Doctors warn that taking high doses of Vitamin D has little or no effect on COVID-19, and they urge against taking more of the supplement than is recommended since it can have adverse health effects.

This update comes in the wake of people pounding down the D supplements as a prophylactic measure, after learning that many patients with the worst symptoms and outcomes after being diagnosed with COVID-19, have also been vitamin D deficient.

Countries, where COVID-19 cases have resulted in the highest death rates, are also those where more of the population has D deficiencies. Researchers across the globe have found that the sickest patients often have the lowest levels of vitamin D. These facts have led individuals who are not sick to start taking large doses of vitamin D.

Vitamin D to Treat or Prevent COVID-19? Not true. Here is What Science Tells Us:

There is a connection between vitamin D and respiratory illness, but that does not mean that overdosing is a healthy move. Experts do say that healthy blood levels of vitamin D may give some protection against the worst symptoms if you do contract COVID-19. One possible advantage is that vitamin D can help prevent the body from experiencing the so-called "cytokine storm," when the body's immune system overreacts and attacks its own cells and tissues, much like a histamine response to an allergen. But too much D is not beneficial.

In a new warning by doctors in the UK, researchers at Birmingham University are warning people to not overdose themselves with D to gain any potential benefits or edge against the virus. According to The Independent, a steady stream of patients are showing up at hospitals in the UK having taken toxic doses of vitamin D in supplements they bought online. The pills that are poisoning them contain up to 2,250 times the recommended daily dose of D (which is 600 IU according to the Mayo Clinic) and this toxic level of D is putting patients at risk of heart and kidney problems, according to the NHS lab, which said it sees two to three overdose cases every week.

Scientists from the UK, Europe and the US, including experts from the University of Birmingham, have published a consensus paper warning against taking high doses of vitamin D supplementation.

According to the study, new research shows high levels of vitamin D provides little or no benefit in preventing or treating Covid-19. The study's authors advise that the population adhere to Public Health England guidance on supplementation.

Following unverified reports that high doses of vitamin D (higher than 4000IU/d) could reduce the risk of contracting COVID-19 and be used to successfully treat the virus, the new report published in the journal BMJ, Nutrition, Prevention and Health, investigated the current scientific evidence base on the vitamin and its use in treating infections.

Vitamin D is a hormone produced in the skin during exposure to sunlight and helps regulate the amount of calcium and phosphate in the body, which are needed to keep bones, teeth and muscles healthy.

Spend Time in the Sunlight, Instead of Taking Supplements

“Most of our vitamin D comes from exposure to sunlight, however for many people, particularly those who are self-isolating with limited access to sunlight during the current pandemic, getting enough vitamin D may be a real challenge. Supplementing with vitamin D ... should be done under the current UK guidance,"  said Professor Carolyn Greig, a co-author of the paper, also from the University of Birmingham.

Professor Judy Buttriss, Director General British Nutrition Foundation and a co-author of the research said: “In line with the latest ... guidance on vitamin D, we recommend that people consider taking a vitamin D supplement of 10 micrograms a day during the winter months (from October to March), and all year round if their time outside is limited.

“Although there is some evidence that low vitamin D is associated with acute respiratory tract infections, there is currently insufficient evidence for vitamin D as a treatment for COVID-19 and over-supplementing must be avoided as it could be harmful.”

Examining previous studies in this field, the scientists found no evidence of a link between high dose supplementation of vitamin D in helping to prevent or successfully treat Covid-19 and cautioned against over-supplementation of the vitamin, without medical supervision, due to health risks. Scientists concluded that assertions about the benefit of the vitamin in treating the virus are not currently supported by adequate human studies and are based on findings from studies that did not specifically examine this area.

Claims of a link between vitamin D levels and respiratory tract infections were also examined by scientists. Previous studies in this area have found that lower vitamin D status is associated with acute respiratory tract infections however limitations of the findings of these studies were identified.  Findings from the majority of studies were based on data gathered from population groups in developing countries and cannot be extrapolated to populations from more developed countries due to external factors. Scientists believe that there is currently no firm link between vitamin D intake and resistance to respiratory tract infections.

Too Much Vitamin D  Can Be Harmful to Your Health

Vitamin D toxicity, also called hypervitaminosis D, is a rare but potentially serious condition that occurs when you have excessive amounts of vitamin D in your body.

Vitamin D toxicity is usually caused by taking supplements — not diet or sun exposure. Your body regulates the amount of vitamin D produced by sun exposure, and even fortified foods don't contain enough vitamin D to worry about.

Too much D can lead to a buildup of calcium in your blood (hypercalcemia), which can cause nausea and vomiting, weakness, and frequent urination. Vitamin D toxicity can also lead to bone pain and kidney stones.

Treatment includes stopping vitamin D intake and restricting your calcium intake. Your doctor might also prescribe intravenous fluids and corticosteroids or bisphosphonates.

Doctors warn against taking anything more than the U.S. Recommended Dietary Allowance of 600 IU of vitamin D per day.

“An adequate level of vitamin D in the body is crucial to our overall health, too little can lead to rickets or the development of osteoporosis but too much can lead to an increase in calcium levels in the blood which could be particularly harmful,” Professor Sue Lanham-New, Head of the Department of Nutritional Sciences at the University of Surrey and lead author of the study, said.

“Levels of the vitamin in the body can also be supplemented through a nutritionally balanced diet including foods that provide the vitamin, such as fortified foods such as breakfast cereals, and safe sunlight exposure to boost vitamin D status.”

Most. people can get enough vitamin D with about ten to 15 minutes of direct sunlight a day.