Vegan Diet Reduces Breast Cancer Risk
Insulin-like growth factor I (IGF-I) is a specific type of hormone that has been linked to a potential increased risk of breast cancer. Similar to measuring cholesterol in the blood to check for heart disease risk, IGF-I is measured over time and depending on the level (i.e., more IGF-I refers to higher cancer risk) can determine cancer risk.
One study looked at women with a genetic susceptibility to cancer risk, and those with a mutation of the BRCA1 and/or BRCA2 gene (tumor suppressor genes). Apparently, those who inherit a mutation of the BRCA1/BRCA2 gene are up to 80 percent more likely to develop breast cancer within their lifetime. Researchers were trying to determine if IGF-I had a connection to breast cancer risk in women genetically susceptible, which could give insight to controlling breast cancer risk by modifying blood levels of IGF-I. Researchers observed 308 women (209 cases and 99 controls) at high genetic risk for breast cancer, and some were carriers of the altered BRCA1or BRCA2 gene. The women already diagnosed with breast cancer (referred to as “cases”) were matched to those unaffected (referred to as “controls”). By observing IGF-I levels from both groups researchers found that those with the highest levels of IGF-I had a 3.5-fold increased breast cancer risk, compared to those with the lowest. When excluding for women on hormone altering medications, like Tamoxifen, the risk was even greater, with a 3.7-fold increased risk. Women with the altered BCRA1/BCRA2 gene who had the highest levels of IGF-I were seven times more likely to develop breast cancer than those with low IGF-I levels. Researchers conclude that if larger studies can confirm these findings, women with genetic susceptibility for breast cancer will have other methods for decreasing risk, such as focusing on lowering IGF-I.
Recent studies suggest a plant-based diet can do just that. Vegetarian and vegan diets tend to be low in circulating levels of IGF-I. Diets high in a variety of fruits and vegetables can significantly reduce breast cancer development in women with BRCA mutations. Since the BRCA gene is responsible for repairing DNA, it is thought that antioxidants in fruits and vegetables can assist the DNA repair system. However, foods most know to increase IGF-I stem from animal protein animal proteins, milk, and dairy protein.
Pasanisi P, Bruno E, Venturelli E, et al. Serum levels of IGF-I and BRCA penetrance: a case control study in breast cancer families. Fam Cancer. Published ahead of print Apr 1, 2011.
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The article comes from the Cancer project, which is a collaborative effort of physicians, researchers, and nutritionists who have joined together to educate the public about the benefits of a healthy diet for cancer prevention and survival. Based in Washington, D.C., The Cancer Project is a program of the Physicians Committee for Responsible Medicine. Foodconsumer.org is not affiliated with nor sponsored by PCRM.
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