Tofu

Tofu is made by coagulating soy milk (usually with calcium or magnesium salts) and pressing the curds. Firmer tofu has more water pressed out, concentrating protein and calcium per gram; silken tofu retains more water and is closer in texture to custard. A 3oz serving of firm tofu provides ~8g of complete protein, ~150mg of calcium (when set with calcium sulfate), and modest amounts of iron and magnesium.

Soy isoflavones — the persistent worry

Tofu contains isoflavones (genistein, daidzein) — plant compounds that weakly bind estrogen receptors. Despite decades of "soy raises estrogen" worry, large prospective cohorts and clinical trials have not shown harmful effects at culinary doses. Current evidence suggests modest benefits for cholesterol (lowering LDL by a few percent), menopausal hot flashes, and possibly breast cancer outcomes in survivors. Major bodies (American Cancer Society, American Heart Association) consider whole soy foods including tofu safe and likely beneficial.

FODMAPs and digestion

Most of the FODMAPs in soybeans are washed away with the whey during tofu-making. Firm and extra-firm tofu are Monash-rated low-FODMAP at typical serving sizes — useful for people with IBS who otherwise struggle with legumes. Silken tofu retains more of the original soy water and can carry more GOS; portions matter more there.

For people with documented soy allergy, all tofu is off-limits. For everyone else, tofu is one of the more flexible protein sources to integrate into a plant-forward diet without losing protein quality.