Thiamin, also known as vitamin B1, is a water-soluble vitamin that can be excreted in increased amounts when a person takes diuretic medications. Diuretics are sometimes referred to as “water pills” and are commonly used in the treatment of high blood pressure and heart conditions.
Research published in Nutrition Reviews (58(10):319–323) notes that heart problems are a characteristic feature of beriberi, a disease caused by thiamin deficiency. Thiamin deficiency has also been linked with congestive heart failure. Because the body stores only a small amount of thiamin—approximately 30 mg—deficiency can develop relatively quickly when intake is inadequate or losses are increased.
Thiamin depletion has been observed in people who consume large amounts of alcohol, since alcohol has a diuretic effect, and in individuals taking diuretic medications. For this reason, low thiamin status has been proposed as a contributing factor in some cases of heart failure.
Symptoms associated with thiamin deficiency may include fatigue, burning sensations in the feet, low blood pressure, frequent nighttime urination with difficulty returning to sleep, and feelings of anxiety or a sense of impending doom.
Diuretic therapy may also reduce magnesium levels. Magnesium is required to convert thiamin into its active form within the body, meaning deficiencies of the two nutrients may be related. For individuals using diuretics—particularly those with cardiovascular risk—nutrient status is sometimes evaluated as part of a broader clinical assessment.
