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Vitamin B1 for Energy

healthy breakfast

What is vitamin B1?
Vitamin B1, more commonly known as thiamin, is a water-soluble vitamin and part of the B vitamin family. B vitamins help support adrenal function, help calm and maintain a healthy nervous system, and are necessary for key metabolic processes.

Why is vitamin B1 necessary?
Thiamin acts as a cofactor for the metabolism of carbohydrates, helping turn starch and sugar into the energy our bodies need, and plays an important role in nerve transmission. Thiamin influences a variety of physiologic functions, including nervous system and muscle functioning; carbohydrate metabolism; healthy digestion; and more.

What are the signs of a deficiency?
Since very little thiamin is stored in the body, depletion can occur in as little as two weeks. Symptoms of thiamin deficiency (also known as "beriberi") can result from inadequate intake or excessive loss of thiamin from the body, an increased requirement for thiamin, or consumption of anti-thiamin factors in food. Some people are at a higher risk for thiamin deficiency, including chronic alcoholics, patients who receive intravenous feeding for more than seven days without additional multivitamins or dietary thiamin, and people on kidney dialysis.

Beriberi has been divided into three subtypes: dry beriberi refers to neuromuscular complications such as peripheral neuropathy and weakness; wet beriberi refers to cardiovascular complications such as heart failure (Shoshin-type beriberi); and cerebral beriberi refers to central nervous system (brain) complications such as Wernicke's encephalopathy (abnormal eye movements, stance/gait abnormalities, mental dysfunction) or Korsakoff's psychosis (apathy, confusion, severe memory deficits/amnesia).

How much, and what kind, does an adult need?
According to the National Institutes of Health (NIH), the U.S. Recommended Daily Allowance (RDA) for adults ages 19 years and older is 1.2mg daily for males and 1.1mg daily for females, taken orally. The RDA for pregnant or breastfeeding women is 1.4mg daily, taken orally. Dr. Weil recommends 50 mg as part of a B-complex supplement that contains a full spectrum of B vitamins, including thiamin (as well as B12, riboflavin and niacin). Those who are at a higher risk of thiamin deficiency (see above) should consult with their physician for dosage amounts.

How much does a child need?
According to the NIH, the RDA for infants age 0-6 months is 0.2 mg; infants 7-12 months is 0.3 mg; for children 1-3 years it is 0.5 mg; for children 4-8 years it is 0.6 mg. Children between 9-13 years of age should get 0.9 mg, for males age 14-18 years it is 1.2 mg; for females age 14-18 years it is 1 mg, taken orally. Dr. Weil recommends 1.5 mg as part of a children's daily multivitamin, but you should always consult with your pediatrician before beginning supplements.

How do you get enough vitamin B1 from foods?
The following are good dietary sources of thiamin: legumes (beans, lentils), beef and pork, Brewer's yeast, whole-grain breads and cereals, oatmeal, enriched pastas, rice bran and wheat germ, milk, nuts, seeds and oranges.

Are there any risks associated with too much vitamin B1?
Thiamin is generally considered safe and nontoxic, even at high doses. Doses higher than 100 mg may cause drowsiness or muscle relaxation, and some people report a burning sensation when thiamin is received via injection.

Are there any other special considerations?
Thiamin can interact adversely with certain drugs, herbs and foods, including:

  • Drugs: Antacids, barbiturates, diuretics, and tobacco may lower levels of thiamin by decreasing absorption
  • Herbs: Betel nut (Areca catechu L.), Horsetail (Equisetum arvense L.), and diuretic herbs may all lead to thiamin deficiency
  • Foods: Alcohol, carbonated beverages, coffee and tea, and raw seafood may all lead to thiamin deficiency


Are you getting the supplements you need?
Everyone's dietary needs are different based on a number of factors including lifestyle, diet, medications and more. To find out which supplements are right for you, take the Weil Vitamin Advisor. This 3-step questionnaire requires just minutes to complete, and generates a free, no-obligation vitamin and nutritional supplement recommendation that is personalized to meet your unique nutritional needs.

The Weil Vitamin Advisor
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