NEW YORK, May 07 (Reuters Health) - Elderly people with low blood levels of vitamin B-12 and folate may face an increased risk of developing Alzheimer's disease, Swedish researchers have found. The findings suggest that monitoring older people's levels of the vitamins may aid in preventing Alzheimer's, according to a report in the May 8th issue of Neurology.

However, the researchers call their findings "surprising," and emphasize that there is no evidence that deficiencies in vitamin B-12 or folate contribute to the brain abnormalities that are the hallmark of Alzheimer's.

Vitamin B-12 plays an important role in maintaining nerve cells, and some research has linked low blood levels of the vitamin to Alzheimer's and mental decline. Few studies have looked at whether there is such a connection between Alzheimer's and folate, a B vitamin key to the production and maintenance of body cells.

In a study of 370 men and women aged 75 and older, investigators found that those with low levels of either vitamin were twice as likely as those with normal levels to develop Alzheimer's over a 3-year period. Surprisingly, the link was even stronger among study participants who performed well on mental tests at the start of the study, according to Dr. Hui-Xin Wang and colleagues at the Karolinska Institute in Stockholm, Sweden.

The reason for the link is unclear, but low blood levels of B-12 and folate can lead to elevations in the protein homocysteine, which may in turn damage nerve cells, the authors note.

Most people get enough vitamin B-12 in their diets to maintain healthful levels, but some--including the elderly--stand a greater chance of being deficient. The vitamin is found in animal products, including meat, fish, eggs and milk. Folate occurs naturally in foods such as leafy green vegetables, dried beans and peas, and citrus fruits; many cereals are fortified with folic acid, the synthetic form of folate.

Alzheimer's is the most common form of dementia, affecting an estimated 4 million Americans. The exact cause remains elusive, but scientists believe genetics and environmental factors conspire to trigger the onset of the disease.

　　From Reutershealth