Functions

Thiamin plays a large role in energy metabolism as part of the enzyme thiamin pyrophosphate.It aids in carbohydrate metabolism. Essential for growth, normal appetite, digestion and healthy nerves. Thiamin is also essential for the metabolism of alcohol.

Uses

Useful in anemia; megaloblastic anemia; beriberi; MS; MG; alcoholism; herpes zoster trigeminal neuralgia; dry sockets after tooth extraction; depression; anxiety; insomnia; sciatica; sensory neuropathy.

Deficiency

Vitamin B1 deficiency symptoms:

• Anorexia
• Severe constipation
• Lower stomach acid secretion
• General apathy & fatigue

Severe deficiency causes dry beriberi, which manifests as paralysis and cardiac failure, lower extremity edema and muscle pain, or wet beriberi: edema begins on feet and ascends. This is thought to occur mainly in areas of the world where white rice is the major foodstuff.

Other symptoms of deficiency include confusion; anorexia; muscle weakness; calf muscle tenderness; ataxia; indigestion; constipation; tachycardia; palpatations; Wernicke Korsakoff syndrome.

Deficiency may be caused by alcohol abuse, chronic illness, pregnancy, lactation. Also, raw freshwater fish and shellfish contain an enzyme which breaks down thiamin.

Antagonists

Digestive diseases will reduce thiamin absorption, as will a deficiency of folic acid or protein. Eating a lot of shellfish (see Deficiency) or consuming a lot of tea and coffee may also reduce absorption. Sulfite food additives destroy thiamin.

Co-factors

The presence of fat and bile is required for vitamin A absorption before transport to the liver. (The liver stores 90% of the body's vitamin A.)

Drug Interactions

Digoxin, indomethacin, anticonvulsants, antacids and some diuretics may lead to deficiency, as may smoking, caffeine, sulfa drugs and estrogens.

Dose

RDA:

Men 1.2 mg, Women 1.1 mg, Pregnancy 1.4 mg, Lactation 1.5 mg

Naturopathically, we would like to see 30 mg/d; therapeutic doses of 10-200 mg.

Toxicity

Very little toxicity; maybe headache, weakness, flushing, itching, irritability. Injected B1 has been reported to cause insomnia if given at night, and anaphylactic reactions to it have been reported (although this form may contain preservatives).

Sources

Vitamin B1 is found in: brewer's yeast; sunflower seeds; beans, nuts, whole grains; green vegs; rice bran; wheat germ; yeast, organ meats; milk, lean meats, potatoes.