Vitamin B1 (thiamine)
Overview:
Vitamin B1, also called thiamine or thiamin, is one of 8 B vitamins. All B vitamins help
the body convert food (carbohydrates) into fuel (glucose), which is "burned" to produce
energy. These B vitamins, often referred to as B complex vitamins, also help the body
metabolize fats and protein. B complex vitamins are necessary for healthy skin, hair,
eyes, and liver. They also help the nervous system function properly, and are necessary
for optimal brain function.
All B vitamins are water-soluble, meaning that the body does not store them.
Like other B complex vitamins, thiamine is considered an "anti-stress" vitamin because it
may strengthen the immune system and improve the body's ability to withstand stressful
conditions. It is named B1 because it was the first B vitamin discovered.
Thiamine is found in both plants and animals and plays a crucial role in certain metabolic
reactions. For example, it is required for the body to form adenosine triphosphate (ATP),
which every cell of the body uses for energy.
Thiamine deficiency is rare, but can occur in people who get most of their calories from
sugar or alcohol. People who are deficient in thiamine may experience fatigue,
irritability, depression and abdominal discomfort. People with thiamine deficiency also
have difficulty digesting carbohydrates. As a result, a substance called pyruvic acid
builds up in their bloodstream, causing a loss of mental alertness, difficulty breathing,
and heart damage (a disease known as beriberi).
Beriberi
The most important use of thiamine is to treat beriberi, which is caused by not getting
enough thiamine in your diet. Symptoms include swelling, tingling, or burning sensation
in the hands and feet, confusion, difficulty breathing (from fluid in the lungs), and
uncontrolled eye movements (called nystagmus). Although people in the developed
world generally do not have to worry about getting enough thiamine because foods such
as cereals and breads are fortified with the vitamin, people can develop a deficiency fairly
quickly, because the body does not store thiamine.
Wernicke-Korsakoff syndrome
Wernicke-Korsakoff syndrome is a brain disorder caused by thiamine deficiency; as with
beriberi, it is treated by giving supplemental thiamine. Wernicke-Korsakoff is actually
two disorders: Wernicke's disease involves damage to nerves in the central and peripheral
nervous systems and is generally caused by malnutrition stemming from habitual alcohol
abuse. Korsakoff syndrome is characterized by memory impairment and nerve damage.
High doses of thiamine can improve muscle coordination and confusion, but rarely
improves memory loss.
Cataracts
Preliminary evidence suggests that thiamine -- along with other nutrients -- may lower
risk of developing cataracts. People with plenty of protein and vitamins A, B1, B2, and
B3 (niacin) in their diet are less likely to develop cataracts. Getting enough vitamins C, E,
and B complex (particularly B1, B2, B9 [folic acid], and B12 [cobalamin) may further
protect the lens of your eyes from developing cataracts. More research is needed.
Alzheimer's disease
Because lack of thiamine can cause dementia in Wernicke-Korsakoff syndrome, it has
been proposed that thiamine might help reduce severity of Alzheimer's disease. Scientific
studies have not always shown any benefit from thiamine, however. More research is
needed before thiamine can be proposed as an effective treatment for Alzheimer's
disease.
Heart failure
Thiamine may be related to heart failure in two ways. First, low levels of thiamine can
lead to "wet beriberi," a condition where fluid builds up around the heart. However, it
isn't clear that taking thiamin will help people with heart failure not related to beriberi.
Many people with heart failure take diuretics (water pills), which help rid the body of
excess fluid. But diuretics may also cause the body to get rid of too much thiamine. A
few small studies suggest that taking thiamine supplements may help. A multivitamin,
taken regularly, should provide enough thiamine.
Dietary Sources:
Most foods contain small amounts of thiamine. Large amounts can be found in pork and
organ meats. Other good dietary sources of thiamine include whole-grain or enriched
cereals and rice, legumes, wheat germ, bran, brewer's yeast, and blackstrap molasses.
However, the vitamin is easily destroyed when exposed to heat.
Available Forms:
Vitamin B1 can be found in multivitamins (including children's chewable and liquid
drops), B complex vitamins, or if can be sold individually. It is available in a variety of
forms, including tablets, softgels, and lozenges. It may also be labeled as thiamine
hydrochloride or thiamine mononitrate.
How to Take It:
As with all medications and supplements, check with a health care provider before giving
vitamin B1 supplements to a child.
Daily recommendations for dietary vitamin B1 are listed below.
Pediatric
Newborns - 6 months: 0.2 mg (adequate intake)
Infants 7 months - 1 year: 0.3 mg (adequate intake)
Children 1 - 3 years: 0.5 mg (RDA)
Children 4 - 8 years: 0.6 mg (RDA)
Children 9 - 13 years: 0.9 mg (RDA)
Males 14 - 18 years: 1.2 mg (RDA)
Females 14 - 18 years: 1 mg (RDA)
Adult
Males 19 years and older: 1.2 mg (RDA)
Females 19 years and older: 1.1 mg (RDA)
Pregnant females: 1.4 mg (RDA)
Breastfeeding females: 1.5 mg (RDA)
Doses for conditions like beriberi and Wernicke-Korsakoff syndrome are determined by a
doctor. For Wernicke-Korsakoff syndrome, thiamine is given intravenously.
A daily dose of 50 - 100 mg is often taken as a supplement. Thiamine appears safe even
at high doses; however, you should talk to your doctor before taking a large amount.
Precautions:
Because of the potential for side effects and interactions with medications, you should
take dietary supplements only under the supervision of a knowledgeable health care
provider.
Thiamine is generally nontoxic. Very high doses may cause stomach upset.
Taking any one of the B vitamins for a long period of time can result in an imbalance of
other important B vitamins. For this reason, you may want to take a B complex vitamin,
which includes all the B vitamins.
Possible Interactions:
If you are currently being treated with any of the following medications, you should not
use vitamin B1 without first talking to your health care provider.
Digoxin -- Laboratory studies suggest that digoxin (a medication used to treat heart
conditions) may reduce the ability of heart cells to absorb and use vitamin B1; this may
be particularly true when digoxin is combined with furosemide (Lasix, a loop diuretic).
Diuretics -- Diuretics (particularly furosemide, which belongs to a class called loop
diuretics) may reduce levels of vitamin B1 in the body. It's possible that other diuretics
may have the same effect. If you take a diuretic, ask your doctor if you need a thiamine
supplement.
Phenytoin (Dilantin) -- Some evidence suggests that some people taking phenytoin have
lower levels of thiamine in their blood, and that may contribute to the side effects of the
drug. However, that is not true of all people who take phenytoin. If you take phenytoin,
ask your doctor if you need a thiamine supplement.
