Nutritional Pearls: Protect Your Eyes With Legumes

Claire is a 55-year-old woman who is worried about her risk of developing cataracts. She read online recently that eggs are supposed to help to prevent age-related eye problems and is wondering if she should start including a few eggs in her diet each day, or if any other foods are known to help in this area.

How would you advise your patient?

(Answer and discussion on next page)

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In the past, I read a study that suggested that consuming eggs, which are high in certain carotenoids such as lutein and zeathanthin, might be related to a reduced risk of age-related macular degeneration. The problem is that the study's conclusions are a bit like assuming that if A=B and B=C, then A=C.

That is: saying that eating more eggs reduces your risk of age-related macular degeneration is a bit of a stretch. Yes, eggs contain lutein and zeathanin, but so does kale and spinach. Eating eggs is one way to get more lutein and zeathanin, but not the only way.

Today's research is a prospective study that followed over 1500 Australians over the age of 49 for over 5 years.

The Research

The authors focused on the risk of cataracts, and all included participants had undergone an opthalmologic checkup at the start of the study to test for the presence of cataracts.

At the start of the study, the authors asked the participants to fill out a food frequency questionnaire specifically designed for Australians, in addition to questionnaires regarding health status, height, weight, educational level, smoking status and alcohol consumption levels, and more.

The authors stratified the intake of whole grains and legumes into 4 increasing levels based on the lowest amounts of intake versus the highest amounts of intake. They then compared the whole grain and legume intake of those who developed cataracts over the course of the study with those who did not.

The Results

Interestingly, they saw no relationship between whole grain intake and the risk of cataracts. On the other hand, those with the highest level of legume intake (of 4 levels) were 67% less likely to develop cataracts than those in the lowest level of legume intake.

Indeed, the authors calculated that increasing one's intake of legumes by 75 grams per day decreased a participants' risk of cortical cataract by 16%, nuclear cataract by 40%, and posterior subcapsular cataract by 41%.

What’s the Take Home? 

While it's likely that legumes are better for your eyes than whole grains, this doesn't tell us what, specifically, is driving those results, whether it's soluble fiber, zeathanthin, lutein, or something else entirely.

The take-home message for you should be that a healthy, varied diet of quality calories including plenty of legumes and whole grains is likely to protect your eyes better than one full of processed foods.

Reference:

Tan AG, Flood VM, Kifley A, et al. Wholegrain and legume consumption and the 5-year incidence of age-related cataract in the Blue Mountains Eye Study. Brit J Nutr 10.1017/S000711452000104X