NOW Calcium & Magnesium Citrate Powder with Vitamin D3 is an optimal bone structure support formula designed by NOW's certified nutritionists.* It contains key nutrients that play essential roles in bone metabolism.* The citrate forms of calcium and magnesium are highly absorbable and support not only strong bones and teeth but muscle and nerve function as well.* Vitamin D3 is included to complement calcium and magnesium and its role in the maintenance of mineral homeostasis and bone structure.* Natural color variation may occur in this product. Mix 1 1⁄2 level teaspoons of powder into at least 8 oz. of cold water or clear liquid. Add powder slowly while stirring. Take once daily with a meal. Pure calcium and magnesium citrate powders can increase the temperature of liquids upon contact; therefore, the recommended serving MUST be mixed into at least 8 oz. of cold liquid to neutralize this reaction prior to ingestion.