... And the risk of developing cataracts.

... and the risk of developing cataracts 

Galactose is a simple sugar derived from the breakdown of the milk sugar lactose. Because galactose is toxic to the lens of the eye, infants lacking the enzyme needed to metabolize it develop cataracts at a young age. Epidemiologist Paul F. Jacques has now compared levels of this enzyme, called galactokinase, with dairy food consumption in 106 persons aged 40 to 70 - 73 of them with cataracts. The just-completed study offers the first strong indication that galactose may play a role in adult cataracts, says Jacques, who works in Boston at the Agriculture Department's Human Nutrition Research Center on Aging.

All but two study participants--both cataract sufferers--had galactokinase levels considered normal. So Jacques arbitrarily defined as "low" the half of his study group with the lowest enzyme levels. People in that subgroup who eschewed lactose-containing products -- such as milk, yogurt and cheese -- had the same cataract incidence as those in the "high" enzyme group, he found. But "low" subjects who regularly consumed even a little dairy food -- such as a cup of milk daily -- ran four times the cataract risk of those in the "high" enzyme group.

These individuals, with their slowed conversion of galactose to glucose, could unwittingly expose their lenses to a lifetime of low but chronic levels of the cataract-causing sugar, the study suggests. Physicians do not routinely screen for galactokinase deficiency, and in any case they would interpret the levels seen in the "low" group as normal by current standards. However, Jacques says his findings are too preliminary to warrant a change in dairy food consumption. He points out that osteoporosis -- the skeletal embrittlement fostered by insufficient calcium intake from dairy foods and other sources -- "can be life threatening," whereas cataracts tend only to disable.