Vitamin D Supplementation Guide - for those (most of us) who are likely to get COVID-19 before too long - and especially for those who are aged, overweight, obese, or suffering other conditions which create high risks of serious symptoms, harm and death.

The best research indicates that we should aim for higher vitamin D levels - and so take greater amounts of supplemental vitamin D - than is recommended by most government health authorities.

2021-01-31: Please see an important update regarding mutations in the SARS-CoV-2 viruses which cause COVID-19. 

The British variant is more transmissible.  The separately evolved, but otherwise identical, South African and Brazilian strain are more transmissible still.  There's no reason to believe they are less harmful, and some reasons to believe they are at least as harmful or more.

Researchers in Israel and France ran experiments with yeast (not viruses) to evolve, in an accelerated manner, the likely mutations which would give rise to more transmissible variants of SARS-CoV-2, due to the variations in the spike protein's Receptor Binding Domain having a greater affinity for the ACE-2 receptor.  Their experiments evolved mutations including the same three which cause the South African /  Brazilian strain to be much more transmissible.   Their experiments also discovered other mutations which would make still more transmissible variants of SARS-CoV-2, but which have not yet evolved in the virus.   The British strain has 3.5 times the RBD affinity for ACE-2 of the strains common in mid-2020.  The South African / Brazilian strain has 12.7 times this affinity.  Their experiments found multiple combinations of mutations, including one which conferred an approximately 640 times the affinity of mid-2020 strains.

It is reasonable to expect that the viruses, in the wild, in the months and years to come, will evolve to embody at least some, and perhaps all, of the mutations this team discovered - and there may be other mutations as well which increase transmissibility.

Therefore, we cannot assume that the strains which affected most countries in the middle of 2020 will be the ones we have to contend with now, in early 2021, much less later in the year and in the future.

These mutations tend to make immunity from prior infections or vaccines against older strains less effective, so reinfection with new strains seems possible and likely.

Perhaps future strains with very high RBD affinity for ACE-2 will render any vaccine-induced immunity, and perhaps infection induced immunity, much less able to prevent infection, or to reduce the extent of an infection once it starts.   If so, then vaccines, social distancing, masks, lockdowns etc. will be even less effective than they are today. 

Since population-wide, year-in year-out, antiviral drugs are impractical and undesirable, then the only option would be to do what I and others have been suggesting since March 2020: population-wide substantial supplementation with vitamin D3 and ideally other nutrients to boost strong initial immune responses to the infection and, most importantly, to reduce, as much as possible, the common tendency for the dysregulated, hyper-inflammatory, self-destructive immune responses which cause some people to have severe COVID-19 symptoms.

I worked unsustainably on these websites from March to December 2020.  I will try to update them with the very most significant research, such as just mentioned - but in general I need to get back to my work with electronic musical instruments.

Robin Whittle .   2020-08-02  Last update 2020-08-08 15:00 UTC

2020-11-19 update: Please see a later page where I suggest D3 supplemental intake quantities as a ratio of bodyweight:

and these two sections of where I suggest a combination of 25OHD calcifediol and bolus D3 for urgent treatment of people with severe or potentially severe COVID-19 symptoms, flu or sepsis:

To the main COVID-19 page of this site:, concerning nutritional supplements - especially vitamin D - for all adults and some children ASAP, so their immune system firstly fight the SARS-CoV-2 virus well, and secondly, if the infection gets to the lungs, will not respond with a dysregulated, overly-inflammatory way which causes the serious harm and risk of death.

The updates/ page lists all the significant updates to these cv19 pages.

Links such as [W] are to the relevant Wikipedia page.  Links such as [DW] are to Henry Lahore's remarkable Vitamin D Wiki.

Be sure to read the Disclaimer!  I am not a doctor, and even if I was, I have not examined you.  Doctors can bring vast experience and knowledge to bear on your particular situation.  It is a very high level skill of immense potential value to you.  However many doctors don't know as much as they should about nutrition - for reasons I discuss below.

A few key points before all the details

How much vitamin D should I take?  COVID-19  Immune system health, Cytokine storm, sepsis, ICU optimal vitamin D intake,  4000IU, vitamin D blood levels, vitamin D dose recommendations

The purpose of this page is to help you or your doctor decide, by reference to the best research, how to improve your general health - and especially your immune system health - with vitamin D supplements.  Before getting to the detailed material, here are a few important points - all of which are explained further below or on the main cv19 page and those which branch from it.

Vitamin D, Immune System Health and COVID-19

You are reading a web page.

I am writing to you as if I am speaking to you, about your health - which I am genuinely concerned about, even though I don't know you.  I am doing this in an effort to make this information easy to understand, and to impress upon you the importance of getting it right.

I know more about vitamin D, nutrition and the immune system than the average bear, but I am not a doctor.  I am an electronic technician and computer programmer.

Ideally you would have a doctor who was up to speed with the latest research, and able to advise you freely about all aspects of healthcare.  Below I discuss the reasons why this may not be the case.  The ideal of a fully informed doctor, examining you and providing personalised medical advice, is not attainable for many people.  

The purpose of this and the other pages here ../is to help you understand more about nutrition, read the best research and make up your own mind on how to proceed.  Perhaps you will feel confident making your own decisions.  Perhaps you will discuss it with other people - and ideally your doctor.  Then, this and the other pages may be an easy way he or she can find the latest research, rather than relying on outdated government guidelines.

There's a general reason I am concerned about your health: it would make me happy if everyone was healthy and happy.   Most people are inadequately nourished, even with the best available food - and almost all of us eat too much salt.

There are two special reasons why I am concerned about your health and the health of every other human.  Both special reasons arise from the coronavirus pandemic in which we all are at high risk of being infected with the SARS-CoV-2 virus, leading to the disease condition COVID-19.  Please see ../3-reasons/ for more details.  I believe that when all things are considered, pretty much everyone has a strong interest in most people improving their nutrition to ensure their immune system works well, especially with the threat of COVID-19.

Many people have no symptoms, or very mild symptoms.  If this was the case for everyone, COVID-19 would be just a nuisance.   The reason it is a worldwide health crisis beyond any in living memory, and the reason why whole countries are in lockdown, with social isolation, little or no productive work or education, reduced access to health care, cancellation of all public gatherings etc. is solely due to the fact that some people suffer severe symptoms and lasting harm, and a subset of these people are killed either directly by COVID-19, or in combination with the impact of other illnesses.

The impact of these severe symptoms is disastrous.  So are the lockdown and other measures which are currently the only way governments have of protecting their people from risk of harm and death.

People who think this is just like the flu are avoiding the harsh reality of the lasting harm and deaths of people of all ages.   From babies, to adolescents, to young adults (with COVID-19, anyone under 50 is young) to middle aged adults and especially the elderly, death is a risk and the chance of lasting harm, such as from organ damage due to micro-embolisms (tiny blood clots) is much higher.

Inadequate nutrition (of which inadequate vitamin D is the most important, best researched and easiest to fix) is already the cause of immense and arguably disastrous suffering from a long list of illnesses and chronic conditions most people accept as normal.  These include many cancers (the rates of which would significantly reduced with adequate vitamin D), most neurodegeneration (dementia, Alzheimer's disease, Parkinson's disease etc.) and numerous auto-immune diseases (asthma, MS, Crohn's disease etc. - subject to considerable genetic variation).

We are already in a vitamin D pandemic with profound impacts of suffering, harm, disability and early death.  

The purpose of this web page is to help you and your family and friends - ideally with the help of your doctor - make the best decisions about nutrition for immune system health.   But it is part of a bigger plan to improve everyone's health.  Whatever I or anyone else seriously suggests should be done must be applicable to most people - including those who are poor and who have no access to the medical care we expect in Western nations.

Working with your doctor . . .

The whole of biology and is complex.  The human nutrition subset of biology is complex and the subject of ongoing research.  Quite a few questions about nutrition are contentious.  This means that even among the best experts, there is disagreement as to mechanisms, how much of a nutrient people need, what interactions the nutrient has with others, whether or not to supplement, how best to supplement, how best to present this information to the public and what recommendations should be made by government health officials.

We must recognise and cope with these controversies when learning about vitamin D, how much to take, and what hopes we might reasonably have of it improving our health.

There is a seemingly endless number of vitamin D research articles, mainly concerning humans.  It is hard for me to imagine how any one person could keep up with these - even the most dedicated vitamin D researcher.   If anyone can do it, it is Henry Lahore, a retired ex-Boeing electronics engineer, whose Vitamin D Wiki is a prodigiously expansive repository of links to, and discussion of, vitamin D research:  
( is a fake clone!)

Doctors are trained in, and continue to learn, a substantial subset of the vast and ever-expanding body of medical knowledge.  They are skilled in assessing the condition of patients, and in applying all their knowledge and experience to improve each patient's health.

Doctors are generally trained in all the things that can go wrong with people's bodies, and in intervention strategies to respond to these.  They are highly trained in the use of drugs for this purpose, but also know lots about immunisation, resuscitation, some aspects of surgery and physical skills such as dealing with warts and blocked ears etc.  Ideally they also kind, sympathetic and get along with all their patients - as well has understanding and being able to help with their mental, emotional and social difficulties,

The scope of doctors' work is broader than that of any profession I know.  They have huge responsibilities and frequently very heavy workloads.

From all I can tell - and this includes what some doctors themselves say - doctors are generally not trained as much as they should be about nutrition.

Furthermore, the pharmaceutical industry has an inordinate influence on doctors initial and continuing education.  Patented drugs are constantly promoted to doctors.  Drugs are promoted to patients as well, and many patients expect their doctors to issue prescriptions for carefully targeted drugs, with few or no side effects, which will quickly resolve or at last contain their health problems.

Supplemental vitamin D3 (cholecalciferol) is a pharmaceutical, made from UVB exposure of 7-dehydro-cholesterol, a cholesterol derivative usually obtained from wool fat.  However, pharmaceutical grade D3 is made by multiple manufacturers - in recent decades primarily in China and India, in a highly competitive market.  In 1kg lots, pharma-grade D3 costs USD$2.50 a gram, which is cheap.   Furthermore, there's not much money to be made from it, per person using it per year, because if they took the impressive sounding 4000IU a day (the upper limit of safety according to the advice of the UK and other governments), this is only 1/10,000th of a gram.  So the ex-factory cost of the D3, per person, would be USD$0.09 per year.  

It would be a mistake to think that people like me - who suggest that almost everyone should be taking substantial (0.1mg a day - or 0.2mg to 0.3mg a day for the obese) vitamin D supplements - are somehow acting in the interests of Big Pharma.

Big Pharma has countless billions of dollars in revenue to loose if everyone got the amount of vitamin D which maximises their health - particularly their immune system health.   Likewise the hospital system.   Likewise quite a lot of medical research industry, which is working on apparently complex and hard-to-solve problems, such as Alzheimers disease, which would be greatly reduced with good nutrition - and vitamin D is the most important of these missing nutrients.

Doctors would have a lot less work to do as well, but most would welcome this because they really want their patients to thrive.

Since medicine is a very well researched field, most doctors are not solving fresh problems every day.  Their primary task is to arrive at a correct diagnosis and to choose the best intervention - which is frequently thought to involve drugs or perhaps surgery.  Some conditions are difficult to clearly diagnose, and some diagnostic categories and the best ways of tackling them are the subject of ongoing debate.  (For instance, fats, statins and heart disease; fibromyaligia.)

In the vast scope of their work, vitamin D is a relatively small sub-field - except for those doctors who have gone to special trouble to study it.  These doctors will recommend D3 supplementation in line with the latest research, and may want to test their patients' 25OHD levels once a year to see that it is within the fairly broad target range - ideally 40 to 60ng/ml, with levels up to 100 to perhaps 150mg a cause for reducing the dose, and not for alarm.   For instance, see what one such doctor wrote about levels and dosing: ../#2020-Baker-a .

I don't have a list of doctor who take a special interest in nutrition and especially vitamin D.  Here are the websites of two:

Most doctors have no time to read the latest vitamin D research.  I don't think there are enough hours in the day for even the keenest vitamin D researchers to read it all.

Most doctors rely on clinical guidelines which are perhaps a decade or more out of step with current research.   There is a great deal of debate about these guidelines, and it seems that the committees which set them are subject to numerous pressures and are reluctant to alter their recommendations significantly, since this would be an admission that their critics, over the years, were right.

For some background on the decades-old debate about vitamin D, please see this extensive article by William B. Grant (PhD, physics) who has written peer-reviewed journal articles concerning UVB, vitamin D, cancer and Alzheimer's disease.   He is one of the 48 researchers and MDs at who since 2008 have advocated 40 to 60ng/ml as the target range for 25OHD.  

Vitamin D acceptance delayed by Big Pharma following the Disinformation Playbook
Commentary by William B. Grant, Ph.D. 2018-10-01

As in any field, I have seen research I consider sound and some not so under the banner: "orthomolecular".  It means [W] maintaining health through nutritional supplementation -  "the right molecules in the right amounts" - which is a perfectly good principle.

Doctors operate under a variety of difficulties which tend to make their treatment decisions more likely to accord with established guidelines, rather than with the best research.  These include:
There is an information chain with numerous delays and distortions.   A discovery is made.  It takes time to write it up in an academic article and have it peer reviewed and published.  Ideally, over months and years, other people read it, cite it and perhaps replicate it, with similarly published research.  Then, perhaps, one or more of these articles will be included in a review article, in which, perhaps, the conclusion of the review article is changed towards the clinical implications of the new (by now a few years old) research.  Then, if there are a few such review articles, some doctors will discuss it in a forum or conference, and many of them will say they will wait for a randomized controlled trial (RCT) - or two - to be performed showing that the potential new treatment approach will be helpful to their patients, if applied as intended, without significant ill-effects.  (Such caution is reasonable in the case of novel drugs being pushed by pharmaceutical companies, where the ill-effects are likely to be unknown without years of extensive testing or clinical use.)

So over the next few years, with luck, some good souls may get the funding (such as millions of dollars) to employ themselves for another year or two to run the RCT.  (Though some RCTs take 5 or 10 years.)   Eventually, if the RCT is done well, and the desired benefit is shown to be significant (useful and unlikely to have occurred by chance) then someone will want a second RCT just to be sure . . . .

All the above is true of patented high-profit single-manufacturer drugs, generic drugs and naturally occurring, if manufactured, nutrients.   In the case of patented drugs, the drug company will invest the money to run the trials and they will be done ASAP.  For generic drugs and nutrients, the only source of funding is government agencies or philanthropic funds - so it is very much harder to fund expensive research into these.

Years later, a committee meets to revise its now 5 or 10 year old guidelines.  Maybe it will be persuaded by the RCT results, as found to be good by one or more subsequent review papers, that its earlier guidelines were wrong and so need to be changed significantly.

If they do this, it takes time for their conclusions to be published, and then time for anyone to take much notice, such as a second committee in another country which sets guidelines in part based on those which have just been changed.  Then, some years later, the guidelines for that country may be changed, and over the next few years, with luck, the doctors in those countries will begin to base their treatment decisions on the "new" guidelines.

Meanwhile, patients are not benefiting from the best research.

There are good reasons for caution in medicine.  There are examples in history of treatment decisions being made according to new information which did not, in the long run, turn out to be accurate.

However, what if the current guidelines are just plain wrong?  Exhibit A is the UK government guidelines that 10ng/ml 25OHD is sufficient, and that most people should take 0.01mg (400IU) vitamin D - and then perhaps only in winter.   For a recent article which defended these awful, deadly, harm-causing standards, see:

Vitamin D and SARS-CoV-2 virus/COVID-19 disease
Susan A Lanham-New et al. bmjnph 2020-05-15

which I discuss further at ../#21authors .   Likewise the UK NICE report, which found no reason to think that low vitamin D levels had anything to do with COVID-19 severe symptoms: , critique: .

Upon the publication of the above article and the NICE report two months later, newspapers, news sites etc. all over the world lit up with headlines to the effect that vitamin D supplementation will be no use in preventing COVID-19 infection (largely true) or reducing the risk of severe symptoms (disastrously false, I am sure).  Some people it is smart to dismiss what they think is a flaky, overly simple, attempt at solving a very complex and serious problem.  They are ill-informed: nutritional deficiencies can and do cause vastly complex, pervasive and seemingly complex patterns of ill-health.  It is not surprising, considering the complexity of a single cell, and of an entire human body and the hundreds of species of bacteria it hosts. 

So there are numerous reasons why reality, as discovered by competent researchers, takes a very long time to influence clinical practice for the better, for most doctors.  However, some are much more attuned to what is actually happening, and will adapt their treatment and advice to the public much more rapidly.

There is an extraordinarily strong herd mentality among medical practitioners.   It took about 30 years before hand washing was widely accepted as being necessary:

The same applies now, with excellent work by doctors, such as Dr Paul Marik ../icu/#Marik-protocol who found intravenous vitamin C in combination with anti-inflammatory corticosteroids saves many ICU patients.  This is not surprising, given the importance of vitamin C to the immune system, and the well known fact that it is drastically depleted, to the point of being impossible to detect, in many ICU patients, especially those with sepsis.  Years later, many doctors are still reluctant to replete this missing vitamin C the way he does, wanting RCTs etc. which Paul Marik will not do, because it would involve denying life-saving treatment to half his patients.  (I think he would do better still with rapid, bolus dose, 250HD vitamin D repletion.)

I am one of a growing number of people, including MDs, who believe that the only way the current COVID-19 crisis can be resolved is a massive program of nutritional supplementation to improve everyone's immune system health.  Vitamin D is the obvious choice.

Meanwhile most doctors haven't really thought about this.  Pretty much everyone assumes the solution must be in avoiding infection until everyone can be protected by a magic vaccine.  

In enquiring into vitamin D supplementation, you can't avoid recognising the divergent views among MDs and other healthcare professionals.  

In 2016, my doctor told me straight that my 0.1mg D3 a day was too much - that I was risking vitamin D toxicity.  We discussed it as "4000IU", which sounds so much more, perhaps scarily more.  I knew then that he was wrong.  Now I know more about it, I take about 0.175mg a day.  I would probably be OK with the old amount.  But not knowing my 25OHD levels  (I haven't needed to see a doctor since then, and I am 64) maybe I would be better off with more.  I could double this again with zero risk of toxicity.

Ideally, everyone would have easy, affordable, access to a doctor whose knowledge of vitamin D and of nutrition in general was up to date with the best, recent, research. 

Ideally everyone would follow their advice, and perhaps get their vitamin D blood levels checked every year or two, or five.   

Most people's immune system would work much better than they do today (especially if they ate less salt, more omega 3 fats and supplemented with vitamin C, potassium and boron).  I believe that if everyone in the world had adequate vitamin D, there would be much less ill-health, COVID-19 would be a minor nuisance except in very rare instances,  there would no lockdowns and I would be designing and building electronic musical instruments rather than writing this web page.

If you can find a good - vitamin D nutrition aware - doctor, get your 25OHD levels tested and proceed from there, then there's no need to read any further.

However, writing in early August 2020 (1.1 million new confirmed COVID-19 cases in the last four days), who wants to go to a doctor's office?  Or sit in the waiting room of a pathology office to have your blood drawn?  No-one in their right mind would want to do this unless they have a medical condition which is likely worse than the risk of contracting COVID-19 from the other people in those rooms.

Not everyone can afford to see a doctor.  I am writing not just for people in the developed West - though many people in the West can't afford to it either.  I am writing for people in all countries - and in many parts of the world, doctors are few and far between, distant, and/or unaffordable.  Likewise pathology labs and 25OHD tests.

. . . or without a personal doctor

Even if all doctors were up-to-speed on vitamin D and nutrition in general, and even if they were nearby, could be visited without risk of catching COVID-19, and were affordable, there are not enough of them to cope with the world's population turning up for consultations, 25OHD tests, individual advice on D3 supplementation etc. in the next few months - prompted by the severe test of their immune system health which will occur if and when they contract COVID-19.

By necessity or choice, most people will be trying to decide about vitamin D supplementation without the personalised assistance of doctors.

Fortunately, it is not hard to do.  There is a wide range between the D3 intakes which will most likely ensure adequate (at least 40ng/ml, for most people) 25OHD levels and those which would cause toxicity.  While toxicity may be a problem above, say, 160ng/ml - a factor of 4 - there is a much wider range of safe dosages, because raising the 25OHD level a factor of 4 can only occur after months of taking a very much larger amount (much greater than a factor of 4) than whatever it takes, in general, to reach 40ng/ml.  The recommendation of the research cited below is a target range of 40 to 60ng/ml, with not too much fuss if it goes above this, and with recognition than for a few people (unless monitored with blood tests) a somewhat lower level will result.

There are peer-reviewed journal articles which present good research - or reviews of the research first reported in other articles - written by highly regarded doctors who are also highly regarded vitamin D researchers.  

The first article I cite below is co-written by PhD endocrinologist and MD Michael J Holick [W who, since 1971 - when he  identified for the first time several forms of vitamin D in the body - has become the world's best known vitamin D researcher.  You may encounter a 2018 hatchet job article about him in the New York Times, by Liz Szabo.  For the background to this, and the critical letters to the editor from other researchers and MDs the NYT never published, see the above article by William B. Grant.   Google Scholar lists 129,482 citations for articles Dr Holick wrote or co-wrote.

D3 supplementation, body weight and long-term 25OHD levels - aiming for 40 to 60ng/ml

If you are keen to raise your vitamin D levels rapidly - as seems reasonable if you have not been supplementing and you are concerned about getting COVID-19 soon - then please see the next section after reading this one.

The aim of this section is to enable you, or your doctor, to estimate the amount of supplemental vitamin D you should take to aim for the 40 to 60ng/ml target range recommended in some research articles cited below.

This assumes that you get little vitamin D from food, unprotected UVB light exposure, multivitamins or other supplement tablets.  If you are taking significant numbers of calcium tablets (citrate is more bioavailable than most other kinds) then these may have vitamin D3 added, so take that into account.

This is not a particularly exact process, since 25OHD levels vary quite a lot between people with the same supplemental intake.  Fortunately, for most people - those without COVID-19 predisposing conditions such as advanced age or being overweight or obese -  there's a large gap between what should do the trick in terms of good health and the much higher amount of supplements which would cause toxicity.

Your doctor might want to be more fussy.  If you have a doctor, and can experiment with dosages and 25OHD levels over months and years, then you don't really need the chart below.

For now we assume we are aiming for about 50ng/ml 25OHD - but below I have some ideas (from an electronic technician - not a doctor) about why some people should aim higher.

The most recent review article concerning immune system health and vitamin D just two weeks old as I write this in early August 2020::

Immunologic Effects of Vitamin D on Human Health and Disease
Nipith Charoenngam, Michael F. Holick 2020-07-15
Nutrients 2020, 12(7), 2097

Another recent article which makes the same recommendation is:

Editorial – Vitamin D status: a key modulator of innate immunity and natural defense from acute viral respiratory infections
A. Fabbri, M. Infante, C. Ricordi Eur Rev Med Pharmacol Sci 2020; 24 (7): 4048-4052 2020-04-05

We also believe that maintenance of circulating 25-hydroxyvitamin D levels of 40 - 60ng/ml would be optimal, since it has been suggested that concentrations amounting to 40ng/ml represent the beginning point of the plateau where the synthesis of the active form calcitriol becomes substrate-independent [2011-Hollis err] [2018-Wagner].

This last point refers to the efficiency with which 1,25OHD (calcitriol) is produced inside cells, such as lymphocytes, as part of their internal, autocrine [W], signaling system.  This system is required for the cells to respond properly to conditions, such as turning on direct anti-viral attack chemicals when they are needed, and turning them off (or signaling to other lymphocytes to turn off theirs) when they are no longer needed and instead are hyper-inflammatory, and so self-destructive.

In biochemistry, the original state of a molecule which an enzyme modifies is called the "substrate".  1,25OHD is the form of vitamin D which activates vitamin D receptors. 

In this autocrine signaling system an enzyme works on a molecule of 25OHD and attaches an OH group to the 1 position, and so converts it into 1,25OHD.  The enzyme ejects this and then waits for another 25OHD molecule to fall into position so it can repeat the process.  (The enzyme is a catalyst which is not changed by this operation.  Other molecules are consumed in providing the OH group and the required energy.)

The 25OHD level (as measured in blood tests) in the blood and so the interstitial fluid in which all cells operate, sets the concentration of 25OHD inside the cells where this enzyme operates.  Below a certain level (very approximately 40ng/ml), this reduces the ability of the enzyme molecules to stay busy and produce 1,25OHD.  So A. Fabbri et al. are saying that if your 25OHD levels are 40 to 60ng/ml, then this will be the concentration in the immune cells, and their internal signaling will work properly, due to the process not being slowed down due to inadequate supplies of 25OHD.  

Now look at the graph on the main page ../#2020-UK-vit-D-BAME  of the appallingly low 25OHD levels of many people in the UK, in winter.  Even in summer, white people on average only reach 25ng/ml for a month or so before dropping back to 16ng/ml in mid-winter.  Black, Asian and Ethnic Minority people's average levels vary from 10 to 15ng/ml all year round.  See also ../#SAAD where we see that in the UK, 44% of South Asian women (from India, Pakistan and Bangladesh) average, year round less than 6ng/ml

Also see, on the icu page, this article ../icu/#2020-McGregor , which reports that lymphocytes removed from the lungs of hospitalised COVID-19 patients remained in their hyper-inflammatory state, not progressing to their anti-inflammatory shut-down phase, due entirely to lack of 25OHD preventing their autocrine signaling system from working.  Yet the system worked fine in the same kinds of lymphocytes from healthy control subjects.

(The first thing I wanted to know was the 25OHD levels of the COVID-19 patients and of the healthy controls.   I wrote a comment to their article asking if this was available.)

Are we connecting the dots boys and girls?  Its not that hard.  I figured this out in March: that the patient's low vitamin D is a major contributing cause of the dysregulated, hyper-inflammatory, immune response which drives COVID-19 hypercoagulation - and sepsis, and influenza-pneumonia. 

Just in, 2020-08-02: An ICU doctor says :

"A lot of COVID patients who require hospitalization do have low vitamin D levels," he says, but is quick to add that correlation does not equal causation. "Does that mean we should give every hospitalized COVID patient big doses of vitamin D when they hit the door? Maybe."

He would be upset if he brought some item of equipment to me and I found its +/- 12 volt power supply lines were sagging and fluctuating around 7 volts or so, and I handed it back to him, with an invoice, and said: "The power rails are drooping.  Maybe the circuit is drawing too much current - so the power supply is OK.  Maybe the circuit is OK and the power supply needs to be fixed.  Here you are.".

What is wrong with so many doctors??   This is the most perplexing thing!

As an electronic technician with a cursory understanding of vitamin D's role in the immune system, it was obvious.  However, it seems that most doctors' minds are filled with thoughts of drugs and vaccines, and of unprecedented global disaster, the need for RCTs before doing anything at all novel . . . and are not attuned to the kind of fault-finding detective work for novel problems which is a normal part of electronic work.  Despite hundreds of articles on low vitamin D and dysregulated immune responses (and some on omega 3s and boron too), most doctors still cannot properly imagine what harm results from inadequate vitamin D. 

Additionally, serum 25-hydroxyvitamin D levels of approximately greater than or equal to 40ng/ml could* provide protection against acute viral respiratory infections, as demonstrated in a prospective cohort study published in PLoS One and conducted on 198 healthy adults [2020-Sabetta].  To reach these concentrations in adults, a dietary and/or supplemental intake of vitamin D up to 6000 IU/day (0.15mg) – deemed to be safe – is required.

However, elderly subjects, overweight/obese and diabetic patients, patients with malabsorption syndromes
**, and patients on medications affecting vitamin D metabolism may require even higher doses under medical supervision.

* In the research article vernacular, "could" and "may" frequently mean "we really think it will, but we can't prove it beyond reasonable doubt and we don't want to look overly confident".

However they boldly use "is" later in the paragraph when they are very sure of themselves.

** See below on Roux-en-Y and other weight-loss bariatric surgeries, many of which are specifically designed to reduce fat absorption, and so will reduce vitamin D3 absorption.

In sunny Africa one might think there's no vitamin D deficiency, but most people wisely stay out of the sun, and with very dark skin, don't make much vitamin D from the small amount of direct sunlight they do get.  So vitamin D deficiency is a problem there too.  Without reference to desired 25OHD levels, Dr David Ajibade of the Nigerian based Brain and Body Foundation (bio) stated, on 2020-07-25 in an interview

In my opinion, the best way for black people to get adequate levels of vitamin D is by supplementation. And the research shows that adults should be getting no less than 10,000IU (0.25mg) a day.  
In my opinion, the best way for black people to get adequate levels of vitamin D is by supplementation. And the research shows that adults should be getting no less than 10,000 IUs a day.

Read more at:
In my opinion, the best way for black people to get adequate levels of vitamin D is by supplementation. And the research shows that adults should be getting no less than 10,000 IUs a day.

Read more at:
In my opinion, the best way for black people to get adequate levels of vitamin D is by supplementation. And the research shows that adults should be getting no less than 10,000 IUs a day.

Read more at:

Finally, 48 vitamin D researchers and MDs (some are both) have been saying the same thing about 40 to 60ng/ml since 2008, with their Call to D*action for Public Health: .  These include Michael Holick.

Here is the vitamin D intake vs. 25OHD by body weight chart and the article which from which it was adapted.  I added the text, the ng/ml and milligram scales, the dots and the green target zone.

How much vitamin D shoudl I take?  COVID-19  Immune system health, Cytokine storm, sepsis, ICU optimal vitamin D intake,  4000IU, vitamin D blood levels, vitamin D dose recommendations

The Importance of Body Weight for the Dose Response Relationship of Oral Vitamin D Supplementation and Serum 25-Hydroxyvitamin D in Healthy Volunteers
John Paul Ekwaru, Jennifer D. Zwicker, Michael F. Holick, Edward Giovannucci, Paul J. Veugelers  PLoS One 2014-11-05

The 17,614 adult subjects in this research study mainly lived in Alberta, Canada, at latitudes of 49 to 60° north.

We recommend vitamin D supplementation be 2 to 3 times higher for obese subjects and 1.5 times higher for overweight subjects relative to normal weight subjects.

Here is a BMI (Body Mass Index [W]) chart (SVG file):

Sidebar on problems inherent in using BMI like this:

There are numerous critiques of the whole concept of Body Mass Index (BMI):  Google: BMI controversy for various websites, academic articles etc. such as this and this.  I think it is best to recognise that the average height of male and female Canadians is 1.75 and 1.62 metres respectively, so the four curves were probably derived mainly from people in the 1.55 to 1.8 metre height range.  

The two primary things we need to account for in increasing the supplemental D3 intake above that of average weight and average height people is that some people are heavier  (the first multiplier) and - independently of this - some people have a greater proportion of their body weight as adipose tissue.

I just want to flag that this is not ideal.  If I devised what looks to me like a better chart to convert height and weight into a daily D3 supplemental quantity, the result would not be based directly on the best available peer-reviewed research articles - which is what I want to achieve.

From the Ekwaru et al. graph it is easy to see vitamin D3 daily intake rates which will, most likely, on average, achieve the 50ng/ml 25OHD level, in the middle of the target range 40 to 60ng/ml, for the four ranges of BMI are:

Body weight
Daily vitamin D3
< 18.5
18.5 - 25 0.125mg
25 - 30
> 30

While this is statistically reasonably valid, each person's final 25OHD is likely to vary quite a lot, so there's no point in fussing about exact doses down to 10% accuracy. 

The first thing people are going to think when looking at this and their bottle of 0.025mg (1000IU) vitamin D capsules is:

How much is this going to cost?

and the second is:

Do I really have to swallow so many capsules?

At a pinch, to start with, use whatever vitamin D3 (or even D2) you have.   For the longer term, it is a cheaper and more convenient to use capsules with larger amounts of vitamin D.

It is relatively easy to get 0.12mg (5000IU) capsules - though in Australia, try eBay or Amazon, since ordinary shops are not allowed to sell capsules with more than 0.025mg = 1000IU.  

Since it takes a week or so for most of the ingested D3 to be converted by the liver into circulating 25OHD, and since the half-life of the 25OHD is generally much longer than this, then there is no need to take vitamin D supplements every day, or probably every week.  Two weeks between taking supplemental D3 is probably fine.  I have an article here somewhere on the half-life decreasing at higher levels.  The self-regulatory system for 25OHD changes some of it into 24,25OHD, at a rate which scales with the 25OHD level.

My wife Tina and I have been using 1.25mg (50,000IU) D3 capsules for a few years:

These are a dry powder in a small capsule and cost USD$30 per 100, so USD$0.24 per milligram. 

0.25mg (10,000IU) capsules are available from several companies, such as:

120 for USD$17 = USD$0.57 per milligram.  This one is a "softgel" capsule, with the D3 dissolved in olive oil.  I guess this makes it more bioavailable than in a dry form.

0.125mg (5000IU) olive oil capsules are also available:

240 for USD$23 = USD$0.77 per milligram.

Here's a table for the three different sizes of D3 capsule, at various intervals, with the resulting average daily dose.  The first one would be pretty close to 0.1mg (4000IU) a day with a small amount of D3 from a multivitamin.

1.25mg (50,000IU) mg /day

1 / 2  weeks

1 Mon, Tue,

1 / 1 day
1 / 2 days
1 / 10 days
e.g. 1st, 10th & 20th
of the month.
1 Mon - Fri,
2 Sat & Sun

2 Mon - Fri
1 Mon - Fri
1 / week
2 Mon - Sat
1 Mon - Sat

2 / day
1 / day
6 / month
e.g. 1st, 6th, 12th,
18th, 24th & 30th
of the month.

1 Mon - Fri,
2 Sat & Sun


2 Mon - Fri
1 Mon & Fri

It would be nice if we could get our 25OHD levels over some threshold, such as 40ng/ml, know this from testing, and then be confident that COVID-19 would not cause us any serious trouble.  The situation is more complex.  Vitamin D levels are a very important thing we can and should raise, but there are numerous factors at work, and it is reasonable to expect that some people will suffer harm and be killed even if their 24OHD levels are above 40ng/ml.   Please see the chart of levels and ages from the Iranian research study at: ../#2020-Maghbooli .

Obesity itself (irrespective of other conditions, including vitamin D deficiency - though without supplements it is safe to assume that obese people have very low vitamin D) presents a very high risk for COVID-19 serious harm and death.   Some of the currently known mechanisms are mentioned in the research articles listed here: ../obesity/ .  Everyone knows that most people who are harmed and killed by COVID-19 are either 70, 80 or 90+ years old, or obese.  There are other risk factors such as diabetes and lung injury. 

Some people with a particular genetic pattern (haplotype) on chromosome 3 are also at a high risk of COVID-19 severe symptoms.  This is rare in Africans, common in Europeans and, apparently, most prevalent in Bangadeshis.  See: ../#haplotypes .   This is a particular concern for Bangladeshis living in the UK, far from the sun, with such low levels in the official guidance for vitamin D supplementation and proper 25OHD levels.

My opinion as an electronic technician:

If I or a loved one was obese, or of advanced years like this, and/or known or likely to have some other risk factor, I would be inclined to err on the high side of these dosages.  Adding another 30% or 50% so is not going to get anyone close to the 150ng/ml where toxicity might be a problem - and there's a good chance that the the higher 25OHD level resulting from the larger intake will make a crucial difference when their immune system is really put to the test by COVID-19.    

Pregnant women need vitamin D3 like anyone else, but it is much more important that they get it than anyone else, because their baby's body building itself.  

We are used to complex products emerging from even more complex factories, but biology builds itself, and problems in prenatal and early childhood development are likely to last a lifetime.   It is well known that pregnant women should never smoke or use alcohol.  It should be better known that they need vitamin D supplementation (unless perhaps they get a lot of sun exposure) and to be replete in all other nutrients. 

VitaminDWiki has hundreds of pages concerning pregnancy.  Here are some links on vitamin D deficiency contributing to the risk of  premature birth , preeclampsia , ADHD and autism .

Babies and children need vitamin D supplements too.   As long as Baby is breastfeeding substantially and Mother is vitamin D replete, there is no need for supplemental D3. 

There are various guidelines for supplementing children, but they may be based on 25OHD levels lower than the 40 to 60ng/ml we are aiming for here.   It seems logical that supplemental doses could be worked out from the baby's or child's weight as a fraction of the 70 kg or so weight of an average weight adult, and the 0.125ng (5000IU) a day amount mentioned above.

Some adults have reduced fat absorption and other reductions in nutrient absorption.  This is certainly the case for anyone who has had Roux-En-Y [W] gastric bypass surgery [W] [DW], which is specifically intended to reduce fat absorption.  The stomach is turned into a pouch there is no stomach sphincter or initial part of the intestine, where a great deal of nutrient absorption takes place.  Food may rush through the system, without the stomach sphincter to regulate its flow.  In the USA, Roux-En-Y is a common form of weight loss surgery.  Roux-En-Y patients must supplement with B12 to avoid brain damage, and require special attention to other nutrients such as iron. 

Roux-En-Y is the most disruptive of several gastric bypass surgeries.  According to this article, which concerns gastric bypass surgeries in general:

Bariatric Surgery: Bad to the Bone, Part 2
Lara Pizzorno 
Integr Med (Encinitas). 2016 Apr; 15(2): 35–46.

bone loss remains a problem even with "normal" levels of 25OHD.  They state:

The results seen in this study suggest that in individuals who have had gastric bypass surgery it may be necessary to maintain the 25(OH)D3 status of 40 to 80 ng/mL recommended by the Vitamin D Council, together with a calcium intake of 1300 mg/day, which is the upper recommended daily intake (RDI) suggested for postmenopausal women. Calcium intake of 1500 mg/day as calcium citrate is now recommended in the 2014 position statement of the American Society for Metabolic and Bariatric Surgery.

Assuming this was for weight loss, these people are likely still to be overweight or obese, but  hopefully no longer morbidly obese, have an unknown deficiency in vitamin D absorption, and we are aiming not for 40 to 60ng/ml but 40 to 80ng/ml.   We see from the graph that higher 25OHD levels become progressively harder to attain.

All these people should be under the medical supervision of doctors who specialise in the nutritional requirements and other health problems resulting from these surgeries.  This article looks good, but it is aiming for only 30ng/ml 25OHD:

Micronutrient Deficiencies After Bariatric Surgery: An Emphasis on Vitamins and Trace Minerals
Jayshil J Patel et al. 2017-06-13 (Paywalled.)
Google Scholar 27 citations.

I haven't found any clear guidance on this, but assuming a person is overweight or borderline obese, and has had Roux-En-Y surgery, here are the reasons I think they need higher D3 intakes than the 0.125mg (5000IU) required (on average) for a normal weight person to attain 50ng/ml:

On that basis, depending on the person's actual weight (a short person with a BMI of 30 weighs less than a tall person with this) . . . and again remembering you are reading the musing of an electronic technician . . .  it looks like giving them 8 times the normal D3 intake would make sense:  1.00mg = 40,000IU.   This seems like a lot, and ideally there would be medical supervision with blood tests and aiming for at least 50ng/ml (see above for 80ng/ml) - but these people face numerous health challenges and it may make good sense for them to take quantities of vitamin D3 which would quite likely lead to toxicity in a normal-weight person with no such surgery, but which pose no such danger for their larger bodies.  

Stomach banding does not involve such malabsorption as Roux-En-Y.  There are too many variables here to warrant more detailed speculation.

Bolus (loading) doses to raise 25OHD levels quickly

No-one should take 1.25mg (50,000IU) capsules once a day for long periods.

Recently I spoke by phone to a musical instrument customer in Europe.  After listening to my obligatory vitamin D pep-talk he told me that he was going to quite some trouble to use supplements to improve his health.   He is educated, in his 30s, average weight, thriving and reasonably knowledgeable about nutrition.

However . . . he had been taking a 12.5mg (50,000IU) capsule once a day for a year!   As far as we know it hasn't done him any harm, but he would probably have some ridiculous 25OHD level and that this may have caused calcification of his blood vessels, which results from hypercalcemia.   This takes months, but drives heart disease.  

Don't do this!

I immediately thought of PMC6334045/ which reports on a 73 year old retired nuclear physicist who took 1.5mg (60,000IU) D3 a day for two years.  He had no previous health problems and did not smoke or drink etc.  He got to 352ng/ml 25OHD, and had profound cognitive problems, including being confused and drowsy.  These and other symptoms including hypercalcemia resolved after he stopped the supplements.

However, it is fine to take high doses of D3 for a short period of time, since it takes a week or so to build up the 25OHD levels in the bloodstream to healthy levels and much longer to reach dangerous levels above 150ng/ml.

In early August 2020, with a quarter million verified new cases of COVID-19 a day worldwide, it is reasonable to expect that we are going to get the virus pretty soon.  So - especially for the elderly or the obese - I think it is a good idea to start supplementation with higher doses to raise 25OHD levels to the desired 40 to 60ng/ml range ASAP. 

In Newcastle upon Tyne, in the far north of England, with predominantly white hospitalised COVID-19 patients, doctors ../#2020-Panagiotou  are starting some of them on  bolus doses of up to 5mg (300,000IU) of D3 on admission.  They only did this for patients with disastrously low vitamin D levels: 5.2ng/ml or less, with lower bolus doses for higher levels.  I think they should have had higher thresholds and much higher maintenance doses. 

There's something odd about UK doctors and vitamin D - it is as if they are dealing out crack, worrying about something terrible happening, as if the vitamin D toxicity bogey man is just around the corner.  Part of the reason for this is probably the UK government's ridiculously low standard of 10ng/ml for being vitamin D replete.  Another may be that in the UK they use nmol/L (nanomols - a number of molecules - per Litre) for 25OHD levels, which are 2.5 times the ng/ml figures.

So to them, 40 to 60ng/ml may seem scarily high at 100 to 150nmol/L, when the population all-year-round average is less than 20ng/ml (50nmol/L).

In this section of the main page : ../#03-vit-d is a link to an article describing a double-blind randomised controlled trial - the highest standard of evidence in medicine.  It concerned ICU patients who needed mechanical ventilation for a variety of illnesses and were on average overweight to obese.  The control group got out of hospital, on average, after 36 days.  Those who received 1.25mg D3 (50,000IU) a day for five days = 6.25mg (250,000IU) got out, on average, after 25 days.   Those who received 2.5mg D3 (100,000IU) a day for five days got out on average after 11 days.

These initial high doses were, on average, beneficial - and there were no adverse outcomes.  However, people in ICU might not be absorbing the D3 very well.

Scaling back the higher of these doses (12.5mg = 500,000IU) total to normal weight people, and assuming good absorption, I guess 5mg (200,000IU) is probably a good way to start, over a day or several days.  

Here are my thoughts as electronic technician of how I would respond in a disastrous situation where medical care was unavailable, such as due to the hospitals being totally overloaded and all the doctors and nurses either sick with the virus or working unsustainably to help other people.  The price of these thoughts is $0.00 with a money back guarantee:

If I, or some adult in my care, was suspected or known to have COVID-19, and was reasonably assumed to have low vitamin D, due to no supplementation beyond perhaps multivitamins, in the absence of any well informed medical advice, I would give them, to start with, for instance:
It is impossible to give someone vitamin D toxicity with intakes such as this for a short period.  There would be unknown unknowns - but with the risk of COVID-19 severe symptoms, lasting harm and death bearing down on them like a freight train, I would do all I could to get their 25OHD levels up to 40 to 60ng/ml ASAP, or ideally higher for someone who was obese, elderly or facing multiple risk factors.

I would give them fish oil capsules such as 8 a day, unless I already knew they had been taking 4 a day for a long time.

I would also give them 10 or so mg boron a day.  ../#08-boron (At this point, your doctor is probably getting cranky because most doctors do not know boron is an important nutrient for animals, that the typical 1mg a day or so intake contributes in some or many people to hyperinflammatory immune dysregulation, or that 20mg a day is the level above which safety might be a concern.  114mg of laundry borax, not substitute, provides 10mg of boron.  The half-life in circulation is 22 hours or so.  My wife and I use 12mg boron a day, but 6 would probably be fine too.) 

I would give them a gram or two of vitamin C a day, and some zinc (chelate, not oxide).

If they had a fever, I would not try to lower it because the pre-COVID-19 research I read ../fever/ indicated strongly that with a few exceptions, fever is a vital part of the early response to infection.

If, despite this, the person developed breathing difficulties or any other signs of severe symptoms, I would raise Hell to get a doctor or nurse to attend, or at least give advice.

Doctors - especially in ICUs!

Please see the ../icu/ page and read up on the Marik Protocol AKA MATH+ Protocol.

Why not give every COVID-19 patient that arrives in hospital a gram of vitamin C and 2.5mg (100,000IU) at least, of vitamin D3?

Better still, can you give them oral (Rayaldee) or injected or IV 25OHD calcifideol? 

Unless you know the patient has been supplementing with substantial D3 for weeks, then you can reasonably assume that their 25OHD levels are low, and that you should move mountains to get it up to 40 to 60ng/ml ASAP, ideally in an hour or so - with oral or parenteral 25OHD.  Oral or IV D3 will take days or a week or so to be converted in the liver (if the liver is working) to the 25OHD your patient's immune cells desperately need.  By then it might be too late - hence the reason for large D3 bolus doses including for instance half a dozen fish oil capsules.

Why not give them plenty of fish oil capsules?  

Likewise zinc?

For you and your colleagues - all those who work in the hospital, or in ambulances - why not raise their 25OHD levels as a matter of utmost urgency, and get them all on vitamin C, omega 3s and zinc?

Vitamin D toxicity

Here are some links to research articles concerning vitamin D toxicity.  

I want to do more work on this section, but it might be a while before I can do so.

It seems that many doctors, through an over-abundance of caution, applied multiple times in series as warnings and maximum 25OHD levels are passed from one doctor or committee to the next, in the chain which links actual observations of hypercalcemia to the ordinary doctor's understanding of those observations . . . that the notion of vitamin D toxicity has been overdramatised to the point where some doctors, especially in the UK, think that 10ng/ml is a healthy 25OHD level, and that anything over 0.1mg (4000IU) a day for any adult carries an unacceptable risk of vitamin D toxicity.

It seems that the best, up-to-date, academic journal article on vitamin D toxicity is:

Vitamin D Toxicity – A Clinical Perspective
Ewa Marcinowska-Suchowierska, Małgorzata Kupisz-Urbańska, Jacek Łukaszkiewicz, Paweł Płudowski and Glenville Jones. Front. Endocrinol. 2018-09-20

I think the previous widely cited reference work on this was:

Vitamin D Toxicity, Policy, and Science
Reinhold Vieth 2009-12-04
Journal of Bone and Mineral Research

An important commentary and related article:

Vitamin D Is Not as Toxic as Was Once Thought: A Historical and an Up-to-Date Perspective
Michael F. Holick 2015-05-01
Mayo Clinic Proceedings

Changing Incidence of Serum 25-Hydroxyvitamin D Values Above 50 ng/mL: A 10-Year Population-Based Study
Daniel V. Dudenkov et al.  2025-05-01
Mayo Clinic Proceedings

Sarcoidosis is a condition in which hypercalcemia can occur due to overproduction of 1,25OHD in some immune system cells leaking into circulation and disturbing calcium regulation.  The most obvious response to this is to reduce both calcium and vitamin D (25OHD) levels.  However this is not necessarily the correct response.

Sarcoidosis involves extreme immune system dysregulation in which various types of immune cells attack each other, mistaking each other for pathogens, and clump together all over the body.  Sounds like a vitamin D deficiency problem, doesn't it?  (Boron, omega 3 PUFAs, vitamin C too??)  There may also be bacteria multiplying inside lymphocytes.

The next article reports that vitamin D and calcium supplementation for sarcoidosis patients is beneficial and does not result in hypercalcemia:

Calcium and Vitamin D in Sarcoidosis: Is Supplementation Safe?
Lieke S Kamphuis, Femke Bonte-Mineur, Jan A van Laar, P Martin van Hagen, Paul L van Daele
Journal of Bone and Mineral Research 2014-04-18  (Paywalled.)

To do: look at the articles which cite this one.

Taking supplemental D3 in various forms, with or without meals

I have only had a quick look at the research on these questions.  The findings seem to involve some contradictions  Google: "fatty meal" "vitamin D"

I understand that D3 already dissolved in water - such as in fruit-juice supplemented with D3 - is quite well absorbed.   However, this is not relevant to the current discussion, since no-one is going to drink so much fruit juice as would be required to total 0.15mg (5000IU) a day.  I guess the same applies to vitamin D gummies.

Not counting D3 in bottles of oil, there are three types of supplemental D3: dry tablets, capsules with dry powder and oil-filled capsules.   Since D3 is fat soluble, I would expect the oil filled capsules to be the most bio-available of these.  However, as far as I know, 1.25mg (50,000IU) capsules all contain dry powder.

Here is some research with mixed results, but overall support for taking oil capsules after a meal containing fat:

With these dry tablets, dry capsules or oil capsules I guess the worst way of taking them would be without a meal, with lots of water.  This would wash them through the intestines relatively quickly, and the intestines would not be geared up for absorbing fats.

I guess that the best approach would be to take D3 capsules towards the end of or after a substantial meal containing at least some fat - as most do - and then not drink too much for a while (which is good general advice anyway).  Then there is a chance for the D3 to spend more time in the upper parts of the intestines, with them being in a fat-absorbing mode of operation.

The same would be true of daily omega 3 capsules - though it is possible that four of these might be detected by the body as a fatty meal, and so be reasonably well absorbed.

My current preference is for taking D3 at the end of dinner, or with omega 3 oil capsules after breakfast - since we don't want to take the omega 3 capsules with or after dinner.

Some supplements, such as iron vs. calcium and/or magnesium, need to be taken at separate times because each upsets the other's absorption processes and the quantities involved, such as for calcium or magnesium are quite large.  D3 quantities are very small and I am not aware of D3 disrupting any other nutrient's absorption, or of any other nutrient disrupting D3's absorption.

The GrassrootsHealth researchers and MDs also recommend taking D3 with a fatty meal.  Their guide to vitamin D supplementation quantities:

cites this 2014 article which supports taking it with a fatty meal to maximise absorption.

../ to the main COVID-19 page of this site.

To the index page of this site: ../../
Contact details and copyright information: ../../contact/
© 2020 Robin Whittle - please link to this site rather than copy the whole of its contents    Daylesford, Victoria, Australia