Zinc, carotenoids and vitamins can help with macular degeneration, but it’s all in the formula.
According to a 2015 study published in the New Zealand Medical Journal, about 10% of New Zealanders aged 45-85 have the disease, which has “dry” and “wet” forms. The former is more common and is caused by small yellow deposits called drusen that develop under the retina.
An eye check by a doctor or optometrist can detect drusen, a retinal waste product, before there are any vision effects. However, it can lead to vision loss by depriving cells in the retina of the oxygen and nutrients they require, causing them to either malfunction or die.
Until the start of this century, it was largely thought that dietary supplements were ineffective against dry macular degeneration. However, in 2001, findings from the US National Eye Institute’s Age-Related Eye Disease Study (Areds) clearly showed that a supplement with high levels of antioxidants and zinc cut the risk of the advanced form of the disease and its associated vision loss.
The trial supplement contained 500mg of vitamin C, 400 international units of vitamin E, 15mg of beta carotene, 80mg of zinc as zinc oxide and 2mg of copper as cupric oxide.
Beta carotene was cause for concern because it increases lung-cancer risk among smokers. So, in 2013, a second trial, Areds2, tested several supplement variants and found that lutein/zeaxanthin (10mg/2mg) were an effective beta-carotene alternative. The researchers also tested a lower dose of zinc (25mg) and found the formulation was about as effective as the higher dose. However, adding omega-3 fatty acids to the supplement had no effect.
“While zinc is an important component of the Areds formulation, based on evidence from Areds2, it’s unclear how much zinc is necessary,” said ophthalmologist Emily Chew, deputy director of the institute’s epidemiology and clinical applications division.
Many New Zealand health practitioners took the Areds2 findings on board and began recommending patients in the early stage of the disease take supplements similar to the trial formulation.
However, not all supplements marketed as good for eye health and reducing the risk of macular degeneration follow the Areds2 formula. A 2017 Cochrane Review called into question the effectiveness of non-conforming supplements.
The UK-based research charity found some, containing lutein alone or in combination with zeaxanthin, may have little or no effect on the disease’s progression or vision loss. Similarly, taking vitamin E alone may have little or no effect.
The best thing for good vision is a healthy, varied diet and not smoking. And people diagnosed with macular degeneration should take a dietary supplement that follows the Areds2 formula, rather than a more limited supplement.
This article was first published in the February 16, 2019 issue of the New Zealand Listener.