About half of thiamin is found in skeletal muscle. Beriberi, more common in the 19th century, is a thiamin deficiency disease caused by a diet of highly polished rice, where the thiamin-rich husk is removed. Deficiency appears in alcoholics, those with malabsorption syndromes, and in long-term use of loop diuretics.
Subclinical thiamin deficiency may be more common than expected, and might appear as abnormal glucose tolerance. Thiamin’s anti-oxidant properties have not been elucidated, but the brain damage associated with thiamin deficit indicates oxidative stress. Absorption of the nutrient is impeded by the tannins in coffee and tea, but may be offset by taking vitamin C. Some supplements used to treat osteoporosis, such as horsetail, can destroy thiamin in the stomach and lead to signs of thiamin deficiency, as can diseases such as Crohn’s, celiac, colitis, and diverticulitis.
*These statements have not been evaluated by the FDA. These products are not intended to treat, diagnose, cure, or prevent any disease.