Vitamin B₁ is also called thiamine. You need vitamin B₁ in your daily diet to help break down carbohydrates (starches). The energy produced by this process helps your body perform functions as basic as breathing and moving. Not getting enough vitamin B₁ in your daily diet leads to a disease called beriberi, which can affect your nervous system and heart. Alcoholics are at a high risk of developing beriberi because prolonged intake of large amounts of alcohol depletes your body's supply of vitamin B₁.

The most important use of vitamin B₁ is to improve symptoms of beriberi. These symptoms include nervous system symptoms such as pain, swelling, and redness of the hands and feet, and a tickling or burning sensation in the hands and feet. Confusion and loss of memory are also potential symptoms.

Other symptoms of beriberi include difficulty in breathing, swelling of the legs, and rapid heart beat. Certain diuretics may cause you to lose Vitamin B₁ through urination, causing a deficiency.

Recent research suggests that vitamin B₁ may help manage congestive heart failure.

Vitamin B₁ may also play a negative role in cancer chemotherapy. Researchers have found that taking too much vitamin B₁ while undergoing chemotherapy may make tumors grow more quickly.

Cereals and pork are excellent sources of vitamin B₁. Other good sources of vitamin B₁ are white enriched rice, sunflower seeds, peanuts, wheat germ, brewer's yeast, soy milk, beans, and pasta.

Milk, fruits, and vegetables are also good sources of vitamin B₁ if consumed in adequate amounts.

Vitamin B₁ is labeled as thiamine hydrochloride and thiamine mononitrate. It is available as tablets or capsules in multivitamin form, including children's chewable and liquid forms, B-complex form, or by itself.

As with all medications and supplements, check with a healthcare provider before giving vitamin B₁ supplements to a child.

Daily recommendations for dietary vitamin B₁ are listed below.

Pediatric

• Neonates to 6 months: 0.2 mg (adequate intake)
• Infants 7 months to 1 year: 0.3 mg (adequate intake)
• Children 1 to 3 years: 0.5 mg (RDA)
• Children 4 to 8 years: 0.6 mg (RDA)
• Children 9 to 13 years: 0.9 mg (RDA)
• Males 14 to 18 years: 1.2 mg (RDA)
• Females 14 to 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)

Vitamin B₁ is generally nontoxic. Stomach upset can occur at very high doses (much higher than the recommended daily doses).

Diuretics, particularly furosemide, may reduce the levels of thiamine in the body. When furosemide is combined with digoxin (a medication used to treat heart conditions) and taken for long periods of time, the ability of thiamine to benefit the heart may be reduced. Please refer to the depletions monographs on loop diuretics and cardiac glycosides for more information.

Taking vitamin B₁ supplements may improve treatment with antidepressants such as nortriptyline, especially in elderly patients. However, you should check with your healthcare practitioner before adding new supplements to your existing medication regimen.

Thiamine may help reduce some of the side effects associated with scopolamine, a medication commonly used to treat motion sickness.

Thiamine should not be taken at the same time as tetracycline, an antibiotic, because it interferes with the absorption and effectiveness of this medication. Thiamine either alone or in combination with other B vitamins should be taken at different times from tetracycline.

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