New research from Brigham and Women's Hospital and Harvard Medical School, both in Boston, MA, has found that long-term daily use of multivitamin supplements could reduce the risk of cataract for men.
The study findings were recently published in the journal Opthalmology.
According to the research team, led by Dr. William Christen of Harvard Medical School, previous research has shown an association between the use of nutritional supplements and eye health.
But the researchers note that there is very limited information on the link between the long-term use of multivitamin supplements and the risk of eye diseases.
To investigate further, the research team analyzed 12,641 male doctors from the US who were aged 50 years or older.
All men were part of the Physicians' Health Study II (PHS II) and were assessed from 1997 to 2011.
Half of the men were randomly assigned to receive a common daily multivitamin, alongside vitamin C, vitamin E and beta carotene supplements, while the other half of the participants took a placebo. Vitamins were given to participants at doses in line with US dietary allowance recommendations.
Cataracts are cloudy areas in the lens of the eye that can cause blurred vision, while AMD is defined as the deterioration of the macula - the part of the eye responsible for sharpness of vision.
Reduced cataract risk 'could have large public health impact'
Results of the study revealed that in the placebo group, there were 945 new cases of cataract reported. However, the multivitamin group reported 872 new cases of cataract, showing a 9% risk reduction for the condition.
When looking at the results in more detail, the researchers found that the men who took multivitamins had a 13% reduced risk for nuclear cataract. This is when a cataract develops at the center of the lens - the most common form of the condition linked to aging.
Commenting on these findings, Dr. Christen says:
"If multivitamins really do reduce the risk of cataract, even by a modest 10%, this rather small reduction would nonetheless have a large public health impact."
The results also revealed that the multivitamin group reported 152 new cases of visually significant AMD (defined as best corrected visual acuity of 20/30 or worse), while the placebo group reported 129 new cases.
But the researchers say these findings for AMD risk were not statistically significant.
The investigators explain that although this finding contradicts other studies showing that supplement use can reduce the risk of AMD, different supplements, doses and objectives were applied in this study, which may explain the results.
However, Dr. Christen says further research into multivitamin supplement use and AMD risk is still warranted.
"This finding of more cases of AMD in the multivitamin group than in the placebo group, although not statistically significant, does raise some concerns," he adds.
"Clearly, this finding needs to be examined further in other trials of multivitamin supplements in both men and women."
Although there have been many studies hailing the health benefits of multivitamins, late last year, Medical News Today reported on a study that claimed multivitamins are a waste of money, suggesting they offer no health benefits and may even cause harm.