Vitamin B1 - Benefits, Deficiency Symptoms And Food Sources

Alternative name :: Thiamine

Thiamin or vitamin B1 was one of the first B vitamins to be discovered and elucidated. The discovery of thiamin provided the answer to the puzzle of beriberi. Beriberi is a disease associated with the consumption of highly polished rice. It was widely prevalent in Asia, and had plagued Asian population for centuries. In 1890, Christian Eijkman, a Dutch physician noticed polyneuritis (a symptom of beriberi) in chicken that were fed polished rice. The symptoms disappeared when the diet was changed to whole grain brown rice. In 1936, Dr. R R Williams identified the structure of thiamin.

Since thiamin is water-soluble, it is actively transported across the small intestine. This process is, however, inhibited by alcohol consumption. Chronic alcohol consumption is associated with thiamin deficiency.

Thiamin is distributed throughout the body but it is not stored in significant amounts in any organ. Highest concentrations are found in the heart, brain, liver and kidney.

Thiamin is stable to heat in the dry form. However, it is readily destroyed by cooking.

Functions of thiamin

The principal functioning form of thiamin is Thiamin Pyrophosphate (TPP). Conversion of thiamin to TPP involves phosphorylation (addition of phosphorus) and requires a molecule of energy called adenosine triphosphate (ATP). TPP acts as a coenzyme in several important metabolic reactions - oxidative decarboxylation and transketolation reactions.

Thiamin functions in the metabolism of carbohydrates, fats and proteins. The carbohydrate in our diet is digested to form glucose - the simplest carbohydrate and the chief fuel for our body. Glucose is converted to a series of compounds in the body, resulting in slow oxidation in stages. Pyruvic acid is an important compound in this series and this compound requires thiamin in the form of TPP for its further metabolism. In thiamin deficiency, pyruvic acid fails to get oxidised and gets converted to lactic acid, which accumulates in the tissues. Since glucose is the main fuel for the body and the only fuel used by the brain, the consequences of its deficiency can be serious.

TPP is required at another point in carbohydrate metabolism. It is required for the metabolism, of another compound called alpha-ketoglutaric acid. This compound is also obtained from fats and proteins; hence thiamin is essential for the metabolIsm of all three energy-giving nutrients, - carbohydrates, fats and proteins.

TPP has also been found to be concentrated in nerve and muscle cells. Thiamin may be involved in some aspects of the function of nerve cell membranes and may influence the functioning of neurotransmitters as well.

Benefits of Vitamin B1

Vitamin B1 enhances circulation, assists in blood formation , aids in carbohydrate metabolism, and is needed to produce hydrochloric acid, which helps digest food. This vitamin improves peristalsis and helps to prevent constipation . It also helps to maintain the normal red blood count, improves circulation, and promotes a healthy skin. It protects against the damaging effect of lead poisoning, and prevents oedema or fluid retention in connection with heart ailments.

Supplemental thiamin can help protect against some of the metabolic imbalances caused by heavy alcohol consumption. It may help protect against Wernicke's encephalopathy and some other forms of brain damage seen in some alcoholics, some with HIV-disease, some with anorexia nervosa and others. It may be helpful in alcohol withdrawal.

Daily allowances of thiamin

The minimum Recommended Dosage Allowance of Vitamin B1 are :-

• Men - 1.5 mg.
• Women - 1.1 mg.
• Pregnant women - 1.5 mg.
• Children - 1.1 mg.

Thiamine is considered nontoxic even in high doses.

Rich sources of thiamin

Thiamine (vitamin B1) is found in fortified breads, cereals, pasta, whole grains (especially wheat germ), lean meats (especially pork), fish, dried beans, peas, and soybeans. Good sources of thiamine include wheat germ, dry beans, peas, enriched cereals and breads, pasta, nuts, eggs, and most vegetables. Dairy products and milk, fruits, and vegetables are not very high in thiamine, but when consumed in a large amounts they become a significant source. The richest food sources of vitamin B1 are brewer's or nutritional yeast, brown rice, egg yolks, fish, legumes, liver, nuts, peas, poultry, rice bran, dulse, kelp, spirulina, wheat germ and whole grains. A high carbohydrate diet will increase the need for thiamin and the use of antibiotics, sulfa drugs, and oral contraceptives may decrease the body's thiamin level.

Deficiency of thiamin

Since thiamin is required for the metabolism of carbohydrates, fats and proteins, a wide range of symptoms develop due to deficiency. The deficiency condition is called beriberi, which literally means 'I cannot'. The clinical effects of deficiency are reflected in the gastrointestinal system, the nervous system, the cardiovascular system, and the musculoskeletal system.

Gastrointestinal system

Various symptoms such as anorexia (loss of appetite), indigestion and constipation may occur. When the cells of the secretory glands of the gastrointestinal system, GI, tract do not receive sufficient energy from glucose, they cannot do their work in digestion to produce more glucose. A vicious cycle of deficiency ensues, leading to weight loss.

Nervous system

The central nervous system is extremely dependent on glucose as fuel, especially the brain, which uses glucose almost exclusively as its source of fuel. Deficiency of thiamin results in reduced alertness, impaired reflex actions, general apathy, and lack of interest and fatigue. This condition is often referred to as 'dry beriberi'. There is increasing nerve irritation, pain, numbness and, burning sensation in feet and cramping of calf muscles. Severe deficiency may ultimately progress to paralysis.

Cardiovascular system

With continuing thiamin deficiency, the heart muscle weakens, resulting in cardiac failure. As a result of cardiac failure, oedema appears in the lower limbs followed by the thighs. The characteristic swelling in the legs due to oedema is referred to as 'wet beriberi'. The patient experiences difficulty in breathing and the heart gets enlarged. Even death may occur due to cardiac impairments.

Wernicke- Korsakoff syndrome

It is a neurological disorder resulting from thiamin deficiency in chronic alcoholics. The symptoms include abnormal eye movements, staggering gait (walk), and abnormalities in mental function ranging from confusion and amnesia to coma.