A decline in vitamin B1 levels occurs with age, irrespective of medical condition. 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. People with chronic fatigue syndrome may also be deficient in vitamin B1. Individuals undergoing regular kidney dialysis may develop severe vitamin B1 deficiency, which can result in potentially fatal complications. Persons receiving dialysis should discuss the need for vitamin B1 supplementation with their physician.