Vitamin B1

Thiamine

Vitamin B1 (thiamine) is a water-soluble vitamin (dissolved in water) and is a derivative of pyrimidine and thiazole rings that are interconnected by a methylene bridge. It occurs in nature in the form of monophosphate and triphosphate esters of thiamine. Vitamin B1 participates in a large number of enzymatic reactions, including the release of energy from glucose. Sources of vitamin B1 are yeast, pork, legumes, whole grains, liver, kidneys and heart. Omitting these foods from the daily diet can lead to vitamin B1 hypovitaminosis. Only small amounts of vitamin B1 are stored in the liver, so thiamine must be obtained through food to meet daily requirements.

Symptoms of vitamin B1 deficiency were first recorded in Chinese medicine texts. In 1884, a Japanese doctor noticed a very high rate of disease and death among Japanese sailors, because they were eating inadequately, they mostly consumed rice that had been polished, which means that in unpolished rice, from which the outer covering has not been removed, there is a large amount of vitamin B1. Other causes of vitamin B1 deficiency may be a consequence of reduced absorption due to prolonged diarrhea or an increased need for the vitamin in hyperthyroidism, pregnancy, or elevated temperature. Thiamine is stable when heated up to 100°C, so an insignificant amount is lost during heat treatment. Bacteria of the gastrointestinal tract synthesize vitamin B1, so it is thought that these bacteria can meet the vitamin B1 needs of humans. Thiamine is excreted in free form, but also in the form of metabolites through urine.

The daily need of thiamine vary depending on the intensity of carbohydrate metabolism, and increased needs occur with increased physical activity, during pregnancy and lactation. The recommended daily intake for men over the age of 19 is 1.2 mg/day, and for women of the same age it is 1.1 mg/day. During pregnancy and breastfeeding, the daily need for vitamin B1 is slightly higher and amounts to 1.4 mg/day.

Recommended Dietary Allowances (RDAs) for Vitamin B1

Age	Male	Female	Pregnancy	Lactation
0-6 months	0.2 mg*	0.2 mg*
7-12 months	0.3 mg*	0.3 mg*
1-3 years	0.5 mg	0.5 mg
4-8 years	0.6 mg	0.6 mg
9-13 years	0.9 mg	0.9 mg
14-18 years	1.2 mg	1.0 mg	1.4 mg	1.4 mg
19-50 years	1.2 mg	1.1 mg	1.4 mg	1.4 mg
51+ years	1.2 mg	1.1 mg

Vitamin B1 metabolism: Various forms of thiamine are subject to hydrolytic degradation. Vitamin B1 is easily absorbed in the small intestine, by the mechanism of active transport, and if it is taken in larger quantities, absorption is done by passive diffusion. When the enzyme thiaminase is found in the digestive tract, it breaks down vitamin B1. Through the portal vein, thiamine reaches the liver. The free form of vitamin B1 is found in the plasma, while it is found in the phosphorylated form in the cells. Thiamine-monophosphate, thiamine-diphosphate, thiamine-triphosphate are synthesized from thiamine and ATP by the action of the thiamine phosphokinase enzyme.

Vitamin B1 deficiency is rare, as most people meet the recommended daily intake through their diet. It can occur due to low intake of food containing thiamine, reduction of absorption in the intestines or due to increased loss through urine (increased intake of alcohol or increased intake of diuretic drugs).

A large lack of thiamine can lead to beriberi disease, which causes muscle loss and reduced sensation in the arms and legs (peripheral neuropathy) and is the so-called dry beriberi with neurological signs. It is a disease that leads to motor dysfunction, ultimately as a complication of this disease it can lead to fluid accumulation in the heart and lower extremities (wet beriberi with cardiovascular signs and symptoms) leading to death. Chronic alcoholism is the usual cause of vitamin B1 deficiency, both due to reduced intake and impaired absorption. Both types of deficit lead to a large number of gastrointestinal diseases, such as celiac disease. Symptoms that occur with mild or moderate vitamin B1 deficiency are: weight loss, memory loss, muscle weakness, peripheral neuropathies, poor immune system.

Many studies have shown that vitamin B1 (thiamine) deficiency can cause some neurological symptoms that resemble those of Alzheimer’s disease, such as disorientation and memory loss. Lack of vitamins in the body causes various neurological disorders, such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, but also psychiatric disorders such as anxiety and depression. Therefore, it was concluded that the lack of vitamins B1, B12 and vitamin A leads to the onset of Alzheimer’s and Parkinson’s disease.

Vitamin B1 excess: An overdose of vitamin B1 is a very rare phenomenon and there is no established toxic level of this vitamin.

Vitamin B1

References