Can vitamin supplements help maintain your vision?

Photo of a woman reading a newspaper (PantherMedia / Diego Cervo)

Dietary supplements containing beta-carotene, vitamin C or vitamin E can neither prevent age-related cataracts nor slow the progression of the condition.

Dietary supplements are often marketed using a lot of health-related claims. They are available over the counter in pharmacies, supermarkets, drugstores or on the internet. They come in many different forms, including tablets, capsules, powder or liquids. Dietary supplements contain nutrients that also occur naturally in our food, such as vitamins and minerals, but in a concentrated form and often at a higher dose. Some of these products are claimed to be especially good for your eyes and vision.

When cataracts develop, the lens of the eye gradually becomes cloudy. This causes your eyesight to become increasingly blurry, as if you were looking at things through a veil or fog. In industrialized countries, cataracts are more common in older people.

According to one popular theory, substances called free radicals develop in the cells of the eyes, where they may damage the tissue. Some vitamin supplements are believed to slow this damage, thereby supposedly preventing cataracts from developing, or slowing down vision loss.

Studies on preventing and treating cataracts with dietary supplements

Researchers from an international research group called the Cochrane Collaboration looked into the benefits of vitamin supplements for cataracts. They looked for special studies called randomized controlled trials that compared these products either with each other or with a fake supplement (placebo). They checked whether taking supplements could prevent cataracts or slow their progression.

The researchers analyzed nine studies involving a total of almost 120,000 people between the ages of 35 and 85. The participants used products with vitamin C, vitamin E and/or beta-carotene – that is, products thought to be especially good for your eyes – for up to twelve years.

Vitamin supplements have no benefit

The results of the studies clearly show that vitamin supplements are not effective against cataracts. People who had taken these products – in some cases for many years – developed cataracts just as often as people who had been taking a placebo. The supplements also didn't slow down the progression of the cataracts, and they didn't have any effect on eyesight. But some products had side effects: Depending on the study, between 7 and 16 out of 100 people who took beta-carotene had their skin turn yellowish-orange. This is a sign that they had taken too much beta-carotene.

Although vitamins are important for the body, a normal, balanced diet usually provides enough vitamins. So there's no reason to take dietary supplements to try to prevent or slow down cataracts. The Cochrane researchers considered the results to be so clear that they see no need for further research in this area.