Terrific Tofu! Soy Strikes Again
That could explain it, says Hauxi Xu, PhD, "but this is very preliminary and definitely requires more careful study before you can conclude anything." Xu, an assistant professor at the Fisher Center for Alzheimer's Research at Rockefeller University in New York, was not involved in the study.
The mechanisms may be mysterious, but the end results are clear, Kim says. Eating soy isoflavones meant fewer tau changes in these monkeys. Now the real question is whether that reduction translates to less dementia in human beings.
"The link between soy consumption and improved [thought] function has not been made," Maki says. "That's not to say that it doesn't exist, it just hasn't been done yet."
Kim agrees. "We cannot make any simple statement about the relation between reduction in tau [changes] and future ... impairment" in thinking or cognition, Kim says. Experts do know, however, that rats that have had their ovaries removed "don't learn as well and don't remember as well. And giving them either pure estrogen or soy isoflavones prevents these deficits," she says.
While the jury may be out on the long-term benefits of soy on cognitive, or thinking, skills, the experts agree that you really can't go wrong adding soy to your diet. "Soy protein in and of itself is good for you," Kim says.
No longer a health food store exclusive, soy is now available at your local supermarket, and there's a formulation to please every taste. Options include crunchy soy nuts, flavored and unflavored soy milk to drink on its own or over cereal, soy-based meat substitutes, and even tofu-based frozen treats.
"You can do a lot by simply buying a block of tofu," Kim says. "You can substitute it for the ricotta in lasagna, for some of the cream cheese in cheesecake, and the really soft kind can be blended with fruit into delicious smoothies," she says. Dietary guidelines currently suggest that adults eat 20-25 g of soy protein daily.
Kim's preliminary findings appeared in the journal Biofactors.The current study is ongoing, with 36 of the monkeys still under investigation. "We haven't looked at [soy's effect on] beta-amyloid yet, but that's definitely something we're going to do," she says.