Walnuts have higher antioxidant levels than any other nut and are rich in polyunsaturated fatty acids, which in various studies have been associated with a reduced risk of type 2 diabetes .
To investigate the association between walnut intake and incident type 2 diabetes, researchers at the Harvard School of Public Health examined two large, 10-year cohort studies involving nearly 140,000 healthy women aged between 35 and 77 years. None of the women had diabetes, cardiovascular disease, or cancer at the outset.
After assessing consumption of walnuts and other nuts and new cases of type 2 diabetes, they found that two or more 29g servings of walnuts per week was associated with a 21% and 15% lower risk of incident type 2 diabetes before and after adjusting for body mass index (BMI), respectively.
Commenting on the findings, US diabetes and obesity expert David Katz, said: "Observational studies can't prove cause and effect, but when associations are seen in large populations, and occur in a well established context- cause and effect may reliably be inferred.
The Harvard University research appears in the Journal of Nutrition and supports a previous study published in July 2011, which showed that adding 2 ounces of unsalted nuts to a daily diet can improve blood glucose control and help lower 'bad' LDL cholesterol – a risk factor for heart disease – in people with type 2 diabetes .