It adequate for its need. The reco­mmended daily

It is a white, crystalline solid readily soluble in water but insoluble in ether and chloroform.

Its melting point is 248°C. It has the odour and flavour characteristic of yeast and salty taste. Its pH value ranges from 3-4, depending upon the concentration.

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Chemically, this vitamin Bi is composed of two different hetero­cyclic nuclei : the pyrimidine and the thiazole rings.

These two rings are connected by a methylene group-CH2. The pyrimidine ring contains a methyl group-CH3 and an amino group-NHa. The thiazole ring contains a methyl group and a hydroxyethyl group, —CH2,CH2,OH.

The structure of thiamine, which was first isolated in crystalline form by Jansen in Holland and Windaus in Germany, was established by R R. Williams et al.

Occurrence and availability Vitamin B1:

Vitamin B1 is found in almost all plant and animal tissues. Among the best sources are peas, dry yeast, egg yolk, liver, heart, pork, milk, kidney, cereal grains (soy, wheat, etc.) and nuts.

Some micro-organisms can synthesize vitamin B1; these micro­organisms are usually found in the intestine of the animals.

Daily requirement: In the body the vitamin B1 is not stored in sufficient amounts to last more than a brief period.

Therefore, the body should receive a daily amount adequate for its need. The reco­mmended daily vitamin B1 requirement for an adult is about 12 to 14 mg for men and 10 mg for women, increasing to 1-1 to 15 mg during pregnancy and lactation. The thiamine requirement of the infants is between 0 2 to 0 5 mg. daily.