NEW YORK, Mar 28 (Reuters Health) -- Women who have low levels of folate, the by-product of folic acid found in the blood, appear to be at greater risk of Alzheimer's disease, according to results of a study in Catholic nuns.

In the study of 30 nuns who participated in a long-term study of Alzheimer's disease, half had brain changes consistent with the memory-robbing illness at autopsy. The women, aged 78 to 101 when they died, had lived at the same convent for most of their lives, according to Dr. David A. Snowdon and colleagues at the University of Kentucky in Lexington.

Snowdon's team looked at data collected earlier in the study and found that those women with Alzheimer's disease were more likely to have low blood levels of folate than women without the illness. None of the other nutritional markers analyzed in the blood samples was related to brain degeneration or Alzheimer's disease, according to the report in the April issue of the American Journal of Clinical Nutrition.

The authors note that the study could not determine whether low levels of folate actually cause Alzheimer's. And the findings do not provide any evidence that taking folic acid supplements can prevent the disease or slow it down. It is possible that the women had low blood levels of folate due to problems absorbing or metabolizing the nutrient. The women all ate in the same kitchen and, presumably, had similar intakes of folic acid.

The researchers call for further research in this area, noting that there are several possible explanations for the relationship between the nutrient and this disease.

Folic acid, a nutrient found in green leafy vegetables, liver, kidney, whole grains and nuts, is important in the development of the central nervous system and in the maintenance of blood vessels. Lack of this nutrient can cause birth defects in the developing fetus.

SOURCE: American Journal of Clinical Nutrition 2000;71:993-998.

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