Monday 8 July 2024

Vitamin D: perinatal mental illness in ethnic Black women

 Why do black mothers in the UK have an increased risk of perinatal mental illness?

The journalist Tobi Thomas continued her concern about the health profile of ethnic Black women in an article in the Guardian on May 7th 2024.

In my recent Blog posts I have presented her concerns about the increased risk of complications following appendix surgery in Black children in the UK, and also about the increased risk of childbirth complications in Black women. They were published in the Guardian earlier in 2024.

Both concerns were stated or assumed to be the result of sociological factors, including racism. It is my concern that there was no mention of the known biological factor of vitamin D deficiency.

The third article to which I draw your attention concerns a high risk of peri-natal mental illness in Black women in the UK. It was based on a Guardian analysis of NHS data. 

There had been 777 admissions to NHS England hospitals on account of puerperal mental illness (within six weeks of childbirth) between 2020 and 2023. 12% were ethnic Black women, despite them having only 5% of the deliveries. 

They were twice as likely to be admitted to hospital, suggesting that medical neglect and failure to use services might not have been a problem, despite a psychiatry commentator suggesting that difficulties in accessing services might be important. 

Other contributing factors suggested were structural inequality, socio-economic disadvantage, and cultural attitudes to mental illness. Dr Rosena Allin-Khan, Labour MP and medical doctor who trained at Cambridge University made the unhelpful suggestion that the reason might be “14 years of Tory mismanagement of our NHS”. 

These factors might be important but correcting them might take many years, and there is no evidence that elusive socio-economic corrections would reverse this “horrifying” problem of excess puerperal mental illness in ethnic Black mothers. Imagine the challenges to constructing a randomised controlled trial.

Several other commentators interviewed by Tobi Thomas repeated the social narrative. There was not a single mention of the biological factor of vitamin D deficiency, known to be very common in this ethnic group.

Why is there so much ignorance?

Most of the published reports and comments on the health disadvantages of ethnic Black African and South Asian people are made by sociologists, such as Tobi Thomas herself, and we might be surprised if they were to have significant knowledge of biomedical science. But some of the comments have been made by health professionals and I would have expected them to have some knowledge of the geography and the ethnicity of vitamin D deficiency. But this has not been apparent. It is possible, perhaps likely that the senior health professionals have knowledge of the importance of vitamin D and themselves take supplements, but if so they are not prepared to say so in public. Why not?


My previous Blog post described some of the large evidence of the importance of maternal vitamin D in brain development of the offspring, with benefits extending into adult life. The benefits of vitamin D acquired in adult lfe have also been investigated.

There is a great deal of evidence that low levels of vitamin D in the blood are associated with brain dysfunction. I first became aware of this with reports of seasonality of presentation with schizophrenia. This incidence was higher during the winter months in the Northern Hemisphere, and then the same in Australia during the winter months of the Southern Hemisphere. In  Singapore, which lies on the equator there was no seasonal variation. 

A review has shown that more than 250 studies, covering 29 Northern and five Southern Hemisphere countries, have been published on the birth seasonality of individuals who develop schizophrenia and/or bipolar disorder. Despite methodological problems, the studies are remarkably consistent in showing a 5-8% winter-spring excess of births for both schizophrenia and mania/bipolar disorder. This seasonal birth excess is also found in schizoaffective disorder (December-March), major depression (March-May), and autism (March).

With knowledge that blood levels of vitamin D are at their lowest in the early sprong, these studies give an impression that vitamin D deficiency might have a role in brain malfunction and mental illness. In recent years confirmatory research has been undertaken, including the role of vitamin D on gene expression in the brain and the production of neurotransmitters.

For example, a great deal of detail can be found in:

It might be several years before more details become understood, but in the meantime we must remember that it is not only puerperal mental health issues (psychosis) to which ethnic Black women are particularly susceptible. We must take this report in conjuction with my two recent Blog posts, which concerned difficulties and death involving childbirth among ethnic Black women in the UK, problems with neurodevelopment of the offspring, and the susceptibility to post-operative problems among their children.

We must not forget that adults of Black African and South Asian ethnicity were very susceptible to death from Covid-19 during the 2020 pandemic.

There is a great deal of research evidence concerning vitamin D and brain malfunction, including mental illness. While research continues it would be in the best interests of ethnic Black women to be checked for vitamin D deficiency, and if found it should be corrected as soon as possible during pregnancy.

This Blog post is not intended to be a full review of vitamin D deficiency in mental illness. It is intended to draw to attention the fact that many health disadvantages of ethnic Black people in the UK are being neglected because of an assumption of sociological causes, without any consideration of biological causes, of which vitamin D deficiency is the most obvious and most easily reversed. 

The ignoring of vitamin D in ethnic Black African and South Asian people in the UK is difficult to understand. There are many doctors of these ethnic groups, but they are silent. This is a very serious problem.

Monday 24 June 2024

Vitamin D: fœtal and neonatal neuro-development

A window in Rajasthan

My two recent Blog posts were on the subjects of the high risk of post-operative complications in ethnic Black children, and the high risk of maternal complications in Black women, both taken from articles in the UK Guardian newspaper. 

Although sociological reasons were suggested in the newspaper articles, I was particularly concerned about the absence of consideration of the vitally important and well-recognised problem of serious vitamin D deficiency in these population groups. There might be some truth in the sociological factors, namely racism, but correction of these is difficult and a randomised controlled trial, if demanded, would be impossible. However correction of vitamin D deficiency could take place immediately, and a randomised controlled trial would be theoretically possible. However it would require major committment by the government public health bodies and funding would need to be found. In the present climate of ignoring vitamin D, both would be unlikely.

The second of these Blog posts, considering maternal risk, was published on June 21st. On the following day a reader, John Enebak, brought to my attention a medical-scientific paper published on-line only on June 19th 2024.

This was a research paper from a team of paediatricians working in Jodhpur, western Rajasthan, India, and it is published in Nutritional Neuroscience, an International Journal on Nutrition, Diet and Nervous System.

In the study 175 mother-child pairs were enrolled. In the third trimester of pregnancy the maternal blood level of vitamin D was measured in the usual way as 25(OH)D.

The maternal blood  level of vitamin D was found to have a significant positive relationship to the cognitive development of the infants as measured at 6 months of age (p=0.047).

Umbilical cord blood was measured immediately after birth. There was a high correlation between vitamin D levels in maternal blood 18.86 +/- 8.53ng/ml (47.15 +/- 21.33nmol/L ) and in cord blood 17.39 +/- 8.87 ng/ml (43.48 +/- 22.18nmol/L).

Cord blood vitamin D levels had a significant associatiion with socio-emotional development of the infants at 6 months (p=0.023) and at 9 months of age (p=0.01).

In this study we have good evidence of the importance of vitamin D during pregnancy to optimise neuro-development of the offspring.

More evidence

The sceptic might say "But this is not proof". I would counter this asking the sceptic of the definition of proof, to which there is most unlikely to be an answer. Very few people seem to know the meaning of "proof", which is the fulfillmentf of pre-determined criteria. "Proof" is often confused with "evidence", and the study above is most certainly evidence. "But it is only observation", might be the retort. 

But science is based on observation. Science is then like a revolving wheel, each revolution representing research producing more evidence. Evidence must be repeated, or supported by complementary evidence. Alternatively reproducible evidence that is in conflict with the hypothesis (the black swan in a world of white swans, after Karl Popper) should bring the line of research to an end.

Month of birth and subsequent Multiple Sclerosis

There is other evidence linking brain function to vitamin D. An example is a study of the results of 42,045 people with multiple sclerosis assembled from individual studies undertaken in Denmark, Sweden, Canada and the UK. It demonstrated that the number of sufferers born in the Spring was above the annual average and the number born in the Autumn was below the annual average. 

This suggests that summer gestation, maximising increased sun exposure and vitamin D production during the third trimester, gives to the offspring an advantage of brain integrity that persists into adult life, and conversely winter gestation gives a disadvantage.

Willer CJ, Dyment DA, Sadovnick AD, et al. Timing of birth and risk of multiple sclerosis: populationbased study. BMJ 2005; 330: 120-123.

We can see the relationship between vitamin D blood levels (male and female) throught the year, and the timing of conception and subsequent delivery.

We can also see the risk of developing multiple sclerosis in relationship to month of birth, remembering the annual cycle of blood levels of vitamin D.

Spring birth after third trimester of pregnancy in the winter gives the greatest risk of multiple sclerosis.

We also know that multiple sclerosis is related to previous low intake of vitamin D.

Child Neurodevelopment : Study published in October 2023

Bruce Hollis has brought to my attention this study of the effect of vitamin D supplementation during pregnancy on subsequent neurodevopment of of offspring. The study was undertaken and the Medical University of Charleston, South Carolina, USA.

350 women were given a vitamin D supplement during pregnancy, randomised to receive either 400units (standard recommendation), 2,000units, or 4,000units each day. 172 consented to allow their offspring to participate in a follow-up study, and 156 were included in the final analysis.

Expressed as ng/ml, as in the paper

Figures:  Average blood vitamin D levels are shown for each group

Expressed as nmol/L

We can see the vitamin D characteristics in the Figures. In all randomised groups the initial blood vitamin D levels were less than 30ng/ml, 75nmol/L, and this is sub-optimal.

Maternal blood testing was repeated within one month of delivery. In all dose groups there was a significant increase in blood levels of vitamin D, the higher the dose, the greater the blood level achieved. 2,000 or 4,000units per day achieved a blood level of 40ng/ml, 100nmol/L and this is satisfactory.

Vitamin D supplements of 2,000 or 4,000 units per day during pregnancy achieved the first benefit of increasing blood levels, but th main purpose of the study was to look at possible benefits in respect of neurodevelopment of the offspring. This was assessed at between 3 and 5 years of age.

The method of assessment was the Brigance Screen II, a validated neurodevelopmental assessment tool. I must admit that I had no prior knowledge of this, but it is from a highly specialised area outside my clinical experience. 

I will not go into detail, but it is available in the original paper. Overall the study found evidence to support the important role that maternal vitamin D status during pregnancy influences child neurodevelopment. This was particularly noticable in respect of language development (also influenced by maternal educational level), in which vitamin D 2,000units per day was clearly superior to the "official" 400units per day, but in this study 4,000units per day showed no further advantage.

There was no analysis of vitamin D status in African American and Hispanic mothers.

Do no harm, but do your best

Medical practice is based on safety ("First do no harm") and also doing one's best to help a patient. "What can I do to help this pregnant mother-to-be to have a healthy baby?" One approach might be to detect and if necessary correct deficiency of the hormone cholecalciferol, that we know as vitamin D. The objective would be to use up-to-date information such as we have seen, to ensure that the maternal blood level of vitamin D is above 30ng/ml (75nmol/L), the maximum and safe level as judged by the valuable studies from India and the USA.  

Experience from the 2020 Covid-19 pandemic indicates that in respect of immunity and prevention of serious or fatal illness, a target blood level of vitamin D should be above 40ng/ml (100nmol/L).

Friday 21 June 2024

Vitamin D: excess birth complications suffered by ethnic Black women

 Why do Black women in England suffer from more serious birth complications?

On April 8th 2024 we read in the Guardian that ”Black women in England suffer more serious birth complications, analysis finds”. Whether “more serious” meant than the complications were more serious or that there were more of the complications was not immediately clear. I was alerted to this article because as a previously practising physician I am concerned about a group of people who are medically disadvantaged, and at an extremely important moment in their lives.

It was clarified that “Black women are up to six times more likely to experience some of the most serious birth complications during hospital delivery across England than their White counterparts”. They are "1.5 times more likely to develop pre-eclampsia”. They were “almost four times more likely to die in pregnancy and childbirth than White women”, and “Black children were twice as likely to be still-born”.

The analysis had been undertaken by the Guardian based on NHS data from 2022–23.

Professor Asma Khalil, vice president of the Royal College of Obstetricians and Gynaecologists, was asked for comments. First, she expressed lack of surprise, that it was already known. This in itself displays serious complacency. She suggested “structural racism” and the “unconscious bias of healthcare professionals”, and that the problem is “multifactorial”.

She went on to suggest that “Healthcare professionals and doctors cannot fix the problem on their own....”


Comments were also made by Dr Anita Banerjee, an Obstetric Physician with expertise in high risk pregnancies. She regarded the results as “disheartening”, and “trust is essential for reducing health inequalities”.

An NHS spokesperson suggested “more holistic support”. Vaguely correct.

The assumptions were that the problem was somehow sociological, someone else’s responsibility, but not that of medical professionals. Why is this? Where is the voice of medical scientists and responsible doctors?

It has been recognised that complications of pregnancy are more likely to occur in association of low blood levels of vitamin D. 

"Adverse health outcomes such as preeclampsia, low birthweight, neonatal hypocalcemia, poor postnatal growth, bone fragility, and increased incidence of autoimmune diseases have been linked to low vitamin D levels during pregnancy and infancy."  Reference

It is arguably not sensible or desirable for pregnant women to have low blood levels of vitamin D. It would be sensible if women were to have blood levels of vitamin D tested at least at the time of their first ante-natal clinic attendance, and ideally at pre-conception clinics or general practice opportunities. Hormone deficiencies should always be taken seriously, and this must apply to deficiency of the hormone cholecalciferol, that we know as vitamin D. It is unfortunate that the vice-president of the Royal College of Obstetricians and Gynaecologists appears to unaware of it.

In the Guardian report and commentaries by “experts”, there was not a single mention of vitamin D deficiency among ethnic Black women and their offspring. This itself is “disheartening”, especially as the two obstetric experts giving their opinions appear to be of South Asian ethnicity and are therefore likely to be seriously vitamin D deficient. But are they themselves taking a vitamin D supplement (I hope so): are they “drinking wine while preaching water”?

If our medical-scientific leaders would accept the correction of this well-recognised human hormone deficiency early in pregnancy, once again they would almost certainly demand an RCT.

It would need to be explained to ethnic Black pregnant women that their collective experience of pregnancy indicates a high incidence of misfortune, and this is probably the result of deficiency of the natural hormone that we know as vitamin D. “We are conducting a study in which half the pregnant women who participate would have the vitamin D deficiency corrected and half would receive a placebo, but no participant or obstetrician would know who was receiving which”. It is unlikely that a pregnant ethnic black woman would agree to receive the placebo.

While we wait for a randomised controlled trial (RCT) to be agreed, to be funded, to receive ethical approval, to be conducted and for the results be analysed, how many more serious birth complications will occur?

If the blood levels of vitamin D are checked early in pregnancy, are half of those with low levels going to be randomised to placebo?

But what about the proposal that racism is the cause of the excess childbirth complications among Black women in the UK? How can this be "treated"? Must Black women and their offspring continue to be disadvantaged in the process and outcome of pregnancy? How long will it take to test this hypothesis? How long will it take to organise an RCT of reduction of racism?

This of course indicates the absurdity of demanding an RCT in all circumstances of patients care. The hypothesis of racism affecting the outcome of pregnancy is assumed, but is untested and untestable. It is also preventing the serious consideration of vitamin D deficiency being the key to the health disadvantages of ethnic Black African and South Asian people, and especially the maternity disadvantages of Black women. 

This Blog post should be taken in conjuction with the previous Blog post concerning the high risk of post-appendicectomy complications of Black children.

Thursday 30 May 2024

Vitamin D : post-operative complications in ethnic Black children

I would like to draw your attention to the first of three recent articles that have been published in the UK national newspaper the Guardian. These were very important in themselves, but unfortunately the important connection between the stories was not recognised.

Why do ethnic Black children suffer from an excess of complications after appendix surgery?

The first story appeared on February 22nd 2024, written by the excellent Tobi Thomas, Health & Inequalities Correspondent. It reported a finding that in England ethnic Black children suffer “more complications” after appendix surgery. 

Surgical removal of the appendix (appendicectomy / appendectomy) is usually an emergency operation performed because of acute appendicitis, a rapidly progressive infection of the appendix. If untreated there will be catastrophic infection within the abdomen (“ruptured or burst appendix”) with a fatal outcome. This an infective process, for which surgical cleaning should be undertaken and antibiotics will be given. However as with any infection our innate defensive immunity is essential.

We know that ethnic Black African people in general and children in particular, when living in the UK are more deficient of vitamin D than ethnic White people. Production of vitamin D in the skin is suppressed by reduced penetration of UV into dark skin, and by relative lack of required UV energy when living closer to the North Pole than to the Equator. This is known and beyond dispute.

We know that the hormone cholecalciferol, also known as vitamin D, is produced in the skin and is essential for optimal immunity, and that low blood levels lead to an increased risk of serious infection. This has been established clearly during the Covid-19 pandemic, but it was previously known in respect of tuberculosis.

It has also been demonstrated that the risk of post-operative infection and hospital acquired infections in general, are increased with low blood levels of vitamin D, and that such infections are rare in people with good blood levels. 

The risk of poet-operative infection related to blood level of vitamin D. 

It would appear that a blood level of 60ng/ml, 150nmol/L 

puts an individual into the safe range.

The problem appears to be straightforward: the most simple explanation of why ethnic Black children have an unusual high incidence of complications after appendix surgery is because they are seriously deficient of vitamin D.  We know this from the observations of infantile rickets in these children. 

Why this is not recognised by health professionals is a mystery. It is an obvious theory, without an obvious alternative explanation. Intervention is simple. Are we dealing with medical ignorance, or do they not care about ethnic Black children?

Even if the problem came to their attention, many so-called medical scientists would almost certainly argue that there must be a randomised controlled trial (RCT) of correcting deficiency of the natural hormone cholecalciferol / vitamin D when given before appendix surgery in ethnic Black children, and that the trial must precede a hormone replacement policy The impossibility would probably not occur to them. Doing one’s best to help individual patients might not be part of their responsibility. Instituting physiological hormone replacement therapy is not the same as testing a new pharmaceutical preparation.

If we think about an RCT we must consider the following. How many ethnic Black children have appendix surgery in the UK each year? How many hospitals would be involved to reach a necessary sample size? How would it be co-ordinated? Where would administrative funding come from? Is there an incentive to make an RCT happen? Does anyone with influence really care? Would the randomisation process, which must include informed consent by the parents, delay what must be emergency surgery? With existing knowledge, would ethical approval be given?

We know that vitamin D given by mouth or injection takes several days to become part-activated into the circulating form 25(OH)D. How does this fit into preventing complications resulting from emergency surgery? The answer is that the child must receive 25(OH)D, calcifediol, which acts within two hours, and which proved itself in the Covid-19 pandemic. How many doctors know this? How many know that calcifediol is now available in the UK for human as well as animal use?

Recruitment into an RCT requires informed consent. Information given by the study administrator might go like this: “We know that ethnic Black children have a high incidence of complications following appendix surgery compared to ethnic White children, and we suspect that this is due to deficiency of the natural hormone vitamin D. We want to try to either prove or disprove this by a randomised trial of vitamin D (as calcifediol) given before surgery. If you give consent to the trial it means that your child might receive vitamin D or might receive a placebo of just olive oil, which has no effect.

The parents are likely to say “I want you to do your best for my child. As vitamin D, being a natural hormone, when given in this way has no dangers and probably has great advantages, after your explanations I want him to have vitamin D, not the placebo”.

The sensible approach is to give vitamin D as Calcifediol to ethnic Black African children with acute appendicitis, and compare the incidence of post-operative complications with historical records.

To appreciate the importance of calcifediol over “raw” vitamin D in emergency care, see:


Monday 1 April 2024

Vitamin D – evidence neglected during the Covid-19 pandemic

The neglected importance of natural immunity and vitamin D during the pandemic of Covid-19

What is natural immunity?

A good starting point is to remember the HG Wells story “War of the Worlds”, published in 1897.  Technologically advanced life forms from Mars invaded Earth, and after leaving a trail of destruction they suddenly all died. The cause of death was considered to be “the bacillus”, an infection. The “germ theory” of the causation of disease was a new medical-scientific concept at the time. The invaders from Mars died because they had no immunity to protect them against the Earth's bacteria that caused fatal infection.

Humankind has inherited natural immunity, which evolved during the 3,500 million years since life on Earth began. It was present in a simple form in early life-forms, including plankton that emerged 1,500 million years ago. 

It is interesting that plankton were, and still are, able to synthesise the oil 7-dehydrocholesterol (7-DHC), which UV from the Sun converts into cholecalciferol. In the early 20th century this became known as vitamin D.

Figure 1. UV from the sun acts on 7-DHC

The hormone cholecalciferol is a vital component of the escalation of defensive immunity in humankind and other advanced land animals, but it was of no value to the plankton that initially produced it. Their immunity had not evolved to require vitamin D / cholecalciferol. The conversion of 7-DHC into cholcalciferol within plankton absorbed damaging energy of UV radiation close to the surface of the ocean and it thus acted as a "sunscreen" to protect the plankton. 

Much later (420 million years ago), fish needed vitamin D for their boney skeleton and advanced immunity, but being covered in scales or thick skin, and living at depths, meant that they could not poduce it from the Sun. They therefore obtain their vitamin D from consumption of plankton in the aquatic foord chain. When we eat fish, the vitamin D that we take in is derived from plankton.

Advanced defensive immunity appeared as a very sopisticated evolutionary development in the complex life-forms that  appeared "suddenly" in the Cambrian era, about 500 million years ago. 

Bacteria and viruses had been present since early evolution, before the critical  appearance of plankton. However further evolution of complex animal life could not advance until defensive immunity against bacterial and virus infection had developed. Any new life form of a more advanced nature would have died in the way of the Martian invaders in the story by HG Wells. The development of sophisticated defensive immunity must have been among the most critical steps in evolution.

The components of immunity

It is as well to know just a little of the highly complex cascade of immunity. Only 10% of the cells of our body are human. 90% are tiny micro-organisms, and they must be kept under control. When we die, they take over and we decompose, but while we are alive our defensive immunity is of vital importance.

There are two major components of immunity, antibodies in the circulation, and the much more complex but the less easy to measure tissue immunity. Both are activated by signals of invasion of our body tissues by micro-organisms.

The genes of the cells of immunity must themselves be activated so as to escalate defensive cell processes and proteins. The key to this is a complex protein molecule called VDR that is synthesised within the cells, and this was a critically important evolutionary event.

But by an “accident" of evolution, VDR is synthesised in an incomplete form: it lacks a small steroid component. We could call this an ecomomy of evolution because this "small steroid component" of a complex molecule is created elsewhere in the body. We synthesise in our skin the oil 7-dehydrocholesterol (7-DHC) and and as we have seen, by another accident of evolution, UV from the sun converts this into the hormone cholecalciferol, that we also know as vitamin D. 

Vitamin D (in the activated form 1,25(OH)D) is the component required by VDR (Vitamin D Receptor) to make it complete and therefore active. It can then switch on the genes that control the escalation of immunity.

There is no need to expand on the highly complex process of defensive immunity at this stage. It is important to appreciate its activation and its importance.

Figure 2: The activation of defensive immunity

What did we know in January 2020?

Vitamin D had been discovered early in the 20th century. It was recognised that deficiency was common in people who were deprived of sunlight, resulting from indoor life and serious atmospheric pollution. 

The main results of this were childhood rickets (vitamin D deficient bone disease) and tuberculosis (due to vitamin D deficient sub-optimal immunity). It was identified that both could be reversed by exposure to the sun or by consumption of fish oils.

An epidemic of AIDS occurred at the end of the 20th century, and this was characterised by defective tissue immunity due to suppression of T-lymphocytes, that under normal circumstances are activated by vitamin D + VDR. This gave us a great deal of insight into the effects of the suppression of immunity, with consequent increased incidence of tuberculosis, other microbial infections, certain cancers, neurological disease, and heart deaths.


From the experience of the early and late 20th century, the importance of natural defensive immunity and the critical role of vitamin D in its escalation were well known before the arrival of the Covid-19 pandemic.

It was also known that vitamin D deficiency is common and that certain groups within the population are especially susceptible.

The elderly

As mentioned, we produce within our skin the oil 7-DHC, in the same way as plankton and many land animals.

UV from the sun converts 7-DHC into cholecalciferol / vitamin D, but the problem in the elderly is that the skin becomes thin and dry. Adequate amounts of 7-DHC are no longer synthesised in the skin, and so adequate amounts of vitamin D cannot be produced. This has been known since 1985.

Figure 3: Production of vitamin D in the skin of the young and the elderly

Elderly people will inevitably be increasingly deficient of vitamin D, no matter how long they sit in the sun. However there will be variation among the elderly and this requires further research with blood levels. 

A supplement of vitamin D in adequate dose is essential in the elderly, so as to prevent deficiency and maintain optimal immunity.

This should have been a public health priority as soon as the onset of the pandemic was anticipated. The neglect of this policy led to large numbers of deaths of the elderly from Covid-19.

A small supplement of vitamin D (400 units each day) was belatedly recommended to elderly people in mid-2020, but with the intention of protecting against the very rare bone disease osteomalacia (not the much more common osteoporosis which is not due to vitamin D deficiency). No mention was made of the need to optimise immunity by correcting vitamin D deficiency, nor any attempt to detect vitamin D deficiency by blood testing.

Black African and South Asian ethnic groups

In the 1920s it was observed informally in Glasgow and other industrial cities that rickets and tuberculosis tend to co-exist within families. A remarkable study conducted in Bombay showed the same thing, but the two conditions occurred in the families of the wealthy, who had an indoor life, whereas these medical conditions were rare in the much more healthy poor families who worked in the fields (Hutchison HS, Shah SJ. QJMed 1922; 15: 167-195). VItamin D deficiency was clearly the problem. 

In the UK since the 1960s it has been known that children of ethnic Black African and South Asian parents have a significantly high incidence of rickets, and that adults have a high incidence of tuberculosis, both resulting from vitamin D deficiency. We have known of the much higher prevalence of severe vitamin D deficiency in people of Black African and South Asian ethnicity in the UK compared to ethnic white. 

It has been known that the pigmentation of dark skin blocks UV penetration, and although of benefit in the intense sunlight of the tropics, it seriously reduces the amount of vitamin D produced in the skin when living in the UK for example, closer to the North Pole than to the Equator. Extensive clothing and vegetarian diet worsen the vitamin D deficiency.

Knowing of their consequent reduced immunity, there should have been a public health imperative to correct the severe vitamin D deficiency in the Black African and South Asian ethnic groups. Failing to do so resulted in the devastating effect of Covid-19 on these groups. 

Figure 4: A view of the Muslim section of
cemetery of Bradford, UK, in 2020

Three official reports into the high mortality of Black African and South Asian ethnic people from Covid-19 concluded that it was the result of socio-economic disadvantage and racism. In just one of the three was vitamin D mentioned, only to be dismissed immediately. There was no biological consideration.

26 practising doctors died from Covid-19 in early 2020, and of these 25 were of Black African and South Asian ethnicity. No notice was taken of this disturbing fact, even though it negated the sociological conclusion of the reports. The relevant racism was the deliberate ignoring of the special needs of the Black African and South Asian ethnic groups.

Figure 5: Practicing doctors who died
from Covid-19 in the UK in 2020

Ignoring the established high prevalence of serious vitamin D deficiency in people of Black African and South Asian ethnicity was a serious dereliction of duty by those responsible for public health, resulting in high death rates from Covid-19. How did this come about? Who was responsible? Have lessons been learned?

The Obese

It was also known before the Covid-19 pandemic that obese people, as well as having overall poor health, have on average low blood levels of vitamin D. It was again predictable that the obese would be vulnerable to serious and perhaps fatal Covid-19. And so it turned out.

If an obese person receives a given exposure to UV, the blood levels of vitamin D will increase less than, perhaps 50% less than, with a non-obese person. The reason is that vitamin D, being an oil, is taken into the fat calls of the body.

Figure 6: Production of vitamin D in the skin
of the obese and the non-obese

The obese could also have been protected against Covid-19 by correction of low blood levels of vitamin D. This did not happen and so when the Covid-19 pandemic arrived, the obese suffered disproportionately, with a large impact on intensive care units.

This was predictable and action should have been taken in early 2020. Why did this not happen?

What did we learn in 2020?

Suggestions that vitamin D should be given to optimise natural immunity during the pandemic of Covid-19 were met by scepticism and claims that there was "no proof of benefit". The definition of “proof” was never declared. Proof is pragmatic and it means the fulfilment of pre-determined criteria, and these criteria must be clear and testable.

When it was stated repeatedly that there was “not enough evidence”, it was not clear how much evidence would be “enough”. The famous criteria of proof defined by Sir Austin Bradford Hill were not considered, even though they were fulfilled.  When the results of randomised trials  became available, it was stated that they were “too small”, despite clear statistical significance and no untoward effects demonstrated.

Observations that people critically ill with Covid-19 almost always had very low blood levels of vitamin D led to criticisms that this was the result of the illness rather than causative. This had some truth, as the low blood levels of vitamin D were both causative and the result. The details were not clearly understood by the critics. 

In Galilee, Israel, severity of Covid-19 was assessed against blood levels of vitamin D that had been recorded before the pandemic. All of the critically ill patients had pre-illness vitamin D deficiency, and most of them had severe deficiency. 

It was clear that a blood level of vitamin D above 100nmol/L (40ng/ml) provided protection against critical Covid-19, whereas blood level below 50nmol/L (20ng/ml) gave a significant risk of critical Covid-19. 

This is the most important message of 2020 that could, or should, have underpinned policy in the future. The obvious public health objective would be to make certain that blood vitamin D levels are in the safe range.

Why was this study ignored by those "experts" who were in charge of public health? Why were they asleep?

How much vitamin D supplement should be taken?

The answer must be “Sufficient to achieve the target blood level”. This is the same as in the treatment of diabetes with insulin or other treatments of deficiency disorders. To heal rickets in children, just a small quantity of vitamin D is necessary, 400 units each day. However it is clear that a higher dose is necessary to optimise immunity.

Vitamin D and insulin were isolated at about the same time, but it was not possible a century ago to measure their mass. They had to be measured in internationally agreed biological units. One unit of vitamin D was defined as the daily requirement of a ten gram mouse. Scaling up from that, the daily requirement of a 60kg human would be 6,000 units per day.

Strictly speaking we should express a dose as for example, 6,000iu per day. However many people might not understand that "iu" means "international units". As with insulin, I use the term "units" as it is clear, well-known, and it is standardised.

To be cautious it is as well to have a starting dose of 3,000 units per day, adjusting the dose as necessary in future months. Dose adjustments do not need to be made for the elderly or those with a dark skin. However the obese will require a higher dose of vitamin D, and this should be related to body weight.

The vitamin D that we take as a supplement is also the result of solar UV acting on 7-DHC, but in the skin and wool of sheep. Vitamin D is a component of the oil in the fleece of a freshly sheared sheep. It is extracted in an organic solvent and purified to provide supplements for indoor farm animals (80%) and for humans (20%). The vets are ahead of the game, and we seem to care more about farm animals than about humans.

Effect of immune response on vitamin D

Vitamin D circulates in the blood as a reservoir, ready for use whenever necessary. Its circulating reservoir form is as 25(OH)D, a hydroxyl group (–OH) being added during a slow process that takes place in the liver. It is as 25(OH)D, also known as calcidiol or calcifediol, that we measure vitamin D in the blood. 

As with all reservoirs, it desirable for it to be almost full rather than almost empty. Water in our reservoirs is continually used and continually refilled by nature; vitamin D is also continually used and must be continually replenished by nature, by the Sun. 

A molecule of vitamin D in its fully activated form 1,25(OH)D can be used only once to activate VDR, the key complex intracellular molecule that will activate the genes necessary to optimise defensive immunity. 1,25(OH)D is then automatically and irreversibly de-activated, so as to prevent dangerous accumulation. Immune cells can synthesise any number of VDR molecules, but vitamin D must come from the skin (as a hormone) or from the diet (as a vitamin).

So when defensive immunity is active, vitamin D will be consumed and stores circulating in the blood will become depleted. Immunity is active in response to an infection, but also in response to a vaccination, which acts like an infection so as to produce defensive capability for the future.

It follows that during the pandemic of Covid-19 repeated infections and repeated vaccinations will have resulted in vitamin D depletion. This in turn could be the reason for the current problem of excess illness and excess deaths, affecting not just the UK but many other countries of the world. 

The answer to current problems of excess illness and death is quite simple. We must apply our knowledge of the great importance of vitamin D. There is a big opportunity, and meeting this opportunity is imperative.