Reduced and total ascorbate in guinea pig eye tissues in response to dietary intake.

Guinea pigs were fed 5 different levels of dietary ascorbate representing a 65-fold range (0.8-52 mg animal-1 day-1). After two months on the diets, levels of reduced and total ascorbate were determined in aqueous humor, vitreous humor, lens and plasma. At low-dietary levels, proportionally higher levels of ascorbate are found in the lens than in other eye tissues. Tissue ascorbate levels began to plateau at dietary intake of approximately 11 mg animal-1 day-1. This is the amount suggested for optimal health, but it is ten times the level needed to prevent scurvy. Over 75% of the eye tissue ascorbate is in the reduced form in animals fed diets which provided 11 mg ascorbate. However, there was less than 50% reduced ascorbate in the eye tissues of the animals fed about 1mg ascorbate per day.