October 2008




Dishing on fruit and vegetable consumption

by Maxine Lipner Senior EyeWorld Contributing Editor



Study highlights the importance of eating certain antioxidants

Eating the right fruits and vegetables may help to keep glaucoma and optic nerve damage such as this at bay Source: Anne L. Coleman, M.D.

New study results suggest that consuming fruits and vegetables such as green collards, kale, carrots, and peaches may help to keep glaucoma at bay. These results published in the June 2008 issue of the Journal of Ophthalmology indicate that consuming some of these foods as infrequently as once a month can still be of significant benefit, according to Anne L. Coleman, M.D., Frances and Ray Stark professor of ophthalmology and epidemiology, Jules Stein Eye Institute, University of California, Los Angeles.

Dr. Coleman and fellow investigators decided to take a look at this after noting that spinach and other leafy green vegetables had been given high marks for helping to prevent age-related macular degeneration. “With glaucoma also being a chronic eye disease and reports that antioxidants are very important in neuronal processes, it just made sense to look,” Dr. Coleman said.

Large cohort study

In the cross sectional study, investigators considered how women over the age of 65 who were participating in the Study of Osteoporotic Fractures fared with regard to glaucoma risk based on what they ate. Included in the study were 1,155 women ages 55 and older. These women were recruited in four different communities back in 1985 to take a closer look at falls and osteoporotic fractures. “They found that women who fell were more likely to have decreased contrast sensitivity or depth perception,” Dr. Coleman said. As a result, investigators were interested in taking a look at cataracts and glaucoma, which are among the top causes of poor contrast sensitivity. “The reasoning was that since they were such big predictors of the women falling and having fractures, if you have eye diseases that are preventable or treatable and you take care of them, then we’ll cut back on the number of hip fractures in the U.S. in the older population,” Dr. Coleman said.

Investigators collected a lot of data about glaucoma patients. Since they were also looking into hip fractures and breast cancer, they had a wealth of information on the patients’ diets. “We had all this information, so it was very easy to at least cross-sectionally look at what these women say that they’re eating and determine if there’s an association with a decreased likelihood of their having glaucoma or not,” Dr. Coleman said.

The antioxidant effect

After reviewing the visual data for these women in conjunction with the dietary information, several associations were discovered. “We found that if they had at least one serving of either green collards or kale a month, they had a decreased likelihood of glaucoma by 69%,” Dr. Coleman said. “We also found that for women who had two servings per week of carrots compared to those who had less than one, there was a 64% decrease.” Investigators also determined that for those who ate canned or dried peaches once a week, there was a 47% decreased likelihood of having glaucoma. Dr. Coleman believes that it may be the antioxidants in the food at work here.

When investigators looked at different vitamin components they also found a correlation. “We found that riboflavin was associated with a decreased likelihood of having glaucoma,” Dr. Coleman said. “Also, vitamin A, which you see a lot of in carrots and green leafy vegetables, was also associated with decreased odds.”

One food, however, seemed to have the opposite effect. “Most fascinating of all was the finding that orange juice was possibly associated with increased odds of having glaucoma,” Dr. Coleman said. In women who drank orange juice at least once a day, the odds of having glaucoma increased by approximately 70% compared with those who drank one serving or less per week. This is likely the result of the cryptoxanthin in the orange juice, Dr. Coleman believes. While the study is a preliminary one, Dr. Coleman does encourage patients to eat their fruits and vegetables, although not necessarily to take their vitamins. “I think that when people in this older group start taking vitamins, it’s hard to regulate the amounts,” Dr. Coleman said. “But if they’re eating fruits and vegetables, their bodies are going to absorb the right amounts, so there is not really a downside.”

Going forward, Dr. Coleman is now conducting studies looking at blood levels of nutrients in glaucoma patients compared with those without the disorder. “One of the problems with nutrition is that people might say that they’re eating a certain amount but then their blood levels are different,” Dr. Coleman said. “It’s because of the metabolism of the different nutrients, and maybe they’re not recalling exactly what they’re eating and when they’re eating it.” Dr. Coleman hopes that by looking into this a bit more, investigators will see some differences in levels of certain antioxidants between people with glaucoma and those without the disease.

Editors’ note: Dr. Coleman has no financial interests related to his comments.

Contacts information

Coleman: 310-825-5298, doctor_coleman@yahoo.com

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