Beriberi, a disabling condition, was endemic for centuries in the Orient & Pacific islands and this was finally proved to be deficiency disease. A similar situation was produced artificially in hens in 1890 when Ejikman found out that birds fed with polished rice developed polyneuritis. In 1911 Dr. Casimir Funk cured polyneuritis in birds by administrering concentrate of rice polishings. In 1926 Jansen and Donath isolated this vitamin in pure form and in 1936 Williams and his coworkers synthesized the vitamin.

It is a white crystalline substance, water soluble and destroyed at elevated temperature unless the pH is low; but can stand short boiling up to 100 degree centigrade. Hence it is only partly missing in cooking or canning processes. Autoclave, long boiling or boiling with alkali, destroys it. But it is stable in acid medium.

Sources of vitamin B1

Vegetable sources - Cereals (in the husk and embryo), pulses, nuts and green vegetables, i.e. beets, carrots, turnip, lettuce, cauliflower, peers, beans, etc are rich sources. Polished rice and white flour are poor in this vitamin content. Animal sources - generally poor. Yeast and egg -yolk contain fair amount (100i.u.). Milk is a vital source of thiamine for infants, provide the thiamine content of their mothers is satisfactory.

The main source of vitamin B1 in the diet of Indian people is cereals (rice and wheat), which contribute from 60-85 percent of the total supply. The thiamine content of selected foodstuff is given below:

Foods of vegetable origin	Mg/100g	Foods of animal origin	Mg/100g
Wheat whole	0.45	Milk, cow's	0.05
Rice, raw home pounded	0.21	Egg hen's	0.10
Rice, milled	0.06	Mutton	0.18
Bengal gram dhal	0.48	Liver, sheep	0.36
Almonds	0.24
Groundnut	0.90

Free thiamine is absorbed readily from the small intestine. It is much stored in the body. About 25% of the ingested vitamin B 1 is excreted in the urine. It has also been created synthetically.

Thiamine losses

Thiamine is readily lost from rice during the process of milling. Being a water-soluble vitamin, additional losses take place for the duration of washing and cooking of rice. Much of thiamine in fruits and vegetables is generally lost during prolonged storage. Thiamine is also destroyed in toast and in cereals cooked with baking soda.

Benefits of vitamin B1

Thiamin increases the blood circulation, helps in the blood formation and the metabolism of carbohydrates. It is also required for the health of the nervous system and is used in the biosynthesis of a number of cell constituents, including the neurotransmitter acetylcholine and gamma-amino butyric acid (GABA). It is used in the formation of hydrochloric acid, and therefore plays a part in digestion.

It is also very great for the brain and may help with depression and help with memory and learning. In children it is required for growth and has shown some indication to assist in arthritis, cataracts as well as infertility.

In the absence of this vitamin, pyruvic and lactic acids fails to be broken down, and hence, accumulate in blood and tissues. Most of the deficiency signs are due to the abnormal accumulation of these acids. It also helps the enzyme system, which is accountable for the synthesis of fats from carbohydrates and proteins.

Without thiamine, the cells cannot make use of oxygen or fuel for energy. The nervous system cannot function properly without thiamine, nor can the muscles perform at their best.

Daily requirement

About 1.8 mgm for a diet producing 3.000 calories. The necessity is improved in pregnancy, lactation, heavy muscular work, high carbohydrate diet etc. every day eating for children range from 0.4 mgm for infants to 1.3 mgm for pre-adolescents. Requirement of thiamine increases in shock, haemorrhage, serious illness or injury, during oral administration of antibiotics etc.

Deficiency signs

The two principal deficiency diseases are beriberi and Wernick's encephalopathy. Beriberi may occur in three main forms:

-The dry form characterized by nerve involvement (peripheral neuritis)

-The wet form characterized by heart involvement (cardiac beriberi)

-Infantile beriberi, seen in infants between 2 and 4 months of age. The affected baby is usually breast fed by a thiamine deficient mother who commonly shows signs of peripheral neuropathy.

The general symptoms in beriberi are as follows:

- There is oedema especially in legs.

- Loss of appetite, atony of the gastrointestinal tract, hypochlorhydria. All these are due to lack of energy derived from the imperfect metabolism of carbohydrate.

- Lactic and pyruvic acids build up in blood.

- In polyneuritis there is gentleness of muscles of feet and legs, ataxia and muscular weakness, is a characteristic attribute. These defects are due to diminish use of carbohydrates and creation of energy. Pyruvic acids accumulate in the brain stem, brain and cerebrospinal fluid.

- Heart also becomes weak and enlarged, due to buildup of pyruvic acid. Cardiac failure may also happen in some subjects.

- Cerebral beriberi has also been reported. In this disease the gray matter of the cerebrum round the third ventricle is affected. When thiamine is missing from the diet, all kinds of muscle pains grow over the body. The nerves become ill-tempered, and the person suffers from weakness, anaemia and lack of appetite.

Wernick's encephalopathy (seen often in alcoholics) is characterized by ophthalmoplegia, polyneuritis, ataxia and mental deterioration. It happens in people who fast.

Toxicity and symptoms of high intake

Thiamin toxicity is uncommon; as excesses are readily excreted, although long-term supplementation of amounts larger than 3 grams have been known to cause toxicity.

Who need more?

People who take alcohol, antacids and birth control pills or patients who have taken hormone replacement therapy need more thiamine in their diet. People anguish from depression or anxiety and those passing huge volumes of urine, or suffering from an infection may all have need of more thiamin.

It is thought that thiamin can be useful for motion sickness in air and sea travel, and that this vitamin also repels insects when excreted through the skin.