What is Thiamine (Vitamin B1)?

B1 rich foods, thiamine
Foods rich in thiamine (vitamin B1) include beef, liver, beans, nuts and rice. (Image credit: Wasu Watcharadachaphong | Shuttstock)

Vitamin B1, also called thiamine, is a B complex vitamin. It is found in many foods and is vitally important to keeping a body operating properly. 

"Thiamine is involved in many body functions including the nervous system, heart and muscles," said Dr. Sherry Ross, gynecologist and Women’s Health Expert at Providence Saint John’s Health Center in Santa Monica, California. "It is also important in the flow of electrolytes in and out of nerve and muscle cells, enzymatic processes and carbohydrate metabolism."

According to the University of Maryland Medical Center (UMM), thiamine was named B1 because it was the first B complex vitamin to be discovered. According to the Mayo Clinic, it was also one of the first vitamins of any kind ever be classified. 

B1 sources

There are many natural ways to add thiamine-rich foods to an everyday diet. Food sources of thiamine include beef, liver, dried milk, nuts, oats, oranges, pork, eggs, seeds, legumes, peas and yeast.  Foods are also fortified with thiamine. Some foods that are often fortified with B1 are rice, pasta, breads, cereals and flour. 

Health benefits of thiamine

Thiamine is used to treat people who have heart disease, metabolic disorders, aging, canker sores, cataracts, glaucoma and motion sickness. There are many studies that seem to back up some of these uses. For example, research published by the Vietnamese American Medical Research Foundation found thiamine might improve the cognitive function of patients with Alzheimer's disease. This vitamin is important for a wide range of brain functions and ailments in others, as well.

According to the UMM, thiamine is sometimes called an "anti-stress" vitamin. Research has found that B1 may strengthen the immune system and improve the body's ability to control mood and physiological impairments due to stress.

"Thiamine is also used for maintaining a positive mental attitude, preventing memory loss, enhancing learning abilities, fighting stress and increasing energy," Ross told Live Science. Thiamine injections are also given to patients who have a memory disorder called Wernicke’s encephalopathy, Ross added. 

B1 may also be good for treating other impairments. According to the Milton S. Hershey Medical Center, many studies have also concluded that B1, along with other vitamins, may prevent cataracts. A study by the Laboratory of Pharmacotherapy at the Osaka University of Pharmaceutical Sciences in Takatsuki, Japan found that thiamine has a potential to prevent obesity and metabolic disorders in rats. Other researchers believe that vitamin B plays a part in the body's metabolism and may be interregnal to the treatment of metabolic disorders. 


The recommended daily allowance (RDA) for B1 varies, depending on age and gender. Here are the RDA levels of B1 according to the U.S. National Library of Medicine

  • Males who are 14 and older should consume 1.2 milligrams per day (mg/day).
  • Females who are 14 to 18 years old should consume 1.0 mg/day.
  • Females who are 19 and older should consume 1.1 mg/day, though women who are pregnant or breastfeeding may need more and should consult her doctor.

Typically, most people can get their daily dose of B1 from eating healthy foods. Some may opt to take a multivitamin or a supplement to ensure that the RDA is met. Many vitamin supplements can cause overdose and medical problems, but B1 is fairly safe in this respect. “Because they are water soluble it is less likely you will overdose on them as other vitamins," said Dr. Kristine Arthur, internist at Orange Coast Memorial Medical Center in Fountain Valley, California. Ross agrees and stated that thiamine is considered safe at high doses and is relatively nontoxic.

B1 deficiency

Though rare in developed countries like the United States, deficiencies in B1 can create serious medical problems. Severe deficiency of thiamine causes complications involving the nervous system, brain, muscles, heart and gastrointestinal system," said Ross.

"If you are deficient you can develop specific disorders such as Beriberi and Wernicke- Korsakoff syndrome," said Arthur. Beriberi can cause abnormal nerve function, heart failure and swelling in the legs, while Wernicke Korsakoff syndrome can cause memory loss, confusion and difficulty with balance. These problems are most common in alcoholics. Drinking too much alcohol makes it harder for the body to absorb and store thiamine, according to the National Library of Medicine. In many cases, alcoholism treatment includes B1 therapy. 

Beriberi can also be passed down through genes. The elderly are also susceptible to thiamine deficiency. This is because their bodies have a harder time absorbing the vitamin. 

The use of diuretics is another cause for B1 deficiency, according to Oregon State University. Since B1 is water soluble and is not stored in the body, diuretics, which primary use is to flush water from the body, also flushes away vitamins like thiamine. 

Symptoms of vitamin B1 deficiency

The symptoms of B1 deficiency are many and typically are related to the nervous, muscular and gastrointestinal systems. According to a review published by the journal Congestive Heart Failure, symptoms include depression, emotional instability, uncooperative behavior, fearfulness, agitation, weakness, dizziness, insomnia, memory loss, pain sensitivity, peripheral neuropathy, sonophobia, backache, muscular atrophy, myalgia, nausea, vomiting and constipation.

Additional resources

Alina Bradford
Live Science Contributor
Alina Bradford is a contributing writer for Live Science. Over the past 16 years, Alina has covered everything from Ebola to androids while writing health, science and tech articles for major publications. She has multiple health, safety and lifesaving certifications from Oklahoma State University. Alina's goal in life is to try as many experiences as possible. To date, she has been a volunteer firefighter, a dispatcher, substitute teacher, artist, janitor, children's book author, pizza maker, event coordinator and much more.