Low-carbohydrate diets high in plant based protein and fat may be better than traditional low fat, high carbohydrate diets at reducing the risk of diabetes according to a new study published in the February 2008 edition of The American Journal of Clinical Nutrition.

The researchers used data from the Nurses’ Health Study which followed over 85,000 women over a 20 year period. The researchers examined the association between the percentage of energy intake from carbohydrates and the probability of developing diabetes.

During the study, 4670 of of the women developed diabetes. The researchers found that low-carbohydrate diets, in particular those with vegetable based sources of protein and fat rather than meat based sources reduced diabetes risk by the greatest amount. Overall, low-carbohydrate diets reduced diabetes risk by around 10 percent. Low-carbohydrate diets rich in plant based sources of protein and fat reduced diabetes risk by almost 20 percent. In contrast low-carbohydrate diets rich in animal based protein and fat had no reduction in diabetes risk.

Furthermore, the researchers found that those women who consumed diets high in carbohydrates were much more likely to develop diabetes with those in the highest 10% for carbohydrate consumption 26 percent more likely to develop diabetes than those in the lowest 10% for carbohydrate consumption.

The study also found an association between glycemic load and the probability of developing diabetes. Those diets in the highest decile for glycemic load were over twice as likely to develop diabetes as those in the lowest decile. Foods with a high glycemic load lead to a larger and more sustained spike in blood glucose levels.

According to lead author Thomas Halton of the Department of Nutrition at the Harvard School of Public Health in Boston: “One study is never enough to change a recommendation, but this study is interesting in that it shows that a low-fat diet is no better than a low-carbohydrate diet in preventing type 2 diabetes. The one diet that did seem to show a protective effect was a vegetable-based, low-carb diet which consisted of higher amounts of vegetable fat and vegetable protein, and lower amounts of carbohydrate.”