Can a Healthy Diet or Dietary Supplements Prevent Cataracts?

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Identifying dietary factors that might help slow cataract formation would be welcome, but for now, the evidence is mixed. For instance, researchers recently conducted a meta-analysis of 20 studies to investigate whether particular vitamins or carotenoids protect against cataracts.

The trials included cohort studies, in which researchers follow groups of people, looking for patterns of health or disease. Also included were randomized intervention studies, in which comparisons are made between people who are given a treatment and others who are not.

The results of the cohort studies strongly suggested that certain vitamins and other nutrients, as part of a healthy diet, may significantly lower the risk of cataracts, especially lutein, zeaxanthin, vitamin C, vitamin A, and beta-carotene. But randomized controlled trials, which are considered much stronger evidence, did not show any benefits.

All the studies included in the meta-analysis, which was published in The American Journal of Clinical Nutrition in 2019, have limitations. Cohort studies typically use food recall questionnaires to estimate dietary intake—a measure that is unreliable. And the randomized trials may have been of too short a duration to show a benefit.

For now, it’s safe to say that diets rich in fruits, vegetables, nuts, and grains—the sources of many of the nutrients analyzed in this study—are a smarter choice than taking supplements for plenty of reasons. More research is needed to know whether one of the benefits is protection against cataracts.