WINSTON-SALEM -- Scientists at Wake Forest University School of Medicine are beginning a five-year study to determine which ingredients in soybeans are the active ones in protecting against heart disease, stroke, cancer and osteoporosis.
Under a new $2.4 million grant from the National Heart, Lung and Blood Institute, the research team, headed by Thomas B. Clarkson, D.V.M., will focus on two isoflavones (also called phytoestrogens -- plant estrogens) in soy: genistein and daidzein.
Clarkson, professor of pathology (comparative medicine), said he is seeking to identify the optimum doses and ratios of genistein to daidzein.
He said, "We have obtained preliminary evidence suggesting that predominantly daidzein rather than predominantly genistein may be of greater cardiovascular benefit."
Genistein is the predominant phytoestrogen in the outer portion of soybeans. Daidzein predominates in the germ of the soybean, he said. (Soy resembles wheat in that respect -- most people want whole wheat, but wheat germ also is available, and some prefer that.) The outer portion is 3 to 1 genistein; the germ is 4 to 1 daidzein.
Most studies so far have focused on genistein as the active ingredient in preventing cardiovascular diseases and cancer.
The comparison between different ratios of daidzein and genistein is just one phase of the project which will "explore several unanswered questions concerning the optimal use of soy supplements by both males and females."
Clarkson said he hopes to pin down just how much soy is needed for the optimum preventive dose of phytoestrogen and the optimum therapeutic dose. (The preventive dose is usually much smaller than the therapeutic dose, in which the active ingredients of the food essentially act as a drug.)
And the research team is looking at safety issues as well: how safe is
soy for the breasts and uteri of females and what effect,
Contact: Robert Conn, Mark Wright or Jim Steele
Wake Forest University Baptist Medical Center