More than two dozen studies of Covid-19 show us the way to TURN BACK the Second Wave.

Vitamin D versus Covid-19

These 27 studies show that having normal blood levels of vitamin D reduces Covid-19 risks:
* vitamin D reduces risk of infection [7, 8, 9, 11, 12, 14, 16, 23, 27]
* vitamin D reduces risk of having a severe case [1, 3, 4, 5, 15, 17, 20, 22, 24, 25, 26]
* vitamin D reduces risk of hospitalization, ICU care, or mechanical ventilation [2, 10, 14, 15, 21, 22, 24, 26]
* vitamin D reduces risk of dying from Covid-19 [4, 6, 7, 9, 12, 13, 17, 18, 19, 22, 24, 25]

And all you need to get those benefits is a normal blood level of vitamin D:
30 to 100 ng/ml, which is the same as 75 to 250 nmol/liter.

Note, however, that one study [27] found that vitamin D levels in the range of 50 to 60 ng/ml had the lowest risk of infection from Covid-19, about half the risk of the blood level 20 ng/ml. But the other studies show that 30 ng/ml (or higher) is enough.

The type of vitamin D measured by lab tests in the blood is called “25(OH)D”.

“Vitamin D deficiency is defined as a 25(OH)D below 20 ng/ml (50 nmol/liter), and vitamin D insufficiency as a 25(OH)D of 21–29 ng/ml (525–725 nmol/liter).” [86]

What is causing the Second Wave? Vitamin D blood levels are seasonal; they rise and fall from one season to another. In summer, vitamin D levels are higher because people are out in the sunshine. When sunshine (specifically UV-B) strikes the skin, the body makes vitamin D. But as people spend more time indoors, in autumn and winter, vitamin D blood levels fall. The levels decrease from late September to October to November, and they reach their lowest extent in December through March.

This type of seasonal vitamin D deficiency and insufficiency is VERY COMMON in nations of the northern hemisphere, especially further north. The Southern States in the U.S. have this problem, but to a lesser extent than the States at higher latitudes in the U.S. Then Europe and Canada also have low vitamin D in autumn and winter.

In Muslim nations and in other nations where the religion or social custom requires covering the skin so that little skin is exposed to sunshine, vitamin D deficiency can be quite widespread. It is too difficult to obtain vitamin D from food, unless it is fortified with vitamin D. But even when, it would be too difficult to get the right amount of vitamin D to everyone in the right dosage through food. Perhaps religious or social rules could be loosened by authorities, so as to permit “sunshine on skin” to make vitamin D. The other possibility is vitamin D supplementation (discussed further below).

In the United States, where the Second Wave will strike next starting in October, more than twice as many adults have a vitamin D deficiency in winter (48%) than in summer (21%) [85]. That increases the number of persons infected with Covid-19, which greatly increases the spread (as the disease is highly contagious), and it also increases the severity of those cases that have low vitamin D, resulting in a much greater need for hospital beds, ICU beds, and ventilators. Low vitamin D in winter increases the fatality rate (percent who die) on top of a higher case rate, meaning that the number of deaths rises faster than the number of cases, since the cases are more severe.

Example

Allow me to explain that point further. Suppose that the number of cases per month rises from 2 million in a summer month to 6 million in a winter month. That type of tripling of the number of cases can easily happen. In some nations, the multiple could be much higher than three times. You might expect the number of deaths to also triple, right? Not so. The low level of vitamin D in the general population results in a higher percentage of deaths. So instead of having a death rate of 2% against 2 million cases, for a death toll in one month of 40,000 (in this hypothetical), we could see a higher death rate of 5% (or more) against the higher number of cases, 6 million, for a monthly death toll of 300,000. In this example, the cases rise by 3 times, but the deaths rise by 7.5 times.

The Vitamin D Solution

The Second Wave is largely caused by low vitamin D levels. But EVEN IF IT IS NOT, the studies show that having higher levels of vitamin D will reduce the infection rate, reduce the severity of cases, and greatly reduce the death rate. Having normal levels of vitamin D results in a risk of death that is 90% lower (i.e. one tenth) the risk of someone with vitamin D deficiency. And, conversely, vitamin D deficiency results in a risk of death that is ten times higher than someone with normal levels of vitamin D.

So IT DOES NOT MATTER if vitamin D is the cause or not (really, it is the cause). IN ANY CASE, vitamin D can reduce the Covid-19 infection rate, but, most importantly, vitamin D can reduce the Covid-19 death rate by 90% or more. It also reduces the severity of cases, meaning we will not need as many hospital beds or mechanical ventilators, even with an increase in cases. So the solution is vitamin D.

Should We Wait?

We need a massive multi-nation vitamin D “supplementation or sunshine” program. And we need it FAST. Please, I’m begging you, just this once, do NOT listen to the overly cautious experts who say we have to wait for more studies and not take any risks. Listen to me, it’s a vitamin pill. It is as safe a medication as you could give to persons facing a deadly disease. Even at high doses, vitamin D is relatively safe and effective [81 to 84]. There are small risks, but the benefits vastly outweigh those risks. So please ignore those few experts who advise caution and waiting — they are implicitly advising not caution and waiting, but suffering and dying. Choose vast benefits now with minor risks, rather than vast deaths now, and the same risks no matter how long we wait. The risks don’t go away. So act now.

— “To reduce the risk of infection, it is recommended that people at risk of influenza and/or COVID-19 consider taking 10,000 IU/d of vitamin D3 for a few weeks to rapidly raise 25(OH)D concentrations, followed by 5000 IU/d…. For treatment of people who become infected with COVID-19, higher vitamin D3 doses might be useful.” [81]

— “Results: Serum 25(OH)D rose as a function of self-reported vitamin D supplement ingestion in a curvilinear fashion, with no intakes of 10,000 IU/d or lower producing 25(OH)D values above the lower-bound of the zone of potential toxicity (200 ng/ml). Unsupplemented all-source input was estimated at 3,300 IU/d. The supplemental dose ensuring that 97.5% of this population achieved a serum 25(OH)D of at least 40 ng/ml was 9,600 IU/d. Conclusion: Universal intake of up to 40,000 IU vitamin D per day is unlikely to result in vitamin D toxicity.” [82]

— “It is therefore proposed that supplementation of vitamin D can reduce the risk and severity of COVID-19 infection.” [83]

— “Therefore, from reviewed literature, it seems fairly appropriate to suggest taking Vit-D at 10,000 IU/day as an adequate dose to enhance circulatory concentration of Vit-D into the optimal range of 40-60 ng/mL; after 1 month the dose can be reduced to 5000 IU/day to maintain serum levels.” [84]

So you can see from the quotes above that some experts recommend Vitamin D supplementation as a measure against Covid-19 [81, 83, 84], at a dosage of 10,000 IU per day for a few weeks or a month, reducing to 5,000 IU/day thereafter [81, 84]. Doses of 10,000 IU/day are necessary to raise vitamin D levels in 97.5% of the population to optimal levels; lower doses may not be effective in everyone [82]. Doses as high as 40,000 IU/day are unlikely to result in vitamin D toxicity [82].

And, as a good side effect for society, there are additional benefits from raising the population’s vitamin D levels. Studies have shown that higher intake of vitamin D reduces risk of respiratory tract infections [101], stroke [102], multiple sclerosis [103], rheumatoid arthritis [104], type 2 diabetes [105], breast cancer [106], prostate cancer [107], colon cancer [108], and all-cause mortality [109].

How Much Vitamin D?

Vitamin D can be taken daily or once-a-week — or even once a month (in a very high “bolus” dose). I think it is preferable to take vitamin D either daily or weekly.

The higher the dose of vitamin D you take, the faster you raise your vitamin D blood levels, within certain limits, of course. If you take the usual daily recommended amount of vitamin D — when you have a vitamin D deficiency — it might not be enough to raise your blood levels at all. And a modestly higher dose might only raise vitamin D blood levels very slowly over the course of months. To raise vitamin D blood levels from 20 ng/ml to 40 ng/ml quickly, an adult would have to take 10,000 IU of vitamin D every day for a month. And those who have vitamin D deficiency — the very persons who need higher blood levels to save their lives — would need to take that dose for at least twice as long. Persons who are over-weight or obese need to take a higher dose of vitamin D to raise their blood levels, as fat tissue absorbs vitamin D; it is stored in body fat.

In winter, 48% of the U.S. adult population is in vitamin D deficiency (below 20 ng/ml) and another 22% or so is in vitamin D insufficiency (20 to 29 ng/ml) [85]. So to correct deficiency or insufficiency quickly, a loading dose is used, i.e. a higher initial dose. Also, persons who are overweight need 1.5 times as much vitamin D, and those who are obese need 2 to 3 times as much vitamin D [110].

For adults of normal body weight or overweight:
* 50,000 IU of vitamin D3 every day for 7 days,
* then 50,000 IU once a week for the rest of the pandemic (or 10,000 IU once a day).

For adults who are obese:
* 50,000 IU of vitamin D3 every day for 7 days,
* then 100,000 IU once a week for the rest of the pandemic (or 20,000 IU once a day).

For adults who are sick with Covid-19:
* 300,000 IU of vitamin D3 on the first day (once only), [87, 90]
* then 50,000 IU every day for 5 more days, [82]
* and then 10,000 IU every day until well
* then 50,000 IU once a week (or 10,000 IU/day).

For Children and Teenagers:

Infants, 400 IU/day
Children, 1-3: 2,000 IU/day
Children, 4-8: 3,000 IU/day
Children, 9-13: 4,000 IU/day
Teens, 14-18: 4,000 IU/day

The above doses were arrived at in the following manner. For infants, the dose is the AI (adequate intake) of 400 IU for birth to one year; that’s what infants should be getting in any year, regardless of the pandemic. It’s the normal healthy amount of vitamin D for infants. For children, 1 to 3 years, the dose is 520 IU less than the TUL (tolerable upper limit). So that is a safe dose for that age group. For children, 4 to 8 years, the dose is the TUL. By definition, the TUL is a dose that is safe to take on a continuing basis. For children, 9 to 13 years, the dose is also the TUL, so that is also safe. For teenagers, 14 to 18, the dose is the TUL for that age, which is 4,000 IU/day.

For adults, the dose is 10,000 IU/day as some experts have recommended [81, 84], but continuously during the pandemic. Some experts believe that the TUL for vitamin D is too low, regardless of the pandemic, and should be as high as 10,000 IU/day for adults [88]. The current TUL for adults is 4,000 IU/day.

SUNSHINE ON SKIN

Many person in the world do not have access to vitamin D supplements. In the developing world, where they tend to have lots of sunshine, people do not have the financial resources to buy supplements, and they generally lack access to any kind of healthcare. But sunshine is free. Sunshine on skin makes vitamin D in the body. It then takes about 11 days for the process to be completed and for you to get the benefits of that vitamin D. But this works and is the natural process for obtaining vitamin D. So if you do not have the ability to obtain vitamin D supplements, sunshine on skin produces vitamin D. It works and its free.

The sunshine needed is UV-B, which is blocked by window panes (glass or plastic). So you have to be in direct sunlight. And the sunlight has to be on the skin, so you cannot be covered with cloth on every area of your body. The more skin exposed to sunshine, the more vitamin D you make.

How much of your body do you need to expose to sunlight? One study of Turkish women found that exposing the face and hands gave vitamin D levels three times higher than women who were completely covered when outdoors. However, the vitamin D levels from exposure of face and hands to sunshine was still low at 31.9 nmol/liter (12.7 ng/ml). Exposure of the arms and neck may improve this level to above that of a vitamin D deficiency. So perhaps religious and social/political authorities could relax the laws and customs, for the sake of health, and allow men and women to expose more skin to sunlight. Otherwise, people might combine time in the sun with vitamin D supplements to reach the desired vitamin D level of 30 ng/ml (75 nmol/liter) or higher.

The best time to make vitamin D by sunshine on skin is between 11 a.m. to 2 p.m. during any day of the entire year. And the amount of time varies with many factors. But for the sake of getting plenty of vitamin D during the pandemic, if you do not have supplements, spend as much time as you can in the sun during that time of day. Your skin will still make some vitamin D during other hours of the day, earlier or later, so do the best you can to get sunshine on skin and vitamin D supplements.

VITAMIN D FROM FOOD

Some foods contain vitamin D, but not in sufficient amounts to maintain a high enough level of vitamin D all year long. Vitamin D naturally found in foods, plus vitamin D fortified foods can help, though. Combining vitamin D foods, plus sunshine on skin, plus some supplements is a good approach.

BEWARE OF SCAMS

I am concerned that if the public finally accepts this message of using vitamin D to protect ourselves from the pandemic, dishonest persons will try to make a profit from the suffering of others. Beware of scams where they sell you fake vitamin D pills, or some other type of pill or concoction that supposedly helps against Covid-19. Beware of scams where they claim that some food they sell has lots of vitamin D, when it actually has little or no vitamin D. Do not accept any of these claims at face value; be reasonably skeptical and make certain you are getting a supplement from a reliable source.

Vitamin D is proven to help by the 27 studies listed below [1 – 27]. And see the expert opinions in the endnotes from 81 and on. But other kinds of treatments should be treated with caution. Do NOT use bleach or alcohol or vinegar or any other substance from around the household. Such things are harmful, not helpful.

Peace to everyone on earth. Let us all work together against this deadly pandemic. God has given us a way to fight off the virus with the natural vitamin made by our skin, vitamin D. And we can choose the modern source of vitamin D, as a supplement, or vitamin D from sunshine on skin, and also some vitamin D from foods. So we have sufficient resources for everyone on earth to raise their vitamin D levels as a shield against this deadly virus.

Ronald L. Conte Jr.
Covid.us.org
I am an author, not a doctor.

Endnotes

[Numbering of references has some gaps, to keep numbering consistent between articles.]

1. Alipio, Mark. “Vitamin D Supplementation Could Possibly Improve Clinical Outcomes of Patients Infected with Coronavirus-2019 (COVID-19).” SSRN 3571484 (9 April 2020).
Study Link

2. Lau, Frank H., et al. “Vitamin D insufficiency is prevalent in severe COVID-19.” medRxiv (28 April 2020).
Study Link

3. Daneshkhah, Ali, et al. “The Possible Role of Vitamin D in Suppressing Cytokine Storm and Associated Mortality in COVID-19 Patients.” medRxiv (2020).
Study Link

4. Davies, Gareth, Attila R. Garami, and Joanna C. Byers. “Evidence Supports a Causal Model for Vitamin D in COVID-19 Outcomes.” medRxiv (2020).
Study Link

5. De Smet, Dieter, et al. “Vitamin D deficiency as risk factor for severe COVID-19: a convergence of two pandemics.” medRxiv (2020).
Study Link

6. Raharusun, Prabowo, et al. “Patterns of COVID-19 Mortality and Vitamin D: An Indonesian Study.” (2020).
PDF file

7. Ilie, Petre Cristian, Simina Stefanescu, and Lee Smith. “The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality.” Aging Clinical and Experimental Research (2020): 1.
Study Link

8. D’Avolio, Antonio, et al. “25-hydroxyvitamin D concentrations are lower in patients with positive PCR for SARS-CoV-2.” Nutrients 12.5 (2020): 1359.
Study Link

9. Laird, E., et al. “Vitamin D and Inflammation: Potential Implications for Severity of Covid-19.” Ir Med J; Vol 113; No. 5; P81: 2020.
PDF file

10. Faul, J.L., et al. “Vitamin D Deficiency and ARDS after SARS-CoV-2 Infection.” Ir Med J; Vol 113; No. 5; P84: 2020.
PDF file

11. Meltzer, David O., et al. “Association of Vitamin D Deficiency and Treatment with COVID-19 Incidence.” medRxiv (2020).
Study Link

12. Li, Yajia, et al. “Sunlight and vitamin D in the prevention of coronavirus disease (COVID-19) infection and mortality in the United States.” (2020).
PDF file

13. Pugach, Isaac Z. and Pugach, Sofya “Strong Correlation Between Prevalence of Severe Vitamin D Deficiency and Population Mortality Rate from COVID-19 in Europe.” medRxiv (2020).
Study Link

14. Merzon, Eugene, et al. “Low plasma 25(OH) vitamin D3 level is associated with increased risk of COVID-19 infection: an Israeli population-based study.” medRxiv (2020). — Low vitamin D increased risk (adjusted OR) of infection with Covid-19 by 45% and of hospitalization for Covid by 95%.
Study Link

15. Panagiotou, Grigorios et al., “Low serum 25-hydroxyvitamin D (25[OH]D) levels in patients hospitalised with COVID-19 are associated with greater disease severity: results of a local audit of practice.” medRxiv (2020). Conclusion: “we found that patients requiring ITU admission [in the ICU] were more frequently vitamin D deficient than those managed on medical wards [on the floor], despite being significantly younger.”
PDF file Link

16. Chang, Timothy S., et al. “Prior diagnoses and medications as risk factors for COVID-19 in a Los Angeles Health System.” medRxiv (2020).
Study Link
~ Risk factors included vitamin D deficiency, which increased risk of COVID-19 diagnosis by 80% (OR 1.8 [1.4-2.2], p=5.7 x 10-6).

17. Maghbooli, Zhila, et al. “Vitamin D Sufficiency Reduced Risk for Morbidity and Mortality in COVID-19 Patients.” Available at SSRN 3616008 (2020).
Study Link
~ Vitamin D sufficiency reduced clinical severity and inpatient mortality.

18. Panarese and Shahini, “Letter: Covid-19 and Vitamin D” Alimentary Pharmacology and Therapeutics, April 12, 2020.
Link to Letter
~ Covid-19 mortality increases with increasing latitude (by nation), and vitamin D blood levels decrease with increasing latitude. The authors propose that low levels of vitamin D increase Covid-19 mortality.

19. Carpagnano, Giovanna Elisiana, et al. “Vitamin D deficiency as a predictor of poor prognosis in patients with acute respiratory failure due to COVID-19.” Journal of Endocrinological Investigation (2020): 1-7. Study Link
~ “A survival analysis highlighted that, after 10 days of hospitalization, severe vitamin D deficiency patients had a 50% mortality probability, while those with vitamin D = 10 ng/mL had a 5% mortality risk (p = 0.019).”

20. Mardani, R., et al. “Association of vitamin D with the modulation of the disease severity in COVID-19.” Virus Research (2020): 198148. Study Link

21. Castillo, Marta Entrenas, et al. “Effect of Calcifediol Treatment and best Available Therapy versus best Available Therapy on Intensive Care Unit Admission and Mortality Among Patients Hospitalized for COVID-19: A Pilot Randomized Clinical study.” The Journal of Steroid Biochemistry and Molecular Biology (2020): 105751. Study Link

22. Radujkovic, et al. “Vitamin D Deficiency and Outcome of COVID-19 Patients.” Nutrients 2020, 12(9), 2757; Study Link
— “The present study demonstrates an association between VitD deficiency and severity of COVID-19.
VitD-deficient patients had a higher hospitalization rate and required more (intensive) oxygen therapy
and IMV. In our patients, when adjusted for age, gender, and comorbidities, VitD deficiency was
associated with a 6-fold higher hazard of severe course of disease and a ~15-fold higher risk of death.”

23. Israel, Ariel, et al. “The link between vitamin D deficiency and Covid-19 in a large population.” MedRxiv 9/7/2020. Study Link

24. Jae Hyoung Im, et al. “Nutritional status of patients with coronavirus disease 2019 (COVID-19).”
International Journal of Infectious Diseases. August 7, 2020. PDF Link

25. Gennari L, et al “Vitamin D deficiency is independently associated with COVID-19 severity and mortality” ASBMR 2020; Abstract 1023. Study Link

26. Baktash, Vadir, et al. “Vitamin D status and outcomes for hospitalised older patients with COVID-19.” Postgraduate Medical Journal (2020). Study Link
— “The main findings of our study suggest that older patients with lower serum concentrations of 25(OH)D, when compared with aged-matched vitamin D-replete patients, may demonstrate worse outcomes from COVID-19. Markers of cytokine release syndrome were raised in these patients and they were more likely to become hypoxic and require ventilatory support in HDU.” [HDU is high dependency unit]

27. Kaufman HW, et al. “SARS-CoV-2 positivity rates associated with circulating 25-hydroxyvitamin D levels.” (2020) PLoS ONE 15(9): e0239252. Study Link
— Optimum vitamin D blood level for reducing Covid-19 infection was found to be in the 50’s (ng/ml). This is the first study to show that 25(OH)D at levels above 30 have additional benefits.

Vitamin D versus Covid, Commentary

81. Grant, William B., et al. “Evidence that vitamin D supplementation could reduce risk of influenza and COVID-19 infections and deaths.” Nutrients 12.4 (2020): 988. Study Link
— “To reduce the risk of infection, it is recommended that people at risk of influenza and/or COVID-19 consider taking 10,000 IU/d of vitamin D3 for a few weeks to rapidly raise 25(OH)D concentrations, followed by 5000 IU/d…. For treatment of people who become infected with COVID-19, higher vitamin D3 doses might be useful.”

82. Garland, Cedric F., et al. “Vitamin D supplement doses and serum 25-hydroxyvitamin D in the range associated with cancer prevention.” Anticancer research 31.2 (2011): 607-611. Study Link
— “Results: Serum 25(OH)D rose as a function of self-reported vitamin D supplement ingestion in a curvilinear fashion, with no intakes of 10,000 IU/d or lower producing 25(OH)D values above the lower-bound of the zone of potential toxicity (200 ng/ml). Unsupplemented all-source input was estimated at 3,300 IU/d. The supplemental dose ensuring that 97.5% of this population achieved a serum 25(OH)D of at least 40 ng/ml was 9,600 IU/d. Conclusion: Universal intake of up to 40,000 IU vitamin D per day is unlikely to result in vitamin D toxicity.”

83. Charoenngam and Holick, “Immunologic Effects of Vitamin D on Human Health and Disease.” Nutrients 2020, 12(7), 2097; Study Link
— “It is therefore proposed that supplementation of vitamin D can reduce the risk and severity of COVID-19 infection.”

84. Sharma, Suresh K., et al. “Vitamin D: A cheap yet effective bullet against coronavirus disease-19-Are we convinced yet?.” National Journal of Physiology, Pharmacy and Pharmacology 10.7 (2020): 0-0.
Study Link
“Therefore, from reviewed literature, it seems fairly appropriate to suggest taking Vit-D at 10,000 IU/day as an adequate dose to enhance circulatory concentration of Vit-D into the optimal range of 40-60 ng/mL; after 1 month the dose can be reduced to 5000 IU/day to maintain serum levels.”

85. Kroll, Martin H., et al. “Temporal relationship between vitamin D status and parathyroid hormone in the United States.” PloS one 10.3 (2015): e0118108. Study Link
– Based on 3.8 million lab results of adults in the U.S.: “Vitamin D deficiency and insufficiency was common (33% <20 ng/mL; 60% <30 ng/mL)…. The percentage of patients deficient in 25(OH)D3 seasonally varied from 21% to 48%…."

86. Holick, Michael F., et al. "Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline." The Journal of Clinical Endocrinology & Metabolism 96.7 (2011): 1911-1930.

87. Kearns, Malcolm, Jessica Alvarez, and Vin Tangpricha. "Large, single-dose, oral vitamin D supplementation in adult populations: a systematic review." Endocrine Practice 20.4 (2014): 341-351.
— "This review recommends that vitamin D3 be used for supplementation over vitamin D2 and concludes that single vitamin D3 doses ≥300,000 IU are most effective at improving vitamin D status and suppressing PTH concentrations for up to 3 months."

88. Robert P. Heaney, The Vitamin D requirement in health and disease; Journal of Steroid Biochemistry & Molecular Biology. doi:10.1016/j.jsbmb.2005.06.020

89. Alagöl, Faruk, et al. "Sunlight exposure and vitamin D deficiency in Turkish women." Journal of endocrinological investigation 23.3 (2000): 173-177.

90. Liu, Guoqiang, Tianpei Hong, and Jin Yang. “A Single Large Dose of Vitamin D Could be Used as a Means of Coronavirus Disease 2019 Prevention and Treatment.” Drug Design, Development and Therapy 14 (2020): 3429.

Vitamin D versus Other Diseases

101. Martineau, Adrian R., et al. “Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data.” bmj 356 (2017).
Study Link
— Recommend daily or weekly dose, but not bolus dosing.

102. Marniemi et al., Dietary and serum vitamins and minerals as predictors of myocardial infarction and stroke in elderly subjects; Nutrition, Metabolism & Cardiovascular Diseases. Volume 15, Issue 3 , Pages 188-197, June 2005. Study Link

103. Munger et al., Vitamin D intake and incidence of multiple sclerosis; Neurology. January 13, 2004 vol. 62 no. 1, p. 60-65. Study Link

104. Merlino et al., Vitamin D intake is inversely associated with rheumatoid arthritis: Results from the Iowa Women’s Health Study; Arthritis & Rheumatism. Volume 50, Issue 1, pages 72-77, January 2004. Study Link

105. Pittas et al., Vitamin D and Calcium Intake in Relation to Type 2 Diabetes in Women; Diabetes Care. March 2006 vol. 29 no. 3 650-656. Study Link

106. Garland et al., Vitamin D and prevention of breast cancer: Pooled analysis; The Journal of Steroid Biochemistry and Molecular Biology, Volume 103, Issues 3-5, March 2007, Pages 708-711; Study Link

107. Garland et al., The Role of Vitamin D in Cancer Prevention; American Journal of Public Health. 2006 February; 96(2): 252-261. Study Link

108. Gorham et al., Optimal Vitamin D Status for Colorectal Cancer Prevention: A Quantitative Meta-Analysis; American Journal of Preventive Medicine. Volume 32, Issue 3 , Pages 210-216, March 2007; Study Link

109. Antonio, Leen, et al. “Free 25-hydroxyvitamin D, but not free 1.25-dihydroxyvitamin D, predicts all-cause mortality in ageing men.” 22nd European Congress of Endocrinology. Vol. 70. BioScientifica, 2020.

110. Ekwaru, John Paul, et al. “The importance of body weight for the dose response relationship of oral vitamin D supplementation and serum 25-hydroxyvitamin D in healthy volunteers.” PLoS One 9.11 (2014): e111265.