A decline in vitamin B1 levels occurs with age, irrespective of medical condition.³ Deficiency is most commonly found in alcoholics, people with malabsorption conditions, and those eating a very poor diet. It is also common in children with congenital heart disease.⁴ People with chronic fatigue syndrome may also be deficient in vitamin B1.^5,6 Individuals undergoing regular kidney dialysis may develop severe vitamin B1 deficiency, which can result in potentially fatal complications.⁷ Persons receiving dialysis should discuss the need for vitamin B1 supplementation with their physician.