Precipitation fractionation of an aqueous extract of soybeans by addition of an organic solvent such as ethanol or molecular weight fractionation of the extract by ultrafiltration or size exclusion chromatography is appropriately combined with activated carbon filtration, cation- or anion-exchange resin treatment or other adsorbent (e.g., polyamide or octadecylsilica) treatment to provide a nicotianamine product of desired purity. The product is added to food and drink to provide health foods.