David Brill
Taking folic acid with vitamins B6 and B12 could help to prevent age-related macular degeneration (AMD) in women at high risk of cardiovascular disease (CVD).
Women who took daily supplements for 7 years reduced their relative risk of AMD by around a third, a recent trial reported.
The analysis included 5,205 women aged over 40 who had a history of CVD and a minimum of three CVD risk factors but no AMD at baseline. There were 55 cases of AMD in the treatment group and 82 in the placebo group at trial’s end. [Arch Intern Med 2009 Feb 23;169:335-41]
Lead author Dr. William Christen, an associate professor at Brigham and Women’s Hospital and Harvard Medical School, US, said that the intervention is safe and inexpensive and could, theoretically, be applied on a wide scale. However, he stressed the need for more research before making any specific recommendations.
“This is the first trial to suggest a possible benefit so I think it’s important at this point to corroborate the findings in other populations,” he said.
“Other than avoiding cigarette smoking we have no means to prevent the early stages of AMD so these findings, if they’re corroborated … will be particularly important from a public health perspective.”
AMD is the leading cause of blindness in European and US over-60s and is thought to be on the rise in Asia.
The Singapore Malay Eye Study found that in its early stages the condition affects 3.5 percent of Malays aged 40 to 80 – a comparable figure to that reported in the Australia. The prevalence of late-stage AMD among Malays was 0.34 percent. [Ophthalmology 2008;115(10):1735-41]
For elderly Singaporeans in general the prevalence of AMD could be as high as 27 percent, according to a study of 574 over-60s. Awareness of the condition however seems to be low – for every AMD patient with a confirmed diagnosis there were 154 who did not know they had the condition. [Singapore Med J 1997;38(4):149-55]
Vitamins are not currently recommended for primary AMD prevention but have been shown to delay progression in those who already have intermediate-stage disease. A combination of high-dose antioxidants (vitamins C, E and beta carotene) and zinc reduced the odds of developing advanced AMD by 28 percent, as compared to placebo, in a trial of 3,640 patients with an average of 6.3 years of follow up. [Arch Ophthalmol 2001 Oct;119(10):1417-36]
Christen et al. randomized participants to placebo or a regimen of 2.5 mg/day folic acid, 50 mg/day vitamin B6 and 1 mg/day vitamin B12 – higher dosages than typically given over the counter. The relative risk in the treatment group was 0.66 for AMD (95 percent CI 0.47-0.93; P=0.02) and 0.59 for visually significant AMD (95 percent CI 0.36-0.95; P=0.03). Mean follow-up was 7.3 years.
The study could also provide important new insights into the much-debated role of homocysteine in vascular disease. The marker has been strongly linked to atherosclerosis, CVD and AMD, but trials have yet to show that homocysteine-lowering therapies, notably folic acid and B vitamins, significantly improve outcomes.
“If these findings are real for AMD then one possible explanation would be … that there may be a difference between small vessel and large vessel disease in the response to homocysteine lowering. At this point we can only speculate,” said Christen.
The analysis included 5,205 women aged over 40 who had a history of CVD and a minimum of three CVD risk factors but no AMD at baseline. There were 55 cases of AMD in the treatment group and 82 in the placebo group at trial’s end. [Arch Intern Med 2009 Feb 23;169:335-41]
Lead author Dr. William Christen, an associate professor at Brigham and Women’s Hospital and Harvard Medical School, US, said that the intervention is safe and inexpensive and could, theoretically, be applied on a wide scale. However, he stressed the need for more research before making any specific recommendations.
“This is the first trial to suggest a possible benefit so I think it’s important at this point to corroborate the findings in other populations,” he said.
“Other than avoiding cigarette smoking we have no means to prevent the early stages of AMD so these findings, if they’re corroborated … will be particularly important from a public health perspective.”
AMD is the leading cause of blindness in European and US over-60s and is thought to be on the rise in Asia.
The Singapore Malay Eye Study found that in its early stages the condition affects 3.5 percent of Malays aged 40 to 80 – a comparable figure to that reported in the Australia. The prevalence of late-stage AMD among Malays was 0.34 percent. [Ophthalmology 2008;115(10):1735-41]
For elderly Singaporeans in general the prevalence of AMD could be as high as 27 percent, according to a study of 574 over-60s. Awareness of the condition however seems to be low – for every AMD patient with a confirmed diagnosis there were 154 who did not know they had the condition. [Singapore Med J 1997;38(4):149-55]
Vitamins are not currently recommended for primary AMD prevention but have been shown to delay progression in those who already have intermediate-stage disease. A combination of high-dose antioxidants (vitamins C, E and beta carotene) and zinc reduced the odds of developing advanced AMD by 28 percent, as compared to placebo, in a trial of 3,640 patients with an average of 6.3 years of follow up. [Arch Ophthalmol 2001 Oct;119(10):1417-36]
Christen et al. randomized participants to placebo or a regimen of 2.5 mg/day folic acid, 50 mg/day vitamin B6 and 1 mg/day vitamin B12 – higher dosages than typically given over the counter. The relative risk in the treatment group was 0.66 for AMD (95 percent CI 0.47-0.93; P=0.02) and 0.59 for visually significant AMD (95 percent CI 0.36-0.95; P=0.03). Mean follow-up was 7.3 years.
The study could also provide important new insights into the much-debated role of homocysteine in vascular disease. The marker has been strongly linked to atherosclerosis, CVD and AMD, but trials have yet to show that homocysteine-lowering therapies, notably folic acid and B vitamins, significantly improve outcomes.
“If these findings are real for AMD then one possible explanation would be … that there may be a difference between small vessel and large vessel disease in the response to homocysteine lowering. At this point we can only speculate,” said Christen.
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