Yes. http://www.ncbi.nlm.nih.gov/pubmed/17413101 http://www.ncbi.nlm.nih.gov/pubmed/1989409 http://www.ncbi.nlm.nih.gov/pubmed/1734671 http://www.ncbi.nlm.nih.gov/pubmed/8968851

Also: http://ajcn.nutrition.org/content/79/5/899S.long