Brussels sprout supplements are concentrated extracts or powders, not the whole vegetable. Manufacturers standardize them for glucosinolates, compounds that trigger phase II detoxification enzymes in the body. This delivers a dose you can't easily get from eating the sprouts themselves. Still, clinical proof for specific health effects remains slim.
People often take these for general antioxidant support, though the benefits rely on basic chemistry rather than solid outcome studies. Taking the supplement with food can help prevent stomach upset. Some formulas add the enzyme myrosinase to boost conversion into sulforaphane.
Watch out for the goitrogens found in all cruciferous vegetables. In raw or concentrated forms they can disrupt thyroid function, so anyone with a thyroid condition or low iodine intake should be careful. Even in supplement form, leftover fiber and raffinose can cause gas and bloating.