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Eating To Extend Our Lifespan

Why can’t we live forever? Some animals do, and I don’t mean some 200 year old whale–I’m talking immortal. There are actually species of animals that don’t age and could technically go on living forever–and why not? In a sense, humans are immortal in that a few of our cells live on as sperm or egg cells lucky enough to find each other. Each of our kids grow out of one of our cells, and that alone (the fact that a single cell can grow into an entire person!) should make, in comparison, the notion of keeping our bodies going indefinitely seem trivial.

Human longevity is certainly a hot research topic. Much of the research has focused on the role of DHEA (dehydroepiandrosterone), the most abundant steroid hormone in the human body. DHEA may help counteract the effects of stress, preserve female fertility, and it appears to be a strong predictor of longevity. Caloric restriction is thought to extend the lifespan of many animals by upregulating DHEA, which normally declines as we age. DHEA is sold as a “fountain of youth” over-the-counter dietary supplement, but concerns have been raised about safety, side effects, and quality control. There is, however, a natural way to boost DHEA levels.

As I note in my 3-min. video The Benefits of Caloric Restriction Without The Actual Restricting, after just 5 days on an egg-free vegetarian diet blood levels of DHEA rise about 20%. Upon further testing, it seems that the bodies of those eating vegetarian weren’t necessarily producing more of it, but just losing less, something one normally only sees in fasting. Thus, by eating vegetarian one may be able to mimic the effects of caloric restriction, but without walking around starving all the time. For more on diet and life expectancy see Research Into Reversing Aging and Harvard’s Meat and Mortality Studies plus my 30 other videos on lifespan. If you haven’t yet, you can subscribe to my videos for free by clicking here.

Recently, the risk factors for mortality were published for the Harvard Nurse’s Health Study, which is currently the most definitive long-term study ever on older women’s health. It is the subject of my 2-min. video What Women Should Eat to Live Longer. Since the leading cause of death was heart disease, it is no surprise that dietary cholesterol consumption was significant risk factor for death. The second leading cause was smoking-related cancer deaths. Comparing the two, consuming the amount of cholesterol found in just a single egg a day appears to cut a woman’s life short as much as smoking 5 cigarettes a day for 15 years.

The most protective behavior they found was fiber consumption. Eating just a cup of oatmeal’s worth of fiber a day appears to extend a woman’s life as much as 4 hours of jogging a week–though there’s no reason we can’t do both!

The one specific food most tied to longevity was nuts. Women appear to get 4 hours of weekly jogging benefit eating just two handfuls of nuts a week as well. Taking a step back, though, it’s worth noting that the intake of cholesterol, only found in animal foods, was associated with living a shorter life and the intake of fiber, only found in plant foods, was associated with living a longer life.

A similar comparison has been made between the risk of smoking and eating processed meat (see Prevention Is Better Than Cured Meat). Though healthy eating can help mediate the devastating effects of smoking (see Smoking Versus Kale JuicePreventing COPD With Diet, and Treating COPD With Diet), if you do smoke, please ask your doctor for help quitting. As a physician I’ve just seen too many good people die really horrible deaths from cigarettes.

Michael Greger, M.D.


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 “Eating To Extend Our Lifespan

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  1. Dr Gregor I would like to thank you for your commitment to the health and welfare of the lives that you touch through your research, this web site, you lectures etc.  I am an RN, I work in a Wellness Center in a Mental Health clinic. The average mental health patient can live up to 25 years less than the population at large. One of my jobs is to teach healthy nutrition. I use your information. It is a fantastic resource.  They are resistant, but I have been at it for four years and I can tell I have made some headway!  

  2. Dr Gregor,

    this is the best set of advice and videos that I have ever encountered! Thank you so much for sharing all of that — I am a real fan!

    warm regards,
    Stefanos Papanikolaou
    Department of Materials Science
    Yale University

  3. I have been following your videos for several months now and on the
    basis of the information therein, have shifted from a casual vegetarian
    diet toward a vegan diet. One request I have for your undoubtedly
    overworked staff — could you please post links to the references you
    cite in your videos? Usually I go to Google Scholar and copy the titles
    by hand. Having links would be a great help, especially if I am going
    to prostelytize the vegan gospel to others. :)

    Thanks for all you do!

    P.S. I don’t know why the website requires me to enter a name and e-mail address after I’ve already logged in?

    1. I post the links to all the papers under every video! Click on the Sources Cited link under any video. And there are two log-ins, one for the site and one for this comment section. I’m so glad you found the site useful!

  4. Dear Dr Greger,

    Upon reviewing your videos and blog posts on longevity I find an issue you have not yet addressed: optimal weight for longevity. There is a demonstrable correlation between longevity and weight as demonstrated by the life insurance mortality tables well-known “BMI J curve”. Since many dieters are doing so for longevity reasons it would be helpful to review the latest findings on optimal BMI for longevity.



  5. we know that short fasts (12-30 hours) are beneficial but what about water fasting for long periods of time (they say 5-40 days)? It looked crazy to me at first but there are a lot of big names that backup water-fasting. I got interested after watching doctor Dr. McDougall vouching for Dr. Goldhammer and his True North water fast center. He has a lot of videos on youtube and what he says make sense (he also uses the whole food plant based diet as a treatment) but I haven’t found good scientific information about it (I don’t have experience I must say) . So I will like to see what Dr. has to say about the water-only fasting for long periods of time.

  6. I realize that this post is quite old so I hope you’ll see my comment!
    I’m wondering if there has been any good science around intermittent fasting related to health and longevity? I’ve heard of people fasting 1-2x per week, some eat 500 calories while others eat none. I’ve even heard of people skipping breakfast and having a daily “intermittent” fast. Any science to validate if any of this is worth doing (in addition to eating well of course!)

    1. Neeraj: Intermittent fasting is the most asked for topic on the site! It’s also a very complicated topic and Dr. Greger wants to give it the attention it deserves. Last I heard, Dr. Greger was working on absorbing the information around intermittent fasting and that this will be a topic that will be addressed at some point in the future. Stay tuned! – Thea, Volunteer Moderator

  7. Dr. Greger,

    Thank you for all of the excellent work providing useful health information to the public. My question is if meat is the main cause of so many illnesses and ailments than why dont vegetarians live at least 20 years longer? I see an average life expectancy increase of about 5 years for the vegetarians. I know that carnosine plays a major role but it seems there must be some other missing links as some vegetarians live well onto the 90s appearently without carnosine either and many non vegetarians live to 100 plus years. Please share the best science and philosophy on this topic. Thanks.

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