Human and bovine milk (supplement or non-supplemented) normally contain small amounts of growth hormone. After ingestion, growth hormone is handled by the gut as any other protein in milk: it is digested into its constituent amino acids and di- and tripeptides. There are no data to suggest that rBST present in milk will survive digestion or produce unique peptide fragments that might have biological effects. Even if rBST is absorbed intact, the growth hormone receptors in the human do not recognize rBST and, therefore, rBST cannot produce effects in humans. (National Institutes of Health Technology Assessment Conference Statement, December 5-7, 1990)
Conventional, rbST-free and organic milk are compositionally similar; they have the same nutrient composition and the same trace levels of hormones regardless of the milk production method used. In fact, such milk label claims are not related to any meaningful differences in the milk's composition of fat, protein or vitamins and minerals. Because of the lack of a difference in the milk, no scientifically proven test exists that can identify how the milk was produced or whether or not rbST was used. (Vicini J et al. Survey of retail milk composition as affected by label claims regarding farm management practice. J Am Diet Assoc. 2008 Jul;108(7):1198-203.)
Drinking milk does not increase breast cancer risk, regardless of whether the milk is organic, rbST-free or conventional. There are many peer-reviewed studies that show no association between consumption of milk and incidence of breast cancer. A recent report that reviewed more than 40 case-control and 12 cohort studies concluded that evidence "does not support an association between dairy product consumption and the risk of breast cancer." (Parodi PW. Dairy product consumption and the risk of breast cancer. J Am Coll Nutr. 2005 Dec;24(6 Suppl):556S-68S.)
When it comes to food, it's personal. Yet, decisions about what foods to eat should also be based on the best information and the best science available. Let's work together to help women make wise choices about their health and nutrition, and give them a complete picture of the issues that relate to dairy foods and dairy consumption. We'll all be healthier for it.
Lloyd Metzger, PhD, Brookings, South Dakota
Thank you for "This Is What 62 Looks Like" in the February issue. I am precisely 62, and really enjoy seeing someone my own age. You help me feel relevant!
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