Doctor's Note

This is the third of a 4-part video series on the latest science on preventing and treating vision loss. In Greens vs. Glaucoma, I detailed the best foods to help prevent glaucoma and in Dietary Prevention of Age-Related Macular Degeneration I did the same for age-related macular degeneration, introducing the concept of retinal pigment epithelial cells. In the last installment, Dietary Treatments for Computer Eye Strain, I’ll address dietary interventions for nearwork-induced visual fatigue.

I’ve mentioned anthocyanins before in:

They may be why purple potatoes (Anti-Inflammatory Effects of Purple Potatoes) and purple cabbage (Superfood Bargains) may be preferable. Anthocyanins are the pigments in red and purple cabbage that allow for the kitchen chemistry in Testing Your Diet with Pee & Purple Cabbage.

And currants in Enhanced Athletic Recovery Without Undermining Adaptation.

My previous treatment of glaucoma can be found in Prevent Glaucoma and See 27 Miles Farther.

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  • Pilz

    Do frozen berries also work or only the fresh ones. If frozen berries work how should we thaw them? Should they be heated, thawed at room temperature or should we eat them frozen?

    I can only get frozen berries most of the year. Fresh berries are very rare where i live.

    • Veganrunner

      Happy New Year Pilz,

      I use frozen in my morning smoothy or bowl of oatmeal. They can be defrosted in the microwave or on the stove. I also love a bowl just barely defrosted for desert. Here is more on frozen fruit.

      Dr Greger has a great frozen desert that is mostly berries.

  • Sebastian Tristan

    Impressive yet again. That means that berries work better than drugs for Glaucoma. Does anyone know the ingredients in Black Current?

    • Darryl

      Blue corn, with its 225.2 μg anthocyanins / g? Pfah. Black rice has 2283.5 μg anthocyanins / g!
      Anthocyanin composition in black, blue, pink, purple, and red cereal grains (2006)

      As an aside, I’ve been following a literature breadcrumb trail having read the recent well-publicised David Sinclair paper, which reveals a largely unappreciated mechanism for the anthocyanins in health promotion. Certain anthocyanins inhibit CD38 at μM concentrations, partial CD38 inhibition plausibly leads to significant increases in NAD⁺, which would activate longevity and metabolism regulating sirtuins, which leads to wonderful things (1, 2, 3, 4, 5, 6). Shorter version: my rice is now black.

      • Veganrunner

        Darry I was just surfing around this sight when I came acoss your link regarding lipids in this interview. Here is the audio version. Such a great explanation of cholesterol, HDL, LDL, and triglycerides. I lost the place where you first linked it so I will have to thank you here.

        Thanks! I passed it along to my heart sick relatives.

      • Annie L

        You have mentioned in the past that taurine might be something vegans should consider supplementing. Do you think that nutritional and brewer’s yeast, due to their high protein content and amino acid profiles, could take the place of a taurine supplement? Thank you.

        • Darryl

          Vegans plasma taurine levels were 14 and 23% lower than levels in omnivores in two studies from the 80s (1, 2). There’s no deficiency disorder in humans as there is with cats, just a number of studies suggesting some benefit to higher levels in oxidative stress, tissue glycation, and CVD risk. And by higher, that means higher than average omnivore intake as well.

          Taurine can be produced from dietary methionine and preferably cysteine (methionine →→ cysteine → taurine), but there other competing requirements of the two precursors. The cysteine, for example is also required for protein and glutathione synthesis. Nutritional yeast is a good vegan source for cysteine, but not the quite the best. On a per gram basis dry soybeans and wheat germ have more, on a per calorie basis, oat bran, mustard greens, carrots, soy & tofu, asparagus, wheat germ and spinach have more.

          I wish that there was an inexpensive vegan “carninutrient” pill, that matched omnivore intakes of vitamin B12, vitamin D, carnitine, creatine, taurine, and EPA/DHA (besides the EPA/DHA, it would fit in a single capsule). Of these, only the B12 is obligatory, but there are still prospective vegans that “fail to thrive” (or claim to) on plant-based diets, and its plausible there’s enough individual variation that some may need the other components. It would simplify guidance, provide peace of mind to some, and might keep others in the fold.

      • Sebastian Tristan

        I meant purple corn. According to, its anthocyanin level is 1,642 mg/100 gr. But, I would love to see the doc make an analysis of the most anthocyanin rich foods.

        • Darryl

          Purple corn is a great source too: in the 2006 survey (with an evidently dead link), it had a very respectable 965.2 μg / g, second only to the black rice.

          The most prominent anthocyanin in purple corn is cyanidin-3-glucoside, synonymous with “kuromanin” from paper 1 above. Compare the effects of CD38 inhibition in 2 and the effects of purple corn color from the decade old paper 6, and they look nearly identical. I strongly suspect that most of the metabolic effects of anthocyanins may arise through their roundabout yet elegant and efficient way of activating the sirtuins

      • nc54

        But what about the Dr. Gregor video where red rice beats black rice? I switched to red after that video, but are you saying black is better then red?

        • Darryl

          That would be this video, where Dr. Greger uses an uncited source for antioxidant capacity. This Malaysian paper also found a higher FRAP score for red over black rice. I respectfully disagree with Dr. Greger about the value of in vitro antioxidant assays as I don’t believe most of the measured “antioxidants” are functioning as radical scavengers in the body (past comments 1, 2, 3, 4, 5, 6). Absorption dietary polyphenols is simply too low for direct antioxidant activity to make a dent, so to achieve their effects, they must be working in a drug-like fashion, targeting regulatory and catalytic proteins.

          What I find intriguing about black rice is that is second only to black elderberries in its content of Cyanidin 3-glucoside, one of the top CD38 inhibitors in 1, and 3 offers a synopsis why that offers a remarkably potent way of modulating energy metabolism and longevity.

      • Thea

        Darryl: I was interested in seeing that 2006 paper that compares the Anthocyanin composition of various colored cereal grains. When I click on it, I get an message saying that there was an error trying to download the .pdf. I wouldn’t want you to go to a lot of effort, but if it would be easy, could you check to see if the link is correct? Thanks.

        • Darryl


          • Thea

            Darryl: Thanks for replacing the link! Worked great this time. This stuff is so interesting.

            I recently bought some popcorn from the bulk bin. The multicolored popcorn was actually cheaper than the pure yellow bin. So, I bought the multicolored. After popping, all all the pieces looked various shades of white/yellow, but I like thinking that maybe I am getting some of extra of this stuff you are talking about.

  • Annie L

    I am eating 8 cups a day of either spinach or kale. I rotate between the two. My question, is this too much? Could I somehow be harming myself by ingesting this large amount of greens….maybe too much of a certain vitamin or mineral? I don’t want to cause harm, but I like the health benefits. I have heard that too much vitamin K can cause issues, not sure if this is true.

    • Darryl

      From the World Health Organization (their vitamin recommendations are more recent than the U.S. IOM’s)

      When taken orally, natural K vitamins seem free of toxic side effects. This apparent safety is bourne out by the common clinical administration of phylloquinone at doses of 10–20 mg or greater.

      That would be 1.2-2.4 kg (2.7-5.4 lbs) of kale, or about half those weights of parsley. K is unusual among the fat soluble vitamins, the rest of which (A, D, E) do have some some some toxicity at extreme doses.

      • Coacervate

        Does dietary Oxalate from raw spinach cause kidney stones? I’ve been warned by my Dr. but he also said he had his own doubts.

        • Darryl

          High dietary oxalate appears to modestly increase risk. Most calcium oxalate in kidney stones arises from metabolism of glycine, glycolate, hydroxyproline, and dietary vitamin C, rather than from dietary oxalate. See:

          Taylor, Eric N., and Gary C. Curhan. “Oxalate intake and the risk for nephrolithiasis.” Journal of the American Society of Nephrology 18.7 (2007): 2198-2204.

          • guest

            Maybe the 5 kiwis I eat per day isn’t such a bright idea. They are sky high in vitamin C, and add to this all the other sky high vitamin C plants I ingest. I’m pausing to think about it all for a bit. I’ve been warned in past about consuming large servings of oxalate-rich fruits.

          • Coacervate

            Thank you. I think I will try to eat high calcium foods along with high oxalate foods to help flush it through. Gosh, 2 billion dollars per year down the drain for K stones. I’d think someone would use isotopes to pin down the relative contribution of metabolic vs. dietary oxalate in Kstones! FWIW, I used to suffer with these little devils but, yep you guessed it, that was when I was a SAD eater. Now? zilch!

      • DanielFaster

        K vitamins in natto?

        • Darryl

          Menaquinone-7 (K2 Mk7), found in natto but also available as a synthetic, appears nontoxic at the highest doses given in a mouse toxicity evaluation. Using the EPA’s dosimetric adjustment factor of 0.14, the mouse 2000 mg/kg acute dose scales to 19.6 g for a 70 kg human, while the mouse 10 mg/kg chronic dose scales to 98 mg / day for the same human. Those are huge amounts. Natto has 775 μg K2Mk7 / 100 g, so theoretically a person could consume 12 kg daily before hitting the scaled chronic max dosing. For 200 μg supplements, that’s 490 capsules, daily.

          Only synthetic menadione (K3), found in animal feeds including dog food, should be avoided.

  • Carol Murphy

    I wonder how many black currants per day the people in the study ate? And I also wonder if other berries work as well, as I have never seen fresh or frozen black currants in the store. I was diagnosed with NTG within the past year so this information is vital to me. I know the short answer is, “eat berries…lots” but would like to tweak that with more specifics.

    • Darryl

      50 mg / d of a black currant anthocyanin extract. From (highly recommended) resource <a href="Phenol-Explorer, it appears that’s the amount in about 9 g of currants, just 1 ⅓ tablespoons. Black currants are fairly unique in anthocyanin concentration and composition.

      • Carol Murphy

        Thanks, Darryl – I appreciate your thoughtful & informative reply! Now, to find some black currants…

      • tedster

        So should I be looking for “real” black currants or can I just go out and get “black currants” which are probably black Corinth raisins (since I’m in Colorado)? Any reason to assume that the raisins will produce the same beneficial effect on nearwork-induced transient myopia?

        • Darryl

          According to Phenol explorer (blackcurrants, black grapes), the fresh fruit have very different anthocyanin content and composition. This 2014 paper indicates much lower anthocyanin content in the Corinthian currants: 0.2-2.2 mg vs 225 mg / 100 g.

          I did find Ribes nigrum on ebay, about five times the cost of the Corinthian/Zante currants, and supposedly suitable for something called “health cake”.

          • tedster

            Thanks, as always, for the helpful information. I went ahead and ordered the Ribes nigrum on ebay before seeing the rest of your post. It will make for an interesting experiment as I may be in the early stages of near work-induced transient myopia.

          • SherriAK

            Would the blackcurrents sold from this farm in NY compare to those mentioned in Dr. Greger’s video?

          • Darryl

            Yes. In the news section on that farm’s site the story of the repeal of an 80 year old law forbidding European blackcurrant cultivation in New York features prominently.

          • Thea

            SherriAK and Darryl: Thanks to your two posts, I was able to really help a family member. She is so excited and ordered from SherriAK’s link. Thanks!

          • Jodancingtree

            Gardeners can grow currants, too. Easy to grow, will produce fruit even in partial shade, beautiful medium-size bushes & the fresh berries are lovely. They freeze well, too.

      • AliceJ

        I want to follow — as closely as possible — the protocol of the “Two-year randomized, placebo-controlled study of blackcurrant anthocyanins on visual field in glaucoma” study and was about to post a question as to how many blackcurrants one should consume to approximate 50 mg / d of a blackcurrant anthocyanin phytonutrient extract given test subjects in the study, when I decided I was less likely to embarrass myself by first reading the already posted comment section. Luckily, I did. Thank you, Darryl! At the moment, I only have access to black currant juice so am guessing
        that juice may be a more diluted form (?) and I would possibly be getting less than the 50 mg of antocyanins needed to help me, if I just downed 1⅓ tablespoons of juice a day. Yes? No? Maybe so? Thanks, again!

        One website from New Zealand is offering 230 mg of black currant antocyanin extract. I don’t know about the quality and if the 230 mg capsule is overkill. I could also buy frozen whole berries on the web.

        I would appreciate any thoughts you might have.

        Thank you.

  • Katie

    I’m 36 years old. Three years ago my eye doctor told me I had increased pressure in both eyes and that it could be an indication of glaucoma. Not soon after, I watched Forks Over Knives. My family has been plant-based vegan since then. I’ve been to the eye doctor twice since that first scary visit. The first time, the pressures were better (but not perfect) and my vision had pretty dramatically improved in both eyes for the first time since I was 12 years old. At my last appointment, one eye was perfect for pressure the other still very slightly raised and my vision better once again. Other than needing to buy new glasses for the last few years I am so grateful for learning about a plant based diet! Thank you for your videos!

    • guest

      god bless you katie! Keep eating and excercising and living right and spread the good news about vegan health! I truly hope you keep getting better and better with it.

      • Katie

        Thank you! The best part is that I discovered vegan eating in time to raise my son this way. He’s 5 and he’ll never know any other way to eat. :)

    • Steveooooo

      Hi Katie what Were/are your current eye pressure readings? Are you on eye drops?

      • Katie

        I don’t recall my doctor telling me what the pressure readings were. At the first appointment she did show me a picture of my optic nerve when explaining her concern. At that visit she told me she wanted to wait a year and watch. I wasn’t given any medicine.

        • Steveooooo

          My pressures are currently high and
          i have an appointment in 2 months’ time to be given eye drops if it hasn’t improved….
          Not sure it’s enough time to lower it but I’m going to eat as a low fat vegan
          until then to see what happens (currently a veggie).. Good to see that you made
          a difference by a dietary change though Katie!! Good luck to you :]

          • Katie

            I was pretty much a vegetarian at my first appointment as well. It was taking that final leap of cutting out dairy and eggs and most fat that seemed to make the difference. Good luck to you as well!

  • Ronald Chavin

    We need to remember that more than 100 beneficial phytochemicals are responsible for the lower rates of various eye diseases among people who eat plenty of vegetables. Swallowing softgels that contain lutein, zeaxanthin, lycopene, or astaxanthin will definitely not work as effectively as eating the whole foods:

    • Ronald Chavin

      Diastolic blood pressure appears to be more strongly correlated with intraocular pressure than systolic blood pressure:

      Therefore, to lower intraocular pressure without prescription drugs, simply eat all the foods that will lower our blood pressure.

      Note: diastolic blood pressure is also more strongly correlated with clogged arteries than systolic blood pressure. Therefore, to lower intraocular pressure without prescription drugs, simply eat the foods that will unclog our arteries.

      As a last resort, get an opthalmologist to prescribe drugs:

  • Michel Voss

    biomarker proteins in serum of patients before clinical manifestation:

  • Tan

    Woah, the good news just keeps coming from berries. Dr. Greger thanks.

  • Jackie

    I have glaucoma and both my parents had glaucoma. Both parents followed standard eye drop routine and both went blind (to be fair – my father lost his vision from detached retinas). I am now doing nightly eye drops…but am concerned that side-effects of these may be impacting my throat membrane. I’ve adopted a whole food vegan diet and drink a black current/blueberry smoothie every day – has anyone out there had success fending off blindness without taking pressure lowering eye drops?

    My eye pressure was high for years and I did not start drops until I had a FOV test indicating I had lost vision. I started my vegan diet at the same time and the following year (spring 2013) my FOV indicated no vision loss – but the doctor wanted me to keep taking the drops and I have done so.
    I am interested in hearing if anyone else has had success without the eye pressure drops?

  • Ruby

    Pithy, critical information. Thank you.

  • Kim

    Do you think Black Currant Juice (from concentrate) would work as well as fresh berries? It’s pretty hard to find fresh black currants!

  • Jackie

    I found the study listed below on an online publication. I am unsure of the quality of the publication or the study and was hoping someone else had seen it or can comment on the publication. The findings would indicate that lower levels of vitamin D were associated with having open-angle glaucoma.

    Tae Keun Yoo, Ein Oh and Samin Hong (2014). Is vitamin D status associated with open-angle glaucoma? A cross-sectional study from South Korea . Public Health Nutrition, 17, pp 833-843. doi:10.1017/S1368980013003492.

  • Annetha

    Has anyone noticed their irises deepening in color with consumption of blueberries? I think mine are–my pupils used to be more noticeable by contrast in my green/hazel eyes, a snake-eye effect I didn’t care for. My opthalmologist gave me one of those “crazy-patient” looks when I asked if blueberry-consumption can deepen the color of one’s irises…

    • Thea

      Annetha: I can’t say I’ve notice any iris color magic, but I wanted to share that I laughed when I read, “My opthalmologist gave me one of those “crazy-patient” looks…”

      I wouldn’t be surprised if this is a real phenomenon. Dr. Greger has a video on this site about people’s skin tones turning a healthier/more atractive color when they eat “carotenoid rich fruit”.

  • saqib waseem

    My left eye cornia transplan but eye rejected new cornia. Now eye pressure is not controlling .pressure 25 to 34 .how to control eye pressure plz mail me

  • Milorisen

    Do the Black Currant oils and powders have the same affect as the raw fruit?

  • Lee Vize

    I believe that NTG is caused by brain damage and requires not an opthamoligist, but a neurologist, to get to the cure. Any nutrition aimed at neuroprotection may be helpful. See related article at Glaucoma Research Foundation: “Brain Holds Early Signs of Glaucoma”.

  • Lee Vize

    I believe that NTG is caused by brain damage and requires not an opthamologist, but a neurologist, to get to the cure. Any nutrition aimed at neuroprotection may be helpful. See related article at Glaucoma Research Foundation: “Brain Holds Early Signs of Glaucoma”.

  • Sara

    Are there any studies that show plant based diets helping with high myopias/and/or reducing their risk of retinal detachment?

  • WOW! WOW! WOW! I told my uncle who is 78 years old and has glaucoma to start eating currants every day when I visited him June 12th. We went to the grocery and bought him a few boxes and he started eating them on his morning Raisin Bran before I left. He’s told me that he’s eating a couple spoonfuls at night before bed also. So he called me today and told me he saw his ophthalmologist today who took his eye pressure today. It is down 6 points! The doctor checked it 3 times because he didn’t believe it. It actually registered 13 once and 14 twice! That’s better than it’s been in years! He was on the verge of needing a laser treatment in that eye and now has avoided the procedure. Thank you Dr. Greger for your work!!! I’m so excited for my uncle!

    • Thea

      Ann T Hotaling: That’s *amazing*. Good for you for telling your uncle about this and good for you uncle for giving it a try!
      Maybe you could get him on a whole food plant based diet next. :-)

      • Ann Hotaling

        LOL. I wish but he’s by himself now. Just lost my aunt. All the little old ladies are bringing him casseroles :)
        I’m impressed that he listened to me and ate the currants consistently. But being on four glaucoma drops is uncomfortable AND he was scheduled for a laser yesterday that the doctor canceled. This really impacted him so I think the door will be open for my next suggestion. I will be strategic with my new (not sure how far it will go) influence.

  • Tom

    Hello,I am looking for something that can help Leber hereditary optic neuropathy (LHON). Only drug called idebenone has any effect at an early stage. Thank you.