This winter, more than two million people at high risk for severe symptoms from COVID-19 will receive vitamin D supplements for free in the United Kingdom. The move comes after several studies have shown that vitamin D may help our immune systems fight the novel coronavirus.

The country’s National Health Service (NHS) plans to distribute vitamin D to residents listed as clinically vulnerable, as well as to those in nursing homes, reports The Daily Telegraph. Clinically vulnerable coronavirus populations include those who are immunocompromised or who have conditions such as cancer or cystic fibrosis, which put them at higher risk of developing severe symptoms due to COVID-19.

Until recently, the country’s health leaders had declined to endorse vitamin D supplements as a way to help protect people from severe coronavirus symptoms. But a slew of recent studies now suggests that getting enough vitamin D is a likely factor in protecting COVID-19 patients from the most frightening effects of the disease. That data agrees with years of previous research reinforcing the close relationship between vitamin D and immune health in general.

UK officials hope that these vitamin D supplements will help protect their nation’s at-risk population through the winter months, when low levels of sunlight lead to chronic shortfalls of vitamin D.

In fact, the UK’s latitude is sufficiently far north that, the NHS points out, it’s impossible for anyone there to make vitamin D from sunlight exposure from October to March (How to Get Vitamin D from Sunlight, 2018). Foods and supplements are the only paths to achieving adequate blood levels of the vitamin there during these months.

(This is something the Brits, Scots and Irish – in fact, everyone on Earth who lives north of the 37th parallel – should likely keep in mind in winter, even post-pandemic.)

We’re Not Getting Enough Vitamin D

Our bodies get vitamin D in two main ways: from our diets and from sunlight. Foods high in vitamin D include seafood, like salmon, as well as eggs and fortified milk. Most people don’t get enough vitamin D from their diets alone (Opinder Sahota, 2014). However, our bodies can also make vitamin D on their own using cholesterol. This process happens in our skin cells, and only after exposure to ultraviolet radiation, a part of sunlight, strikes our bare skin. Further, the sun’s angle through the atmosphere must be sufficiently direct (Christakos et al., 2010).

Because we often need sunlight to get enough vitamin D, many people run a deficiency in winter months when the sun strikes us at an indirect angle. In fact, studies estimate that as many as a billion people worldwide don’t get enough vitamin D (Opinder Sahota, 2014).

That’s potentially dangerous because vitamin D plays a role in a number of key bodily processes. Vitamin D helps our bones take up calcium, and it helps our skin heal from wounds (Martin et al., 1969, Ding et al., 2016). There’s also evidence it plays a role in mental health, especially during the winter months (Jorde et al., 2008).

Vitamin D and COVID-19

But, most importantly, vitamin D boosts the immune system. The vitamin helps immunity in a variety of ways, from helping control inflammation responses to assisting in the production of antimicrobial peptides and the T cells used by our bodies’ natural defenses (Schwalfenberg GK, 2010). There’s also evidence that low levels of vitamin D can help lead to pneumonia and more severe upper respiratory tract infections (Bartley, J, 2010). (Read more: Vitamin D Likely Fights Lung-Focused Viral Villains)

Recent studies have linked low levels of vitamin D to more severe cases of COVID-19 as well. One study in Spain, for example, found that 80 percent of people hospitalized for COVID-19 had a deficiency of vitamin D (Hernandez et al., 2020). A different study from Italy found similar results, and it also indicated that a lack of vitamin D was associated with a higher risk of dying from COVID-19 (Carpagnano et al., 2020).

On the strength of these studies, it’s not surprising the British government has looked to vitamin D supplements to help its most vulnerable people add a measure of protection against the coronavirus. In the UK, as in most of Europe, coronavirus cases are steadily rising again, and the country just surpassed 50,000 deaths from the virus.

While vitamin D is not a guaranteed protection against severe COVID-19 symptoms, its immune-boosting effects might keep more patients out of hospitals and reduce the strain on the medical system.

Foods High in Vitamin D

Here in the U.S., the government has yet to officially endorse using vitamin D for reducing symptoms of the coronavirus. Though the National Institutes of Health does recognize the immune-enhancing effects of vitamin D supplements, the agency has refrained from following the UK’s lead in issuing supplements. But across the pond, some scientists have even encouraged the government to fortify foods like milk and bread with vitamin D to help the general population get enough in their diets.

That doesn’t mean you can’t take your vitamin D levels into your own hands, though. There are plenty of foods that have naturally high levels. And as we Americans move into the winter months and sunlight becomes scarce – especially for those in the northern half of the continental U.S. - you should make sure you’re getting enough of this critical ingredient by packing your diet with vitamin D-rich foods like sardines, herring, and other oily fish, like salmon. Sockeye salmon in particular has more vitamin D than almost any other species.

It’s also important to make sure that you’re eating wild-caught salmon. There are many nutritional differences between wild salmon and farmed salmon, and that’s especially true when it comes to vitamin D. Studies suggest that farmed salmon can have as little as one-quarter of the amount of vitamin D found in wild-caught salmon (Lu et al., 2007).

And it’s never a bad idea to consider adding supplements to your diet, either. Vitamin D supplement capsules offer an easy way to make sure you’re giving your immune system the help it needs to fight off infections and keep you safe this season.


Bartley J. Vitamin D, innate immunity and upper respiratory tract infection. The Journal of Laryngology & Otology. 2010;124(5):465-469. doi:10.1017/s0022215109992684

Christakos S, Ajibade DV, Dhawan P, Fechner AJ, Mady LJ. Vitamin D: Metabolism. Endocrinology and Metabolism Clinics of North America. 2010;39(2):243-253. doi:10.1016/j.ecl.2010.02.002

Carpagnano GE, Di Lecce V, Quaranta VN, 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. Published online August 9, 2020. doi:10.1007/s40618-020-01370-x

Ding J, Kwan P, Ma Z, et al. Synergistic effect of vitamin D and low concentration of transforming growth factor beta 1, a potential role in dermal wound healing. Burns. 2016;42(6):1277-1286. doi:10.1016/j.burns.2016.03.009

Hernández JL, Nan D, Fernandez-Ayala M, et al. Vitamin D Status in Hospitalized Patients with SARS-CoV-2 Infection. The Journal of Clinical Endocrinology & Metabolism. Published online October 27, 2020. doi:10.1210/clinem/dgaa733

How to Get Vitamin D from Sunlight, 2018. Retrieved November 13, 2020, from

Jorde R, Sneve M, Figenschau Y, Svartberg J, Waterloo K. Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial. Journal of Internal Medicine. 2008;264(6):599-609. doi:10.1111/j.1365-2796.2008.02008.x

Lu, Z et al. “An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D?.” The Journal of steroid biochemistry and molecular biology vol. 103,3-5 (2007): 642-4. doi:10.1016/j.jsbmb.2006.12.010

Martin DL, Deluca HF. Calcium transport and the role of vitamin D. Archives of Biochemistry and Biophysics. 1969;134(1):139-148. doi:10.1016/0003-9861(69)90260-4

Sahota O. Understanding vitamin D deficiency. Age and Ageing. 2014;43(5):589-591. doi:10.1093/ageing/afu104

Schwalfenberg GK. A review of the critical role of vitamin D in the functioning of the immune system and the clinical implications of vitamin D deficiency. Molecular Nutrition & Food Research. 2010;55(1):96-108. doi:10.1002/mnfr.201000174