Vitamin B1

Vitamin B1 or thiamine is a water-soluble vitamin that plays an important role in the translation of nerve signals between nerve cells. In some enzymatic reactions in the metabolic pathways of carbohydrates and amino acids, it acts as a cofactor and, also, maintains normal brain function.

Vitamin B1 is taken into the body through food. In plant nutrition, it is found mainly in the form of thiamine or thiamine monophosphate, and in the food of animal origin, it is mainly in the form of thiamine diphosphate, and less frequently as thiamine triphosphate. Its stability depends on the shape and pH value.

It is most stable in dry foods, room temperature, and slightly acidic environments. With cooking, vitamin B1 is partially degraded, but it is extremely sensitive to sulfites in food, as they deactivate it at room or slightly lower temperatures. Sulfites, however, are not the only ones that react with and deactivate vitamin B1, such as caffeic acid, tannic acid, and similar compounds present in plants, and some plant flavonoids. It can also become inactive at room temperature due to oxidation with UV and ionizing radiation, or due to contamination of food with bacteria containing thiaminase enzymes, which change its chemical structure.

By heating food, vitamin B1 becomes inactive, and freezing food keeps the vitamin in active form.

The European Food Safety Authority (EFSA) has approved the following claims for vitamin B1:

  • contributes to the normal metabolism of energy production
  • contributes to the normal functioning of the nervous system
  • contributes to normal physiological functions
  • contributes to the normal functioning of the heart

In general, the needs for different vitamins vary from person to person as they depend on internal and external influences. Vitamin B1 needs to vary according to gender and age, a physiological condition such as e.g. physical activity, pregnancy, and breastfeeding when the need for the vitamin is greater.

Babies get enough vitamin already through breastfeeding, and from the 7th to the 11th month, girls need it 0.24-0.28 mg/day, and boys 0.27-0.31 mg/day. The need increases from one year onwards (0.30 mg/day for girls, 0.33 mg/day for boys) until the age of 18.

For an adult woman, the daily requirement of the vitamin is 0.80-0.76 mg and an additional 0.21 mg for pregnant women and nursing mothers, while for adult men it is 0.99-0.94 mg. The more athletically active we are, or our work is physically active (mostly standing), the higher the daily requirement of vitamin B1 (1.13 mg for women and 1.41 for men).

Bacteria in the gut can produce larger amounts of the vitamin in free form (without the phosphate group), which can also be absorbed into the body. An average of 30 mg of vitamin B1 is stored in the body of an adult, so the supply is sufficient for more than a month. About half of it is stored in the muscles, some also in the liver and kidneys. Vitamin B1 is excreted from the body through urine as well as sweat. When we sweat a lot, there can also be major losses.





Vitamin B1 content

per 100g of food (mg)

Recommended Dietary Allowances (RDA) in %

Sunflower seeds















Wholemeal wheat flour






















Vitamin B1 is found in many different foods but smaller amounts. The richest sources of the vitamin are whole grains, sunflower seeds, kale, soybeans, legumes, as well as foods of animal origin such as pork, fish, and beef liver.

In the 19th century, eating a monotonous diet, especially white rice, often resulted in a deficiency of this vitamin and also resulted in many diseases of beriberi, which affected the heart and nervous system.

Some suggestions of our lunches that were very rich in vitamin B1:

Vitamin deficiency

The main signs of vitamin B1 deficiency are loss of appetite and cardiac and neurological signs. Because many of the signs are mild, we can quickly ignore them at first, as they seem normal to us. Such are, for example, mental weakness, emotional lability, general fatigue, muscle aches, tingling in the skin, low back pain, nausea, decreased physical ability. Prolonged deficiency, however, can lead to nerve damage and heart failure.

Signs of vitamin B1 deficiency depend on age, the caloric intake of food, and the presence or absence of micronutrients. Deficiency often occurs in alcoholics and frequent drug users, as these substances interfere with absorption.

Because vitamin B1 is constantly excreted from the body, it is difficult to achieve excessive food intake. This can only happen if it is injected in large doses. In this case, however, signs of excess are lower blood pressure, nervousness, allergic reactions, limb tremors, and heart palpitations.