Antioxidant vitamin and mineral supplements to prevent the development of age-related macular degeneration (AMD)

Full citation: Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration. Cochrane Database of Systematic Reviews 2017, Issue 7. Art. No.: CD000253. DOI: 10.1002/14651858.CD000253.pub4

What is the aim of this review? 
The aim of this Cochrane Review was to find out whether taking antioxidant vitamin and mineral supplements prevents the development of AMD. Cochrane researchers collected and analysed all relevant studies to answer this question and found five studies.

Key messages 
Taking vitamin E or beta-carotene supplements will not prevent the onset of AMD in people who do not have signs of the condition. The same probably applies to vitamin C and multivitamin tablets. There is no evidence for other supplements, such as lutein and zeaxanthin.

What was studied in the review
AMD is a condition of the central area (macula) of the back of the eye (retina). The macula degenerates with age. In some people, this deterioration happens more quickly, and is associated with a particular appearance at the back of the eye. In its earliest stage (early AMD), yellow spots (drusen) can be seen under the retina by an eye health professional on examining the eye. The affected person will probably be unaware that they have a problem. As AMD progresses, it can lead to the loss of the cells in the back of the eye, which are needed for vision. This is known as geographic atrophy. Sometimes, new (harmful) blood vessels grow in the macula. These new blood vessels may bleed and cause scarring. This is known as neovascular or wet AMD. Any damage to the macula can affect vision, particularly central vision. Neovascular AMD and geographic atrophy are known as late AMD.

It is possible that antioxidant vitamins may help to protect the macula against this deterioration and loss of vision. Vitamin C, E, beta-carotene, lutein, zeaxanthin, and zinc are examples of antioxidant vitamins commonly found in vitamin supplements.

The Cochrane researchers only looked at the effects of these supplements in healthy people in the general population who did not yet have AMD. There is another Cochrane Review on the effects of these supplements in people who already have AMD.

What are the main results of the review
The Cochrane researchers found five relevant studies. The studies were large and included a total of 76,756 people. They took place in Australia, Finland, and the USA. The studies compared vitamin C, vitamin E, beta-carotene, and multivitamin supplements with placebo.

The review showed that, compared with taking a placebo:

  • Taking vitamin E supplements made little or no difference to the chances of developing AMD (high-certainty evidence).
  • Taking vitamin E supplements made little difference, or slightly increased, the chances of developing late AMD (moderate-certainty evidence).
  • Taking beta-carotene made little or no difference to the chances of developing any AMD (high-certainty evidence) or late AMD (moderate-certainty evidence).
  • Taking vitamin C made little or no difference to the chances of developing any AMD (high-certainty evidence) or late AMD (moderate-certainty evidence).
  • Taking multivitamin tablets may slightly increase the chances of developing any AMD or late AMD (moderate-certainty evidence).
  • Adverse effects were not consistently reported in these eye studies, but there is evidence from other large studies that beta-carotene increases the risk of lung cancer in people who smoke, or who have been exposed to asbestos.

None of the studies reported quality of life or resource use and costs.

How up-to-date is this review
The Cochrane researchers searched for studies that had been published up to 29 March 2017.