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  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on DNA damage, and aging. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

    • HemoDynamic, M.D.

      So the Fountain of Youth is. . . A Vegan Diet!!

      • HemoDynamic, M.D.

        Maybe that is the Holy Grail that many fail to find. . .A Vegan Lifestyle

        • Seth Gitter

          This is the easiest, cheapest, healthiest, tastiest way to be vegan
          here … .

          • Charlene Thorson

            I agree 100%

    • t

      I would be interested in knowing if they made distinctions between canned (ie canned tuna), processed or smoked fish. I could see that maybe some of the same treatments applied to processed meats could apply to these. It could be possible that a significant percentage of respondents’ fish intake could correspond to canned tuna. I also wonder if uncooked fish (sushi) has the same effect as cooked fish.

  • Toxins

    Does that mean we can keep our cells dividing forever with a whole foods plant based diet?

  • BPCveg

    Dear Dr. Greger,

    Thank you for bringing this exciting research to the attention of your followers. I admire your tireless devotion to the very important cause of lifestyle medicine.

    I have a specific concern, however, that when I followed the link to the cited article by Dean Ornish, I discovered that he is not advocating a strictly vegetarian diet. In fact, he used a whole foods, plant-based diet, which included fish oil supplements daily (This made me cringe because of your other video on highest PCB levels present in fish oil?!).

    While the article presented an intriguing pilot study, nothing in it even suggested that vegetarianism was responsible for the increased telomerase activity.

    You may wish to consider this feedback to improve the accuracy of your video.


    • DrDons

      I agree with your concerns about fish oil and no longer recommend for my patients. I was present at a McDougall Advanced Study Weekend where Dr. Ornish presented. He was asked about his fish oil recommendation. His response was, in my opinion, dismissive and didn’t address the issue. Based on the best current science I would avoid fish oil and if you feel that you should take an omega 3 supplement I would follow Dr. Greger’s recommendation of an algae based product… see video, not to mention the lack of adequate labeling see

      • Ornish recommends a whole-food plant-based diet with a bit of fish oil, dairy (yogurt) and eggs. Guess Dr. Ornish needs to see Dr. Greger’s videos.

    • Occams_Razor

      Dr. McDougall’s website has an article or newsletter or one of his “hot topics”, in which he supports his claim that the people eating the traditional Japanese diet with fish are healthy in spite of eating the fish, not because of it.

      No need for me to elaborate; Dr. McDougall writes and supports it well enough for anyone interested to go straight to the source.

      • Occams_Razor

        And, that source would be: the February 2003 newsletter, article “Fish Is Not Health Food”.

        There: I made it easy for you. *And* surprised myself that I so clearly remembered something from that long ago. Hm… Must have made an impression.

  • I don’t understand why fish would decrease telemores since the Japanese have traditionally eating a diet rich in fish and have also had the longest lifespans.

    • trefoglio

      If you heat fish it will form oxidized cholesterol and this will shorten telomeres: Front Biosci (Elite Ed). 2010 Jun 1;2:1164-8. Telomere length and its associations with oxidized-LDL, carotid artery distensibility and smoking. Nawrot TS, Staessen JA, Holvoet P, Struijker-Boudier HA, Schiffers P, Van Bortel LM, Fagard RH, Gardner JP, Kimura M, Aviv A. Department of Molecular and Cardiovascular Research, Laboratory of Hypertension, University of Leuven, Study Coordinating Centre, Leuven, Belgium.

    • They have the longest lifespans compared with cultures that eat many animal products. Okinawans, the Japanese people with the longest lifespans don’t eat a lot of fish. And since the nuclear disaster I wouldn’t trust any fish within 25,000 miles of Japan. Not a problem for me anyway, since I’m vegan. Here’s one source about what Okinawans eat:

  • DrDons

    One of the best studies on longevity was done on residents on Okinawa. Many folks assume that because they lived on an island that they consumed alot of fish. Actually the long living study participants ate a small per cent of fish… they ate about 70% sweet potatoes. Fish has omega 3, EPA & DHA(antiinflammatory substances) which they get from algae they eat. Unfortunately fish also comes with cholesterol, saturated fat and all sorts of chemicals including mercury, arsenic, drugs, pcb’s and other organic chemicals including fire retardants. Therefore it is not surprising that fish has an adverse effect on our telomeres. See,, & We are learning more about aging see… so keep tuned to for updates.

  • Toxins

    Do you think that the fish caused a shortening of telomeres due to the contaminants themselves? Or do you think it was independent of the contaminants?

  • DrDons

    Good questions. I don’t know. The sample size of the study was small. If it had been larger it might have helped answer your question(s). The Ornish study involved diet and exercise. So there may be confounding variables as well. I view them as more evidence which supports the “paradigm” that eating a whole food plant based diet with B12 supplementation is the best way to eat… for individuals, families, communities, nations and the world.

    • Toxins

      O I am well aware of the benefits of a whole foods plant based diet, I am just curious to know if the contaminants in fish increased telomere shortening. I would think the nitrosamines in processed meats would be the culprit in rapid telomere shortening.

  • mikeroyo

    I just discovered your website a few days ago(Dr. McDougal e- mail) and have shared it with multiple friends. I was familiar more than 15 years ago with some of Dr. McDougal’s work, also the China study, the recent “forks over Knives”, some of the videos of Dr. Ornish. I just wanted to thank you for all the information you have put together here and also the way you present it. My wife is Chinese so this type of plant strong diet is easy for us and quite normal. What I like is that you bring in a lot of new ideas as to the why’s and how things work. thanks again for all you effort.

  • kimmi

    This is a very interesting video! My concern is that if the telomerase activity was significant, wouldn’t this cause a flaw in the blood/dna aging procedure? IE: They wouldn’t be able to correctly identify a persons age by their blood, because they wouldn’t know if that person was vegan or not.
    What do you think? Do you know how significant this telomerase activity is?

  • Elpooishere

    I’m just wondering, when Ornish says that a vegan diet along with exercise can boost telomere strength – how much exercise must one do? I’m a vegan, but I really super enjoy sitting. It’s so awesome, is sitting.
    Just wondering.
    And thanks for all these great videos. It’s a great service you are doing. Thank you!
    Ellen Reid

    • Toxins

      For optimum health, recommendations have increased to 2 hours a day of rigorous physical activity.

      • That’s not possible for most people, especially as people age. Actually 30 minutes of moderate-intensity exercise plus as much activity as possible throughout the day does wonders. Mild – moderate – rigorous are all relative to the capabilities of the individual. For exercise, some aerobic activity at least 5 daya, strength training 2-3 days (full-body), and stretching at least 5 days.

  • Michael Greger M.D.

    Also be sure to check out my associated blog post How to live longer in four easy steps!

  • CAPT Steven Lucks

    This is why I take Reliv now with Lunasin see:

  • Rick

    What about Lavaza ?

  • JBlea

    The study discussion states: “Food groups such as whole grains, nuts, fish, fruit, and vegetables and prudent dietary patterns rich in these foods were inversely associated with several age-related diseases and total rate of mortality (14–19, 21–29, 46).” Yet the results found that “With the exception of nonfried fish (P = 0.04), processed meat consumption (P = 0.001), and the dietary pattern scores for fats and processed meat, which were each inversely associated with telomere length.” This “inverse association” found between fish and telomere length was ignored in the discussion.

    Additional studies have found fish consumption to correlate with increased telomere length. It would be nice to see more recent data on this topic.

  • omnimatty

    The tip of a shoelace is called an AGLET. FYI.

  • John M. Benton

    If eating fish will shorten you life span do you think taking fish oil will shorten your tellameres ?

  • confused??

    According to this article telomerase activity increases in the presence of cancer cells…if Dr Ornish’s research was done on subjects with cancer…might not the increase in telomerase activity indicate that the cancer was progressing and not an indication that the telomere’s were lengthening
    ? I would love to believe that we can lengthen our telomere with a low fat whole foods vegan diet but I don’t see how this proves it…Please help me understand! I’m looking online and not finding anything other than maybe eating more folate rich foods!

  • Kaleb

    I’m looking into intermittent fasting for its supposed health benefits. Have you come across any research in this area? Although caloric restriction is generally associated with longevity, I do not wish to be malnourished and nutrient deficient.

  • William Dwyer

    According to researchers from the University of California, San Francisco, the higher the blood levels of fish-derived omega-3 fatty acids in patients with coronary heart disease, the longer the telomeres. Their study, published in the January 2010 issue of the Journal of the American Medical Association, found that leukocyte telomere length (LTL) was positively associated with higher (not lower) blood levels of omega-3 fatty acids. (

    Far from causing a shortening of telomere length, fish oil appears to increase it.

    • Michael Gmirkin

      Wonder if they get the same results from Krill, Flax & Chia, as “fish-derived” omega 3? Side-stepping the negative effects apparently associated with eating “fish” by getting Omega 3’s elsewhere?

      Of course, I don’t know whether plant-derived sources ever have EPA/DHA or just ALA…

  • michael

    Here is the link to a new article about telomere research in patients with prostate cancer lifestyle change and telomere length.

  • Katherine Leiby

    I am wondering if there is such a thing as too much fruit. I eat approximately 7-8 servings of fruit per day. My husband says too much fruit can have a bad effect on my blood sugar. Is this true? The rest of my diet is pretty healthy. Incidentally, I also eat around 4-5 servings of vegetables per day.

  • Uncle Siam

    This would bring us into a bigger question as to why Japan and in particular Okinawa have one of the longest lived and healthy populations when they consume alot of fish. The Okinawan diet includes the consumption of all things pork as well. I have adopted the eating of bitter melons and okinawan sweet potatoes and await more studies into this subject.

  • Ben Goldenberg

    reference to the study would be helpful we know to read English and some of us have taken science classes …

  • kant

    How about sushi?

    • NFModeratorKatie

      There are lots of veggie roll sushi options that would work nicely when following a whole-food, plant-based diet. :)

      • kant

        I am not saying I want sushi. From this video I wanted to understand if sushi will also reduce telomeres?

        • NFModeratorKatie

          So sorry for the confusion! Eating fish appeared to age people’s DNA six years. From this information, I believe it’s safe to assume that this would include sushi that contains fish products.