Novel salts are prepared wherein the cation of the salt comprises a 1:1 ratio complex of a complex ion formed between manganese and an alpha amino acid, and any suitable anion, either inorganic or organic but preferably a monovalent inorganic anion. The novel salts have the formula: ##EQU1## wherein X is an anion, W is an integer equal to the anionic charge of X, and R is an alpha position moiety of an essential amino acid. The preferred amino acids are methionine and glycine. These compounds are useful nutritional supplements, both for animals and humans in that they provide a readily available source of manganese ions necessary for dietary balance. In addition, these complexed salts also provide a readily available source for certain amino acids needed in a balanced diet, such as methionine.