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Diet high in fruit associated with lower risk of age-related maculopathy, study shows
Researchers were surprised that no link was found with other dietary elements such as vegetables, antioxidants and carotenoids.
Eating fruit may offer protection against the development of age-related maculopathy, according to a recently published large cohort study.
“We found that eating more than three servings a day of fruits was associated with a 36% decreased risk of neovascular age-related maculopathy (ARM) compared with eating less than 1.5 servings of fruits a day,” said lead author Eunyoung Cho, ScD, an epidemiologist at Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women’s Hospital in Boston.
“We were surprised by the results of the study because we did not find any strong inverse association between the intake of vitamins and carotenoids and ARM. We also did not expect a fruit association that was not driven by vitamins and carotenoids,” she said.
The study
The objective of the study, which appeared in the June issue of Archives of Ophthalmology, was to examine the intake of antioxidant vitamins and carotenoids, as well as fruits and vegetables, in relation to the development of ARM.
The prospective follow-up study consisted of 77,562 women enrolled in the Nurses’ Health Study and 40,866 men from the Health Professionals Follow-up Study. All participants were at least 50 years old and had no diagnosis of ARM or cancer at baseline.
A semiquantitative food-frequency questionnaire (FFQ) with roughly 60 food items was sent to members of the female cohort in 1980. An expanded FFQ with about 130 food items was also administered to women in 1984, 1986, 1990 and 1994. Men were given the expanded FFQ in 1986, 1990 and 1994.
The reproducibility and validity of food intake measured by FFQ was assessed in both sexes by diet records for fruits and vegetables and by plasma levels for vitamins and carotenoids.
All stages of ARM included
For the study, the authors defined all stages of the disease as ARM. “According to one classification system, the latest stages of ARM are also referred to as age-related macular degeneration,” stated the authors. Cases were defined as incident ARM when best corrected visual loss was 20/30 or worse, due primarily to ARM in at least one eye. The authors began obtaining data on the diagnosis of ARM in women in 1986 and for men in 1988.
A total of 464 cases of early ARM (329 women, 135 men) and 316 cases of neovascular ARM (217 women, 99 men) were documented during up to 18 years of follow-up in women and up to 12 years in men.
“We don’t know much about the risk factors for ARM,” Dr. Cho told Ocular Surgery News. “But smoking is an important nondietary risk factor.” Participants with higher fruit or vegetable intake were less likely to smoke and more likely to be physically active and to consume fish, she said.
Fruit intake
The pooled multivariate relative risk (RR) for participants who consumed three or more servings per day of fruits was 0.64 compared to those who consumed less than 1.5 servings per day. Results were similar for women and men. “There was a nonsignificant inverse association between fruit intake and early ARM,” the authors said. The difference in results for early vs. neovascular ARM was also not statistically significant.
The authors mentioned other constituents of fruits with potential health benefits. These include flavonoids, isothiocyanates, phenolds, fiber, folate and potassium.
Conversely, vegetable intake was not related to early or neovascular ARM risk in either the male or female cohort, according to the study. Results were also similar after adjusting for total fat intake. Among vegetable items, carrot was the only one with a weak, nonsignificant inverse association with the neovascular form. But increasing intake of spinach or other greens had multivariate RRs ranging from 1 to 1.14 for neovascular ARM. The lack of an association between lutein/zeaxanthin or green leafy vegetables “is inconsistent with many recent experimental studies that have suggested the importance of these carotenoids as a macular pigment and as a possible preventive factor for ARM,” the authors stated.
Suggestive inverse association
When examining whether any specific nutrients were responsible for the inverse association between ARM risk and fruit intake, none of the antioxidant vitamins and carotenoids from foods (mainly fruits and vegetables) were strongly related to either early or neovascular ARM risk, the study found. However, many of them, including total carotenoids, had a suggestive inverse association with neovascular ARM risk. For example, intake of beta-cryptoxanthin was related to a lower risk of neovascular ARM, but not statistically significant.
The authors also assessed the impact of multivitamins and vitamin C and E supplements. But there were not enough users of vitamin A and beta carotene supplements to examine separately. Regardless, none of the supplements were related to either early or neovascular ARM risk.
“Although our preliminary finding about the benefits of fruit needs to be replicated in other studies, fruit intake has been related to reduced risk of other chronic diseases such as cardiovascular disease and some forms of cancer. Therefore, I am comfortable with recommending fruit intake,” Dr. Cho said. “As a next step, we will look for components in fruits that drive this inverse association. We will examine some nutrients besides vitamins and carotenoids, such as flavonoids.”
For Your Information:Reference:
- Eunyoung Cho, ScD, can be reached at Channing Laboratory, 181 Longwood Ave., Boston, MA 02115; 617-525-2091; fax: 617-525-2008; e-mail: eunyoung.cho@channing.harvard.edu.
- Cho E, Seddon JM, et al. Prospective study of intake of fruits, vegetables, vitamins, and carotenoids and risk of age-related maculopathy. Arch Ophthalmol. 2004;122:883-892.