Vitamin D plays a role in immunity, which is one of the reasons scientists are exploring it as a potential COVID-19 aid.iStock
You probably read a news article last week about how getting enough vitamin D could protect you from COVID-19. Maybe your friend posted it on Facebook, or you came across it in your daily reading about the pandemic. What’s the deal?
It’s true: New, preliminary research suggests taking a vitamin D supplement may play a role in preventing or managing COVID-19. But not so fast. When it comes to supplementing to protect against respiratory illness, the research isn’t there yet. Yet that doesn’t mean you won’t benefit from taking a vitamin D supplement or taking a socially distanced walk to soak up the sun, which is a natural source of the essential nutrient.
Why Are Scientists Talking About Vitamin D to Help Fight COVID-19?
It’s no surprise why scientists are interested in studying vitamin D as a treatment tool for COVID-19, or its deficiency as a potential risk factor for serious illness from the respiratory disease that is caused by the novel coronavirus.
After all, vitamin D deficiency is common among many groups at high risk for COVID-19, including the elderly and people with obesity, diabetes, and high blood pressure, says Rose Anne Kenny, chair of medical gerontology at Trinity College in Dublin. Aging and obesity both reduce the ability of the skin to make vitamin D from exposure to the sun’s ultraviolet rays, Kenny says, and these diseases are associated with aging and carrying extra weight.
Vitamin D is known for aiding several essential body functions that, when compromised, may affect COVID-19 outcomes. “Vitamin D is best known for its effects on bone, but it also has important effects on the immune system,” says Adrian Martineau, PhD, a clinical professor of respiratory infection and immunity at Queen Mary University of London. According to the National Institutes of Health, vitamin D is also important for fighting inflammation and contributing to cell growth.
Vitamin D supports the ability of the innate immune system to mount a range of antiviral responses, including production of substances called antimicrobial peptides that are produced by white blood cells and the lining of the lung, Dr. Martineau says. These peptides have antiviral properties as well as antibacterial ones. Vitamin D also acts to dampen down potentially harmful inflammatory responses in the body that can be more active in people with health conditions such as obesity and diabetes, which are also risk factors for COVID-19, Martineau adds.
Scientific Research on Using Vitamin D for Respiratory Illnesses, Including COVID-19
Some preliminary research explores the potential uses of vitamin D in preventing or treating COVID-19. Here’s a look at them:
Vitamin D Deficiency Is Associated With Greater Death Risk From COVID-19
One study, published in May 2020 in the Irish Medical Journal, counterintuitively found that people who live in typically sunny countries in southern Europe, such as Spain and Italy, had higher rates of vitamin D deficiency — and higher COVID-19 infection and death rates — than people in countries including Norway, Finland, and Sweden, which are further north and comparatively less sunny.
Kenny says it’s possible people to the north have higher levels of vitamin D because their diets are high in food that has been fortified with vitamin D.
Yet this study is circumstantial; it wasn’t a controlled experiment designed to prove whether or how vitamin D levels may directly impact the risk of developing or dying from COVID-19. Researchers also got their data on vitamin D levels and supplementation policies in different countries via previously published papers that used a wide variety of methods to determine what proportion of people had vitamin D deficiency. Also, researchers didn’t examine other micronutrients, including zinc, selenium, and vitamin B6, which may also influence immune function and COVID-19 risk, the study team wrote.
Vitamin D May Protect Against Respiratory Infections in General
Another study, published in February 2017 in The BMJ, examined data from 25 clinical trials testing the impact of vitamin D supplements on acute respiratory infections, including bronchitis, pneumonia, and sinusitis (a common sinus infection). Combined, these trials involved a total of 11,321 participants who were randomly assigned to take vitamin D supplements or placebo pills and followed for up to 1.5 years. Randomized, controlled trials are the gold standard of medical research because they can show whether an intervention directly causes specific outcomes, a past paper explains.
Results from these trials suggested that people who took vitamin D supplements were 12 percent less likely to develop acute respiratory infections than people who didn’t. And among people with the most severe vitamin D deficiency, taking supplements reduced their respiratory infection risk by 70 percent.
Yet one limitation of this study is that researchers didn’t have data on whether people received flu shots or if they were diagnosed with chronic obstructive pulmonary disease (COPD), two factors that can independently affect the risk for acute respiratory infections.
This study was also done several years before COVID-19 began circling the globe. So although it provides strong evidence that vitamin D supplementation may help with other respiratory infections, it doesn’t prove beyond a doubt that vitamin D will help fight COVID-19.
Still, the results do suggest that this is possible given the known functions of vitamin D, says Martineau, who was one of the authors of the BMJ study.
Vitamin D Could Play a Role in Preventing the Flu, Which Is Another Respiratory Illness
Previous studies have had mixed results on the role of vitamin D in preventing the flu, which, though markedly different from COVID-19, as the World Health Organization (WHO) notes, is another severe respiratory illness.
A meta-analysis of four studies examining the link between vitamin D supplements and the effectiveness of the flu vaccine and published in March 2018 in Nutrients didn’t find any connection between the two. One limitation of this analysis is that it’s possible results could vary depending on the quality of the flu vaccine and the strains of influenza in circulation.
Previous research may suggest promise, though. One study examined influenza cases among Japanese school children who were randomly assigned to take vitamin D supplements or a placebo. The children who received vitamin D were 42 percent less likely to get the flu.
What Do I Take Away From the Research on Vitamin D and Respiratory Illnesses Like COVID-19?
Larger, more rigorous studies are needed before healthcare professionals recommend vitamin D supplementation for the general public, for COVID-19 prevention or treatment, or otherwise.
Why You May Still Want to Consider Taking a Vitamin D Supplement
That said, regardless of your risk for COVID-19, some groups may benefit from supplementation.
People of color, breastfed infants, and people who take certain medications are among the other groups of people at a higher risk for vitamin D deficiency, according to Medline Plus.
Not getting enough direct sunlight is also a risk factor. “Supplementation with vitamin D is particularly important during times of self-isolation associated with limited sunlight exposure,” says Dr. Lanham-New.
Wearing sunscreen or clothing that covers most of the skin (whether to prevent skin cancer or premature signs of aging) limits the amount of vitamin D the body can produce from sun exposure, says Matthew Drake, MD, PhD, an associate professor of medicine at the Mayo Clinic in Rochester, Minnesota. And so does sheltering in place to help avoid the spread of COVID-19.
“For the majority of people, particularly those unable to spend at least 15 to 30 minutes with direct sun exposure each day, the easiest way to obtain vitamin D is through supplementation with either a multivitamin or with vitamin D directly, both of which can be obtained over the counter and do not require a prescription,” Dr. Drake says.
While eating foods high in vitamin D (think: cod liver oil, salmon, trout, and fortified milk) can also help you reach the optimal amount, it isn’t enough, notes the Cleveland Clinic. Exposure to direct sunlight and possibly a supplement can get you there, though.
How Much Vitamin D Should You Take and Is There an Upper Limit?
For the record, vitamin D recommendations vary widely around the world. Most people should get 600 IU of vitamin D daily, according to the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies. For people older than 70 it’s 800 IU, and for infants it’s 400 IU.
Because high daily doses of vitamin D can be harmful, don’t exceed standard recommended doses without first checking with your doctor, says Lanham-New. In fact, because everyone’s nutrient needs differ, asking your healthcare team about the right dose for you is smart. You can do that via telemedicine if an in-person visit is less preferable or unavailable.
Taking Vitamin D During the COVID-19 Pandemic: What’s the Bottom Line?
At this point, it is not clear that vitamin D supplementation will help prevent or treat COVID-19 infection, Drake says.
But because vitamin D is safe when taken at reasonable dosages, there is not likely to be any harm for older adults to take recommended amounts of vitamin D, especially if you’re in a high-risk group.
“It is now increasingly recognized that vitamin D likely plays a role in immune cell function, such that low vitamin D levels may lead to a reduced ability for each of our immune systems to fight various insults including infections,” says Drake. “Maintaining vitamin D levels within a normal range, therefore, might be one way to improve the immune system’s ability to fight an infection — perhaps such as COVID-19.”
Get Your Gut Back On Track!
An estimated 110,000 people consume antibiotics daily in Ireland, between December/March. (Source: Health Protection Surveillance Centre).
We asked Nutritional Therapist Rosanna Davison for her Top Tips to get your gut back on track after an illness.
1. Take time out
Don’t push yourself too quickly. Remember your body needs time to rebuild its reserves and regain strength.
Take more rest than usual. If you need to sleep longer, go to bed earlier.
Cut back on non-essential activities; they can wait until you are feeling 100%.
- Embrace fibre-rich foods full of protective nutrients
Fresh vegetables and fruits are rich in dietary fibre, vitamins and antioxidants. Try eating seven to nine portions over the course of each day. Choose different colours so that you nourish your body with a variety of phytonutrients.
Eat a portion of complete protein at each meal, such as poultry, fish, eggs, beans, pulses or tofu.
Consume essential omega-3 fatty acids daily. Avocados, seeds (flax, chia) and oily fish (mackerel, wild and organic salmon), are naturally rich in anti-inflammatory fats.
- Go ‘fermented’
Fermented foods are rich in ‘friendly’ bacteria. Sauerkraut is simple to make at home or buy kefir or kimchi in your local health store.
- Reduce or eliminate sugary foods
Processed foods often contain refined sugars to enhance taste. Excess refined sugar and processed foods may encourage the growth of ‘unfriendly’ bacteria, so aim to buy and eat fresh food.
If you have a sweet tooth, try eating berries (strawberries, blackberries, blueberries, raspberries). They are rich in antioxidants and naturally low in sugar.
If you need a sweetener, try Stevia which is extracted from plant leaves and doesn’t impact blood sugar levels.
Do vegans need to take supplements?
A varied, wholesome vegan diet provides almost all essential nutrients in sufficient quantities. I hear you shouting ‘Noooo! It provides absolutely everything we need!’ and you may be right, but only if you regularly eat certain fortified foods. The sad truth is that modern food production systems and lifestyles make it more difficult for everyone – vegans or not – to get all they need from diet alone. It doesn’t mean a vegan diet is unnatural or unhealthy, in fact the opposite is true. It means that how we grow, produce and consume food has changed and, with an ever-growing population, the demands on the systems that produce our food are so high that certain nutrients become harder to obtain.
I get a lot of questions about supplements and understand why people are confused. Over the years, I’ve worked on many vegan research projects and as science and population studies reveal ever more data, the guidelines and recommendations change and evolve. Hence, what we were told 10 years ago may no longer be up-to-date and that’s why different opinions arise, depending on where and when we got our information. It’s my job to keep up-to-date, so hopefully I can bring some clarity to the supplement discussion!
So what’s needed? The trio of nutrients to keep a close eye on are vitamin B12, vitamin D and iodine. You may not need to supplement with all these, all year long, but it depends on several factors. Read on…
Vitamin B12 naturally comes from bacteria in the soil and both people and animals would traditionally have got it from eating unwashed plants. However, we not only wash vegetables before we eat them (and for good reasons), but food production is now so sanitised that most vegetables are washed in chlorine, or other sterilising solutions, so there’s not a trace of B12 left.
People are not generally aware that most farmed animals are given B12 supplements and this is how the vitamin eventually ends up in their flesh. So, the argument that meat is a natural source of B12 doesn’t really stack up as meat-eaters essentially consume B12 supplements recycled by the animals that were given them!
It is absolutely necessary that we have a reliable source of vitamin B12 for our bodies. We need it to make red blood cells, for a healthy heart and circulation, and it’s essential for the nervous system. It takes years to develop a B12 deficiency, so on one hand, you don’t need to worry about not having taken B12 for a while. On the other hand, you do need to pay attention, as when symptoms develop, it’s usually serious.
To ensure adequate intake, you should have at least 5µg (micrograms) daily from supplements or fortified foods. The B12 used in both foods and supplements is produced commercially by growing bacterial cultures in large vats – and it’s always suitable for vegans.
There are two forms of B12 in supplements – cyanocobalamin (cheap) and methylcobalamin (expensive). Cyanocobalamin is the stable ‘inactive,’ form of B12 and is used in supplements and to fortify foods and drinks. Once ingested, it’s activated by your body so it can be used. Methylcobalamin is the ‘active’ form of vitamin B12 as it does not require any metabolic reactions to be activated. It costs more and is not so stable.
So which one to choose? Unless you’re a heavy smoker, have kidney failure or any other serious condition affecting your metabolism, cyanocobalamin – the cheap form of B12 – is perfectly fine. Intakes up to 2,000µg a day are safe and you can take either a lower dose daily or a higher dose a couple of times a week.
We need vitamin D for healthy bones, teeth and muscles and it also performs other essential functions in our metabolism. It is produced in the skin when exposed to sunlight and this is the main source of vitamin D for most people. However, if you always use sun-block, cover most of your skin or live in a country, like the UK, where we don’t get enough sunlight over the winter, you need a supplement, whether you’re vegan or not.
The UK Government now recommends that we all take a supplement from October to April and, if you protect your skin ferociously over the sunnier spring and summer months, you should take a supplement all year long. Otherwise, just 20 minutes of sunlight on the face and arms is all that is required by the body to manufacture sufficient vitamin D.
Fortified breakfast cereals, bread, plant milks and vegan margarines can be useful sources if exposure to sunlight is not practicable, but may not be enough. When it comes to supplements, there are two types and your body can use both, but it’s advisable to check the source – vitamin D2 is always vegan, but vitamin D3 can be of animal origin. Many vegan foods are fortified with vitamin D2 and labelled so, but if not specified, especially on cereal products, vitamin D tends to be of animal origin. If you choose to supplement your diet, there’s a range of quality and affordable vegan supplements with vitamin D2. There are also those made from algae or mushrooms that contain D3 and these are recommended if you need a higher dose. When deciding on your dosage, 10µg per day is enough and you shouldn’t go above 25µg.
Iodine has been a hot topic lately, especially with plenty of tabloid ‘experts’ warning that vegans are missing out. This mineral is necessary for thyroid function and helps to regulate how energy is produced and used in the body.
The amount of iodine in plants depends upon the iodine content of the soil in/on which they are grown. The closer to the sea, the more iodine and therefore vegans can get enough from plant foods, but there’s no guarantee. Seaweed, which of course grows in seawater, is always a good source and includes nori, laver, dulse and the kelp family (kombu, arame, wakame). But be warned – kelp absorbs far more than other seaweeds and you can get too much iodine from it. So, while seaweed consumption is encouraged, kelp should be used only sparingly.
It’s best to use a kelp supplement so you know exactly how much iodine you’re taking – it’s cheap, reliable and you don’t have to worry about taking too much. The recommended daily intake is 140µg and intakes up to 500µg are considered safe. In many countries, iodised salt is commonly used to ensure iodine intake, but it’s not the norm in the UK.
The dairy industry has been boasting about the iodine content of cow’s milk. What they don’t tell you is that it’s not a natural component of milk, but comes from iodinated cattle feed, supplements, iodophor medication, iodine-containing sterilisers of milking equipment, teat dips and udder washes. Cow’s milk is neither a natural nor the best source of iodine, so we can happily leave all that dairy out of our diet.
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