Fresh fruit and green leafy vegetables such as spinach, silver-beet, and lettuce reduce the risk of developing type-2 diabetes according to a new study published in the journal Diabetes Care. The same study also found that consumption of fruit juice may increase the risk of diabetes.

The researchers analyzed data from 71,346 healthy female nurses between the ages of 38 and 63 over an 18 year period between 1984 and 2002. Over the study period, 4,529 new cases of type-2 diabetes were diagnosed.

The researchers found that a 3-serving increase in fruit each day resulted in an 18% decreased risk of developing type-2 diabetes. Vegetable consumption as a whole was not associated with a decrease in diabetes risk, however consumption of green leafy vegetables was associated with a slight reduction in diabetes risk. Each additional serving of green leafy vegetables per day led to a 9% decrease in the risk of diabetes.

Green leafy vegetables include bok choy, cabbage, lettuce, kale, spinach, watercress, and mustard greens.

Interestingly, fruit juice consumption was linked to an increase in diabetes risk with each additional serving of fruit juice raising diabetes risk by 18%.

The researchers recommend eating fresh fruits rather than fruit juices whenever possible. In particular, people should avoid processed fruit drinks that have large amounts of added sugar as these high calorie beverages provide little nutritional benefit.

The researchers also recommend people limit their consumption of potatoes, white rice, and processed grains as heavy consumption of these foods has been linked to type-2 diabetes in some studies.

It is believed that fiber, which is naturally present in high amounts in both fruit and vegetables may be responsible for their observed benefits. Fresh fruits and vegetables are also high in antioxidants and tend to have lower glycemic index values than processed foods meaning they have a smaller impact on blood sugar levels.