The invention is dietary supplements, nutraceutical compositions, medical foods, and animal feeds that have cytoprotective (cell and tissue protection) and health promoting effects. The compositions contain a high dose range of agmatine and nutraceutical acceptable salts thereof as dietary fortification for providing effective long-term cytoprotection and affording for soft stool. The compositions may contain agmatine alone or in combination with other dietary ingredients having health promoting effects. The compositions can be prepared with dietary accepted excipients and compatible forms of carriers, including but not limited to, powders, tablets, capsules, controlled release carriers, lozenges and chewable preparations, liquid suspensions, suspensions in an edible supporting matrix or foodstuff and oral rehydration solutions, to enable consumption of said compositions.