Googling produces a ton of results, but here's one that looks pretty reputable (USDA, based off many other studies): http://www.sciencedaily.com/releases/2001/0

Googling produces a ton of results, but here's one that looks pretty reputable (USDA, based off many other studies): http://www.sciencedaily.com/releases/2001/05/010511074623.htm http://www.sciencedaily.com/releases/2001/05/010511074623.ht...