An independent Japanese isoflavone analysis of people who ate up to 50 grams per day of soy protein, the most it seems one human being can eat in a day, and the most that lowers your LDL — finds that it’s not just the protein. 50 grams of soy protein with low isoflavones (just 6 mg per day) barely dents the LDL. But 50 grams of soy protein rich in isoflavones (96 mg per day) knocks it out of the park, dropping your LDL signfificantly. So, isoflavones may have LDL cholesterol-lowering effects independent of soy protein.
Isoflavones are natural phytoestrogens–compounds in plants that are chemically active. Where soy is grown and how it is processed changes how much isoflavone is in soy foods, whether beans, bars or shakes. Isoflavones can be washed away during alcohol extraction. Soy sauce and soybean oil have no isoflavones. Soy protein concentrate might or might not contain isoflavones.
But tofu, soy milk, tempeh and miso are rich sources of isoflavones: about 30 to 40 milligrams per serving. Find more foods are rich in isoflavones.