Retinal degeneration in primates raised on a synthetic human infant formula

A degeneration of the retinal cone photoreceptor cells, but not of the rod photoreceptor cells, is present in rhesus monkeys raised from birth for 26 months on a commercially available human infant protein hydrolyzate formula. This degeneration is associated with a selective decrease in plasma taurine concentration, and is entirely prevented by supplementing the formula with taurine. A reduced conedominated ERG was present at 10 months, but not at 18 or 26 months. These results suggest that the implications of the reduced taurine concentrations in human infants fed synthetic formulas containing little or no taurine should be reconsidered, since adverse effects on the visual system may only be detectable at the ultrastructural level.