Vitamin B1, Thiamine, Properties and Role in Health
Synonyms: Thiamine; antiberiberi factor; aneurine; antineuritic factor.
Principal sources in nature : Thiamine occurs widely in foods, but mostly in small amounts. The best source of thiamine is dried brewers yeast. Other good sources include meat (pork, lamb, beef), poultry, whole grain cereals, nuts, pulse, dried legumes and animal foods.
In cereal grains, the thiamine-rich bran is removed during the milling of wheat to produce white flour, and during the polishing of brown rice to produce white rice.
Body stores: Because thiamine has a high turnover rate and is not appreciably stored in the body (approx. 1 mg per day is used up in tissues), a continuous supply is required. The limited stores may be depleted within two weeks or less on a thiamine-free diet, with clinical signs of deficiency beginning shortly after. The heart, kidney, liver and brain have the highest concentrations, followed by the leukocytes and red blood cells. Normal blood levels in man are 0.5-1.3 µg per 100 mL of serum and 3.5-11.5 µg per 100 mL blood.
Stability: Vitamin B1 is unstable to heat, alkali, oxygen and radiation. Water solubility is also a factor in the loss of thiamine from foods. About 25% of the thiamine in food is lost during the normal cooking process. Considerable amounts may be lost in thaw drip from frozen meats or in the water used to cook meats and vegetables. To preserve thiamine, foods should be cooked in a covered pan for the shortest time possible and should not be soaked in water or heated for too long. Juices and water used for cooking should be re-used in stews and sauces.
Principal antagonists: A number of foods such as coffee, tea, raw fish, betel nuts and some cereals may act as antagonists.
Drugs that cause nausea and lack of appetite, or which increase intestinal function or urinary excretion decrease the availability of thiamine.
Poisoning from arsenic or other heavy metals produces the neurological symptoms of thiamine deficiency. These metals act by blocking a crucial metabolic step involving thiamine in its coenzyme form.
Principal synergists: Vitamins B12, B6, niacin and pantothenic acid.
Functions: Thiamine is essential for carbohydrate metabolism through its coenzyme functions. Coenzymes are 'helper molecules' which activate enzymes, the proteins that control the thousands of biochemical processes occurring in the body. The thiamine-coenzyme – thiamine pyrophosphate or TPP – is the key for several reactions in the breakdown of glucose to energy. TPP acts as coenzyme in oxidative decar