Vitamin D - Will You Protect Me?

This coronavirus doesn’t appear to be going away anytime soon, and despite masks and distancing, it seems likely that a high percentage of people may eventually be exposed to it. There may be a vaccine someday, hopefully some drugs and treatments will help with symptoms and keep people from dying. But is there anything that we should be doing nutritionally to keep us from getting really sick? Some medical experts are actually looking into certain micronutrients such as Vitamins C and D and Zinc, so I wanted to share with you my thoughts as a dietitian based on the science.

Many of us have been brought up thinking that Vitamin C can help treat the common cold, leading us to stock up on OJ and EmergenC when we get the sniffles. Studies have actually shown that though people who regularly supplement with Vitamin C may experience fewer days of cold symptoms, they are not less likely to catch a cold, and taking Vitamin C when you first notice symptoms does little or nothing to reduce the length or severity of the illness(1). But it’s pretty ingrained in our belief system, so no wonder many store shelves have been emptied of Vitamin C supplements this season. Zinc is a similar story – lots of people think it helps, but the science isn’t super supportive of that idea. Coronavirus is different from a cold or the flu though, so research is currently being done to see if either could play a role in supporting immunity to keep people healthier. We’ll see!

Vitamin D seems a little more promising at this point. Vitamin D is mainly responsible for maintaining blood calcium levels in the body, but it does a bunch of other things as well, including supporting the immune system and preventing inflammation. Some studies have been done in the past to see if taking Vitamin D might keep people from developing the flu with mixed results(2). However, D has specifically been shown to protect against acute respiratory infections, which is noteworthy considering COVID-19 seems to be attacking people’s respiratory systems.

Our bodies can make Vitamin D when our skin is exposed to sunlight, which is historically how we have met our D needs. Interestingly, most flus including COVID-19 begin to spread during winter months when there is less sunlight. People’s ability to make Vitamin D from sunlight declines with age, so lots of older individuals have low Vitamin D levels, and older individuals also tend to be more at risk for bad outcomes with COVID-19. These parallels could be purely coincidental, but again, researchers want to know if there might be an actual relationship between Vitamin D levels and susceptibility to the virus.
I looked up a few recent studies to understand what the thinking is, and here is what I found:

• A pilot* study done several years ago on ventilated ICU patients found that high dose Vitamin D safely increased blood concentration of the vitamin and was associated with decreased hospital length of stay(3).
• A more recent study found correlations** between low blood levels of Vitamin D and increased severity of coronavirus symptoms, meaning the odds of having a critical outcome increased when blood levels decreased, and vice versa(4).
• An association was identified between average vitamin D levels in various European countries and COVID-19 cases and mortalities. Low vitamin D levels correlated** to more cases and deaths(5).

*pilot studies are a kind of practice, they can’t officially conclude anything
**correlation does not equal causation

The bottom line for these studies is that more studies need to be done. It’s not that they don’t have anything to show for themselves, but usually it is something like “hey, this is what might be happening, let’s come up with a better study to really test this idea.” COVID-19 is very new, so randomized clinical trials (the gold standard), which could test whether or not increasing vitamin D intake could actually benefit infected patients, just haven’t happened yet. However, according to one research team, “Vitamin D has already been shown to protect against acute respiratory infections and it was shown to be safe. It should be advisable to perform dedicated studies about vitamin D levels in COVID-19 patients with different degrees of disease severity(5).”

So, we don’t know yet if Vitamin D is going to be any help in the fight against COVID-19, but Vitamin D is a nutrient of concern, pandemic or not. You need to get about 15 minutes per day of full sun exposure on your arms to meet the recommendation for Vitamin D for most people, which doesn’t sound like much, but nowadays we work inside or live in climates where there is little sunlight during winter months or slather on sunscreen to block harmful UV rays. Few people get enough vitamin D from sun exposure, especially during winter months. There are not a lot of food sources of this important vitamin. It is found in fish, egg yolks, liver, fortified dairy products, and irradiated mushrooms, but it’s hard to eat enough of these foods to get adequate D. For example, one egg has less than 10% of what a typical healthy person needs in a day, and some people may need more.
Dietitians generally recommend getting vitamins and minerals through food rather than taking a supplement, but considering the above, supplementing may be necessary for some of us. If you can get a blood test to learn your Vitamin D levels, I would recommend finding out if you are okay, but the reality is, many people fall short of the mark. Here are few things to think about for yourself:

• The Recommended Dietary Allowance (RDA) for Vitamin D is 15 mcg / 600 IU per day for adults.
• Our bodies store Vitamin D, so if our blood levels get low, we can draw from storage. But if you find your serum D level is low, it means your body has already depleted its stores. Therefore, not only do you need to get the RDA, but you may need to take more to replete your stores.
• If you are trying to replete your vitamin D levels with sun exposure, you need to consider that too much sun can increase your risk for skin cancer.
• Certain medications may block the body’s ability to make Vitamin D from sunlight, which is another reason older adults tend to be low in D.

One of the recent studies I read about D and COVID-19 recommended people who are at risk get their vitamin D levels up by taking 10,000 IU (International Units) per day for a few weeks, and then going down to 5000 IU for a while. However, the tolerable upper level (TUL) for the vitamin is currently set at 4000 IU. Although doses up to 10,000 IU have not shown any negative effects, you don’t want to risk getting too much D! Its toxic effects are bad including calcification of organs. Dosing needs to be tested further to establish safe and practical guidelines. There are a couple additional points worth making:

• Don’t take high doses of calcium with high doses of D if you want to avoid the calcified organs.
• Some sources recommend supplementing Magnesium along with D.
• The supplement industry is not regulated – what’s on the label may not be what’s in the bottle.
• You won’t get Vit D toxicity from too much sun exposure, but UV rays can still be harmful.
• Fun Fact: Infants need a Vitamin D supplement because breast milk does not contain it.

So what does it all mean? Well, don’t get too excited about Vitamin D being the coronavirus hero, but it is something we should be addressing for our overall health anyway. If you choose to supplement, do some research rather than relying on labels when choosing a brand and a dosage. Personally, I had my blood tested a while ago, and my levels were a little low, so I get a bit of sun when I can and supplement above the RDA, but below the TUL. Done right, supplementing with Vitamin D won’t hurt us, and it might give us a leg up should we get exposed to COVID-19. Bummer that it took a terrible virus to get us to start paying more attention to Vitamin D.

Here are some resources I used, in case you are interested:

1. Ran L, Zhao W, Wang J, et al. Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials. Biomed Res Int. 2018;2018:1837634. Published 2018 Jul 5. doi:10.1155/2018/1837634
2. Grant WB, Lahore H, McDonnell SL, et al. Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths. Nutrients. 2020;12(4):988. Published 2020 Apr 2. doi:10.3390/nu12040988
3. Han JE, Jones JL, Tangpricha V, et al. High Dose Vitamin D Administration in Ventilated Intensive Care Unit Patients: A Pilot Double Blind Randomized Controlled Trial. J Clin Transl Endocrinol. 2016;4:59‐65. doi:10.1016/j.jcte.2016.04.004
4. Alipio MM. Vitamin D supplementation could possibly improve clinical outcomes of patients infected with Coronavirus-2019 (COVID2019). This preprint research paper has not been peer reviewed. 2020 Apr 9. Electronic copy available at: https://ssrn.com/abstract=3571484.
5. Ilie PC, Stefanescu S, Smith L. The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality [published online ahead of print, 2020 May 6]. Aging Clin Exp Res. 2020;1‐4. doi:10.1007/s40520-020-01570-8
6. Ross AC, Taylor CL, Yaktine AL, et al., editors. Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium; Washington (DC): National Academies Press (US); 2011.

My name is Lorelei Sturm. Some of you may know me as a yoga instructor with Chicago’s Neighborhood Fitness Centers. I am also a Registered Dietitian with a Master’s degree in Nutrition. CNF is committed to helping its members lead healthier lives by encouraging wellness and a healthy lifestyle in addition to fitness. Let me know if you have any nutrition questions in the comments below.
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