Vitamin B1 (Thiamine) - Deficiency Symptoms And Food Sources
Vitamin B1 is historically very important. It was deficiency of this vitamin that for the first time conclusively proved that a disease syndrome could be produced by an inadequate supply of minute amounts of certain factors in food. Casimir Funk in 1911 obtained vitamin B1 as a crystalline substance from rice polishings. He called it 'vitalamine' because it was vital and contained nitrogen as an amine. Some food factors active in minute amounts, and discovered since then, are not amines; yet the term vitamin is used to describe them.
Just as the discovery of microbes as a cause of disease opened a new era in medicine, so too have mil!ions been helped by the discovery that deficiency of vitamins in food can produce debilitating and even fatal diseases especially in the East, where the diet is generally poor.
Takaki, a physician in the Japanese navy, first demonstrated that a grossly debilitating and fatal disease like beriberi could not only be treated but also eradicated from the Japanese navy by adding vegetables, fish and meat to the rice diet.
Later, Eijkman, a Dutch physician in Java, noted that a diet consisting mainly of polished rice was responsible for beriberi; hence, as a corollary, rice polishings were extensively investigated in an attempt to extract the antineuritic principle. The word 'thiamine', originally used in the US, has been adopted internationally as the standard name for vitamin B1 Aneurine is the British pharmacopoeial word, from anti-neuritic vitamin.
Benefits and functions of vitamin B1
Thiamine pyrophosphate (diphosphothiamine) is the physiologically active form of thiamine. It functions as a co-enzyme (thiamine phosphate) in the transketolase system. In the absence of thiamine, the intermediate products of carbohydrate metabolism (glycolysis) -lactic acid and pyruvic acid-accumulate, and may lead to lactic acidosis.
The nervous tissue derives all its energy from carbohydrates. If carbohydrates cannot be properly metabolized the peripheral nerves degenerate, giving rise to peripheral neuropathy. The vitamin B1 also maintains the muscles of the intestines, stomach, and heart. Thiamine additionally has an antioxidant effect, protecting the body from the harmful effects of alcohol, pollutants, and smoking.
Recommended dosage of vitamin B1
Various factors influence the daily requirement of Vitamin B1.
Daily vitamin B1 requirement is 0.4 mg per 1000 kcal (4.2 MJ) for infants, children and adults. As vitamin B1 is excreted in milk, more vitamin B1 is required by nursing mothers. The total daily vitamin B1 requirement for an average adult can be taken as about 1 mg, while for a nursing mother it is 1.4 mg.
Deficiency symptoms of vitamin B1
Deficiency of thiamine is frequently associated with low calorie intake and deficiency of other factors of the vitamin B-complex. In clinical practice, therefore, pure thiamine deficiency is not usually seen; it is usually accompanied by deficiency of other vitamins of the B group. A deficiency will result in beriberi, and minor deficiencies may be indicated with extreme fatigue, irritability, constipation, edema and an enlarged liver.
Subclinical deficiency is more common in women because the weight-reducing diets of the highincome group and the inadequate diets of the lowincome group cannot cope with the large demands for vitamin b1 during pregnancy and lactation. The symptoms and signs of early vitamin b1 deficiency are vague. Typical symptoms include anorexia, weakness, evening tiredness and constipation. On examination, the calf muscles may be slightly tender and ankle jerks sluggish. Thiamine deficiency is suspected when the history suggests poor intake or excessive loss. If the symptoms are due to vitamin b1 deficiency, its administration produces rapid relief; this is the easiest and most reliable criterion of vitamin b1 deficiency.
Food sources of vitamin B1
Sunflower seeds, peanuts, wheat bran, beef liver, pork, seafood, egg-yolk, beans all contain good amounts of thiamin.
Overdose toxicity has not been reported with thiamine. However, allergic manifestations like urticaria, sensations of burning or warmth, nausea, sweating and tachycardia may occur. Rarely, anaphylactic shock with collapse and death has been reported after thiamine injection.
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