Which Foods Fight Glaucoma?

Image Credit: bruno garciact / Flickr. This image has been modified.

Foods for Glaucoma

Glaucoma is the second leading cause of legal blindness in white women, and the number one cause of blindness in African-American women. In a study I profile in the video Greens vs. Glaucoma, researchers chose a population of African-American women to study the effects of fruit and vegetable consumption on glaucoma risk because they were specifically interested in studying the effect of foods with the highest concentration of those eye-protecting phytonutrients like zeaxanthin. Zeaxanthin is found primarily in plants such as kale and collard greens. (It is also found in eggs—find out how much in Egg Industry Blind Spot). However, we’d be lucky if we could find one in ten white people eating even a single serving of these dark green leafy vegetables a month, whereas nearly nine out of ten African-American women in the study consumed this amount.

What did the researchers find? Well, as I’ve stressed over the years, all fruits and vegetables are not the same (see for example, How to Reach the Antioxidant “RDA). Whether the participants hardly ever ate bananas or had one or more every day didn’t seem to matter much in terms of the risk of glaucoma. However, eating only a couple oranges every week was associated with dramatically lower risk. Orange juice was not associated with a lower risk, though, even if drunk every day. A similar finding was found for peaches: fresh peaches seemed to help, but canned peaches didn’t.

Similarly the intake of vegetables in general as a catch-all term didn’t seem to matter. For example, whether subjects ate a green salad twice a week, once a week, or zero times a week didn’t seem to matter when it came to reducing glaucoma risk, but most people’s salads are pretty pitiful. It was a different story for kale and collard greens: just two or three servings a month was associated with half the risk of glaucoma compared to once a month or less.

It may be especially important for white people to consume kale and collard greens. The lighter our eye color, the more greens we need to eat. Blue eyes let 100 times more light through, so people with blue or gray eyes appear significantly more vulnerable to damage compared to brown or black. Green and hazel fall somewhere in the middle.

This is interesting: carrots appeared to be less protective in black women compared to white women. They suggest it could be a difference in food preparation methods. Perhaps the African-American subjects tended to eat carrots raw, limiting the absorption of certain nutrients, while they chopped and prepared their collard greens with oil, making the nutrients more bioavailable because the absorption of carotenoid phytonutrients depends on the presence of fat. This is why I encourage people to eat nuts or seeds with the greens—such as a little tahini sauce or something.

Why not just take a zeaxanthin pill? We don’t know what exactly it is in these wonderful foods that’s working their wonders, so it’s probably better to just eat our greens rather than supplements. In fact, people that take calcium or iron supplements may even be doubling, quadrupling, or septupling their odds of glaucoma. It’s better to get most of our nutrients from produce, not pills.

I wish there were more studies on under-represented populations. I’ve covered a few, such as Preventing Breast Cancer By Any Greens Necessary, but I am constantly on the lookout for more.

My other videos on glaucoma include Prevent Glaucoma and See 27 Miles Farther and Dietary Treatment of Glaucoma. For more on eye health check out my video, Dietary Prevention of Age-Related Macular Degeneration.

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Discuss

Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.


14 responses to “Foods for Glaucoma

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  1. I see nothing on this website suggestion plant-based diet suggestions for those with cystic fibrosis. Maybe in 2015 you can provide some data on best diets for cystic fibrosis. This is a tough go for some, and special diets and nutrient intake seem to be of the utmost concern and need.

  2. Then why don’t you do your own study on under-represented populations? As a half American Indian, half Mexican (does that make me 3/4 American Indian?), I can plainly see what the standard American has done to our population. I try my best to stay away from sugar and flour of all colors, not just white. At family gatherings, I bring a big bowl of green beans to share. Maybe it helps a little.

    1. “At family gatherings, I bring a big bowl of green beans to share. Maybe it helps a little.” Yes, I believe it does from my own experience bringing plant-based dishes to family gatherings. It’s a great way to encourage people to try foods they don’t normally prepare at home and maybe inspire them to do so. A recent example was an acorn squash recipe I prepared for a family event this fall; it was devoured and received many, “ooh, this is really good”.

  3. what about if you already have glaucoma? do these foods also help lessen the severity of the condition (assuming you haven’t gone blind yet)?

  4. Is cabbage as healthy as collard greens (collard greens aren’t common here). What about spinach, silverbeet, turnip leaves, radish leaves, beetroot leaves, mustard greens, bok choy leaves, choy sum leaves

    1. I did a pubmed search of glaucoma and diet and couldn’t find any information on cabbage and the other foods you mentioned. Given the complexity of the antioxidants in plants I believe eating a variety with a focus on kale and collards… if available would be consistent with the best current science. Good luck.

  5. My mother began suffering the effects of glaucoma at 60… my grandmother suffered the same disease. Both were declared “legally blind” in their late 70’s and, of course, I figured it is a genetic thing. Maybe it’s genetic but only to a certain degree, though. Our lineage is Caucasian. Neither my mother nor my grandmother were inclined to eat kale, spinach, or carrots, but I eat really huge servings of all three as a trio cooked gently in water with olive oil at least three times a week, and I make smoothies with kale, carrots, avocado, onion and garlic on days I don’t cook ’em up. Hopefully, my eyes will remain unaffected by glaucoma (I’m 65+ and regular eye exams show no trace of that disease). Thanks, Doc, for this post… I feel less worried about ocular health, for it appears I’ve been taking care of my eyes with diet for quite a few years.

  6. Re: the paper by Wang et al that suggests calcium/iron supplementation increases risk of glaucoma: This paper’s results are disputed in a Comment to the publication by Shaikh Y, Yu F, Coleman AL at UCLA. Rather than analyzing the data based on participants’ self-reported values, they used the participants’ serum levels of iron and calcium, and their clinically diagnosed glaucoma incidence. They found “no statistically significant associations between self-reported glaucoma and highest quintiles of albumin-corrected serum calcium… or serum iron”. Full text at http://www.iovs.org/content/53/8/4941.long

    One implication is that self reported data must be considered carefully, and if possible backed up with measurements (a pattern also seen in many other studies).

  7. There are too many contradictions in this article. You say that white women don’t eat collard greens, but black women do. Yet at the beginning of the article you say “Glaucoma is the second leading cause of legal blindness in white women,
    and the number one cause of blindness in African-American women. Obviously, according to these two statements we can conclude that collard greens haven’t helped the black women very much then.

    I find your views very ethnocentric, and somewhat racist, and very narrow to only include blacks and whites, hardly representative of the world in which Glaucoma appears throughout. Not all white women come from a British or Irish background. Varieties of collard greens (Brassica Oleracea) trace back to ancient Greeks, as well as the Romans who grew several varieties including a less poignant variety that had larger leaves and stalk, and was mild in flavor. Last I checked neither Greeks nor Romans were black.

    Collard greens also existed in diets for centuries in Brazil, Portugal, Kashmir Valley, the Congo, Kenya and Tanzania, not all of the African nations, so therefore not all black women would eat them, as you imply in your article.

    In terms of North America, Brassica Oleracea existed before blacks were brought here against their will. The Native Americans ate wild Brassica Oleracea before blacks arrived. What did happen however, is that blacks from certain African countries, once in the USA, specifically the southern states, shared how they cooked collard greens, which helped make collard greens more popular in the USA.

    In Canada, and the USA spinach, broccoli, and cabbage have been popular since these countries were founded. All of these are in the same Acephala group as collard greens, and contain the same nutritional values, thus once again calling into question the validity of your article , Once including that fact, we now see how people around the world have been eating greens in the same family possibly since time began, once again leaving us wondering how beneficial they are to preventing Glaucoma.

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