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vitamin D and melatonin, and how they may help with COVID-19.


In the video featured - Dr. Mobeen Syed interviews Dr. Paul Marik, MD, about vitamin D and melatonin, and how they may help with COVID-19. 

Dr. Marik is currently Professor of Medicine and Chief of Pulmonary and Critical Care Medicine at Eastern Virginia Medical School in Norfolk, Virginia, and is board certified in Internal Medicine, Critical Care Medicine, Neurocritical Care and Nutrition Science. Dr. Marik is the 2nd most published critical care physician in the world, having written over 500 peer-reviewed journal articles, 80 book chapters, and four critical care books; he has already co-authored 10 papers on therapeutic aspects of COVID-19. He has been cited over 43,000 times in peer-reviewed publications and has delivered over 350 lectures at international conferences and visiting professorships. Dr. Marik has received numerous teaching awards, including the National Teacher of the Year award by the American College of Physicians in 2017.  Dr. Marik is also a founding physician of the Front Line COVID-19 Critical Care Alliance, which began in March 2020 to develop treatment protocols to help prevent the transmission of COVID-19 and improve outcomes for patients ill with the disease. Among the therapeutics included in these protocols is vitamin D!

As Dr. Marik states in the video below, "it remains mysterious to me why we do not promote the widespread use of vitamin D - it is safe and it appears to be very effective for both preventing and treating SARS-CoV-2.”

Building on what Sandy posted:

The single most important step you can take to protect yourself from Covid (and other respiratory virus') is verify your vitamin D level and supplement accordingly to raise it above 55 ng/ml.

Having low vitamin D will render the Covid vaccines practically useless because it is vitamin D which activates and then  "tames" your immune response to Covid. All Covid vaccines do is 'tell' your immune system what to attack. The vaccines themselves do not attack the virus - only your immune system can do that. And it is vitamin D which ramps up the process.

Putative Role of Vitamin D for COVID-19 Vaccination-
August 27, 2021


Severe acute respiratory syndrome coronavirus 2 is a new, highly pathogenic virus that has recently elicited a global pandemic called the 2019 coronavirus disease (COVID-19). COVID-19 is characterized by significant immune dysfunction, which is caused by strong but unregulated innate immunity with depressed adaptive immunity. Reduced and delayed responses to interferons (IFN-I/IFN-III) can increase the synthesis of proinflammatory cytokines and extensive immune cell infiltration into the airways, leading to pulmonary disease. The development of effective treatments for severe COVID-19 patients relies on our knowledge of the pathophysiological components of this imbalanced innate immune response. Strategies to address innate response factors will be essential. Significant efforts are currently underway to develop vaccines against SARS-CoV-2. COVID-19 vaccines, such as inactivated DNA, mRNA, and protein subunit vaccines, have already been applied in clinical use. Various vaccines display different levels of effectiveness, and it is important to continue to optimize and update their composition in order to increase their effectiveness. However, due to the continuous emergence of variant viruses, improving the immunity of the general public may also increase the effectiveness of the vaccines. Many observational studies have demonstrated that serum levels of vitamin D are inversely correlated with the incidence or severity of COVID-19. Extensive evidence has shown that vitamin D supplementation could be vital in mitigating the progression of COVID-19 to reduce its severity. Vitamin D defends against SARS-CoV-2 through a complex mechanism through interactions between the modulation of innate and adaptive immune reactions, ACE2 expression, and inhibition of the renin-angiotensin system (RAS). However, it remains unclear whether Vit-D also plays an important role in the effectiveness of different COVID-19 vaccines. Based on analysis of the molecular mechanism involved, we speculated that vit-D, via various immune signaling pathways, plays a complementary role in the development of vaccine efficacy.


Regarding Melatonin in UK after 1995 or thereabouts health food shops were not permitted to sell it as it was deemed to be a medicine;now it is only available on prescription.What is confusing is to track down what conditions  for which Melatonin might be used -normally it seems it is used to treat sleep disorders but the FDA advice in USA is not clear.Has anyone in UK been prescribed this for a specific condition I wonder?

Using it as a propylactic for Covid would mean having to use it off label and medical practitioners might for insurance reasons baulk at this .When I see my specialist next who is  a private practitioner  I will ask if he will give a private prescription.

I suspect that it is available online without a prescription from a number of countries overseas such as Hong Kong,Singapore and Thailand for instance.I used to take it to minimise jet lag but cant remember if it  had any benefit or not.I still have some but perhaps it is out of date though.The side effects apparently are sleepiness next morning and it should not be combined with some blood pressure medications I believe.



I did not realize you now need a prescription for melatonin. I just took 3 mg on my flights to the U.K. (pre-covid) and it did wonders! Jet lag over in one day instead of 3. Made pub crawls much easier.

I miss pub crawls.

I miss pubs.

Great stuff, melatonin!

Hi Scuba

I have just looked on the Amazon site for UK and it only offers a substitute of natural sources of melatonin of magnessium and other minerals but not melatonin as such.If I go into the Amazon US site then it is available as the real melatonin but the shipping costs to UK are steep about 40$ for a container of 100 tablets making a total cost to me of say 70$.

The video seemed to offer good evidence of the good effect of using melatonin as a prophylactic for Covid though.



Hi John, melatonin is available by prescription in the UK as you have already said. This does not mean you should be wary of taking it. See this link...

You can find a way around this as melatonin is made in the body so has precursors such as Tryptophan - which you can get over the counter. or you can buy 5mg melatonin here


Hi John,

Get and keep your vitamin D level above 55 ng/ml along with vitamin C, zinc and magnesium and Covid won't be an issue. It really is as simple as that.

Even if one gets a Covid vaccine, vitamin D is still needed to activate T-cells in response to Covid exposure. I would be guessing, but I suspect many of the breakthrough Covid cases in vaccinated people are likely due to their having low vitamin D.

The correlation between low vitamin D and potential severe Covid is just too strong to ignore. Likewise, no one - not one data point I could find - shows severe Covid occuring in individuals with vitamin D > 55 ng/ml. None. That's good enough for me.

As for Melatonin - best used for sleep! (or time zone adjustment due to jet lag)

Hi Scuba, would it be of concern on taking vitamin D without K2 as my wife is also taking warfarin (vitamin k antagonist) and her doctor advised it against vka and K2 interaction, but not against vka and vitamin D? Thanks

You can absolutely take vitamin D without K2, but just need to be aware of dose and D base level. Vitamin K2 is a sort of safety valve for D. Take in too much D and the k2 helps mop it up. I did learn I needed more vitamin D3 supplementation once I started K2. As long as she tests once or twice a year and supplement D3 accordingly, she will be fine. Also, as Sandy has pointed out through the articles she cited, it really is hard to overdose on D if daily intake does not exceed 10,000 IU's. And this is without K2 considerations.

There is scientific debate on how much vitamin K2 and warfarin (vka) interact. Vitamin K2 is part of the vitamin K family,  but vitamin K1 has a markedly known interaction with warfarin. If her doctor truly understands the differences biochemically between K1 and K2, it might be beneficial for her to have some K2 in order to help with any bone issues (osteoporosis).

Thanks Scuba, her vitamin D is in its 40s, she really tests twice a year and supplement with 12.000 IU weekly. Our concern was related to an eventual complication in her chronic portal vein thrombosis (derived from JAK2 mutation/diagnosis of MPN) for the use of the vitamin D alone. And, yes we questioned her doctor and she seems aware of the differentiation between K1 and K2 mechanism. In some moment in the future we hope to exchange warfarin for Apixaban/DOAC - which would allow her to eat food with vitamin K source, but the use of DOAC for her case (thrombosis in unusual site as SVT and PVT) seems to be off-label yet. I also have similar levels of vitamin D and supplement it in the same way hers. Again, really appreciate your time and thoughts.

If you are going to take 12,000 IU's weekly, best to spread it out during the week (2,000 IU's per day) rather than taking at one time on one day. Any level much above 10,000 per day is not natural for the body.

Her vitamin D level in the 40's is fine, but likely won't prevent Covid or help much with CML either. It's too low. In her place, I would have no problem whatsoever doubling or tripling the vitamin D dose to 6,000 IU's per day to get the protection vitamin D confers.

Dr. Fauci, by the way, takes 6,000 IU's per day vitamin D3 (42,000 IU's per week). It's sad he doesn't shout this out from his perch as so-called expert (

As long as blood vitamin D levels are less than 100 ng/ml, risk of excess calcium is zero. In fact, vitamin D levels < 200 ng/ml, risk of hypercalcemia is still near zero. It really is hard to overdose on vitamin D if you keep vitamin D intake to no greater than 10,000 IU's per day. And this is without consideration of vitamin K2. Adding vitamin K2 to the mix and hypercalcemia is just not going to happen without extraordinary amounts of vitamin D ingested (i.e. rat poison).

(I would still ask her doctor what does  "seems aware of difference between k1 and k2 is not the same as knowing" mean?).

Vitamin K2 and D3 work together:

It's best to take both together (together = daily, not necessarily at the same time together).