Increased thiamine intake may be suggested for numerous mental illnesses and problems that affect the nerves. These include alcoholism and its nerve problems, multiple sclerosis, Bell's palsy (a facial nerve paralysis), and neuritis. Treatment with thiamine, for example, has been helpful in decreasing the sensory neuropathy that accompanies diabetes and in lessening the pain of trigeminal neuralgia. Thiamine also has a mild diuretic effect and is supportive of heart function, so it is suggested in the treatment program for many cardiovascular problems.

Since thiamine is eliminated through the skin somewhat, doses of over 50-100 mg. per day may help repel insects such as flies and mosquitos from those with "sweet blood." Other uses for increased thiamine include treatment of stress and muscle tensions, diarrhea, fever and infections, cramps, and headaches.

Deficiency and toxicity: There is no known toxicity in humans from thiamine taken orally. People have taken hundreds of milligrams daily without any harmful effect, although some may become more stimulated than others. Thiamine injections, however, have occasionally been associated with trauma or edema.

Prolonged restriction of thiamine intake may produce a wide variety of symptoms, particularly affecting the general disposition, nervous system, gastrointestinal tract, and heart. With thiamine deficiency, as with deficiency of most any essential nutrient, symptoms range from mild to moderate depletion disorders to the serious disease state that RDA amounts usually prevent.

Beriberi is the name given to the disease caused by thiamine deficiency. There are three basic expressions of beriberi, namely childhood, wet, and dry beriberi. Childhood beriberi stunts the growth process, and in infants high-pitched scream and rapid heartbeat are associated with the disease. Wet beriberi is the classic form with edema (swelling) in the feet and legs, spreading to the body, and associated decreased function of the heart. Dry beriberi is not accompanied by swelling but seems to be manifested by weight loss, muscle wasting, and nerve degeneration. Another thiamine deficiency disease involves degeneration of the brain and affects the general orientation, attitude, and ability to walk. This has been termed the Wernicke-Korsakoff syndrome and is usually seen in people who have been addicted to alcohol for many years.

These severe problems can and do lead to death when they are not corrected with dietary change or supplemental thiamine. Before vitamin B1 was discovered, this affected many people who ate a diet consisting mainly of polished rice. Today, deficiency of this vitamin is still quite common. Although it does not usually lead to beriberi, a number of symptoms can result from a depletion of thiamine body levels. A low-B1 diet consisting of polished rice or unenriched white flour is not often the culprit in our culture. The diet that contributes to deficiency today, especially among teenagers, is high in colas, sweets, fast foods, and many other empty-calorie foods. This diet can also lead to skin problems and symptoms of neurosis, almost like a Jekyll-and-Hyde disposition.

With a deficiency of thiamine, carbohydrate digestion and the metabolism of glucose are diminished. There is a build-up of pyruvic acid in the blood, which can lead to decreased oxygen utilization and therefore mental deficiency and even difficulty in breathing. While B1 is needed for alcohol metabolism, alcohol abuse is often associated with a poor diet and poor B1 absorption. The poor perceptions, mental states, and nerve problems that come with alcoholism may be associated with thiamine deficiency.