Abstract: [OBJECT] The object of the present invention is to provide a method for producing a food supplement in powder form to which hydrogen gas is adsorbed. [SOLUTION] Seashells have a layered structure containing CaCO3 as the principal component before calcination. Conchiolin, a protein characteristic to seashells, is sandwiched between layers to maintain a fixed shape. This protein is not removed under a usual condition. Therefore, it is inferred from analytical results described later as well that a protein-derived hydrogen gas is adsorbed and retained between layers.