The present invention relates to a slow-release solid oral nutraceutical and/or pharmaceutical composition comprising: a core containing a donor of methyl groups and at least one pharmaceutically acceptable excipient, and an outer coating containing shellac and/or a pharmaceutically acceptable salt thereof, magnesium stearate, and at least one pharmaceutically acceptable excipient. The coating of said solid oral composition allows the donor of methyl groups, preferably SAMe and/or a pharmaceutically acceptable salt thereof, to cross intact the gastric barrier and release the same in a continuous and complete manner along the entire digestive tract.