Thiamin (vitamin B1) acts as a coenzyme for certain chemical reactions in the body. This means that it works along with enzymes, the catalysts for those reactions. Thiamin deficiency is called beriberi and affects primarily the heart and the nervous system. In the United States it occurs mainly in alcoholics, whereas in developing countries it occurs in people consuming mostly refined white flour or white rice. One study whose results have not been replicated showed lower blood levels of thiamin in glaucoma patients than in people without glaucoma. Good sources of thiamin include whole or fortified grains, legumes (beans, peas, and lentils), nuts and seeds, and brewer’s yeast.
