DISTURBED GALACTOSE METABOLISM IN ELDERLY AND DIABETIC HUMANS IS ASSOCIATED WITH CATARACT FORMATION

Lactose consumption has been associated with a high incidence of catar act in northern Indian and southern Italian populations. Galactose abs orbed after hydrolysis of lactose from milk in individuals with normal lactase activity is considered responsible. However, lactase-deficien t subjects who often avoid drinking milk are able to digest lactose an d absorb free galactose in fermented milk and yogurt. This study was c onducted to evaluate the relationships between milk and yogurt consump tion, galactose metabolism and cataract risk. Milk ingestion was dose- related with cataract risk in lactose digesters (particularly in diabe tics) but not in lactose maldigesters. Conversely, yogurt intake had a protective dose-effect on cataract formation for the whole population . Maximal galactose concentrations after an oral galactose test increa sed exponentially with age. Red blood cell galactokinase activity was significantly lower in elderly subjects (> 60 y) than in young individ uals (P < 0.05), and galactose-1-phosphate uridyl-transferase activity was significantly lower in institutionalized subjects and in home-liv ing elderly with cataract than in healthy elderly subjects (P < 0.05). We conclude that the cataractogenic action of milk lactose is depende nt on the disturbance of galactose metabolism in elderly subjects and that yogurt is not cataractogenic, although the mechanism of the prote ctive effect of yogurt remains unknown.