B Vitamins

The B-complex vitamins are found in brewer's yeast, liver, whole-grain cereals, rice, nuts, milk, eggs, meats, fish, fruits, leafy green vegetables and many other foods. Keep reading for more specifics about each of the B vitamins:

Thiamine (B1)

The B vitamin thiamine is essential for the metabolism of carbohydrates into the simple sugar glucose. The chemical process involves the combination of thiamine with pyruvic acid to form a coenzyme, a substance that, when combined with other substances, forms an enzyme. Enzymes are those all-important proteins that speed up chemical reactions in the body. Thiamine is also important for the proper functioning of the nervous system. In this instance, thiamine acts as a coenzyme in the production of the neurotransmitter (chemical messenger between nerve fibers) acetylcholine.

Thiamine deficiency is rare but often occurs in alcoholics, because alcohol interferes with the absorption of thiamine through the intestines. There are several health problems associated with a deficiency of thiamine. The first is beriberi, a disease that is characterized by anemia, paralysis, muscular atrophy and weakness, and spasms in the muscles of the legs. Other disorders caused by thiamine deficiency include Wernicke's encephelopathy, which causes lack of coordination, and Korsakoff's psychosis, which affects short-term memory. The mouth can also be affected by thiamine deficiency, increasing the sensitivity of the teeth, cheeks and gums, as well as "cracks" in the lips. Fortunately, these conditions can be reversed with the addition of the vitamin.

Thiamine is found in whole-grain cereals, bread, red meat, egg yolks, green leafy vegetables, legumes, sweet corn, brown rice, berries, yeast, the germ and husks of grains and nuts. Mega-doses (very high doses) of thiamine have not been associated with adverse health effects, and excess of the water-soluble vitamin is excreted.