Dear Mark: Coronavirus Edition 2 – COVID-19 Questions, Answered

For today’s edition of Dear Mark, I’m answering more COVID-19 (coronavirus) questions. If you’re getting tired of coronavirus content, I understand, but I also owe it to my readers to give them my take on the research—and the questions have been pouring in. Information is coming out at a rapid pace and there are a lot of wild claims and recommendations flying around. With any luck, we’ll all be able to focus on something else in the near future. Thanks for your understanding.

Let’s go:

Is the fever threshold higher in hypothyroid?

I work in the health care field and need to be at work but also must remain healthy. I take my temperature often. There are still no cases reported in my county. Over the years I randomly have taken my temp. It is always low…ranging from 95.5 to rarely over 97. If my temp suddenly approached 98 or over would I be considered to possibly have a fever?

That is a great question. I’ve actually wondered the same thing.

We know that mice with hypothyroidism have delayed “sickness behavior” when challenged with an immune stimulus (in this case, endotoxin).1 Whereas normal mice with healthy thyroid function display normal reactions and symptoms to the endotoxin, the hypothyroid mice take much longer to show symptoms and change their behavior. That study doesn’t say anything about body temperature or fever, but I can imagine that if other sickness behaviors and symptoms are inhibited, fever might be as well.

Experts say 70-80% of your immune system is in your gut.2 Instantly download your free guide to a healthy gut.

Does asthma increase the risk of coronavirus?

So what’s a 62 yo with asthma as general anxiety to do? Gotten lots of sleepless nights. BTW, my wife is a GP and will be continuing to work, oh…and I’m going to be taking care of my autistic teenage daughter.

That’s a lot to handle. Hats off to you.

There (may) be good news. Asthma does not seem to increase the risk of coronavirus severity. In an early study out of Wuhan, China, neither asthma nor other allergic diseases were risk factors for it. Meanwhile, metabolic diseases and conditions were.3

This is a preliminary result using a small sample size (140 patients). So it may change.

Can colostrum help against coronavirus? How can you increase nitric oxide?

Mark, thank for the usual thoughtful post. Is there any usefulness in taking supplementing with colostrum at this time? Also, aside from exercise are there other ways to increase nitric oxide?
thanks again

I don’t think colostrum will be much help. It can help with leaky gut,4 but I haven’t seen anything about that being linked to coronavirus.

As for nitric oxide, which has shown efficacy against SARS5 (a related virus), there are other ways to increase it. My favorite way is to get sunlight. Even in the absence of vitamin D-giving UVB, sunlight increases nitric oxide synthesis.

Does melatonin help against coronavirus?

Children have up to 10x more melatonin than adults. Melatonin inhibits the NLRP3 inflammasome protein from inciting cytokine storms. Coincidence?

That’s very possible. Melatonin (and circadian rhythm) has its mitts in just about every physiological function of which we’re aware, including innate immunity, so I could see disrupted sleep and poor melatonin status helping. I don’t know this means you should start megadosing melatonin, of course, but it does suggest you should—as always—practice proper sleep hygiene.

Of course, there is no “one factor.” There are probably dozens of factors that predispose a person or a population or a region to coronavirus susceptibility.

Does iron help against coronavirus?

I would encourage any women who are anaemic to remedy that immediately.
Increasing iron increases haemoglobin and the oxygen-carrying ability in your blood.
COVID patients get interstitial pneumonia and require oxygen!

There is an interesting (and awful) connection to iron. Check out this paper:

The coronavirus produces these “extra” helper proteins that aren’t even part of the virus itself. It sends the proteins out into the blood to attach to our red blood cells and remove the heme iron. This reduces the ability of our RBCs to deliver oxygen to the rest of our body, so even if you’re on a ventilator and having fresh oxygen pumped into you, your ability to utilize that oxygen and deliver it via RBCs is reduced.

This is probably why coronavirus patients are often presenting with elevated ferritin levels: the iron is removed from the RBCs and has to be stored as ferritin.

I’m not in a position to say if eating more heme iron can help overcome the virus’ tendency to remove it from your red blood cells. I can imagine that early intervention with anti-virals or perhaps chloroquine could help before the virus gets really embedded. I can imagine that fresh blood transfusions could help.

Can coconut oil kill coronavirus?

Also, coronavirus is one of 14 RNA and DNA viruses whose envelopes are lipid coated. It’s been shown that monolaurin (extracted from lauric acid from coconut oil) dissolves these envelopes and the virus loses its protective envelope and dies.

Dietary coconut oil will not kill coronavirus (unless, perhaps, you slathered it in the stuff directly). Monolaurin has proven effective mainly in in vitro studies using isolated cells and viruses. Applying monolaurin directly to coronavirus in a lab setting probably will have an effect. There was a study where they applied vaginal monolaurin in female macaques prior to HIV exposure (a simulation of how infection occurs), and it was effective at preventing infection.6 But that was direct topical contact. Eating coconut oil or even taking monolaurin supplements probably won’t.

That’s not to say you shouldn’t eat coconut oil. It’s a great fat to eat and cook with, and doing so will probably improve your metabolic health and reduce the tendency of your tissues to oxidize and improve the resilience and function of your mitochondria—all of which will improve your general health and innate immunity. But it’s not a magic bullet and I don’t think the monolaurin has much to do with it.

Are asymptomatic people contagious?

Do aymptomatic people and especially children continue to shed indefinitely or does their body take care of the virus?

I don’t think we know for sure. I’ve seen references to viral shedding that lasts for weeks. We know that nasal swabs of both asymptomatic and symptomatic people show similar levels of viral loads,7 so the potential for transmission exists regardless of symptoms.

Asymptomatic people will probably be coughing and sneezing less, so that should reduce the amount of viral particles they release. But they’ll also be unaware of their condition, so they may be more likely to mingle with people and less likely to self-isolate. That will increase the number of people they’re exposed to.

This is where universal mask use can really help.

Does NAC help against coronavirus?

What about N-acetyl-cysteine?

NAC is worth a try. I don’t see any indication that it will reduce the chance of infection, but if you are infected and progress to ARDS (acute respiratory distress syndrome), it shows promise in protecting your lungs from damage.8

The reason I’m hopeful about NAC for COVID-19 is because it helps your body make glutathione, your body’s most important antioxidant. Research says that glutathione deficiency is most likely “the most likely cause” of serious symptoms and death from COVID-19.9 NAC is the raw material that your body uses to make glutathione.

Glutathione prevents cellular damage and aging in so many contexts, not just coronavirus. That’s why I included NAC in Master Formula and Damage Control when I developed them. I’ve been taking Master Formula every day for years, so I expect my glutathione reserves are built up enough, should I, you know, need it.

NAC isn’t the only factor here. A major part of this is nutrition. For instance, a previous paper in elderly folks homes found that just giving each person 8 grams of high quality amino acids lowered the infection rate—not of this latest coronavirus, but in general.10

Does sauna kill coronavirus?

Mark, do you think it worth using a sauna every day, ie would that keep the virus from taking hold if one was exposed?
20 minutes above 135f, for example.

Saunas won’t hurt. They’ve been linked to improved resistance to colds and a reduction in the incidence of pneumonia. All good things.

The only angle I can think of for this in an acute sense is that the virus is sensitive to heat. If you’ve only just been exposed to the virus and it’s hanging out in the throat and nose, perhaps breathing in hot air from the sauna may reduce its activity.

According to a new study (pre-print only), the coronavirus initially infects the throat and nasal passage before eventually replicating enough to make it to the lungs. If that’s true, and you can breathe in enough 135 degree sauna air through both nose and mouth, you may be able to reduce the activity of the virus.

That’s very speculative, however, and there are many reasons to think it’s probably not enough.

  1. By the time the air gets into your throat and nose, it’s already cooled off.
  2. The heat exposure isn’t consistent. Breathing in means a second or two of sufficient heat exposure (assuming the air remains hot enough). Then you’re breathing cooler air out. Then you breathe in again. You’re not holding the temperature at a consistent 135 degrees for the 15 minutes it takes to really reduce activity.
  3. The original SARS coronavirus from the 2000s is sensitive to 135 degrees. We don’t know for sure if this latest one has the same sensitivity.

Another reason to be suspicious of relying on the sauna is that getting to the sauna will mean possible exposure, particularly if you’re in an area with high infection rates. If you have one at your house, then have at it! I don’t see it hurting and it could help your overall health.

Does healthy eating prevent coronavirus?

Mark, I’m surprised that you didn’t come right out and suggest the Primal Blueprint as an effective way to fight co-morbidities that are responsible for 99% of covid-19 deaths. In the end, isn’t it all about our metabolic health?

Yes, metabolic health seems to play a huge role in how patients are handling COVID-19. That is, many of the hardest hit people appear to have metabolic co-morbidities like heart disease, diabetes, and hypertension. For example, in Italy And in China, patients with one or more co-morbidities were more likely to progress to severe symptoms.11

There’s a study just out in kids showing that a fairly healthy “immune-boosting” (their words) diet consisting of green vegetables, beef, and dairy (whole milk, butter on bread) reduced the incidence of upper respiratory tract infections.12 Again, this wasn’t COVID-19, but it suggests that diet plays a role in immune health and resistance to infectious disease.

We also know that the really severe consequences seem to operate via pro-inflammatory cytokine storms, specifically IL-6 and IL-1B.13 The balance between inflammatory and anti-inflammatory cytokines rests largely upon the omega-3:omega-6 balance of our tissues, so I think there’s probably a role for improving that O3/O6 ratio in our diets. I’d be curious to see the breakdown of tissue or red blood cell O3/O6 ratio in coronavirus patients and outcomes.

That said, it’s upon us. I don’t want people cutting out grains and eating more meat and thinking they’re all of a sudden immune to the disease. This is something you should be doing as a lifestyle from the very beginning. This is something you should be preparing for, for life. Diet matters in the short term, but it’s most important taken as a long game.

That’s it for today, folks. I’ll definitely be revisiting this topic, as new information is coming out every day. One thing I’m still pondering and researching is the vitamin D issue. Does it increase ACE2 expression and does this result in an increase in susceptibility? Or can it help?

If you have any other questions, ask away.


Silva VC, Giusti-paiva A. Sickness behavior is delayed in hypothyroid mice. Brain Behav Immun. 2015;45:109-17.
Zhang JJ, Dong X, Cao YY, et al. Clinical characteristics of 140 patients infected with SARS-CoV-2 in Wuhan, China. Allergy. 2020;
Anderson RC, Dalziel JE, Haggarty NW, Dunstan KE, Gopal PK, Roy NC. Short communication: Processed bovine colostrum milk protein concentrate increases epithelial barrier integrity of Caco-2 cell layers. J Dairy Sci. 2019;102(12):10772-10778.
Haase AT, Rakasz E, Schultz-darken N, et al. Glycerol Monolaurate Microbicide Protection against Repeat High-Dose SIV Vaginal Challenge. PLoS ONE. 2015;10(6):e0129465.
Zhang Y, Ding S, Li C, Wang Y, Chen Z, Wang Z. Effects of N-acetylcysteine treatment in acute respiratory distress syndrome: A meta-analysis. Exp Ther Med. 2017;14(4):2863-2868.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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26 thoughts on “Dear Mark: Coronavirus Edition 2 – COVID-19 Questions, Answered”

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  1. fwiw, nose breathing, certainly, but also humming, greatly increase nitric oxide. It can be part of a meditation practice. There’s a yoga practice called brahmari pranayam which is similar.

  2. Good stuff Mark, much appreciated, as always you are a valuable source of well-reasoned, research-backed information.

  3. Good information. Thanks for doing articles like this. Right now, with so much fear in the news, it truly helps to have calm, collected posts that just talk about the current science with this thing.

    A funny aside, my kids are currently in the kitchen eating grassfed beef burgers and spinach from local farms, and rice covered in butter. I got a kick out of reading that at the same time this was going on in my house.

  4. Hi
    In the UK, C19 symptoms have been formally prescribed as dry cough + fever. However, interweb increasingly reports cases with nil symptoms, or classic runny nose & & sore throat. I’ve had the latter for some weeks now, and becoming worried that I’ve been afflicted. Thanks 99 % to MDA, I’ve been paleo for +2 years, and supp with resvertrol turmeric NAC etc for anti oxy/infamm support. In a suspect case such as mine, is it better to lay off the anti inflam to help let the body do its defensive thing? Worry is that in bad cases, the C19 seems to cause an extreme immune response – -> fatality.
    Dilemma = drop anti inflamms to boost body’s initial defence, or increase anti inflamms to help if the disease takes hold.
    Appreciate any wise words you can offer.

  5. I’m keen on hearing your thoughts on vitamin D Mark as soon as possible after your previous post and worries over ACE 2 expression. Just read a paper on this in JAHA (Guo et al) as well as others. From what I’ve read you really want ACE 2 expression to protect your lungs and other organs from damage. Sure, ACE 2 receptors are how the virus infects you but it’s still going to infect you whether you try and down-regulate ACE 2 or not I would imagine. Once you’re infected it looks like you want all the ACE 2 expression possible to help prevent the devastating damage to lungs and other organs by activation of the Renin-angiotensin system. In fact I did see a note in the BMJ (Bahat) that the virus causes down-regulation of ACE 2.

  6. Hi Mark,
    When available, will you get a COVID-19 vaccination? I have never had a flu shot and have not had the flu for 21 years now. I rely on clean diet, moderate exercise and making sleep a priority. Personally I don’t trust flu shots but COVID-19 seems pretty vicious and I’m not sure even good health habits will protect me. What are your thoughts on this?


    1. I’m in the same boat and would also like Mark’s thoughts on this. The only 2 years in the last 14 that I had the flu were the only 2 years I had a flu shot. I don’t seem to have a problem with other vaccinations but when I got a flu shot annually 1994-2003 I had the flu 2-4 times a year every year – so you see my concern!

  7. I read your newsletters on a regular basis. I like the content you bring. But in this case, you have committed a major faux pas. Since you’re not an expert in epidemiology or virology, giving out advice with merely anecdotal opinion and primary research to back you up is irresponsible – if not potentially dangerous. You MUST preface your opinion with a clear disclaimer…especially in giving advice re COVID-19 treatment options.

    Rant over. Other than the above…

    Keep up the good work 🙂

    1. Mark has addressed this in the past (although years ago). This is a blog where he is giving his opinion on health matters, not the end all of knowledge on any topic and he is not claiming any of that in writing blog posts. And of course people are welcome to give feedback in the comments. So I don’t feel a disclaimer is needed, besides, NOBODY is an expert in COVID19, even the virologists and epidemioloigsts right? (just look at the WHO advice and comments over the last two months, all over the place)

  8. Very helpful as always. On the subject or melatonin dr dadamo has been running a series of articles on the epidemic. In particular he has weighed in on melatonin. See the banner atop his front page at Note some of the pieces are super sciency.

  9. Mark, what about the benefits of Quercetin and zinc supplementation to combat Covid-19? There has been little known promising literature about this…

  10. Mark — good stuff. In regards to Vitamin D … I’d suggest looking at the work from Chris Masterjohn – who was all over this several weeks ago.
    Interestingly, while most suggest increasing Vit D to up to 10,000 units — Masterjohn is hesitant (keep at 2,000 -3,000 levels) as may increase ACE2 receptor accessibility.
    Keep it up

  11. Hi Mark,

    Great Post. Thanks.

    I have been breathing in boiled filtered water (1/2 to 3/4 of a 4 1/2 qt. dutch oven) with one capful of Alkalol for 15 minutes, with thick towel over the pot, my head and neck, once daily. I breathe deeply, getting the steam to the top of my throat via my nose and separately by mouth breathing. I know this is thinning my residual mucous from allergies and “dormant” EBV (now almost gone due to a homeopathic protocol) and making me feel better in general.

    QUESTION: Would this possibly also kill or at least injure any coronavirus I might have breathed in? Or would that be too good to be true? Obviously the breathing out issue you mentioned about sauna usage applies here; however, the temp of my steam is, at least at the beginning approx. 212 deg. F and my nose is right on the steam source.

    Yes, I am wearing a mask at all times outside of my house/yard. Thanks for your opinion Mark!. I don’t need any disclaimer, I’m just asking a simple opinion of one who is probably more widely read on this subject than I and one who has access to experts, which I do not have.

    Source Healthy, Cook Healthy, Eat Healthy to Work on Staying Healthy!

  12. As always, Mark is very careful about what he writes. I don’t see how your recommendation would be helpful at all.

    1. Hi Harry,

      Is your post referring to my post or Andrew B’s post about Mark needing to preface his opinions with a clear disclaimer?

      If you are referring to mine, I re-read my post…I don’t see how it could be interpreted to be a recommendation. In case my post was interpreted to be a recommendation, I want to make it clear that I was merely describing what I do and asking a question about it. A description is not a recommendation!!!! Since we are told the virus seems to be killed by heat, and it is in the throat before going further into the respiratory system, I just wondered if breathing steam approx. 212 deg. F for about 15 minutes might kill it before it went any farther into a person’s respiratory system.

      I just want to make sure all readers know I am not making any recommendation. I am not qualified and would never do so!

      Everyone have a good day and stay healthy!

  13. There’s data being published about using Ozone against COVID-19, in and elsewhere.

    Drinking ozonated water will up your nitric oxide per the literature.

  14. Mark, can we do a readership survey or volunteer for a formal study, that out of say, 10,000 paleo/keto folks, no one got sick? (I’m being optimistic here)

    Or a study that will reverse those red meat/cardiac arrest/fat studies? Let’s get a volunteer page, sign up and start gathering stats!

    1. If people are volunteering for a survey, the results are going to be grossly inaccurate, because people only volunteer for things if they are passionate about something one way or the other. If your sample is taken solely from readers of this blog, we are assuming that they are healthy enough to take the survey (not dead or struggling to breathe in the ICU), so of course the results would be in favor of Primal lifestyle to eradicate covid-19.

  15. Great questions and answers. I believe most of these remedies that were mentioned (NAC, sauna, nitric oxide) will help boost the immune system and help fight or protect against the virus. I was also wondering about megadosing vitamin C. I know many people, including health experts, believe that high doses of vitamin C can help fight the virus. Do you think megadosing Vit C is effective? If so, is liposomal vitamin C the best kind?

  16. In your first COVID-19 Q&A, you talked about ACE 2 receptors being the doorway into cells for the virus, and how the lungs are rich in these, and you mentioned the role of Vitamin D in that. Are you still avoiding your Vitamin D supplements?

  17. Hi Mark,
    In regards to iron, I would think that the reason for an increase in ferritin is more likely due to the fact that ferritin is an acute phase reactant, which means it increases in inflammatory states, than with release of heme iron from red blood cells. I also think transfusion for the purpose of an iron deficiency anemia would do more harm than good. Blood transfusion are not without risk, and do not treat the underlying cause of the iron deficiency. I recommend checking out Choosing Wisely guidelines for hematology and transfusion medicine (I’m from Canada but I think most countries have similar recommendations)

    1. I’ve commented before about Mark saying bizarre things about ferritin. He completely disappoints once he gets anywhere remotely into Medical topics, sounding like my patients who reference Dr. Google and have no handle on basic human physiology/pathology concepts.

      Also, Mark, don’t quote people, without correction, that say “co-morbidities… are responsible for 99% of covid-19 deaths”. Um, WHAT? What about my healthy 90 year old that died? Is being 90 “morbid”, and is the Primal Blueprint the cure?

      You continue to lose all credibility, which is disappointing, as I used to use your site to find useful references.