The effects of moderate dietary zinc deprivation (2 mcg/gm diet) compared to an adequate zinc intake (50 mcg/gm) were compared using 24-hour activity patterns and an attention task performance in 10 adolescent female monkeys (18-33 months of age) at the California Regional Primate Research Center, University of California, Davis, CA. Zinc deprivation caused a progressive decrease in daytime activity levels and impaired attention followed by growth retardation. 
COMMENT. Motor activity levels and attention may be decreased during early stages of zinc deprivation and before the onset of growth retardation. The authors cite references to estimates of zinc deficiency in 50% of US children, and especially in adolescent girls, 80% of whom consume less than the recommended dietary allowance of 12 mg/day. Behavioral effects of zinc malnutrition may be observed before the more obvious onset of growth retardation. Children who eat primarily cereal proteins and little meat may be susceptible to zinc deficiency syndrome . ADD without hyperactivity is more prevalent than ADHD in girls compared to boys, and zinc deficiency should be considered as a factor in the etiology of inattentiveness, especially in girls.