Vitamin B1/thiamine

Vitamin B1 or thiamine is a water soluble vitamin. Its biochemical synonyms are also anti neurite vitamin, aneurin and anti-beriberi factor. The most bioactive form of the vitamin is thiamine pyrophosphate or thiamine diphosphate (TPP, TDP, cocarboxylase). Less active are forms are thiamine monophosphate and thiamine triphosphate. Vitamin B is a thermolabile vitamin which is not very persistent in alkaline solutions.

 

Which foods contain the vitamin?

• Millet
• Oat flakes
• Chicken
• Whole grain bread
• Sunflower seeds

Biological functions of the vitamin

Thiamine is needed in the catabolism or decomposition of carbohydrates, lipides and amino acids. TTP or thiamine pyrophosphate is the coenzyme of various compound enzymes — in the pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase complex and transketolase, which are all essential for converting carbohydrates in the organism into usable energy. The metabolism of carbohydrates is the first process to be interfered by thiamine deficiency.

Thiamine also participates in the synthesis of nucleotides (monomers of DNA and RNA).

Vitamin B1 also plays an important role in nerve impulse transmission in the synapse (e.g., synthesis of acetylcholine, translocation of ions). This is due to the importance of thiamine in the metabolism of carbohydrates because in case of thiamine deficiency in the organism, the use of glucose, the main energetic substrate, is disturbed, and pyruvate, a substance toxic to the nervous tissue, starts accumulating in the cells.

Thiamine deficiency causes a reduction in the activeness of the transketolase of gastric mucosa and the level of NADPH, which inhibits the formation of hydrochloric acid and secretion.

Absorption, storage and excretion

Vitamin B1 is absorbed in the small intestine if either mediated by a carrier or through passive diffusion, whereas the absorption is hindered by antibiotics, smoking, alcohol and caffeine.

50% of thiamine is stored in skeletal muscles, 40% in liver and the rest in kidneys and nervous tissue. Since it is a water soluble vitamin, the reserves last for 1–2 weeks. 80% of the thiamine found in the organism is stored as TDP, 10% as triphosphate and the rest 10% is free-thiamine together with monophosphate. Free-thiamine is mainly contained in blood, TDP in cells.

Excess thiamine is quickly excreted with urine.

Problems resulting from deficiency

• Digestive disorders, weakness, loss of appetite, emotional lability
• Nervous system disorders
• Decrease in the decomposition of fatty acids and amino acids
• Beriberi (dry and wet)
• Wernicke–Korsakoff syndrome for the alcoholics

Risk groups for developing the deficiency

• Alcoholics (accumulation of acetaldehyde in the organism, which hinders the use of thiamine)
• People consuming excess amount of black coffee and tea in a day (more than 4 cups) (polyphenolic ingredients inactivate thiamine)
• Pregnant women, especially those with gestational diabetes
• Diabetics (especially with neuropathy)
• Post bariatric surgery
• Continuous consumers of abundant amounts of refined sugar
• Smokers
• People with magnesium deficiency
• Consumers of thiaminase-rich foods (raw freshwater fish, molluscs)
• People with thiamine-dependent megaloblastic anaemia

Toxicity

Early symptoms include weakness, hypotension, hypersensitivity, vomiting, heart palpitations and redness of the skin. Symptoms of acute toxicity include acute tachycardia, respiratory insufficiency and ir rare cases also anaphylactic shock. It must also be kept in mind that the kidneys remove somewhat larger quantities of thiamine from blood than stated in the recommended daily allowance.

Use of vitamin preparations

Additional need also depends on burnt calories, i.e., the intake of thiamine for 1,000 burnt calories is approximately 0.5 mg. Athletes with carbohydrates rich diet may need additional thiamine to convert a larger number of consumed carbohydrates.

Alcoholics, excessive consumers of tea or coffee and smokers should also administer the given vitamin.

As an additional treatment component, thiamine is also administered in case of senility, Alzheimer, diabetes, anaemia, alcoholism, pellagra, herpes, influenza and neuritis.

Vitamin B1 should be taken together with riboflavin, folic acid, vitamin C, manganese and vitamin E.

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