Antioxidant vitamin and mineral supplements to slow down the progression of age-related macular degeneration (AMD)

Full citation: Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration. Cochrane Database of Systematic Reviews 2017, Issue 7. Art. No.: CD000254. DOI: 10.1002/14651858.CD000254.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 slows down the progression of AMD and prevents visual loss. Cochrane researchers collected and analysed all relevant studies to answer this question and found 19 studies.

Key messages 
Taking an antioxidant multivitamin supplement may slow down the progression of AMD. Most benefit will be seen in people who have a higher chance of progression. Although vitamin supplements are generally regarded as safe, the studies included in this review did not provide good evidence as to safety as they were generally too small.

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 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 people with AMD. There is another Cochrane Review on the effects of these supplements in people who do not already have AMD.

What are the main results of the review
The Cochrane researchers found 19 relevant studies. Ten studies were from Europe, six from USA, two from China, and one from Australia. These studies compared multivitamin supplements, zinc, vitamin E and lutein and zeaxanthin with placebo.

•Taking antioxidant vitamins plus zinc probably slows down the progression to late AMD and vision loss (moderate-certainty evidence). This may result in a small improvement in quality of life (low-certainty evidence).
•Taking lutein alone (or combined with zeaxanthin) may have little or no effect on progression to late AMD and vision loss (low-certainty evidence).
•Taking vitamin E alone may have little or no effect on the progression to late AMD and vision loss (low-certainty evidence).

Although vitamin supplements are generally regarded as safe, the studies included in this review did not provide good evidence as to safety as they were generally too small and adverse effects were reported inconsistently.

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