I am sure that most of us have wondered how we might be able to boost our immune defence in order to minimise the risk of catching the corona-virus. Many have asked, what role does nutrition play? There is, of course, a substantial amount of research on this topic, but are there any clinical trials at all? And if  such studies have been published, how rigorous are they?

Here is a brand-new paper that might answer these questions.

In this review, the authors aimed to evaluate evidence from clinical trials that studied nutrition-based interventions for viral diseases (with special emphasis on respiratory infections). Studies were considered eligible if they were controlled trials in humans, measuring immunological parameters, on viral and respiratory infections. Clinical trials on vitamins, minerals, nutraceuticals and probiotics were included.

A total 43 studies met the inclusion criteria:

  • vitamins: 13;
  • minerals: 8;
  • nutraceuticals: 18
  • probiotics: 4

Among vitamins, A and D showed a potential benefit, especially in deficient populations. Among trace elements, selenium and zinc have also shown favourable immune-modulatory effects in viral respiratory infections. Several nutraceuticals and probiotics may also have some role in enhancing immune functions. Micronutrients may be beneficial in nutritionally depleted elderly population.

There were 15 studies with a high score for methodological quality. Here is what their results showed:

  1. No significant difference in incidence of winter-time upper respiratory tract infection in children with high versus low dose vitamin D.
  2. Significantly less acute respiratory infections in elderly individuals with vitamin D versus placebo.
  3. Higher TGFbeta plasma level in response to influenza vaccination but no improved antibody response in elderly, vitamin D-deficient individuals with vitamin D versus placebo.
  4. No effect on lower respiratory tract infections; however, a protective effect was noted on upper respiratory tract infections in elderly individuals with vitamin E versus placebo.
  5. Neither daily multivitamin + mineral supplementation at physiological dose nor 200 mg of vitamin E showed a favourable effect on incidence and severity of acute respiratory tract infections in well-nourished, non- institutionalized elderly individuals.
  6. Better improvement in the clinical status, respiratory rate and oxygen saturation in children suffering from pneumonia with zinc sulphate versus placebo.
  7. Selenium-yeast increased Tctx-antibody-dependent cellular cytotoxicity cell counts in blood before flu vaccination + dose-dependent increase in T cell proliferation, IL-8 and IL-10 secretion after in vivo flu challenge in healthy volunteers.
  8. Frequency and duration of acute respiratory infections during the first two months was unaffected in healthy elderly with ginseng versus placebo.
  9. Broccoli sprout homogenate favourably affected immunological variables in healthy volunteers.
  10. The incidence of illness was not reduced, however significantly fewer symptoms were reported and the proliferation index of gd-T cells in culture was almost five times higher after 10 weeks of cranberry polyphenol supplements versus placebo.
  11. Higher antibody titres against all 3 strains contained in the seasonal influenza virus vaccine than the placebo in healthy elderly individuals with a sea-weed extract versus placebo.
  12. Non-inferiority was demonstrated for Echinacea compared to oseltamivir in early treatment of clinically diagnosed and virologically confirmed influenza virus infections.
  13. Significant reduction of cold duration and severity in air travellers with elderberry supplement versus placebo.
  14. Increased NK cell activity with probiotics versus placebo in tube-fed elderly patients.
  15. Titres against the influenza B strain increased significantly more with probiotics compared to placebo in healthy elderly individuals.

The authors concluded that nutrition principles based on these data could be useful in possible prevention and management of COVID-19.

Given the current concern of millions of people, this is a most useful review, in my view. The paper also has a table recommending the following nutrients from food or as dietary supplements as possibly effective:

  • Vitamin A
  • Vitamin D
  • Zinc
  • Selenium
  • Copper
  • Garlic
  • Fish
  • Cranberry
  • Broccoli sprouts
  • Probiotics

I am not sure that the evidence is sufficiently strong for such explicit advice, but I am quite certain that the recommendations are nevertheless more suitable than Trump’s little ramblings on disinfectant.

14 Responses to How can I stimulate my immune system? A systematic review of clinical trials

  • Edzard, you said “in order to minimise the risk of catching the corona-virus”. I need to correct you! No drug or nutrient or anything similar will reduce the risk of catching a virus. Everyone, healthy or not, is CAPABLE of catching a virus. This virus finds an easy route into the lungs and takes advantage of the vulnerable cells that form the lining of the lungs.
    It is then a matter of how our immune system responds to that invader.
    I assume you meant to say: in order to minimise the EFFECTS and severity of contracting the virus?

  • Ernst, dear fellow,

    Such sanguine advice regarding nutritional medicine! Are you feeling out of sorts? I do hope you get (even) better soon.

    I’m intrigued by the current downplaying of vitamin C (and by the rather strange presumably ‘knocking’ research I read about recently, involving 24mg daily IV doses, in China). It seems the star vitamin is more out of favour than usual, for some reason. Are you quite certain there is no ‘good’ research on it? Unarguably that seems to have been the FDA’s thinking in offering a monopoly status to some suitable company in return for ‘acceptable’ evidence on IV vitamin C – and reporting selectively on bad manufacture – whilst suggesting a ban on same. A stunt they pull from time to time. Perhaps money has something to do with it. “The best Science money can buy”, as I often say. Nevertheless I am surprised.

    Meanwhile, eliding a passing thought of some orthomolecular Pascal’s wager, this has me wondering if the Ernst household avails itself of such supplements? And whether one sticks to the official RDAs?

    I’m currently ignoring the advice not to exceed the stated dose on some fairly random “senior” combination horse pills. Between meals. And I have run out of zinc citrate.

  • It is refreshing that we are on the same page on certain subjects.

    I’m sorry that this review did not include a review of research on medicinal mushrooms. However, this website found the National Cancer Institute provided some significant encouragement to consider these medicinal mushrooms for PULMONARY DISEASE and CANCER.

    • Oh dear! I do worry when you think we are on the ‘same page’. Luckily, it does not take long to discover that, in fact, we are not.
      The paper you cite is mostly about non-clinical evidence. Specifically on clinical evidence, it provides nothing to show that medicinal mushrooms might effectively prevent or treat viral infections. Why? Probably there is no evidence!

  • Does this mean that Edzard will be launching a new supplement? Broccoli flavoured Vit A D E zinc selenium under the brand name ‘ Eddie’s Immunity.’
    Watch out for dastardly homeopaths diluting it down and flogging a potency of it.

  • Edzard, could you PLEASE explain to me your background? What jobs, positions have you held and what have you contributed to society? Have you ever even worked with patients or just ramble on your website? I’m serious, because if this website is it, wow… ALL I see is you constantly arguing with people and commenting back with exact opposite of what that person said… so in order for anyone to take you as a reputable source, you may want to engage in productive discussions with MAYBE the thought of learning something from someone else versus thinking you are the smartest man to ever live. Because from the discussions I’ve seen on here, you are 1. Not correct on everything. 2. All you do is bash and become defensive, which shows signs of someone who was deeply effected some how in their line of work and now feel inferior so have to be rude to make yourself feel better. 3. You need to seriously Learn how to engage in civil, productive conversations…. incredible….

    • you are incapable of finding info about my career?
      let me help you:
      1) read the wiki page about me
      2) study my memoir
      3) read any one of the posts on this blog that deal with my past
      in this case, have my CV:
      Edzard Ernst was born on 30 January 1948. He went to school in Germany and the US and studied psychology and medicine at the LM University in Munich. In 1977, he qualified as a physician in Germany where he also completed his MD and PhD theses.
      He was Professor in Physical Medicine and Rehabilitation (PMR) at Hannover Medical School (Germany) and Head of the PMR Department at the University of Vienna (Austria). He came to the University of Exeter in 1993 to establish the world’s first Chair in complementary medicine. In 1999, he took British nationality. Since 2012, he is Emeritus Professor at the University of Exeter and now lives in Cambridge, UK as well as in Britany, France.
      Professor Ernst is/was founder/Editor-in-Chief of three medical journals (‘Focus on Alternative and Complementary Therapies’, ‘European Journal of Physical medicine and Rehabilitation’ and ‘Perfusion’). He has been a columnist for many publications (BMJ, GP, PJ, The Guardian, The Independent, The Spectator, etc.). His work has been awarded with 17 scientific awards (most recent: John Maddox Prize 2015 and Ockham Award 2017) and two Visiting Professorships (Canada and USA). He served on the ‘Medicines Commission’ of the British ‘Medicines and Healthcare Products Regulatory Agency’ (1994 – 2005).
      According to Ioannidis et al (2019 PLOS Biology) standardized citation metrics, he is currently ranked No104 amongst 100 000 scientists of all disciplines and No1 amongst all researchers in the category of ‘Complementary & Alternative Medicine’. He as published >1000 papers in the peer-reviewed medical literature (H-Index=97 [2017]), 53 books, translated into over a dozen languages (most recent: Alternative medicine, a critical assessment of 150 modalities, Springer 2019), >100 book-chapters. In 2019, the ‘book authority’ included ‘Trick or Treatment’ (book authored by Simon Singh and Edzard Ernst) in the list of ‘best mental health books of all time’. Prof Ernst has given > 700 invited lectures worldwide and supervised >50 MD and PhD theses.

    • @Mark

      Saw this kick in the shorts delivered by Edzard coming from a mile away.

      Mark, did you not have the presence of mind to read the “About” section of the website before asking this silly question? It is THE MOST BASIC research one could do.

    • There’s a useful website, if you’ve never heard, that is called: GOOGLE. How come you ended up here on this blog if you have no idea about Prof. Ernst anyway? It is so ironic that a professor who has spent his life trying to raise awareness about the possible harms of CAM, also gets on target when he posts scientific information that says some vitamins or plants could be beneficial for the prevention of some diseases, within his expertise 100% for sure, but yeah it’s “positive” so it shouldn’t be here. Open your eyes, people. Science is science. Have some respect.

  • Many thanks Edzard. Very useful advice for anyone who wants to at least try to rationally reduce their risk of having a severe Covid-19 infection experience with an aim to have a less symptomatic experience if they do contract it. The clinical trials evidence review is most useful.

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