Taking a combination of vitamins B6, B12 and folic acid appears to lower the risk of one of the leading causes of blindness in Canadians, a new study finds.
Researchers reporting in the Archives of Internal Medicine say their findings suggest that the vitamins can lower the risk of women developing age-related macular degeneration by 34 per cent.
Age-related macular degeneration is the most common cause of severe vision loss in Canada, with 78,000 new cases reported in this country last year -- the majority of them in women. The condition blurs the centre of the field of vision, making it difficult to read, drive and perform everyday tasks.
Certain factors are known to increase the risk of developing AMD, including obesity, smoking and a family history of the irreversible condition. The only known way to prevent AMD is to avoid smoking.
Now, researchers think they may have found a new prevention method through vitamin supplementation.
The study involved 5,442 women aged 40 and older who already had heart disease or at least three risk factors for AMD. Starting in April 1998, these women were randomly assigned to take either a placebo or a combination of:
- folic acid (2.5 milligrams per day)
- vitamin B6 (50 milligrams per day)
- and vitamin B12 (1 milligram per day)
They were then tested for the development of AMD until November 2005.
At the end of the study, 137 new cases of AMD were found, including 70 cases that that were significant enough to impede vision. They found that the women taking the supplements had a 34 per cent lower risk of developing AMD and a 41 per cent lower risk of visually significant AMD.
"The beneficial effect of treatment began to emerge at approximately two years of follow-up and persisted throughout the trial," the authors write.
The researchers aren't sure why the vitamins seem to lower AMD risk but they note that recent studies have found a connection between AMD and high blood levels of homocysteine, an amino acid that seems to damage blood vessel linings.
Treatment with vitamin B6, vitamin B12 and folic acid appears to reduce homocysteine levels and may reverse this blood vessel dysfunction.
The researchers also think the B vitamins and folic acid may have antioxidant effects and help to improve function of blood vessels in the eye.
The study authors say their findings are "the strongest evidence to date in support of a possible beneficial effect of folic acid and B vitamin supplements in AMD prevention,"
"Because they apply to the early stages of disease development, they appear to represent the first identified way--other than not smoking--to reduce the risk of AMD in individuals at an average risk," they write.
