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What is Thiamin (Vitamin B1) + Food Sources of Thiamin + Role of Thiamin in the Body

What is thiamin?

Thiamin is classically known as vitamin B1 and sometimes aneurine. It was identified in the 1930s and is one of the first substances to be classified as a vitamin. Along with the other water-soluble vitamins (except vitamin C and choline), thiamin is a B-complex vitamin. The most salient role of B-complex vitamins is their involvement in energy metabolism.


What foods have thiamin and what form is found in supplements?

Thiamin is found widely distributed in foods, although most contain low concentrations. Brewer’s yeast, pork, and whole grain and enriched grain products are better sources of thiamin (see Thiamin Table). Thiamin is found is nutritional supplements and for fortification as thiamin hydrochloride and thiamin nitrate (e.g. thiamin mononitrate).



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How much thiamin do we need?

The RDA for men and women is 1.2 and 1.1 mg of thiamin. Meanwhile the RDA for pregnant and lactating women is 1.4 mg. LIke other vitamins these are minimum intake levels. Because thiamin is important in energy operations it is more appropriate to express thiamin recommendation based on level of additional calories burned during exercise and sport training/competition. Here recommendations 0.5 mg of thiamin would be recommended for every 1000 calories expended daily. Thus athletes expending 3000 to 6000 calories daily would have a recommendation of 1.5 and 3 mg. See DRI/RDA Table for minimum recommendations levels for children and teens.


Does thiamin breakdown during cooking?

Similar to vitamin C, thiamin is not very stable during cooking processes. Convection cooking of meat may result in destruction of roughly half of its thiamin content. The baking of breads and the pasteurization of milk may result in destruction of approximately 25 percent and 15 percent of thiamin content, respectively. In light of its water-soluble nature, some thiamin may also be washed away in the thaw drip. The thaw drip is the watery fluid that drains from thawing meats.In addition, certain fish and shellfish contain natural thiaminases, which are enzymes that break down thiamin. Fortunately, cooking inactivates these enzymes.


Where is thiamin found in our body?

Most of the thiamin that we eat is absorbed in the small intestine. Once in the body, thiamin does not seem to have a primary organ of storage, however, the brain, kidneys, liver, and skeletal muscle seem to have higher concentrations. In fact, because of its high energy demands, the brain accounts for as much as one-half of the total thiamin in the body. Thiamin circulates around primarily aboard red blood cells (RBCs) and the activity of a thiamin associated enzyme is used to gauge thiamin status. Thiamin and its metabolites are subject to removal from the body in urine.


What does thiamin do in our body?

Thiamin serves as acoenzyme in many key reactions in the cells. A coenzyme is a substance that will interact directly with an enzyme; together the two allow a chemical reaction to proceed. The enzyme will not function optimally without the presence of the coenzyme. Many water-soluble vitamins function as coenzymes. Thiamin is active in the form of thiamin pyrophosphate (TPP) which is a coenzyme for a couple of enzymes involved in energy pathways .As a co-enzyme, thiamin is involved in complete carbohydrate, protein and fat breakdown for energy (see Thiamin Metabolic Role Figure). Chemical reaction pathways in our mitochondria allow for electrons to be removed from involved molecules and they are carried to electron transport chains found in the mitochondria membrane (inner). The carriers are niacin and riboflavin based blueprints and constructing proteins. Thiamin is also involved in converting glucose to ribose in the cells. Ribose, and a slightly modified form, deoxyribose, are key components of deoxyribonucleic acids (DNA) and ribonucleic acids (RNA). You will remember that DNA provides the instructions or blueprints for making cells, while RNA is involved in reading the blueprints and constructing proteins.


What does thiamin do in the brain and muscle?

Without question thiamin is crucial to the proper functioning of the brain, nerves and muscle. However, the exact involvement of thiamin may not be easily explained within the confines of thiamin’s classic energy support functions. Thiamin appears to have the ability to increase the efficiency of the electrical events that allow nerves and muscle to function properly. Interestingly, when thiamin is deficient in the diet the brain tends to hold on to its thiamin more vigorously than other tissues do. This suggests that a very special relationship exists between the brain and thiamin. We will discuss thiamin’s role in the aging brain and conditions such as Alzheimer’s disease in Disease/Prevention.


What happens if too little thiamin is consumed?

If thiamin is deficient from our diet for several weeks, symptoms will begin to appear. Classic thiamin deficiency has been termedberiberi, which is often separated into two types. Wet and dry beriberi describe the effects of thiamin deficiency with special reference to the presence of fluid buildup in tissue (edema). Enlargement of the heart sometimes occurs and appears to be more prevalent in those individuals with the fluid buildup (wet beriberi). Muscular weakness, loss of appetite, and atrophy of legs are also characteristic symptoms of thiamin deficiency. Beriberi is said to mean “I can’t, I can’t,” which probably refers to the deficits in voluntary movement that accompany thiamin deficiency.An infant who is breast-fed by a thiamin-deficient mother is also at risk of thiamin deficiency. This situation, called infantile beriberi, typically occurs between two and six months of age, and these infants may lose their desire to eat, may regurgitate milk, and may also experience vomiting and diarrhea. A rapid heart rate and a bluish tint to the skin may also develop.


Can alcohol consumption affect thiamin status?

Mild alcohol consumption doesn’t impact thiamin status in the body. However, the heavy, chronic alcohol consumption of a alcoholic increases the risk for thiamin deficiency for a couple of reasons. An alcoholic’s diet is typically low in thiamin along with other essential nutrients. Furthermore, there appears to be a reduced ability to absorb thiamin in the digestive tract of alcoholics with an accompanying increase in metabolic need for this vitamin. Can too much thiamin be consumed? Because much of excessive thiamin will be rapidly removed from the body in the urine, excessive consumption of thiamin appears relatively safe. In fact, the current DRIs do not include a Tolerable Upper Limit (UL) for thiamin (see DRI Table). However, long-term thiamin intake of greater than 100 times the RDA (1200 mg) has been associated with headaches, convulsions, weakness, allergic reactions, and irregular heart rhythms.

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