Night blind? Carrots may not help.

Night blind? Carrots may not help

It's common knowledge that carrots, as a rich source ofvitamin A, are useful in preventing night blindness. So when night blindness showed up among malnourished individuals, researchers assumed it was because a protein shortage disrupted the transport of vitamin A to the eye from its storage in the liver, says Daniel Bankson, a clinical biochemist at the University of North Carolina in Chapel Hill. While a protein shortage will disrupt vitamin A transport, Bankson says, his recent research, done while he was at the Agriculture Department's Human Nutrition Research Center on Aging in Boston, indicates that is not necessarily the primary reason malnutrition affects night vision.

Rats fed a growth-stunting diet (having only a third to a fifthof their normal protein intake) along with four times the daily requirement for vitamin A suffered night blindness, despite maintaining sufficient levels of vitamin A in the eye. Rats fed a fully balanced diet, but with only enough calories to maintain the size and weight of animals on the protein-deficient diet, suffered even worse night vision--again while maintaining normal eye levels of vitamin A. Bankson says this suggests that a lack of protein and/or energy can also cause night blindness.