Fresh fruit and vegetables – underused option for prevention and “treatment” of type 2 diabetes

Three summary reports in this issue emphasize the benefit of fresh fruit and vegetables (F&V) in the prevention and “treatment” of type 2 diabetes. Franziska Jannasch and co-authors summarize the main results of their systematic review and meta-analysis on different dietary patterns in prevention of diabetes. Three different patterns had beneficial impact; Mediterranean type, DASH (Dietary Approach to Stop Hypertension) and AHEI (Alternative Healthy Eating Index) diets were associated with 13 to 20 % reduction of diabetes. Intriguingly, both low and high fat (Mediterranean type diet) diets seem to decrease the risk of type 2 diabetes. These observational findings are in line with longterm follow results obtained from type 2 diabetes prevention trials where diet has been moderately low in fat but counselling encouraged increasing use of fruit, vegetables and whole grains.

In a large Chinese study published recently by Huaidong Hu, fresh fruit consumption was associated with 12% lower risk of incident diabetes in people who were non-diabetic at the onset of the study. Furthermore, a lower risk of total mortality, cardiovascular diseases and microvascular complications was observed among diabetic patients who used fresh fruit regularly at the onset of follow-up. Curiously, patients with known diabetes used less fresh fruit than individuals without diabetes.

Richard Bryce reports about the health effects of a farmers’ market fruit and vegetable prescription program in type 2 diabetic patients with poor glycemic control. Interestingly, there was a significant decrease in hemoglobin HbA1c. The reduction in HbA1c (average 0.7 % units) is of clinical significance and is comparable to that reported to achieve with many diabetes drugs. Unfortunately, interest to participate remained quite low among those invited, and control group was missing. Nevertheless, the results suggest that cheap and innovative dietary approaches are needed to improve glycemic control in patients with type 2 diabetes.

F&V are rich in nutrients, vitamins and minerals, and they are important sources of dietary fiber and other non-nutritive compounds that may play a role in the prevention of chronic diseases. Besides F&V, whole grains and berries, used plenty e.g. in Nordic countries, have beneficial health effects. Replacing unhealthier food choices rich in saturated fats and processed meat products by fruit, vegetables and whole grain products has per se beneficial health effects. Furthermore, health impact may also originate from anti-oxidative and anti-inflammatory effects of F&V, and changes in gut microbiota may also play a role. Plenty of novel compounds are being recovered from human biological samples that are involved in health benefits of vegetable food.