Evidence that histidine is an essential amino acid in normal and chronically uremic man

Abstract

The requirement for dietary histidine was investigated in 4 normal and 3 chronically uremic men. Subjects lived in a metabolic unit where they were fed 3 isonitrogenous diets in the following order: a 40 g protein diet (28±SD 8 days), a semi synthetic amino acid diet deficient in histidine (35±2 days), and an amino acid diet which contained histidine (31±5 days). With ingestion of the histidine deficient diet, nitrogen balance gradually became negative, and serum albumin decreased in 6 subjects. Plasma histidine fell by 82±6%; muscle histidine decreased by 62±19%; the hematocrit fell by 25±9%; and serum iron rose. Subjects felt unwell, and in 5 cases, a skin lesion consisting of fine scales, dry skin, and mild erythema developed. After administration of the histidine repletion diet, nitrogen balance became positive in 6 subjects; serum albumin increased in 5 cases; plasma and muscle histidine rose; serum iron fell abruptly; a reticulocytosis ensued; and the hematocrit rose. The clinical symptoms and skin lesions disappeared. These observations indicate that histidine is an essential amino acid in normal and chronically uremic man. The absence of dietary histidine is associated with failure of normal erythropoiesis.