The B group of vitamins includes eight distinct types, which together are referred to as the vitamin B complex. One of these is vitamin B1, also known as thiamine or thiamin. This vitamin is an essential part of metabolism, and it helps ensure healthy eyes, skin, hair, nails and liver. It also is essential for nervous system function, brain function and a healthy immune system, and it improves the body’s ability to withstand physical and mental stress.
Every cell in the body preferentially uses a molecule called adenosine triphosphate (ATP) as a source of energy. Vitamin B1 is essential for the metabolic process in which ATP is formed, so this vitamin is extremely important for both physical and mental health. ATP is used more rapidly in cells of the nervous system, brain and immune system, meaning that these cells are more vulnerable to deficiency.
Vitamin B1 deficiency is rare but serious. This vitamin deficiency is most likely to develop in people who abuse alcohol or obtain a large proportion of their calories from sugar. Deficiency can cause fatigue, abdominal pain, abdominal discomfort, depression and irritability. In addition, people who are deficient in B1 are not able to digest carbohydrates effectively. This leads to a toxic build-up of a substance called pyruvic acid, which can cause a disease called beriberi. Symptoms of beriberi include heart damage, confusion, difficulty breathing and reduced mental alertness.
To get the recommended daily allowance of vitamin B1, one should eat a variety of foods each day, including a mixture of two or more B1-containing foods if possible. Animal products that are good sources of B1 include beef and pork, animal liver, eggs and milk. Many plant foods also are good B1 sources. These include legumes such as lentils and beans, whole grains, cereals with whole grains, wheat, seeds, brown rice and nuts. Yeast also is an extremely rich source of B1.
Vitamin B1 is a water-soluble vitamin. This means it is generally not stored in the body, and excess amounts of the vitamin are excreted in the urine. Because of this, it is important to ensure that the diet includes a regular supply of foods containing B1.
This vitamin generally is not toxic in high doses, but very large doses of B1 might cause an stomach upset. In addition, some interactions can occur if B1 supplements are taken in conjunction with certain medications. For example, diuretics can reduce B1 levels in the body, and the heart medication digoxin can prevent the use of this vitamin by heart cells. Phenytoin also can reduce the body’s ability to use B1. People who take these medications should consult a doctor to find out whether they need vitamin B1 supplements.