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A Supplement Shown to Improve Asthma

Asthma, “a chronic inflammatory disorder of the airways,” affects approximately 10 percent of children. About half the risk is genetically determined, but we may have some control over the rest, which is the focus of my video Vitamin D for Asthma.

One reason asthma rates may be rising is because of our rising rates of vitamin D deficiency. Kids just aren’t going out to play anymore, which, as you can see at 0:30 in my video, resulted in a doubling of vitamin D insufficiency levels in recent years, such that less than a quarter of U.S. teens hit the mark.

We can’t make vitamin D, known as the sunshine vitamin, from the light coming from our TV, phone, and computer screens. “The primary sources of this vitamin are natural production in the skin secondary to sun exposure, and secondarily from fortified foods and supplements.” So, do kids with lower vitamin D levels in their blood have worse asthma? Apparently so. One of more than a dozen observational studies suggests that vitamin D is protective against “asthma exacerbations.”

Should we start giving kids with asthma vitamin D supplements if they’re not going to play outside? Correlation doesn’t mean causation. Perhaps “subjects with more severe asthma are likely to spend more time indoors,” thereby leading to less vitamin D, instead of the other way around. To prove cause and effect, we need to put it to the test. How? Randomize kids with asthma into one of two groups, receiving either vitamin D or an identical-looking sugar pill, and see what happens. There had never been clinical trials like that…until now.

Asthmatic kids were given 500 to 1,000 international units (IU) of vitamin D3 a day, and their asthma exacerbations were cut by more than half. Researchers suggest this may be due to decreasing the incidence of respiratory infections by boosting immunity, while, at the same time, diminishing inflammation.

If it helps with inflammation, what about inflammatory bowel disease? My video Vitamin D for Inflammatory Bowel Disease discusses exactly that.

For other videos in my extended series on vitamin D, see:

For more on preventing and treating asthma, check out:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live 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 “A Supplement Shown to Improve Asthma

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  1. That is very cool that it cuts the asthma episodes in half and decreases respiratory infections.

    So many young people have asthma nowadays.

    The pain studies with D interest me, too.

    D3 is something that I look at the results with the Black community and suspect that if they did studies with obese people and people who don’t get out in the sun that the study results might be so much more conclusive with other conditions.

    I really like the video you put up on the grapes with how the statistics were presented. I find that most people with things like Vitamin D3 either do “It is worthless” or “It is miraculous” and when I look it up, I see things like “Helps the immune system” and “Decreases inflammation” and those things seem to have enough value for me to not care as much if it actually prevents Breast Cancer or not.

    I would rather have the P value than the spin that is out there about things like Vitamin D3.

      1. Low vitamin D status may often be just a marker of disease rather than being a causal factor itself

        ‘The authors identified 82 prospective cohort studies, 84 randomised controlled trials, 20 meta-analyses of 208 prospective studies, and eight meta-analyses of 88 randomised controlled trials. Similarly to our findings, this overview identified a discrepancy between findings of observational studies and of randomised controlled trials, with most supplementation trials not showing an effect of vitamin D on disease occurrence, and the authors concluded that low vitamin D status is more likely to be a marker of ill health than a cause of disease.’

        This may also be worth a read

    1. That’s interesting demetracord, but I am just wondering if you drink green tea or ever tried? Or just take a supplement? Plant foods in general including fruits, vegetables, tea , coffee herbs and spices have done great things in reducing inflammation in the body as in arthritis for example. I struggle with allergies and exercise asthma but can only imagine it would be much worse if I didn’t eat wfpb.

    1. Barb,
      Excellent point (good video). The effects of large fat store of D are unclear according ti the article below. My take away is: get rid if fat!

      “Vitamin D and adipose tissue—more than storage

      Shivaprakash J. Mutt, Elina Hyppönen, […], and Karl-Heinz Herzig

      Additional article information


      The pandemic increase in obesity is inversely associated with vitamin D levels. While a higher BMI was causally related to lower 25-hydroxyvitamin D (25(OH)D), no evidence was obtained for a BMI lowering effect by higher 25(OH)D. Some of the physiological functions of 1,25(OH)2D3 (1,25-dihydroxycholecalciferol or calcitriol) via its receptor within the adipose tissue have been investigated such as its effect on energy balance, adipogenesis, adipokine, and cytokine secretion. Adipose tissue inflammation has been recognized as the key component of metabolic disorders, e.g., in the metabolic syndrome. The adipose organ secretes more than 260 different proteins/peptides. However, the molecular basis of the interactions of 1,25(OH)2D3, vitamin D binding proteins (VDBPs) and nuclear vitamin D receptor (VDR) after sequestration in adipose tissue and their regulations are still ***unclear***.”

      Dr. Mirkin agrees sunlight generated vitamin D is best, and points out not that much sun is needed. In his view, above 20 ng/dL is sufficient (the older standard). I’m not entirely convinced and try to stay above 30 ng/dL but I appreciate his conservative on the topic and take it seriously.
      “For many years I have offered my opinion that sunlight provides benefits that are not gained just from taking vitamin D pills. Recent research is confirming that opinion, and many scientists now believe that low vitamin D blood levels are only a marker for not getting enough sunlight.

      People who get little sunlight are at increased risk for heart attacks, strokes, several types of cancers, infections, bone fractures, diabetes, obesity, depression, auto-immune diseases and other diseases that can cause premature death (J Intern Med, Oct 2016;280(4):375-87), yet the increased risks for these diseases are not reduced by taking vitamin D pills:”

      He lists a number of studies supporting his view, in his typically succinct manner.

        1. Thank you gengo for your post, as always! It’s an interesting topic, and so is what it is all saying about our culture today . I firmly believe that a vitamin d pill can not hope to have the same effect on us as the sun… love that video by Dr Greger talking about the sun lighting up our skull ! And, how the sun’s effect upon the greens we eat manufactures coq10! Amazing.

          Anyway, I agree re losing the fat stores, and with Dr Mirkin’s view that sunlight is best. ty for the link. I would think this is all a part of the chronobiology topic gengo, which is fascinating ! We rebel against it as a society to our own detriment.

      1. Gengo,

        Still, studies of supplementing do accomplish things.

        And most people are deficient.

        And the studies where it did help, supplements helped the people who were most likely to need more Vitamin D3.

        Supplementing if you get enough Vitamin D3 would be where I wouldn’t necessarily see a benefit.

        But elderly people, overweight people, people with dark skin color tend to be very low in Vitamin D3 – often severely deficient.

        Those are the groups where taking them definitely does something.

        Weeding out the people who didn’t need it is what didn’t happen in most of those studies. Also, I remember Dr. Fuhrman talking about many of the studies using the wrong type of Vitamin D or unrealistic doses.

        1. There are studies like one with elderly women in Scotland where they had less hip bone loss if they supplemented D3 – but there was almost no difference between women taking 400 IU versus not supplementing, but there was a significant difference between women taking 1000 IU and the ones who didn’t supplement.

          Mean BMD loss at the hip was significantly less for the 1000 IU vitamin D group (0.05% ± 1.46%) compared with the 400 IU vitamin D or placebo groups (0.57% ± 1.33% and 0.60% ± 1.67%, respectively) (p < 0.05).

          I know that many of the studies were not statistically significant, but what I remember was that dark-skinned people had a crazy improvement and for the rest of the people mortality was the only category where there was a statistical significance, but mortality is a pretty good category to have a benefit.

          1. I also wonder because when they do the studies do they use people who have never supplemented?

            I say it because they have shown in a study that supplementing continues to affect Vitamin D levels for a few years after people stop taking them.

            It seems like that would make it hard for so many of these studies to be accurate because of how many people have taken multi-vitamins.

        2. Deb, Yes, pretty much everything depends to some degree on individual circumstances. It’s up to the individual to weigh the risks versus benefits. But it is misguided to simply assume there are no risks, which seems to be the assumption some people have.

          1. Dr. Fuhrman talked about the “risk” and noted that some studies where there seemed to be risk used outrageously high doses of D. Those studies obviously show us that extremely high doses are contraindicated, but there are risks to being deficient and the studies in countries where there is less sunlight have more positives.

            There are some studies that have said that when they separated out people by body mass index, they showed more significant results.

            Going back to obesity, they did a study in Poland and obese women showed more of an improvement in Blood Pressure and Cholesterol than normal-weight people.

            There is also a study where they gave overweight people Vitamin D and the ones who supplemented had more weight loss, reductions in waist circumference, hip circumference and their BMI improved significantly.

            1. Plus, there is a study where they gave overweight, Vitamin D deficient women supplements for 8 weeks and they said that there was an improvement in insulin levels and triglycerides and VLDL-cholesterol and something called a QUICKI. (Laughing because I am not sure what a QUICKI is but whatever it is, I am pretty sure my mind went in the wrong direction)

              1. How does something improve blood pressure, cholesterol, triglycerides, weight loss, insulin levels, immune system, waist circumference, etc. and not help any diseases?

                1. For institutionalized Down Syndrome people, it helped their bone measures.

                  They said: The remaining parameters showed differences between the two groups consistent with a beneficial effect of the intervention: serum levels of parathyroid hormone, osteocalcin and crosslaps diminished while serum 25 OH vitamin D3 level increased.

                  So elderly people maybe losing less hip bone and having beneficial effects on parathyroid hormone and other things, would be another area where elderly people are so often deficient and it takes more time in the sun for them to get their levels up and more skin exposure.

                  For me, whenever I look for the studies with the groups that are genuinely “at risk” I see that there might be “risks” to not supplementing, even if you are right that there might be other risks to supplementing.

                  1. One of the things one of the studies said was that compliance and noncompliance affected study outcomes:

                    The findings of community-based clinical trials with vitamin D and calcium supplementation in which compliance was moderate or less have often been negative, whereas studies in institutionalized patients in whom medication administration was supervised ensuring adequate compliance demonstrated significant benefits.

            2. Deb, You seem to have gotten the impression I am against any supplementation of vitamin D. I am not. The amount should reflect individual circumstances.

              Taking large doses simply to avoid sun strikes me as misguided. Nothing prevents getting some sun and taking a supplement. In fact, I still do both.

              1. Gengo,

                Thank you for saying that. I did think you were against it.

                The thing with me is that I feel like the WFPB community has started to be against it.

                Yet, when I look at studies of places where the people get less sunlight, I see things like Finland where Type 1 Diabetes rates decreased after they started adding Vitamin D and that is amazing to me.

                When they did studies for cancer prevention just using the African-American community (They used the words African-American. I use the word black when they don’t differentiate that there is an African ancestry out of respect for the rest of the black community, but they said, African-American and out of respect for the history of so many people being ripped from a homeland and brought to the USA, I will use that when it really means that, seems to me that they might not mean African ancestry, but they said it so I assume it is people from African origin only.)

                Anyway, those groups, who are way more likely to require supplementation is where there is a decrease in incidence of cancer, metastases of cancer and mortality associated with cancer.

                The people criticizing the review felt that they over-represented African-Americans, so it shouldn’t be taken as any of those things might happen if people who are not African-American improve their deficiency, but the Finland thing already makes me think that if people are deficient, they need to hear the message from that direction.

                1. Sorry if I am too passionate. I worry that the message is going out that Vitamin D supplementation isn’t beneficial and Jeff Nelson is one of the people who came strongly against Dr. Greger about this issue and he felt that Dr. Greger didn’t present the data thoroughly enough and I tried to point out that Dr. Greger had a lot of videos on the topic and that even with all of those videos, he still couldn’t possibly be thorough enough because of how many studies there are and how complicated it is and Jeff crossed out every study of benefit entirely and that was a bigger risk to me.

                  If we are talking modern lifestyle risk/benefit ratio of deficiency versus potential risk of supplementation.

                  The only group that showed toxicity was the one where the dose was so extremely high. I think it was like 100,000 versus the beneficial studies used 1,000.

                    1. Laughing.

                      I don’t mind watching and learning his opinions, but I find the way he debates to be stressful.

                      I don’t mind that he has a strong opinion. I just don’t like the way he debates.

                      Anyway, I am interested in the topic of Vitamin D. Finland lowering their Type 1 Diabetes rate after adding it to their products is interesting to me.

                      I would like to understand the mechanism for autoimmune.

                      I did find some charts that I have been looking at.


                    2. A question to anyone who knows how to figure out diseases by year.

                      Did any of the other autoimmune diseases improve when Finland did that?

                      Or did any other diseases show improvement?

                      I already know that I am not good at finding the real country disease numbers online.

                      But I want to hear about their disease rates the years after.

                      I would ask if America has results from the year after Vitamin D was added to our milk, but our eating got worse and worse and I don’t know if there might have been a few years before the eating got worse to see if anything got better where it might look related to that change.

                      I guess I would put which years were bad rickets years and look at other diseases those years or something like that.

      2. Gengo,

        When you say, “Get rid of fat” my internal response is that Dr. Lisle said that it is a very small percentage of people who succeed in getting rid of fat and keeping it off, even with WFPB.

        What I also know is that I have had insomnia for decades and that would be a case where my fat to lean ratio would skew toward fat even if I had only been deprived of 1 hour of sleep per night or something like that. Yes, it is a Dr. Greger video, but the specifics are less important than what do the obese people do. Do they skip taking D or take it?

        The percentage of overweight and obese people is growing every year worldwide now.

        Dr. Greger said that the Adventists were the only Blue Zone left, so Vitamin D supplementation isn’t in a vacuum separated from things like an obesity epidemic.

        I say it because Dr. Greger’s book How Not To Diet will be attracting in people who are overweight and need more Vitamin D and they will have to make decisions and the issue is complicated.

        1. Laughing.


          This year hasn’t been nearly as bad as last year.

          But it is still Winter and they say we are going to get weather whiplash this week.

          I don’t mind because the first few weeks of January were really nice.

          I actually did sit on a bench to try to get Vitamin D from the sun one day in January. Maybe for 3 minutes. That hasn’t happened almost at all in years, but it was a nice day and I had 3 minutes.

  2. My husband had periodic episodes of asthma throughout his adult life. After we switched to a plant-based whole foods diet, he stopped getting asthma attacks and hasn’t had one in 10 years now.

    1. That is fabulous Beverly.

      Did he also become more active?

      I am not asking that to put down WFPB. I am just curious.

      Sometimes people suddenly have more energy and less pain and take up things like cycling or other activities.

      Meaning, is he also getting more Vitamin D from the sun?

  3. Back to the Coronavirus (nothing to do with drinking too much Corona beer ‘-):

    “The ketogenic diet — which for people includes meat, fish, poultry, and non-starchy vegetables — activates a subset of T cells in the lungs not previously associated with the immune system’s response to influenza, enhancing mucus production from airway cells that can effectively trap the virus, the researchers report.

    They showed that mice fed a ketogenic diet and infected with the influenza virus had a higher survival rate than mice on a high-carb normal diet. Specifically, the researchers found that the ketogenic diet triggered the release of gamma delta T cells, immune system cells that produce mucus in the cell linings of the lung — while the high-carbohydrate diet did not.”
    But another study suggest keto diets should be of short duration:

    “A ketogenic diet — which provides 99% of calories from fat and only 1% from carbohydrates — produces health benefits in the short term, but negative effects after about a week, Yale researchers found in a study of mice.”

      1. Good link Deb.

        I especially liked the following passage from your link:

        “Some common dietary modifiers of gammadelta T cell numbers or activity are apple condensed tannins, dietary nucleotides, fatty acids, and dietary alkylamines. A recent clinical study demonstrated that ingesting a fruit and vegetable juice concentrate increased the number of circulating gammadelta T cells. Clinical studies also document that the oral consumption of a tea component, L-theanine, enhances gammadelta T cell proliferation and interferon-gamma secretion…”

        My take is that your link suggests how to create gammadelta T cells and my link shows how to utilize them.

        I think my plan of action, should the 2019-nCov virus reach epidemic proportions, will be to drink a lot of theanine-containing tea and go keto for short durations… well, after getting a viral pneumonia vaccination. ‘-)

        1. Sounds like you have a plan.

          For me, I got my hospital-grade air purifier, my silver ion infused cloths to wipe my hands, I will be getting a UV lamp and a commercial-grade steam-cleaner and I am eating WFPB.

          I am literally the only person where I work and in my family who didn’t get sick this year.

          Many of them got a few colds and the flu.

          I love my gadgets and my fruits and vegetables.

          I still haven’t figured out how to be both a coffee and tea drinker. I like them both, but when I start drinking one, I stay there until something eventually knocks me over to the other category.

          Right now, I am still a morning coffee drinker. My coworker lectures me if I try to drink a cup after 3 PM.

    1. I understand that having high cholesterol may be beneficial in the case of infections and trauma.

      Cholesterol is one of the building blocks of cells and when the body produces new killer cells to fight infections it uses the body’s cholesterol to construct them. Similarly when the body repairs damaged tissue and/or constructs new tissue, it uses cholesterol to synthesise that new tissue. That’s why when people get infections or suffer physical trauma (including surgery), their serum cholesterol levels usually decline. Having high serum cholesterol presumably allows the body to produce more killer cells and speeds wound healing.

      It is therefore plausible that diets that significantly increase serum cholesterol levels would be associated with increased survival from virulent infections and/or more rapid wound healing. Just as with giving certain toxic chemicals to cancer patients might improve survival, though, it doesn’t mean that such diets would benefit healthy people or increase long term survival rates.

      1. Tom, no offense and I am by no means throwing shade on your detailed explanation of how this may work. (I usually yearn to know how things work. ‘-)

        But in this case and suspecting there’s going to be a Pandemic designation before long, all
        I want to know from reputable sources is what may work in defending against this disease. (They are saying now that even if you survive it after coming down with it, that doesn’t necessarily protect you against re-infection.)

        I’m not in panic mode and am not trying to foment panic. I’m just trying to plan ahead and quite frankly do not care if the course of action I have outlined causes (your words) ” Just as with giving certain toxic chemicals to cancer patients might improve survival, though, it doesn’t mean that such diets would benefit healthy people or increase long term survival rates.”

        If this virus mutates and becomes as deadly as SARS, percentage-wise, I’ll drink coal oil if it is found to be effective at killing the virus.

        Funny story: A British guy living in China at the epi-centre of the 2019-nCov outbreak and an early patient, refused anti-biotics and drank hot toddies. That is, whiskey and honey. He got well and chose not to leave China when the British govt. was flying people out. Says he’s confident in the hot toddie treatment.

        1. No problem Lonie. I am always a bit doubtful about the relevance of mice studies to humans.
          However, I thought that in this case, cholesterol-raising diets might well be protective in humans too, for the reasons I outlined.

          You might also want to consider supplements like lysine and zinc, since both of these have been shown to inhibit viral replication. From personal experience, I have certainly seen lysine stopping cold sores/herpes simplex Zinc also appears to stop coronavirus replication


          1. You might also want to consider supplements like lysine and zinc, since both of these have been shown to inhibit viral replication. From personal experience, I have certainly seen lysine stopping cold sores/herpes simplex Zinc also appears to stop coronavirus replication
            Thanks Tom,

            Duly noted and adopted!

              1. Thanks Deb, but about a minute and a half in I knew that I was more up-to-date so I moved on to other things. I’ve found yahoo! is pretty good about furnishing up dates.

                But I do appreciate your intentions.

  4. What would you say is the ideal level for Vitamin D to be in children? I’m just thinking we wouldn’t want them to be taking supplements if they don’t need to?
    My daughter does have asthma, he levels are usually on the lower side of the range and she does supplement in winter.

    1. Hello Corrina,

      Consensus recommendations for vitamin D supplementation in children are 400IU/day 0-12months and 600IU/day 1-18years. As for what optimal levels are, it’s best to discuss with your pediatrician where in the reference range you should aim for.

      I hope this helps,
      Dr. Matt

  5. I think the doses of vitamin D that many people are taking in general are too low. Apparently, there was a miscalculation in the NIH’s vitamin D study. There is an excellent article about it here.

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