The systematic review assessed the evidence for a diet rich in antioxidant vitamins (carotenoids, vitamins C and E) or minerals (selenium and zinc) for the prevention of age-related macular degeneration (AMD).
The team assessed four randomised controlled trials with data from 62,520 people in Australia, Finland and the USA. Led by Jennifer Evans of the London School of Hygiene & Tropical Medicine, UK, the review concluded that there is simply not enough evidence to assess the potential benefits of many supplements such as vitamin C, lutein and zeaxanthin, “or any of the commonly marketed multivitamin combinations” on AMD.
The review team did however note that there is ‘accumulating’ evidence that taking vitamin E or beta-carotene supplements “will not prevent or delay the onset of AMD.”
“These trials provide evidence that taking vitamin E and beta-carotene supplements is unlikely to prevent the onset of AMD,” wrote Evans and her colleagues.
“Overall the quality of the evidence was high. People who took these supplements were not at decreased (or increased) risk of developing AMD,” they explained.
The team added that was no evidence for other antioxidant supplements and commonly marketed combinations.
“Although generally regarded as safe, vitamin supplements may have harmful effects and clear evidence of benefit is needed before they can be recommended,” they concluded.
Reacting to the review specialists DSM told NutraIngredients that continuing to insist upon the randomised controlled trials (RCT) data that Cochrane reviews use for validation of the health benefits of nutrients “would guarantee not certainty but stagnation.”
“Policy makers must now accept that intervention trials designed to test the efficacy of powerful drugs on sick people are not always suitable for determining the benefits of nutrients.
"The presence or absence of positive RCT data should not therefore be a gate-keeper criterion in the evaluation of nutrient or food claims," said DSM.
Kemin president Pedro Vieira told NutraIngredients that to date there are no studies that meet the Cochrane group’s highly exclusionary criteria for RCTs that have studied the relationship between AMD prevention and dietary intervention with lutein and zeaxanthin.
“Given the large body of evidence that already exists as well as the substantial number of studies still underway, namely the AREDS 2 study, Kemin strongly believes in the beneficial effects of lutein and zeaxanthin in both AMD and healthy subjects,” said Vieira.
Source: Cochrane Collaboration
Published online ahead of print, doi: 10.1002/14651858.CD000253.pub3
“Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration”
Authors: J.R. Evans, J.G. Lawrenson