Since
soybeans contain approximately 3.5 milligrams of
isoflavones per gram of protein, and since one cup of cooked
soybeans contain about 29 grams of protein, we're talking about intake of approximately 100 milligrams of
isoflavones from 1 cup of cooked
soybeans, or an amount about 40 % less
than the supplemented amount that was found to have no impact on thyroid function.