This invention relates to solid oral compositions based on SAMe and/or NADH or their salts in association with calcium oxide and/or calcium hydroxide and a process for obtaining them. This invention also relates to a method for stabilising a solid oral composition based on SAMe and/or NADH or their salts, making use of calcium oxide, calcium hydroxide optionally in association with malic acid, glutamic acid, xylitol, calcium sulphate hemihydrate, magnesium oxide and/or mixtures thereof. This invention also relates to the use of SAMe or its salts in association with calcium oxide and/or calcium hydroxide with the possible further addition of melatonin and/or 1-theanine and/or 1-tryptophan and/or 5-hydroxytryptophan for the treatment of depressive states.