The Two Most Active Ingredients of the Mediterranean Diet

Image Credit: garlandcannon / Flickr. This image has been modified.

The Two Most Active Ingredients of the Mediterranean Diet

Olives and nuts are plant foods, and as such, are packed with antioxidants, raising the antioxidant level of our bloodstream resulting in lower fat oxidation and free radical DNA damage, but what’s happening inside people’s arteries?

Researchers measured the amount of atherosclerotic plaque in the neck arteries going to the brain in folks who for years were eating added nuts, added extra virgin olive oil, or neither to their daily diets. In the control group, the plaque got worse, which is what happens when one continues to eat an artery-clogging diet, but there were no significant changes in the added extra virgin olive oil group, and the plaque in the added nut group appeared to get better. The nuts appeared to induce a regression of the disease, or at least a significant delay in the progression. The nut group was still suffering strokes, but only half as many, perhaps because the reduction in plaque height within the arteries on extra nuts was indicating a stabilization of the plaque, rendering them less likely to rupture. You can see these results in my video Which Parts of the Mediterranean Diet Extended Life?

Adding nuts to our diet may also improve endothelial function, boosting the ability of our arteries to dilate naturally by about 30 percent. If you look at the baseline adherence to Mediterranean diet principles and control for things like smoking and exercise, there were only two factors significantly associated with reduced heart attack and stroke risk: more vegetables and more nuts. No significant association with the olive oil, wine, fish or cutting back on soda and cookies. Among the individual components, only increased consumption of vegetables and nuts were related to reduced cardiovascular events.

On the one hand, cutting stroke risk in half just by eating a handful of nuts a day is pretty amazing, but those in the added nut group didn’t appear to live any longer overall. This is in contrast to other studies that suggested that frequent nut consumption may extend life. For example, the Harvard Health Professionals studies, involving a whopping three million person-years of follow-up over decades, found nut consumption associated with fewer deaths from cancer, heart disease, respiratory disease, and most importantly, fewer deaths overall. In a recent review, this was confirmed by all the other big major prospective studies.

So, what’s going on here with the study showing no longevity benefit from nuts? Did they just not wait long enough? Just because people were randomized to the nut group didn’t mean they actually ate more nuts, and those randomized to the other groups didn’t necessarily stay away.

If you re-analyze the data comparing the death rates of those who actually ate more nuts to those who actually didn’t, nut consumption was indeed associated with significantly reduced risk of death. If you do the same kind of post hoc analysis with olive oil, even with the extra virgin, there is no benefit in terms of living longer. This is consistent with how Ancel Keys, the so-called Father of the Mediterranean diet, viewed olive oil. He thought of its benefit more as a way of just replacing animal fats: anything to get people to eat less lard and butter.

What is the best kind of nut? The greatest benefits were attributed to walnuts, particularly for preventing cancer deaths. Those eating more than three servings of walnuts a week appeared to cut their risk of dying from cancer in half.

Now, it’s just a matter of communicating the research to the public. All the major cancer groups emphasize a more plant-based diet, remarkably consistent with the World Health Organization guidelines for healthy eating. The far-reaching positive effects of a plant-based diet—including walnuts—may be the most critical message for the public.

Here are some of my previous videos on the Mediterranean diet:

Think the effects of adding a few nuts to one’s daily diet are too good to believe? Check out my video Four Nuts Once a Month. For more on Walnuts and Artery Function, check out the video, and for more on nuts and cancer prevention, see Which Nut Fights Cancer Better?

Nuts May Help Prevent Death and so may beans; see Increased Lifespan from Beans. What about Fruits and Longevity: How Many Minutes per Mouthful?

More on protecting ourselves from “brain attacks” in Preventing Strokes with Diet.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:


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.

47 responses to “The Two Most Active Ingredients of the Mediterranean Diet

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    1. Thanks for your question Slick.

      In this video, Dr Greger addresses flaxseed oil but in a different context.

      However, flaxseed is an important source of ALA (omega-3). According to this review:

      “Whole foods containing ALA, such as walnuts and flaxseed, provide other bioactive constituents that act synergistically with ALA to produce favorable modification of disease risk factors. It may be prudent to include such foods in the diet to provide ALA.

      (…) In summary, it appears that ALA confers modest protection against CVD.”

      The table below, provides information about sources of ALA, which can help balance the omega-6:omega-3 ratio.

      I may not be understating your question entirely, so if I have not clarified what you asked, please do tell me and I will try my best to help.

    2. Look at the whole picture instead of just conceptual labels. ALA oils are very perishable. The extraction process reduces the antioxidants. Partial rancid oil is bad. Best is to use a cheap coffee blade grinder and toss some flaxseeds before consumption.

        1. My personal recommendation: avoid all oils except marine vegan EPA/DHA (individual sealed softgels). Nuts good. Flaxseeds good. To avoid the nasties of the EPA/DHA softgel (the chemicals in the vessel), bite the softgel inside your mouth, and spit out the softgel.

      1. I buy flax meal and keep it in the freezer and only take out enough for a few weeks and keep that in the refrigerator. Never had a problem with it being rancid

    3. i consider all oils as ‘concentrated chemicals’ devoid of any other beneficial aspects of the whole food.

      i take whole ground flaxseed but would never take the oil specifically because of that reason.

      just my 2 cents.



  1. OK, this is confusing: “If you do the same kind of post hoc analysis with olive oil, even with the extra virgin, there is no benefit in terms of living longer”, which links to a study that states, “CONCLUSIONS:
    Olive oil consumption, specifically the extra-virgin variety, is associated with reduced risks of cardiovascular disease and mortality in individuals at high cardiovascular risk.”

    1. Thanks for pointing this out.

      A few things to take into consideration:

      “As compared with participants in the lowest tertile of total olive oil intake, those in the highest tertile were more likely to have secondary education, lower total energy intake, lower consumption of red meat and dairy products, and also to drink less alcohol.”

      “Each increase of 10 g/d in EVOO intake was associated with a 10% reduction in the risk of cardiovascular events. To the contrary, consumption of common olive oil was not significantly associated with cardiovascular morbidity and mortality. (…) Our findings suggest a non-significant possible inverse relation between each 10 g/d (one tablespoon of oil) increase in total olive oil and EVOO consumption and all-cause mortality.”

      So I am assuming, Dr Greger, like stated is strictly referring to “living longer” and in this case, the statement above would be correct.

      Hope this answer helps.

  2. Dr. Greger,
    My husband has serious CAD and is following Dr. Esselstyn’s way of eating which says no nuts. His rules are: whole-foods, plant-based foods with no oils, no salt, no sugar. I am curious. You relay the clear benefits of nuts. Any way you can clarify?

    1. Thanks for your question Ingrid.

      I would like to wish your husband the fastest recovery and glad to hear he is following a WFPB diet.

      According to Dr Esseltyn’s paper, here is the food guidance he gave to his patients (see here):

      “The core diet:
      Whole grains, legumes, lentils, other vegetables, and fruit comprised the major portion of the diet. We reassured patients that balanced and varied plant-based nutrition would cover their needs for amino acids, and we encouraged them to take a multivitamin and vitamin B12 supplement. We also advised the use of flaxseed meal, which served as an additional source of omega-6 and omega-3 essential fatty acids.

      Foods prohibited:
      Initially the intervention avoided all added oils and processed foods that contain oils, fish, meat, fowl, dairy products, avocado, nuts, and excess salt. Patients were also asked to avoid sugary foods (sucrose, fructose, and drinks containing them, refined carbohydrates, fruit juices, syrups, and molasses). Subsequently, we also excluded caffeine and fructose.”

      If we were to strictly follow Dr Esselstyn, we would have to avoid nuts. However, others may disagree and include a small amount of nuts during the day.

      Hope this answer helps.

      1. Have you witnessed any negative reactions in people to B12 supplements?
        They are causing what appears to be blood clots in me, possibly. And i read that
        this can be side effect for a small but certain group of people who supplement
        with B12.

        1. As a moderator on, I would encourage you to research that article you read about blood clots for a small group of people who supplement and carefully review with your physician. I did a search on PubMed and found the general consenses is that there adverse effects of Vit B12 supplementation are rare : “No toxic or adverse effects have been associated with large intakes of vitamin B12 from food or supplements in healthy people.,”

          This link: indicated there may be drug interactions you might review: “Vitamin B12 has not been shown to cause any harm…. Vitamin B12 can interact or interfere with medicines that you take…”
          Certainly blood clots are a serious concern and you’ll want to consider all potential causes, working with your doctor to minimize your risk. We know if you are not eating animal products you need your B12 so this is a definite issue you must work with your doctor to resolve clarifying any personal risks with B12 supplementation.
          Best of health to you as you try to resolve this issue.
          Joan-Nurse Educator

        2. hi brenda,

          are you on a No Oil WFPBD?

          people who have a high omega 6/3 ratio (basically the western world) have CLOTTING diseases.

          people who have a high omega 3/6 ratio have BLEEDING diseases.

          old time eskimos had these high 3/6 ratios and if they got a nosebleed, it was a death sentence as they would bleed out and never clot.

          those of us on a No Oil WFPBD should be in the 6/3 ratio of less than 4:1, ideally 1.5-3 to 1.

          if you’re at those levels then your clotting mechanisms should be working perfectly and you should NOT be getting blood clots, if indeed, that’s what they are.

          if you are truly getting blood clots then you should be in the hospital as they are life threatening and you need to be on blood thinners and closely monitored.

          you could get bloodwork for your omega 6/3 ratios which would give you a good idea of where you stand.

          if it’s way out of whack then you know where to begin in healing yourself.

          take care,


      2. Yes, I think so. It sounds to me that in severe cases of CAD following Dr. Esselstyn’s way of eating prevents eating nuts to get as close to zero fat as possible. For folks with “normal” risk for heart disease, in other words the average person, small amounts are OK. Thank you so much.

    2. hello ingrid,

      almost 6 years ago i was in the same situation as your husband and he sounds to be doing the same exact thing that i’ve done.

      i had inoperable, progressive brain disease, told there was nothing left that medical science could do and to go home and get my affairs in order.

      i immediately went on the esselstyn diet, not having one molecule of added fat since then and followed his recommendations to the “T” now for 5.75 years.

      i was so against fats/oils that it took me 4 years before i realized the benefit of ground flax seed and since then have taken basically 1 TBS/day.

      within 20 months, the 3 virtually complete blockages of my anterior cerebral arteries had completely cleared up. not a trace or hint of blockage left, the vessels were COMPLETELY PATENT.

      NOW is not the time to reinvent the wheel when esselstyn has proven beyond the shadow of a doubt that HIS program works.

      first it was with the 24 terminal, end stage patients, 18 of whom followed the diet and lived a full life for the last 35 years while the rest who couldn’t handle the diet died off quickly or the recent study with 200 patients that had a 99.4% success rate with HIS No Fat WFPB diet.

      esselstyns diet does NOT include nuts or any fats at all and there’s a reason for it, inflammation. go on YouTube, search “dr esselstyn no oil” and make sure to go onto pages 2, 3, 4 etc.

      now is not the time to experiment with or try this theory or that theory or maybe this or possibly that or anything else and then someday find out its right or worse, completely wrong. remember, he is literally a cobweb thin plaque layer just waiting to burst away from a serious event and in nearly 1 of 2 people their first ‘symptom’ is death, not chest pain or a TIA.

      it’s hard enough knowing you have to eat a certain way without deviation for the rest of your life (i know that intimately) so don’t tease him with the idea of adding extra fats in the form of great tasting nuts because you read a study that doesn’t even apply to anyone here except those eating the SAD diet. every single study is flawed in some way when you delve into it far enough.

      i would only trust studies done on RURAL indigenous peoples or No Oil Vegans but those are far and few between and everything else is flawed from my perspective.

      esselstyns work is rock solid.

      here are two videos which will open your eyes to excess fat in the diet even though it was from ‘good’ plant fats.

      the first guy was a 17 year long raw vegan who had a stroke specifically because he ate added nuts, seeds and other fatty plants.

      he learned his lesson very fast, quickly went back to more of an esselstyn type diet and reversed his disease so please don’t fall for the studies which keep coming out concluding that this fat or those nuts are good for you.

      i can promise you that if i added any nuts to my diet that my cholesterol level of 102 and LDL level of 37 would rise, not lower. getting my levels down like this is exactly why i did not die off years ago and why i reversed my “progressive, inoperable” disease.

      Can a Vegan Get a Stroke? YES–Here’s How

      Long Term Raw Vegan Has a Stroke: Why a Raw Diet May Not be Healthy

      1. Thank you AZ Donald for your in depth answer. So far my husband has followed Dr. E’s way of eating perfectly and has no plans to include nuts. My question is more a puzzlement in my own mind. Dr. Greger’s videos relay that nuts are healthy so I wondered how both could be true, but each of us has a different body ecosystem and not one size fits all. We both are on a whole-food plant-based diet but I eat avocados & nuts whereas he doesn’t. There is no question in my mind that a WFPB diet is the way to go for health and longevity.

      1. click the ‘edit’ button under your post beside the up down arrows, reply and share buttons.

        edit the mistake.

        delete the last post about the mistake and violet! it’s gone, lol.

  3. I expect that the walnuts looked best because they are the only nuts you can’t buy roasted. It would be interesting to know if “roasted: nuts were supplied to the participants. It is my opinion that roasted nuts are more inflammatory and artery clogging because they are “cooked oils” and likely cause inflammation.

      1. rats, i just saw a graphic about flax, walnuts etc.
        flax was definitely tops with walnuts second but significantly lower, maybe ~25% lower.
        enough that i think i’d only use walnuts as a last resort.
        i’m kicking myself for not noting that chart and i don’t even know where to begin looking for it as i do so much research.

          1. wow, i never even knew there was another type of walnut.
            either way though, i’m sticking with the 1 TBS ground flax per day because if i had just one handful of walnuts…. it would end up being the whole bag lol.

  4. Are the oils in” UDO’S oil 7″ and “3 – 6 -9″supplement an OK thing to be putting on my food? They sell an oil supplement that has flax, sunflower seed, vegan DHA, and some other oils but I am wondering if this is harmful, as Dr. G and other vegans say no added oil. But a lot of vegans use this in place of DHA pills (that also contain oil, which Dr. G suggests we do take).

    1. Thanks for your question Julie.

      I highly recommend you read this summary by NF and this article by PCRM to get an idea of what type of fatty acids you want to include or supplement in your diet.

      After reading these two links, I have attached an image form this review, that will help you maximise the benefits of ALA.

      Hope this answer helps.

  5. Could the benefits of nuts especially related to atherosclerosis be attributed to its phytic acid content which inhibits absorption of calcium thereby preventing the build up of it in the arteries?

  6. I’d like to point out here that olive oil consumption was not associated with greater risk which I think is important. A lot of people here demonize any refined oil at all. Maybe instead of demonizing refined oils we should put them in the category of just limit the amount that you eat. Especially, because although they may not have nutritional benefit for many people including me they make vegetables taste really good. Moreover, using it increases my consumption of them by a lot especially dark leafy greens like spinach and collard greens which I just don’t like the taste of any other way.

    1. Well they didn’t compare an oil group, a nut group to no oil and/or nut group. or simply no oil group-WFPB. Now that would be interesting.

    2. Hi Guest – you are still talking about a very small amount of olive oil per day. One tablespoon is equivalent to 3 teaspoons which is equivalent to 44 olives (roughly). One tablespoon of olive oil is approximately 120 calories which, if you are on a 2,000calorie/day diet, is 0.06% or 6% of your daily calories. Still very much less than the 10% fat the WFBP, SOS experts suggest as healthy.
      How you are using your olive oil – and the amount – is in great contrast to how I see other people using olive oil. Pouring it over their food, dipping their bread in it, using it as a base for sauces which gets slathered on their food, vegetarian/vegan/or not. Not to mention cooking “everything” in it.
      I agree with what you said that using it increases your consumption of leafy greens and I understand. I make a Korean sauce using sesame oil with ginger, garlic, tamari, a little sugar that makes me wolf down my greens. So yummy. And sesame oil is more omega 6 and not as healthy as olive oil I would venture. But it makes me eat my greens. I have learned to dispense with the oil and grind the whole seed in my mortar and pestle and use that instead of the straight oil. I wonder, now, if one could just simply blend up some whole olives in a little H2O with lemon juice, perhaps, and make a whole food olive drizzle for their greens? You are making me think out loud . . . .

      1. This is true, because I am a small person. I cannot do what you are suggesting other vegans/vegetarians are doing without becoming morbidly obese. Some people may have more latitude than I do. One thing is that the amount of olives your talking about is a lot more expensive than olive oil and it’s not really in my budget.

  7. One practical problem is that nuts are quite expensive compared to olive oil. To get to my calorie intake of about 3800 Kcal/day (I exercise a lot, my BMI is 19.5 kg/m^2, so I shouldn’t reduce my calorie intake), I do need to use oils, my total intake of fats is about 130 grams per day (which includes some walnuts). Getting rid of all the olive oil I use and trying to get almost all of the fats from walnuts would be quite expensive in my case. Trying to get around thus by increasing the intake of carbs so that I could reduce the amount of oils isn’t going to work well, my stomach would not tolerate eating larger volumes of food than I’m already eating. If I eat potatoes for dinner then I’ll have 1 kg of potatoes, there is no way I could add an additional kg of potatoes.

    1. What price do you put on your health?

      Eat more high caloric whole food, such as avocados and flax and chia seeds etc. Find carbs that are easier on your stomach. I find rice very easy to tolerate. Maybe lots more fruit.

  8. Hi, I would like to ask your opinion (and papers) about an Eco Atkins diet, take the Atkins out and think high fat, whole foods, plant based diet with vegetables too. What would you think?

    1. Hi Alexis, I am a volunteer for Dr. Greger. Thank you for your question. There are some research studies suggesting that an Eco-Atkins diet, which only contains plant foods, is beneficial for lowering risk of heart disease. However, these studies were compared to high-carbohydrate lacto-ovo vegetarian diets (subjects still ate milk and egg whites), which may have weighted the scale favorably for the low-carbohydrate group. Therefore, more research needs to be done on Eco-Atkins diets. However, because these studies found that Eco-Atkins diets were effective at lowering cardiovascular disease risk, I would say that they are healthful diets, and certainly advantageous over typical Atkins diets. However, no evidence is present yet to suggest that an Eco-Atkins diet is advantageous over a high carbohydrate, whole food, plant-based diet. I hope that helps answer your question!

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