Q. Ive read numerous articles about the benefits of drinking coffee; however, none of them addresses whether these benefits are affected when milk is added. What about soy milk?

A. Jeffrey B. Blumberg, PhD, director of Tufts HNRCA Antioxidants Research Laboratory, replies: Casein, the protein in cows milk, does bind to chlorogenic acids, the principal bioactive constituents of coffee (other than caffeine). Depending on the amount of milk added to the coffee, this may decrease the absorption of chlorogenic acids into the body, although its ultimate impact on antioxidant activity or other actions is not clear. There do not appear to be any human studies investigating the possible interactions between soy milk and chlorogenic acids. While the protein present in soy and other plant-based milks is different than casein, the available evidence suggests that protein may not hinder the putative benefits of coffee. For more on plant-based milks, see this issues Special Report.