Written by Chrystal Moulton, Staff Writer. Researchers have found that two servings of whole grains per day are associated with a 21% decrease in the risk of developing type 2 diabetes.
Type 2 diabetes is the most common form of diabetes in the United States. Currently 90-95% of 26 million cases of diabetes in the United States are type 2 diabetes, which is characterized by the cells inability to absorb sugar from the bloodstream despite the presence of insulin.(1)
Consumption of whole grains have long been associated with reduced risk in developing chronic diseases including diabetes.(2-4) Large prospective studies such as the Nurse’s Health Study, documented the effects of whole grain consumption on the development of diabetes and other chronic diseases. Within that study, researchers found that 2 servings/day of whole grains was associated with a 21% decrease in the risk of developing type 2 diabetes. (3)
The Stockholm Diabetes Prevention Program(5) is a prospective study based on the Swedish population. Women and men aged 35-56 without diabetes were enrolled between 1992 and 1998. At the beginning, all subjects were given a health examination measuring height, weight, and blood pressure, and a glucose tolerance test was also given. Participants also completed a Food Frequency Questionnaire (to determine whole grains consumed regularly) and a questionnaire on lifestyle factors (including smoking, physical activity, alcohol intake, and socioeconomic status). All subjects who completed both questionnaires were included into the study. By design, 50% of participants included had a family history of diabetes. Also, whole grain food was defined as food containing ≥50% of whole grain/serving (i.e., crisp bread, whole-meal bread, oatmeal, and muesli). A follow up study was performed in women 8 years after starting the study and in men 10 years after starting.
The researchers established two samples from the study. Sample 1 were participants with either normal glucose tolerance or pre-diabetes (defined as impaired glucose tolerance, impaired fasting glycemia or a combination of both) at the beginning of the study with deteriorated glucose tolerance by the end of the study at follow up (272 women and 429 men). Sample 2 is a subgroup of sample 1 that includes only participants with normal glucose tolerance at baseline who developed either type 2 diabetes (57 women and 108 men) or prediabetic symptoms (174 women and 250 men) at follow up.
There was a total of 5,477 participants who completed the study. Results showed that about 12% (701) of the total subjects had deteriorated glucose tolerance by the end of the study. At follow up, 424 subjects with normal glucose tolerance developed prediabetic symptoms and 165 with normal glucose tolerance developed type 2 diabetes. The rate of development was higher in men (18.7%) than in women (8.6%). Furthermore, while comparing baseline characteristics of samples to its results, researchers found that whole grain consumption was associated with a lower incidence of developing type 2 diabetes or prediabetic symptoms. In particular, intake of whole grain greater than 59g/d (after ruling out other factors that may contribute to development of diabetes) was significantly associated with a 38% decreased risk of developing prediabetic symptoms or type 2 diabetes. When these results were compared with the association between cereal fiber and development of type 2 diabetes, whole grains was more significantly correlated with a reduction in diabetes progression than cereal fibers in all groups. Researchers also evaluated a subset of males known to have genes that make them more susceptible to developing diabetes. In those with the risk genotype, consumption of whole grains showed no effect on the development of type 2 diabetes. However, in men with the non-risk genotype, high intakes of whole grains were associated with a decreased risk of developing type 2 diabetes.
In all, researchers in the Stockholm study emphasized that consumption of whole grain is associated with reduce risk of prediabetes and type 2 diabetes. Researchers also attempted to determine a genetic link to development of type 2 diabetes and whole grain consumption. More studies are needed to explain how various factors along with diet link to type 2 diabetes.
Source: Wirström, Tina, et al. “Consumption of whole grain reduces risk of deteriorating glucose tolerance, including progression to prediabetes.” The American journal of clinical nutrition 97.1 (2013): 179-187.
© 2013 American Society for Nutrition
Posted January 7, 2013.
Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.
References:
Type 2 Diabetes Overview. Available at: http://diabetes.webmd.com/guide/type-2-diabetes Accessed January 1, 2013.
- Whole-grain, cereal fiber, bran, and germ intake and the risks of all-cause and cardiovascular disease-specific mortality among women with type 2 diabetes mellitus. He M, van Dam RM, Rimm E, et al. Circulation. 2010 May 25;121(20):2162-8.
- Whole grain, bran, and germ intake and risk of type 2 diabetes: a prospective cohort study and systematic review. de Munter JS, Hu FB, Spiegelman D, et al. PLoS Med. 2007 Aug;4(8):e261.
- Whole grain foods for the prevention of type 2 diabetes mellitus. Priebe MG, van Binsbergen JJ, de Vos R, et al. Cochrane Database Syst Rev. 2008 Jan 23;(1):CD006061.
- Consumption of whole grain reduces risk of deteriorating glucose tolerance, including progression to prediabetes. Wirström T, Hilding A, Gu HF, et al. Am J Clin Nutr. 2012 Dec 12. [Epub ahead of print].
