly consumed by the study cohort, and fruit juice and measures of insulin resistance and β-cell dysfunction and incident diabetes at 5- and 12-years’ follow-up.
Participants were drawn from the national population-based Australian Diabetes, Obesity, and Lifestyle Study, a national survey of diabetes mellitus prevalence and associated risk factors in Australian adults recruited between 1999-2000 and followed until 2012. From the 11 247 who had an examination at baseline, authors excluded those without completed food frequency questionnaires, those who had diabetes at baseline, were pregnant, or were missing data for important covariates for a final cohort of 7675 participants. Among those, follow-up data were available for 4674 participants at 5 years and 3518 participants at 12 years.
Primary outcomes included measures of fasting plasma glucose (FPG), 2-hour postload plasma glucose (PLG), updated homeostasis model assessment of β-cell function (HOMA2-%β), HOMA2 of insulin sensitivity (HOMA2-%S), and fasting insulin levels obtained at baseline. The secondary outcome was incident T2DM at 5- and 12-year follow-up.
Participants in the final cohort of 7674 were 45% men, had a mean ± SD age of 54 ± 12 years at baseline, and mean BMI 26.8±4.7 kg/m2. Nearly half (48%) the group had a physical activity level classified as insufficient or sedentary.
Median total fruit intake was 162 (interquartile range [IQR], 95-283) g/day. Compared to those with the lowest total fruit intake (Q1), participants with the highest intakes (Q4) were more likely to be women, slightly older, more physically active, less disadvantaged, less likely to be smokers and were more highly educated. While those who ate more fruit had a higher total caloric intake than those who consumed less, their overall diet included more vegetables and less red/processed meat.
Analysis of data for the primary endpoint found a significant inverse relationship between total fruit intake and serum insulin and HOMA2-%β and significant positive association with HOMA2-%S. Total fruit intake was not associated with PLG or FPG.
Of the 4674 participants who had follow up at 5 years, 179 had T2D. Total fruit intake showed a nonlinear inverse association with incident diabetes at 5 years. Participants with moderate total fruit intake (Q3) had 36% lower odds of having T2D at 5 years vs those with the lowest intake (Q!). Among participants with follow-up at 12 years, odds ratios indicated lower odds of diabetes for those with moderate to high intake of total fruit and some individual fruits, but associations were not statistically significant. in Q3 and Q4
The authors point out that they did not see similar patterns for intake of fruit juice. They conclude that the findings support consumption of whole fruits, and not fruit juices, to maintain insulin sensitivity and mitigate T2D risk. “Promoting a healthy diet and lifestyle which includes the consumption of popular fruits, may lower T2DM incidence," they wrote.
Reference: Bondonno NP, Davey RJ, Murray K, et al. Associations between fruit intake and risk of diabetes in the AusDiab cohort. Published online June 3, 2021. doi:10.1210/clinem/dgab335