In this example the Nation is the UK where I live.
There is no doubt that the best way to have adequate levels of vitamin D is through sun exposure and food. Being in the sun has many beneficial effects as well as manufacturing vitamin D by Ultraviolet B converting 7-dehydrocholesterol into cholecalciferol (vitamin D3).
However, in the UK the sun is too low in the sky for most of the year and the sunlight travels a longer path through air which absorbs a lot of the UV B. Also life has changed, most people do not work outdoors, they travel to their work offices in enclosed vehicles, and even when in the sun use protection creams for fear of getting skin cancer; that SPF is about blocking UV B. Most people in the UK are deficient in vitamin D. Even in sunnier places people are still deficient if they do not work outdoors and live in a city with vehicle pollution [1].
First, my own experience of taking a vitamin D3 supplement. The idea of taking supplements started in 1970. I had a bad cold and one of my students at that time asked if I had read Pauling's book Vitamin C and the Common Cold. As I had not he gave me his copy to read. I started taking about a gram a day of vitamin C powder. I did not notice it had much effect on common colds but it helped a lot with small burns and other minor cuts that I got cooking food or doing DIY.
My interest in vitamin D started when I read some of the work of Frank and Cedric Garland, for example [2]. I don’t remember when I started taking a D3 supplement but it was many years ago. I took a 2000 IU D3 capsule a day. This did seem to make a difference to common colds, they never developed as before, just a day or two of nose blowing. If I had a sore throat I made a bread & butter sandwich of chopped fresh garlic and chewed it well – a pungent resolution. One thing that still popped out from time to time was a ‘cold sore’, some hibernating herpes simplex viruses suddenly picked up that I was a bit run down - work stress, getting chilled or whatever - and I got an itchy spot under my nose. I repressed it immediately with an aciclovir cream and it cleared in a day or two – for a few weeks or months. I always kept one fresh tube of cream for next time.
When SAR-COV-2 appeared I thought that I would check my serum vitamin D level. The result was 35 ng/mL. I thought that too low and started taking 10,000 IU D3 a day sometime in 2020 to put my serum level over 50 ng/mL. Not only have I had no significant respiratory infection (though that could be chance) but the ‘cold sores’ have not reappeared, which for me was the most significant effect – the tube of cream I had passed its expiry date. That’s my relevant story.
We know that T and B lymphocytes express vitamin D receptors when they become active. Clearly, vitamin D is critical to immune function. You don’t install a letter box in your door unless you expect some letters. Vitamin D is needed for our immune system to work properly [3].
We can estimate the optimal serum level from native Africans whose ancestors have lived in the equatorial sun for millennia giving evolution time to balance skin pigment to avoid damage and D3 production: 50 ng/mL is a good ballpark number [4].
In the UK, government data shows that over half the population does not get to 20ng/ml, which is insufficient [5] (50 mmol/L is near to 20 ng/mL). Therefore, a supplement is needed.
We need two other ingredients to allow the vitamin D to do its job correctly. Vitamin D does many things, one is calcium and phosphate regulation. We need vitamin K2 to make sure that calcium goes into bones and not the vascular system. Magnesium is also critical for vitamin D actions. Magnesium intake also seems to be deficient [6, 7]. They say subclinical compared with Reference Nutrient Intakes but the RNIs are generally the minimum you can get away with.
We know that taking a D supplement is safe up to absurd doses. Because there is a convenient capsule, 10,000IU D3 + 200mcg K2, that's what I take, always with food, giving me a serum calcifediol of >50ng/mL - I occasionally do a blood test.
I think it is important to take every day - this is what would happen if we lived in a sunny place, we would get the vitamin D update every day. Vitamin D3 (colecalciferol) is not an active molecule, it is converted by the liver into calcifediol the active form of the molecule, which takes time [8]. You cannot just take a big dose of D3 and expect the active form of vitamin D in your blood a few hours later, it takes some days. You need good vitamin D status before a pathogen gets you. Calcifediol is what a serum test measures, it circulates for about two weeks. It has actions in its own right but some is converted by the kidneys into the hormone calcitriol in pg/mL quantities.
Therefore, give everyone a free prescription for it. It will pay for itself many times over by 'saving the NHS', both GPs and hospitals will get fewer people in a critical state, and everyone will be healthier and more productive (and less will be spent on medical drugs - aye there's the rub ....). I do wonder if better D3 and magnesium levels would improve mental health, I personally find it hard to feel depressed for more than an hour.
My 10,000IU D3 + 200mcg K2 + 500mg Magnesium Citrate costs ~£10 a month. This is delivered to the door from commercial suppliers. Were the NHS to bulk buy it could cost a lot less. Taking this all year would cost me £120. For comparison, one visit to an NHS A&E department had an internal cost of £419 (in February 2020) before any specialist treatment.
I wrote the draft of this over a year ago. I have not looked up the latest costs because even if they doubled it would not alter the essence of my argument. In any case I just took some value within a range. The UK population is 68 million.
Taking costs from suppliers in China with a $ to £ conversion factor 0.8
I multiply: population, days in a year, dose in grams, and cost per gram.
D3 $30/Kg
10,000 IU is 250mcg
68,000,000 * 365 * 0.250/1000 * 30/1000 = $186,150 = £148,920
K2 $600/Kg
68,000,000 * 365 * 0.200/1000 * 600/1000 = $2,978,400 = £2,382,720
Magnesium Citrate $2/Kg
68,000,000 * 365 * 0.500 * 2/1000 = $24,820,000= £19,856,000
Total £ 22,387,640
Of course, this has to be compounded and delivered. I looked up the retail cost of Paracetamol and compared with bulk cost of Acetaminophen. That gave a factor of 16. There will be profits in that so I will just multiply the total I calculated above by 10, and round it up to £250,000,000. That’s less than £4 per person per year. Prices for thousands of tonnes of the ingredients would probably be less than I found. The current NHS budget is £180 billion. The cost above is 0.0014 of that.
We already have a system for prescription and supply of medications that we can use for this supplement too. We could have local delivery and instruction by local volunteers.
I think we can afford a year’s trial. The dose should be smaller for children and maybe this could just be for six months, October to March. Maybe we need to test serum D levels in different cohorts of the population. People with darker skin are more likely to be vitamin D deficient. COVID-19 caused proportionately more deaths in people with darker skin in the UK. Maybe some people will find magnesium citrate does not suit and we should swap to magnesium glycinate. There are many such details to decide.
My bottom line is, if people are deficient they need a supplement, that there is a little money to lose if the effect is minor but a huge amount to gain if it does work to reduce illness.
Oh, and that awful COVID-19. The latest research on vitamin D levels from Israel indicate that it does help [9].
Appendix for updates
1/03/2023. Something that I intended to add but forgot about is the importance of vitamin D for healthy gums and teeth. Don’t add a fluoride to drinking water that gives an unmetered amount of a potential toxin, just make sure people, especially children, have good vitamin D status [10].
3/03/2023. When I suggested vitamin D could be important for mental health I did not know of any research on that matter. However, here it is from 1/02/2023. This is a stunning result reducing suicide [11].
5/03/2023. Here are higher intakes of vitamin D for several years resulting in resolution of other illnesses [12].
First sentence: Vitamin D3 is a secosteroid hormone produced in the skin in amounts estimated up to 25,000 international units (IUs) a day by the action of UVB radiation on 7-dehydrocholesterol.
Also: During this time, we have admitted over 4700 patients, the vast majority of whom agreed to supplementation with either 5000 or 10,000 IUs/day. Due to disease concerns, a few agreed to larger amounts, ranging from 20,000 to 50,000 IUs/day. There have been no cases of vitamin D3 induced hypercalcemia or any adverse events attributable to vitamin D3 supplementation in any patient.
References
[1] The impact of air pollutants, UV exposure and geographic location on vitamin D deficiency. https://pubmed.ncbi.nlm.nih.gov/29409825/
[2] Could sunscreens increase melanoma risk? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1694089/
[3] Vitamin D and the Immune System.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166406/
[4] Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l.
https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/traditionally-living-populations-in-east-africa-have-a-mean-serum-25hydroxyvitamin-d-concentration-of-115-nmoll/6188564A01361C5CF5F196229430E475
[5] Distribution of vitamin D status in the UK: a cross-sectional analysis of UK Biobank.
https://bmjopen.bmj.com/content/11/1/e038503
[6] Micronutrient Intakes of British Adults Across Mid-Life: A Secondary Analysis of the UK National Diet and Nutrition Survey
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6060686/
[7] Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786912/
[8] However, colecalciferol can diffuse directly into cells or get in via membrane proteins like megalin, with mechanisms in those cells to converting it to the active form. So better late than never, but better never late.
Vitamin D: The “sunshine” vitamin
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/
[9] Pre-infection 25-hydroxyvitamin D3 levels and association with severity of COVID-19 illness
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0263069
[10] Vitamin D Deficiency and Oral Health: A Comprehensive Review. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7285165/
[11] The association between vitamin D serum levels, supplementation, and suicide attempts and intentional self-harm.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0279166
[12] Daily oral dosing of vitamin D3 using 5000 TO 50,000 international units a day in long-term hospitalized patients: Insights from a seven year experience