Both genetic components and environmental factors play a role in most chronic diseases, including type 2 diabetes. In the same way that researchers use a Genome-Wide Association Study (GWAS) to evaluate the role of genetic factors in disease, scientists at Stanford University have used an Environmental-Wide Association Study (EWAS) to evaluate environmental factors on diabetes.
The first-of-its-kind study appears in the May 20, 2010, issue of PLoS One, an interactive, open-access journal for peer-reviewed scientific and medical research. Over 250 environmental factors, including nutrition and exposure to bacteria, viruses, allergens and toxins, were examined to discover their contribution to the development of type 2 diabetes.
Public databases and high-speed computer analyses reconfirmed the association of PCBs with type 2 diabetes (see the related Diabetes Health article here). Protective factors associated with type 2 diabetes included beta-carotene, a precursor to vitamin A. The researchers also discovered that higher levels of γ-tocopherol, one form of vitamin E, were associated with higher likelihood of diabetes, independent of dietary intake. In the diet, γ-tocopherol is the most abundant form of vitamin E, and it composes up to 50 per cent of the total vitamin E in two known insulin-target tissues, muscle and fat. Because γ-tocopherol has been touted as a preventive agent against colon cancer, the authors caution that any potential adverse metabolic effects for this vitamin should be studied closely.
The authors conclude that “this methodology can be reconfigured to measure the relationship between environmental factors and other disorders, such as obesity, lipid level abnormalities, hypertension, and/or cardiovascular disease”.
Like genome-wide studies, the environmental-wide studies can be used to propose environmental targets for further study. Future studies can also begin to look at “gene-environment” interactions, the complex causes for disease.
The study was funded by the National Institutes of Health (NIH), “The Nation’s Medical Research Agency.” The NIH, which includes 27 Institutes and Centers, is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical, and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. In addition to the National Institute of General Medical Sciences (NIGMS), the National Library of Medicine and National Institute on Aging supported the study. NIGMS is a part of NIH that supports basic research to increase our understanding of life processes and lay the foundation for advances in disease diagnosis, treatment, and prevention.
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