Vitamin B1

Vitamin B1, also called as Thiamine is a vitamin that plays an important role in the body.

Updated: May 5, 2019

Vitamin B1, also called as Thiamine is a vitamin that plays an important role in the body. It is needed to maintain the health of the nerves and the heart. Thiamine is required by our bodies to properly use carbohydrates. Low levels of vitamin B1 may cause heart failure and mental/nerve problems. Vitamin B1 is found in many foods including yeast, cereal grains, beans, nuts, and meat.
Most people who eat a normal diet do not need extra vitamin B1. However, some conditions (such as alcoholism, cirrhosis, stomach/intestinal problems) can cause low levels of vitamin B1. Conditions related to low levels of thiamine (thiamine deficiency syndromes), include beriberi and inflammation of the nerves (neuritis) associated with pellagra or pregnancy. Thiamine is also used for digestive problems including poor appetite, ulcerative colitis, and ongoing diarrhea.It is often used in combination with other B vitamins, and found in many vitamin B complex products.

Dietary Sources:

Foods that are rich in Vitamin B1 include the outer layers and germ of cereals, as well as in yeast, beef, pork, nuts, whole grains, and pulses. Fruit and vegetables that contain it include cauliflower, liver, oranges, eggs, potatoes, asparagus, and kale. Other sources include brewer's yeast and blackstrap molasses.
Heating, cooking, and processing foods, and boiling them in water, destroy thiamin. As vitamin B1 is water-soluble, it dissolves into cooking water. White rice that is not enriched will contain only one tenth of the thiamin available in brown rice.
One serving of fortified breakfast cereal provides 1.5 milligrams (mg) of thiamin, which is more than 100 percent of the daily recommended amount.
One slice of whole wheat bread contains 0.1 mg, or 7 percent of the daily requirement, where as Cheese, chicken, and apples contain no thiamin.
As the vitamin is not stored in the body, it should be part of the daily diet to get a continuous supply of vitamin B1.


  • People with poor diet, cancer, morning sickness during pregnancy, bariatric surgery, and hemodialysis are at risk of thiamin deficiency.
  • People who regularly drink excess alcohol may not absorb thiamin from their food and therefore may have a deficiency.
  • Wernicke-Korsakoff syndrome is a disorder that affects people with chronic alcoholism. It is linked to a lack of thiamin, and it can be fatal if not treated.
  • People with Wernicke-Korsakoff syndrome and those who are withdrawing from alcohol can be given thiamin injections to help them recover.
  • Some other diseases, such as HIV, can reduce the absorption of nutrients which can lead to a deficiency of vitamin B1.

A deficiency of vitamin B1 commonly leads to beriberi. It is a condition that features problems with the peripheral nerves and wasting. It can affects the cardiovascular system resulting in a fast heart rate, shortness of breath, and leg swelling. There may be mental problems, including confusion and short-term memory loss. Weight loss, anorexia and weak muscles can be a result of deficiency in this vitamin.

Uses & Effectiveness:

Effective for:

Thiamine deficiency:

Taking thiamine by mouth helps prevent and treat thiamine deficiency.

Metabolic disorders:

Taking thiamine by mouth helps correct metabolic disorders associated with genetic diseases, including Leigh's disease, maple syrup urine disease, and others.

Wernicke-Korsakoff syndrome:

This is a brain disorder due to thiamine deficiency. Thiamine helps decrease the risk and symptoms of Wernicke-Korsakoff syndrome (WKS). This brain disorder is related to low levels of thiamine (thiamine deficiency) and is often seen in alcoholics. Most of the alcoholics are believed to have thiamine deficiency. Giving thiamine shots seems to help decrease the risk of developing WKS and decrease symptoms of WKS during alcohol withdrawal.

Possibly Effective for:


Taking higher thiamine intake as part of the diet can reduce the risk of developing cataracts.

Kidney disease in people with diabetes:

Taking high-dose thiamine (100 mg three times daily) for 3 months decreases the amount of albumin in the urine in people with type 2 diabetes. Albumin in the urine is an indication of kidney damage.


Taking thiamine for 90 days stops pain associated with menstruation in girls 12-21 years-old. It is helpful in painful menstruation.
Possibly Ineffective for:

Repelling mosquitos:

Taking B vitamins, including thiamine, does not help repel mosquitos.

Insufficient Evidence for:

Athletic performance:

Taking thiamine together with pantethine and pantothenic acid (vitamin B5) does not improve muscle strength or endurance in athletes.

Preventing cervical cancer:

Increasing intake of thiamine from dietary and supplement sources, along with other folic acid, riboflavin, and vitamin B12, might decrease the risk of precancerous spots on the cervix.
More evidence is needed to rate thiamine for the uses in below condition:   

  •     Poor appetite.
  •     Ulcerative colitis.
  •     Chronic diarrhea.
  •     Stomach problems.
  •     Brain conditions.
  •     AIDS.
  •     Heart disease.
  •     Alcoholism.
  •     Stress.
  •     Aging.
  •     Canker sores.
  •     Other conditions.

Side Effects & Safety:

Thiamine is likely safe when taken by mouth in appropriate amounts. Sometimes rare allergic reactions and skin irritation can occur however. Seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
It is also likely safe when given appropriately intravenously (by IV) by a healthcare provider. Thiamine shots are an FDA-approved prescription product.
Thiamine might not properly enter the body in some people who have liver problems, drink a lot of alcohol, or have other conditions.

Special Precautions & Warnings:

Pregnancy and breast-feeding:

Thiamine is likely safe for pregnant or breast-feeding women when taken in the recommended amount of 1.4 mg daily. The safety of using larger amounts during pregnancy or breast-feeding is unknown.


Tea and coffee contain tannins, chemicals that may interact with thiamin, making it harder to absorb. Some of the chemicals in raw shellfish and fish can destroy thiamin, if eaten in large quantities potentially leading to a deficiency. Cooking destroys these chemicals, but it destroys thiamin too.
The effects of some drugs can change if you take other drugs or herbal products at the same time. This can increase your risk for serious side effects or may cause your medications not to work correctly. Make sure to tell your doctor about all the products you use including prescription drugs, nonprescription drugs, and herbal products before starting this vitamin. Do not start, stop, or change the dosage of any other medicines you are using without your doctor's approval.
This vitamin may interfere with certain laboratory tests including uric acid levels, urobilinogen urine test, possibly causing false test results. Therefore inform your doctor before these test if you are taking Vitamin B1.


The following doses have been studied in scientific research and is recommended:

By Mouth:

For adults with somewhat low levels of thiamine in their body (mild thiamine deficiency):

The usual dose of thiamine is 5-30 mg daily in either a single dose or divided doses for one month. The typical dose for severe deficiency can be up to 300 mg per day.

For reducing the risk of getting cataracts:

A daily dietary intake of approximately 10 mg of thiamine.
As a dietary supplement in adults, 1-2 mg of thiamine per day is commonly used.
The daily recommended dietary allowances (RDAs) of thiamine are:

  • Infants 0-6 months, 0.2 mg
  • infants 7-12 months, 0.3 mg
  • children 1-3 years, 0.5 mg
  • children 4-8 years, 0.6 mg
  • boys 9-13 years, 0.9 mg
  • men 14 years and older, 1.2 mg
  • girls 9-13 years, 0.9 mg
  • women 14-18 years, 1 mg
  • women over 18 years, 1.1 mg
  • pregnant women, 1.4 mg
  • breast-feeding women, 1.5 mg.

By Injection:

Thiamine shots can be given by healthcare providers for treating and preventing symptoms of alcohol withdrawal (Wernicke-Korsakoff syndrome).

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