rBST stands for recombinant bovine somatotropin and is also sometimes referred to as rBGH or recombinant bovine growth hormone. rBST is a genetically engineered hormone originally developed and manufactured by Monsanto under the “Posilac” name. This division of Monsanto was sold to Eli Lilly and Company who continues to market rBST.

Somatotropin is a naturally occurring hormone produced in the pituitary gland of cows that normally helps with milk production. The purpose of injecting dairy cows with rBST is to enhance milk production by as much as 15%. One of the ways rBST increases milk production is by stimulating the production of another hormone called IGF-1 (Insulin Growth Factor – 1). Milk from cows treated with rBST contains higher levels of IGF-1. Humans also naturally have IGF-1. Human IGF-1 and bovine IGF-1 have nearly identical biological activity. There is growing concern that the consumption of milk from cows treated with rBST increases the IGF-1 levels in humans and is possibly related to colon and breast cancers.

In addition to the concern about increased IGF-1 levels, the other concern with use of rBST is the health effects this genetically engineered hormone causes to dairy cows. Problems have included a rise in the number of deformed calves, increases in mastitis (a bacterial infection of the udders) resulting in increased use of antibiotics, hoof diseases, open sores, calcium deficiencies and resulting bone weakness, and even death from intestinal bleeding.

Due to animal and human health concerns, many countries including the European Union, Japan, Australia and Canada have banned the use of rBST. The United States has yet to do so. However, consumers can avoid milk from cows treated with rBST by purchasing organic milk containing products. Organic regulations prohibit the use of rBST.

Baby’s Only Organic® dairy formulas and PediaSmart®Dairy Complete Nutrition beverage are USDA certified organic and made with organic milk from organic dairy herds not injected with rBST.

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