TABLE 3.

Potential mechanisms of thiamin deficiency

Decreased intake/absorption	Increased destruction/inactivation	Excessive losses	Increased use/metabolism
Poor diet quality	Polyphenols (e.g., in coffee, tea, and betel nut)	Diuretics	High-carbohydrate diets
Excessive alcohol	Thiaminases (e.g., in raw seafood and human gut flora)	Peritoneal or hemodialysis	Hypermetabolic states (e.g., hyperthyroidism)
Excessive simple sugars, milk products, fats	Hypomagnesemia	Renal losses in diabetes	Strenuous activity
	Heat processing of food		Acute illness/fever
	Irradiation of food		Pregnancy and lactation
Inadequate whole grains/legumes	Prolonged contact with amino acids in parenteral nutrition		Adolescent growth
			Major trauma
Anorexia			Major surgery
Prolonged emesis			Refeeding syndrome
Intestinal malabsorption (e.g., duodenal bypass, short gut syndrome, Crohn’s disease, proton pump inhibitors)			Chemotherapeutic agents (e.g., 5-flourouracil)