Definition Thiamin, or Vitamin B1, is a water-soluble vitamin. It was the first vitamin to be discovered. Thiamin is one of eight members of the vitamin B complex. The complex includes: vitamins B2, niacin, B6, B12, folate, biotin, and pantothenic acid. Because thiamin is water-soluble, any extra is passed in the urine. Thiamin is needed each day for good health.
What food source is the nutrient found in? Thiamin is found in foods such as:
meats (pork and liver)
whole or enriched breads, grains, and cereals
Enriched products add back the vitamins that are lost when grains are processed. Thiamin is lost in cooking water due to heat. The thiamin contents of some foods are:
How does the nutrient affect the body? Thiamin works with the other B vitamins. They work together to change protein, carbohydrate, and fat to energy or to storage. Thiamin is especially vital for changing carbohydrates to energy. It is important for normal functioning of all the body's cells, especially the nerves.
Information Daily needs for thiamin are based on the amount of kilojoules taken in each day. The recommended daily intake, or RDI, for thiamin is based on 0.5 milligram (mg) for every 4,000 kilojoules consumed. Based on the recommended kilojoule intake for men and women at certain age levels, the RDI for thiamin is:
men from 15 to 50 years = 1.5 mg
men over 50 years = 1.2 mg
women from 11 to 50 years = 1.1 mg
women over 50 years = 1.0 mg
pregnant women = 1.5 mg
breastfeeding women = 1.6 mg
Thiamin is common in foods. A balanced diet based on the Australian Guide To Healthy Eating should provide enough thiamin daily.
A disease called beriberi, which affects the nerves and heart, is caused by thiamin deficiency. This is extremely rare in Australia, because enriched grain products are so common. Before grains were enriched, it was much more common.
Severe thiamin deficiency is rare in Australia today. Mild deficiencies are more common. Exceptions may be found with chronic alcoholism, fasting, the elderly, and chronic dieting. Deficiency is rare mainly due to enriched grain products. Symptoms usually show up in the nerves, stomach, and heart. Early warning signs include:
If deficiency continues, symptoms can get worse, and some damage can be permanent.
There is little chance of thiamin toxicity, even when it is taken at high doses. Because it is water soluble and not stored in the body, it is not likely to build up to toxic levels. In elderly people with decreased concentrations of thiamin, supplementation has enhanced quality of life by decreasing both blood pressure and weight.
In isolated cases, however, thiamin toxicity has occurred from injections or concentrated formulas used with hospital patients. Toxicity symptoms include nervous irritability, headaches, insomnia, and a rapid pulse.
Author: Kimberly Tessmer, RD, LD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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