A new study published in the 27th November 2002 issue of the Journal of the American Medical Association says that consuming one tablespoon of peanut butter or 28g of peanuts or other nuts five or more times a week is associated with a 20–30 percent reduced risk of developing Type 2 diabetes.
The study involved over 83,000 female nurses who were followed for an average of 16 years in the Brigham and Women’s Hospital–based Nurses’ Health Study. The women in the study completed food frequency questionnaires approximately every four years between 1980 and 1996, and had no history of diabetes, cardiovascular disease, or cancer.
The researchers from the Harvard School of Public Health concluded that women who eat nuts regularly can reduce their risk of developing Type 2 diabetes. Furthermore, the relationship between consuming peanut butter, peanuts, and diabetes is linear – higher consumption provided a greater protective effect. The group of women consuming a half serving of peanut butter or a full serving of peanuts and other nuts one to four times per week had a 15 percent reduced risk of developing the disease.
Dr. Frank Hu, associate professor of Nutrition and Epidemiology at Harvard School of Public Health and an author of the study, said:
“Given the observed inverse association between nuts and risk of coronary heart disease as well as type 2 diabetes, it is advisable to recommend regular peanut butter and nut consumption as a replacement for refined grain products or red or processed meats, which would avoid increasing caloric intake.”
Peanuts contain mainly unsaturated fat and are low in saturated fat, characteristics which lower risk of type 2 diabetes. Many peanut butters contain a high proportion of unsaturated fat, a very small amount of salt and sugar for taste, and have undetectable levels of trans fats even though labels list partially hydrogenated oil as a minor ingredient.
Nuts also contain fiber and magnesium, which decrease insulin resistance and have been inversely associated with risk of type 2 diabetes. Peanuts have more plant protein than any other nut. They are also rich in vitamin E, folate, potassium, zinc, phytosterols, and antioxidants, which are thought to be important to health.
The study is published in the 27 November issue of the Journal of the American Medical Association.
Because peanuts are rich in monounsaturated fats (MUFA), they found that total and LDL cholesterol was lowered by 11–14%. The peanut diets reduced the risk of cardiovascular disease by 21% compared to the average American diet, whereas a low-fat diet reduced the risk by only 12%.
Peanuts and peanut products also contain the phytosterol beta-sitosterol (SIT), which has been shown to inhibit cancer growth and protect against heart disease. SIT may offer protection from colon, prostate and breast cancer, all of which tend to occur at higher rates in Americans than in other populations. This exciting new research was recently published in the journal Nutrition and Cancer. In addition, The Journal of Nutrition review of phytosterols as anticancer dietary components concludes:
“The best dietary sources of phytosterols are unrefined plant oils, seeds, nuts, and legumes.”
In addition to a significant amount of phytosterols and heart-healthy monounsaturated fat, peanuts and peanut butter also contain vitamin E, folate, potassium, magnesium, zinc, and fiber, all of which are thought to benefit health.
The Peanut Institute is a non-profit organization that supports nutrition research and develops educational programs to encourage healthful lifestyles. The Purdue study was funded by the U.S. Agency for International Development.