Doctor's Note

Exercise itself can improve immune function in general (Preserving Immune Function in Athletes With Nutritional Yeast), but the blueberry finding, so far, is unique. The oxidative stress part of the story is told in Reducing Muscle Soreness With Berries.

Just because the study was funded by the blueberry councils doesn’t necessarily mean the science is suspect, but you would want to see this independently verified, especially a finding so dramatic.

What else can berries do? Check out:

 You can check out my blueberry smoothie recipe here in A Better Breakfast.

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  • Ronald Chavin

    Black pepper and red pepper are very risky dietary choices if we want to live longer:

    In the case of black pepper eaters, the real cause of the higher cancer rates could be a higher meat consumption required by black pepper recipes or the saffrole that the black pepper contains. In the case of red pepper eaters, the real cause of the higher cancer rates could be nitrosamines, mycotoxins, the capsaicin itself, or the combination of all 3 of these causes.

    • Paddycakes

      Meat and dairy are primary causes of cancer: Ninety five percent of cancers can be avoided and cured by diet, assuming of course, that the cancer has not already reached the ‘point of no return’; which, of course, no one knows. Even given the death sentence and sent home to die, one may not have reached that point, and cancer very well may be reversed with proper dietary recovery ingestion and maintenance. If however, one does reverse their cancer and return to meat and fair, the cancer may well return with a vengeance and probably not curable irrespective of diet.

      • DH

        There are anecdotes about buddhist monks in Thailand being diagnosed with cancer in the big city hospital and sent home to die, only to live another 20-30 years. This was apparently a fairly common scenario, and is possibly related to the combinations of plant-based diet, meditation and metta practice.

      • Jed L

        you wrote…..”Ninety five percent of cancers can be avoided and cured by diet, assuming of course, that the cancer has not already reached the ‘point of no return’; which, of course, no one knows.”

        Where did you get this stat. – the 95%? I’d love to read the studies that led to this number, and would be grateful if you could provide the sources. Thanks.

        • Paddycakes

          Read Dr. Campbell’s book: the China Study; Caldwell B. Esselstyn, Jr., M.D., “You Can Reverse Heart Disease”,;;

          Animal protein/dairy cause cancer:

          There is a plethora of Google sites which make the same claim: Do your homework, please.

          • jazzfeed

            And here is a thoughtful and thorough critique: The China Study: Fact or Fallacy?

            Doing your homework is the best health advice IF you CONTINUE doing your homework. What ‘truths’ you find today may be negated tomorrow or 30 years later.

          • guest

            Minger ? Thoughtful , thorough ? ! ? View PlantPositive’s review of Minger tonight for YOUR homework and post in the morning…

        • Darryl

          95% is optimistic, but in The China Study the American death rate from breast cancer was five times higher than the rural Chinese rate, which sets a pretty high bar for what’s possible with a life-long diet low in complete protein, saturated & ω-6 fats, and insulinemic food combinations, and high in fiber and beneficial phytochemicals (phytoestrogens; Nrf2 and AhR inducers; NF-κB, CD38, and angiogenesis inhibitors; epigenetically active compounds, and immune stimulants). As much precancerous epigenetic cell programming occurs from conception through puberty, I think its unlikely that perfect diets adopted later in life can achieve quite the same risk reduction. Vegans in AHRII had only a 16% overall (and 34% female-specific) risk reduction compared to a rather healthy omnivore cohort, but I think 80% is possible if one starts with a health-conscious B-12 supplemented vegan diets in the womb. Future generations will reap the full benefits of what we’re learning now.

          • guest

            The phrase you used ” insulinemic food combinations” has me curious. What exactly is the “combination” part? I know what foods create insulin issues. This combination thing I may be messing up because I often mix high carbs with some fat-filled vegan foods.

          • Darryl

            Protein potentiates the insulin response to high-glycemic carbs, but fat doesn’t have an immediate effect. (Saturated fats will lead to muscular insulin resistance and progressive type 2 diabetes, though).

            While insulin’s control of blood glucose is a good thing, the receptors for insulin and insulin-like growth factor are related in their downstream effects and often hybridized on cells. Attention on this site has been given to IGF-1 in cancer proliferation, but the phrase “Insulin and Insulin-like growth factor Signalling” (IIS) is increasingly common in the literature. For the curious:
            Insulin and insulin-like growth factor signalling in neoplasia.. (2008)
            The insulin and insulin-like growth factor receptor family in neoplasia: an update (2012)

          • guest

            Does the “protein potentiates the insulin response…” apply to vegan protein sources such as canned beans?

            I have eaten an entire can of beans 6 days a week for the past couple years, and add to those beans 1/4 cup of pumpkin seeds and some steamed veggies. Well over 35 grams of protein in one meal, and this is when my diabetic issues started, when I went with the beans. That’s 3 1/2 cups of beans per day. Whether causative or not, I never knew about the protein-diabetes relationship.

          • Darryl

            Beans have little sugar, and their starches are conmingled with fiber, so they have rather low glycemic or insulinemic indices to begin with. Nothing like steak (highly insulinotropic animal protein) + baked potatoes (high glycemic index starch. If you’re curious about insulin indexes:

            An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods (1997)
            Food insulin index – physiologic basis for predicting insulin demand evoked by composite meals (2009)
            Prediction of postprandial glycemia and insulinemia in lean, young, healthy adults glycemic load compared with carbohydrate content alone (2011)

            From the first paper that note lentils have a low insulin index, but baked beans, with their added sugar, have a higher one. From the second note the most insulinotropic meal was bananas (sugar) + yogurt (dairy protein). I think the rural Chinese diet, because it is largely just starches, with only a little coingested protein or sugar, and scarce saturated fat to reduce insulin sensitivity, results in significantly lower insulin responses than occurs when high-glycemic white rice is added to Western diets (without other changes).

          • Timar

            Darryl, I don’t think that those studies support your hypothesis. The first study actually shows a negative association between the insulin response and protein content of the food (“Total carbohydrate and sugar contents were positively related to the mean insulin scores, whereas fat and protein contents were negatively related”) while the test meal #2 from the second study, which you refer to as the banana and yogurt meal, actually contained sweetened jogurt with 44g(!) of CHO (most of it added sugar), plus honedew melon and apple juice, adding to total of 90g of carbohydrates, amost exclusively from sugar.

          • How does protein affect the insulin response to co-ingested glucose in people who are not diabetic? And I saw elsewhere that you are raising some doubt about glucose metabolism creating ROS. Did I read that comment correctly?

          • Corina-Aurelia Zugravu
          • Could you clarify the “fat doesn’t have an immediate effect” line? I’ve always heard to eat some fat with carbs to slow down blood sugar spikes? Correct? What’s the mechanism?

          • Darryl

            I was referring to insulin response. From some subsequent studies, it appears coingested fat does markedly reduce glucose spikes in response to a starch meal (potato) in normal subjects, though had little effect in diabetics. However the insulin response to the meal was still slightly greater (8% in normal subjects, up to 40% greater in diabetics) when consumed with fat. This is a small effect in comparison with that from high protein foods; 25 g protein from cottage cheese increased insulin response to 50 g glucose by 360% in the study cited above.

        • Richard

          There is no science justifying the 95%, wakeup and smell the roses!

    • Darryl

      Piperine, the pungent principle of black pepper, has the remarkable property of increasing bioavailability of many other beneficial phytochemicals, including β-carotene, coenzyme Q10, curcumin, EGCG (from green tea), gallic acid, and resveratrol. So black pepper would play a useful role in preventative nutrition even if it didn’t have independent therapeutic potential against cancer, inflammation, hypertension, asthma, depression, infertility, genotoxicity, and clotting as reviewed here.

  • Tom S

    hi dr greger,

    is there any way to increase the number of youtube playlists?

    this website is amazing, but the functionality of youtube playlists (being able to watch 20 videos back to back with one click) is really appealling.

    if this website could turn the search by topic into back-to-back continuous playlists that would be amazing. less clicking, more watching!

  • DavEd CamerBand

    “The results of this study suggest that capsaicin may serve as an anti-tumorigenic agent in human gastric cancer.”
    “Capsaicin induces apoptosis in PC12 cells through ER stress.”
    However I am a little concerned that the high sugar level in fruit inc berries may encourage cancer growth?

    • Brandon Klinedinst

      Berries aren’t high in sugar.They have more grams of fiber than sugar.

      • Mitt

        I just checked for blueberries and strawberries. Strawberries contain 2g fiber and 4.88g sugar.
        Blueberries have 2.4g fiber and 9.96g of sugar, both 100g berries each, according to cronometer.

    • Paddycakes

      Excellent point. Cancer thrives on sugar and in spite of the killer properties, it will have side affects, common sense and being alert is critical for survival.

    • Julot Julott

      Cancers cells thrive on sugars as much as non cancer cells simply because cancers celles are body cells also and all of them feeds on carbs~
      So avoiding carbs with cancer is non sense, you certainly dont want to starve your billions of cells, avoid medium to high protein and fat is the good idea.

    • Leslie

      Interesting comment on the high sugar level in fruit possibly encouraging cancer growth. I have tried to find data to suggest this possibility but have come up short. Do you have any sources to share that have led you to have this concern? Thank you.

  • Tractor Guy

    Anyone know the amounts of black pepper and cardamom for this synergy to work?

    • puntloos

      It seems to me the ‘right amount’ is simply how much you can stomach without it killing the taste. I’d say a teaspoon of cardamon and 1/2 tsp of black pepper is all one could put in a 750ml (3-cup) smoothie.

  • Darryl
    • DH

      Is nutritional yeast rich in these beta-glucans?

      • Darryl

        It seems so, but I haven’t had time to investigate details of how β-glucans from nutritional yeast stack up those from edible mushroms in bioavailability or NK cell activity.

        Immunomodulatory activities associated with beta-glucan derived from Saccharomyces cerevisiae (2005)
        Saccharomyces cerevisiae, the Baker’s Yeast, suppresses the growth of Ehrlich carcinoma-bearing mice (2008)

        β-glucans are common cell wall components throughout the fungal and bacterial kingdoms, and it appears that our innate immune system ramps up after their detection in anticipation of fungal infection. When some soluble varieties pass through the intestinal wall after eating fungi, NK cells find other things to kill, like cancer cells. Whether there is some “sweet-spot” for cancer prevention but not excess systemic inflammation, I can’t say. But between β-glucans and ergothioneine, I make sure to eat some every day.

        Tip: One can find sliced dried king oyster mushrooms (a top source for both β-glucans and ergothioneine) at Asian markets, and once rehydrated and sauteed, they make an excellent, inexpensive textural substitute for sliced meat in dishes like pepper steak. I may never buy seitan again.

        • DH

          I didn’t realize fungi (mushrooms) were so important. How does one rehydrate dried sliced king oyster mushrooms, so that “fungus may be among us” (poor pun).

          • Darryl

            Any dried mushroom can be rehydrated by covering in warm water for 30 minutes or less. I save the soak water, as it makes a great sauce base once reduced (boiled), with a pinch of cornstarch as a thickener (Chinese restaurant style). It also ensures none of the ergothioneine, a pretty heat stable compound, is lost.

      • Darryl

        It seems so, but I haven’t had time to investigate details of how β-glucans from nutritional yeast stack up those from edible mushroms in bioavailability or NK cell activity.

        Immunomodulatory activities associated with beta-glucan derived from Saccharomyces cerevisiae (2005)
        Saccharomyces cerevisiae, the Baker’s Yeast, suppresses the growth of Ehrlich carcinoma-bearing mice (2008)

        β-glucans are common cell wall components throughout the fungal and bacterial kingdoms, and it appears that our innate immune system ramps up after their detection in anticipation of infection. When some soluble varieties pass through the intestinal wall after eating fungi, activated NK cells find other things to kill, like cancer cells. Between β-glucans and ergothioneine, I try to eat some mushrooms every day.

        • Tip: One can find dried sliced king oyster mushrooms (a top source for both β-glucans and ergothioneine) at East Asian groceries, and once rehydrated (30 mins in warm water) and sauteed, they make an excellent, inexpensive, gluten-free textural substitute for sliced meat in dishes like pepper steak, without the sometimes overwhelming flavor of shiitake etc. I may never buy seitan again. There’s a company that exposes dried king oyster powder to UV to create high vitamin D2+ergothioneine+β-glucan prescription nutraceuticals, but for those who prefer food, perhaps sunny-day backyard experiments are in order.

        • Thea

          Darryl: Great tip! I find myself eating a lot of white button mushrooms because I like them and they are easy to find and cook. But I have been wanting to branch out. The dried king oyster mushrooms is a great idea.

    • Do beta glucans in oats and barley also activate NK cells? Do other types of berries besides blueberries activate NK cells? And might other spices have similar synergistic effects?

  • eva101eva

    Merry christmas , Dr. greger amd Team

  • Richard Frazee

    May you have a wonderful Christmas and may God look after you in all your years to come. We NEED all the wonderful info you provide!

  • Derrek

    Is it safe to consume caffeine supplements like green tea extract? I’m trying to lower my body fat percentage particularly around my stomach?

    • Toxins

      Dr. Greger does not recommend green tea supplements. Adopting a whole foods plant based diet without refined flours or oils can lead to significant, healthy weight loss.

    • Darryl

      Speaking of which, a Dec 21 NYT story about green tea supplements and jaundice.

      Green tea isn’t just caffeine. It has numerous polyphenol compounds (the most studied being epigallocatechin-3-gallate, EGCG) that in small doses stimulate endogenous stress responses, having a protective effect, but in larger doses, as achieved in test-tubes or when supplement overdoses are metabolized in the liver, overwhelm any induced protective responses and are toxic to cells. I think of green tea and other herbs that work through similar mechanisms as “eustressors” (good stress), which I think is clearer than alternatives terms “hormetin” or “adaptogen”. As with lifestyle eustressors (exercise, fasting, saunas, sunlight) one can overdo it, and green tea extract pills make it all too easy.

  • Derrek

    Also is like Prolab caffeine safe?

  • Thea

    I love this video because it jives so much with something I actually like. One of my favorite smoothies is from (I think) PCRM and was called mango lassie. The ingredients: frozen mango, dates, almond milk, cardamom and black pepper. It sounds weird, but the pepper perfectly balances the drink so that it isn’t too sweet.

    How “sweet” that my lassie is so powerfully healthy! (Well, I’m assuming that mangoes work a bit like blueberries – which is a stretch given the goji berry experiment. And I’m assuming that I’m getting enough cardamom and pepper to make a difference, which I’m probably not. … BUUUUT it still makes me feel good/like I’m going in the right direction. ;-) )

    • Darryl

      Mangiferin is a plant natural polyphenol of C-glycosylxanthone structure and various pharmacological activities. It can be found in many plant species, among which the mango tree (Mangifera indica) is one of the primary sources. In the mangiferin molecule, four aromatic hydroxyl groups determine its strong antiradical and antioxidant properties. Mangiferin is also an efficient iron chelator, therefore preventing the generation of hydroxyl radical in Fenton-type reactions. Numerous published in vitro and in vivo pharmacological studies, demonstrated many other activities of mangiferin: analgesic, antidiabetic, antisclerotic, antimicrobial and antiviral, cardio-, hepato-, and neuroprotective, antiinflammatory, antiallergic, MAO inhibiting and memory improving, as well as radioprotective against X-ray, gamma, and UV radiation. Several studies indicated also its ability to inhibit cancerogenesis and cancer cells growth by apoptosis induction in vitro and in vivo.

      There, feel better?

      • Thea

        Wow. That’s really awesome. Thanks Darryl!!!

  • UCBAlum

    I am interested to know if the different amounts of cardamom and pepper tested in the research mentioned above could be achieved by dietary consumption, and if so, how much one would have to consume to reach those amounts.

  • I m wondering if the studies on the effect of blueberries use the kind of berries readily available in the grocery stores, which I understand have often been treated with bud nip or maybe other herbicides or pesticides?

  • Cameron s

    This web site really makes it so easy for me to use science based evidence in my reports and my assignments. Its been so helpful as a dietetic intern, and i really believe in what you are doing for the nutrition community who knows foods can really make a difference in health care. This website is awesome thank you.

    • Toxins

      Cameron S, that is excellent to hear. I use a great deal as well in school and am applying for my dietetic internship in the winter. I plan to apply the seemingly endless amount of knowledge on this website to aid my future patients.

  • KittyCat

    DR Michael What’s your thought on Colloidal Silver

  • Bruce Cropley

    I am curious about the amounts of blueberries, pepper and cardamom that were used. I have a brain tumour, and want to boost my NK cells as much as possible. Thx :)

    • Jon Lefave

      I’m curious as well.

      PS. All the best in your fight!

    • Bruce Cropley

      Thanks Jon :)
      Also, I’m curious about whether NK cells have any effect on brain tumour cells given the “blood brain barrier”, and if my anaplastic astrocytoma cells are even vulnerable to NK cells? (please excuse the tricky questions) :)

      • I’ve read that polyphenols actually cross the blood-brain barrier. Can anyone shed more light on that?

        • Bruce Cropley

          Thanks Harriet :)
          I know almost nothing about polyphenols, and most of that I learnt since I read your comment here ;)

          • Here’s my attempt to summarize polyphenols in clear, succinct language. How did I do?

          • Bruce Cropley

            Very well explained :) I am eating a handful of blueberries and 6 or 7 strawberries each day, and I make up capsules containing black pepper and cardamom (~50/50) which I take twice a day – morning and evening. I’m thinking I should add some ground cloves to the mix. Any suggestions to the proportions? If not, I’ll go with 1/3 each.
            Thanks again!

          • Here’s the “messipe”for a chai spice mix that I came up with for a book I’m writing. Feel free to futz (is that a word?) with it to suit your tastebuds. I keep the mix in a dark container, then whisk some into almond milk and add the berries. Would love everybody’s feedback

            2 tsp each: ground cinnamon, ginger, cardamom

            1 tsp ground cloves

            ½ tsp each: black pepper, nutmeg

            Wonder if that’s enough black pepper to get the piperine’s benefits? Maybe Darryl will pipe in?

          • Just curious, Bruce. What does your doctor think about using the drug Metformin for your brain tumor?

          • Bruce Cropley

            No idea, but I’m seeing him in a few days, so I’ll ask him. Thanks again :)

          • Bruce Cropley

            Looks good :) I’m a bit confused about how much of this mixture for one cup of chai: all of it? or 1 tsp of the mixture? And which berries, and how much of each type?

          • Try 1 tsp of the mixture for a cup of almond milk, for starters. It depends on your tastes. Which berries? Purple to blackish ones are highest in anthocyanins.Only strawberries have fisetin. Raspberries, blackberries and black raspberries (and pomegranate seeds) have ellagic acid. Wild blueberries and especially elderberries high in quercetin. In other words, eat them all. You can also buy concentrated berry powders (Make sure they’re freeze dried, not spray dried) and mix them into the milk.

            But don’t forget the vegetables–alliums and crucifers and dark leafy greens, especially. For those you can add turmeric and black pepper.Here’s my favorite onions messipe.

          • Bruce Cropley

            I have been having a raw garlic mix for supper daily for about a month now, based off this:
            ~1/3 tsp Cinnamon for the spice
            No oil
            2 BIG tbsp of Hommus
            I have been crushing the garlic first, I’ll adapt to your method now (cut, wait, crush, eat)
            Eating it with a bowl full of baby spinach leaves.
            I find the garlic intense as I have been doing it. Perhaps crushing it is just making it unnecessarily strong, and I should just cut it into small pieces?

          • Have you tried aged garlic extract?

          • About the garlic: Try making a gremolata like the Italians do. Mince garlic and some lemon peel (organic), add a little olive oil and maybe salt, chop up some herbs (parsley,cilantro, fennel–Take your pic/all are really healthy) and mix them together. Proportions? I’m working on that. Just have fun making up your own messipe.

          • Bruce Cropley

            Very nice :) I used oat milk instead of almond milk, I’m guessing that doesn’t make much difference. I’ll be having one of these per day I think. One tsp of the mixture for one cup was about right for me.

          • Check the carbs in that oat milk. Almond’s quite low. Last time I checked, oat milk was pretty high.

          • Bruce Cropley

            Shall do, thx :) I am quite thin already, should I be keeping my carbs down because of the cancer?

          • Yes, the carbs–minimize them. You might want to discuss a ketogenic diet with your doctor as well. Check out the short explanatory piece below–along with the 3d Thomas Seyfried presentation I link to, for starters. If if were me, I think I’d go that route–and focus on healthy fats. There’s also a nutrition consultant who consults on cancer who could be very helpful. She’s worked with lots of people with brain cancer (including the late great MD-PhD, Dr. David Servan-Schreiber, who lived 19 years with a deadly form of it) and will look at your bloodwork, etc. and personalize your nutrition plan. Her name is Jeanne Wallace– her website is below, too.



          • Bruce Cropley

            This is great – reminds me of my hippy days, and it is healthy too ;) Do you have a link for this?

          • a link for what? Do you want to contact me privately? There are some special considerations for brain cancer–such as CLA and goldenseal (both good) but cashews and foods with MSG that contain neuroexciters should be avoided. Jeanne Wallace is really THE nutritional expert on brain cancer.

          • Bruce Cropley

            Thanks for that, I was actually after a link to the chai recipe, but you have given me yet more useful information. Much appreciated :)

          • Bruce Cropley

            Here is yet another question for you Harriet:
            Braggs has been shown to be MSG here, but it is classed as “Harmless”, for most people at least. Does it contain neuroexciters that I should be avoiding – i.e. are these neuroexciters an inherent part of MSG, or something that often accompanies MSG?
            TIA :)

  • DiabetesIsCured

    Natural Killer cells can also cause miscarriages in women. Is there a way to reduce natural killer cells? or help the natural killer cells distinguish between the fetus and diseases/tumors?