Nutrition and COVID-19 - Can We Boost Our Immunity?

In the early days of the pandemic sales of dietary supplements skyrocketed - in part driven by a perception that these pills and capsules could protect us due to their “immune-boosting” properties. But when it comes to preventing, or managing, a viral infection (including COVID-19) can nutrition and supplements help us out? Tune in to find out.

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Credit to MonoSheep for the theme music.

Transcript

Welcome to Nutrition Bites. The no nonsense podcast where you get the truth about food so you can eat what you want, and be healthy. I’m your host Maggie and welcome to Episode 28 of this series! Right now we are dealing with an infectious trifecta: the common cold, seasonal flu, and of course, COVID-19. And people are curious, can our diet do anything to help us out? On the menu today, nutrition and immunity.

A few years ago I received a hot tip from a colleague when we were talking about common cold remedies. He told me to chow down on raw garlic as soon as I felt a cold coming on. There are some studies that show specific compounds in garlic have antiviral effects, so a girl could hope. Unfortunately there’s just not enough evidence for this to be doctor-recommended advice, but in spite of this, I still find myself turning to the terrible experience of eating raw garlic whenever I get the slightest tickle in my throat. And why is that? Well, even though I know it’s not guaranteed to help with a cold, taking any kind of action makes me feel a little more in control. And it’s this desire to outwit a virus, especially with natural ingredients, that not only makes me feel like a powerful witch, but also motivates many people to turn to nutritional supplements in times of infectious panic. In the early days of the pandemic sales of dietary supplements skyrocketed and this was in part driven by a perception that these pills and capsules could protect us due to their “immune-boosting” properties. But when it comes to preventing, or managing, a viral infection can nutrition and supplements help us out? Let’s dig in!

Whenever we talk about infection, we have to introduce our body’s security network - the immune system. The immune system is our defense against anything the body deems a threat, including allergens, parasites, bacteria and viruses. It’s an insanely complex network of different cells and organs all working together to protect you. You have molecules that act in tandem like a SWAT team, organs that coordinate communication like the Houston Space Center, and cells that take inspiration from Jason Bourne by going rogue but doing a really good job at catching the bad guy. Like all things in our body, the strength of our immune system is dependent on our general health. Lack of sleep, chronic mental stress and excess weight are all things that weaken our ability to spot, and fight off, an infection. Of course, another important factor that influences our immunity is…what we eat. 

Across the board scientists agree that our diet drastically influences the strength of our immune system. People who are malnourished, meaning they are NOT meeting their daily nutrient needs, are more likely to become infected, have more severe symptoms, and take longer to recover from infection. And I’m sorry to reveal that no secret recipe for an immune-boosting diet exists. If you want a strong immune system you gotta follow the classic advice you’ve heard before - eat a diet full of fruits, veggies, whole grains , legumes, and lean proteins, and avoid eating red meat and processed foods. Look, I know, this is kind of tiresome advice, but also, this isn’t Goop - I’m here to give you the boring truth backed by science. And it’s proven time and time again that this type of diet allows us to meet our daily nutrient needs. So far, no single food, ingredient or nutrient has been found to help improve our immunity above and beyond it’s baseline. In fact, the main reason why nutrition is so tightly linked with immunity is because when we don't meet our normal, daily, nutrient needs, then we are at greater risk of infection. And eating a whole-foods, plant-based diet helps provide all the vitamins and minerals the immune system requires to go all military combat on a virus or bacteria.

Now because our immune system is so incredibly complicated, it requires a whole variety of vitamins and minerals to function. Zinc, Vitamin C, Vitamin E, Selenium, Vitamin B6, Vitamin D, and Beta-carotene have all been identified as nutrients which support immunity. They either function as an antioxidant, encourage the growth or activation of immune cells, or help produce antibodies. But just because these nutrients are important for a well-functioning immune system, doesn’t mean that you should be throwing back 7 different supplements everyday to protect yourself against infection. In fact, if you already eat well, it’s unlikely that adding additional doses of these nutrients is going to help you out that much. Let’s take the common cold for example.

Now the popular association of Vitamin C with the common cold is next level. It almost makes me wonder if Kris Jenner might have been hired to run PR for this micronutrient. But despite very limited proof that Vitamin C is helpful in battling this infection, many people still buy into emergen-c hype. Evidence from many studies show that supplementation with Vitamin C doesn’t actually prevent you from catching a cold. What it can do, is slightly reduce the severity of symptoms and duration of a cold, and by slightly I mean like overcoming a cold 9 hours before someone not supplementing with Vitamin C. But, this only occurs if you were already regularly supplementing well before you got a cold. Researchers agree that once you start to feel symptoms, it’s too late for Vitamin C to help. But what about the more…relevant respiratory virus of the moment. Does any micronutrient have a role to play in COVID-19?

Of all the vitamins and minerals that support our immune system, three have regularly been called out as important to investigate when it comes to COVID-19: Zinc, Vitamin C, and Vitamin D. Zinc is a mineral necessary for hundreds of enzymes in our body to complete so many vital reactions, from creating DNA, to healing damaged tissue, and of course, supporting immunity. Zinc deficiency is known to decrease our resistance to infections, and many studies in adults across the world have shown that taking a zinc supplement may be helpful for specific infections, like shortening the duration of symptoms if you have the flu. But despite this potential, there just hasn’t been any proof yet that zinc has a role to play in preventing, or managing, a COVID-19 infection. And it’s a similar story with Vitamin C.

This vitamin is used by enzymes across our nervous, bone, blood, and immune systems, and it’s also a powerful antioxidant. And with it’s cult-like status in the immunity community, one would think it would help with COVID-19. But the only research done so far on Vitamin C, and zinc, with respect to this virus, showed no benefit with supplementation. It’s important to call out here that in particular, this study was investigating if supplementation with either nutrient could improve symptoms in non-hospitalized people who had contracted COVID. But it’s also important to note that the safety monitoring board who oversaw this clinical trial actually called for it to stop early, due to what they call “futility”. Which is a rather politically correct way to say “it’s useless - please go do something else”. Now keep in mind, it takes years for researchers to properly investigate this stuff, and we’ve only been in this pandemic for around 2. So it’s not like I’m saying zinc and Vitamin C supplementation will never have a role to play when it comes to COVID-19, but we just don’t have enough evidence right now to say that they do. Even the National Institutes of Health in the US has a similar perspective. For Vitamin C in particular they state that there is insufficient evidence to recommend either for or against the use of this vitamin in the treatment of COVID-19. 

Now unlike the single, futile, trial investigating Vitamin C and zinc, a lot more research has been conducted on Vitamin D and it’s impact on COVID-19 infections. Now, Vitamin D is actually a misnomer - it’s technically a group of hormones whose main role is to help increase the absorption of calcium, magnesium and phosphate from the food you eat. So naturally it has a big role to play in bone health. But Vitamin D is also thought to have anti-inflammatory properties - in particular decreasing the release of a specific group of immunity molecules called “inflammatory cytokines”. The job of these molecules is to help coordinate the immune response whenever you have an infection, kind of like a back-stage production team at a fashion show. But what doctors have been finding with some severe, and often deadly, cases of COVID-19 is hyperactivity of the immune system, where instead of releasing a regular amount of cytokines, your body is blasted with these inflammatory molecules, which end up killing a lot of healthy cells. Now because Vitamin D is thought to tamper down the release of these cytokines, people were excited about its potential in helping to prevent severe cases of COVID-19 infection. 

And so far, dozens of trials, covering over half a million patients, have been conducted on this relationship. And this amount of research makes me feel pretty confident about the general findings, which show….nothing. Overwhelmingly Vitamin D supplementation did not improve patient outcomes, and even Vitamin D deficiency was not associated with an increased risk of infection, severity, or death. Which sucks…I know. We all had hope for this one. But like I said earlier, this type of research is still in its infancy, so maybe one day, we’ll find out differently.

But as of right now, no health authority has stated that we need to take any vitamin or mineral supplement to help us prevent, or manage, COVID-19. The gold standard advice still remains to get our nutrients through food and make sure we meet our daily requirements. But the reality is, most of us don’t eat a diverse and healthy enough diet to get all of the micronutrients we need. Which means we could very well be deficient in something. And we know with certainty that micronutrient deficiency weakens our immune system. So with this in mind, it may actually be helpful to take a daily multivitamin, just so your bases are covered. But also maybe you don’t need to and it’s just a waste of money. There are however a few specific groups of people where supplementation is more strongly advised.

In general, older people, which is anyone above the age of 65, are recommended to add a general multivitamin to their diet, simply because our ability to absorb nutrients from food naturally decreases with age. And for those who eat a predominantly plant-based diet, a zinc supplement could be worth looking into. That’s because zinc is mostly found in animal products, and beans and fortified grains are really the only vegetarian sources. For the general population, a Vitamin D supplement might be helpful, especially right now. Although Vitamin D is found in some foods, including fatty fish, mushrooms, egg yolks, and fortified dairy and soy products, unless you’re dropping bills on sashimi every day, you’re probably not meeting your daily quota via food. That’s because we actually make most of our Vitamin D through skin exposure to the sun. It’s like our own little version of photosynthesis! But this reliance on the sun can be a problem if you live in a Northern climate where a good chunk of the year is spent in darkness or inside. Over a quarter of the US population, and almost 40% of the Canadian and many European populations are estimated to be Vitamin D deficient. If you’re like me and live in one of these places, you’re probably stuck inside right now. Not just because it’s cold and dark but also because you may have transitioned to “working from home”, “virtual school” or are under some sort of “stay at home” order. But even though there is a decent likelihood that you are Vitamin D deficient, there still isn’t much consensus on whether we should be taking a daily supplement or not. The FDA doesn’t have a recommendation, Health Canada only suggests it for adults over the age of 50, and the UK’s Public Health England, recommends adult supplementation but only during the autumn and winter. So it’s really up to you and your doctor to decide what to do here. Personally, I take it every day during the winter, but I think that’s mostly because I once had a nutrition professor yell at our class about this topic, and I still haven’t worked through that psychological attack yet. 

Now if you’re curious about adding any supplement to your diet, whether it’s to ensure you meet your daily needs for optimal immune functioning or another reason, you have to be aware of some risks. All micronutrients have an “upper limit” which is the max amount to take before experiencing, essentially, an overdose. Most won’t kill you, but too much Vitamin D for example may lead to nausea, weakness or even kidney stones. So leave the experimentation to your home cooked meals, and not to your supplementation. Not only can it be confusing to determine the dose of a supplement to take, but also which kind of supplement because they come in different forms - like zinc acetate versus zinc gluconate. And keep in mind that supplements can negatively interact with medication, including antibiotics. Main point, if you’re curious about adding a daily vitamin or mineral into your life, discuss it with your GP or dietitian first. 

No matter what you decide to do, please remember this: no one micronutrient, ingredient or food will “boost” your immunity beyond what it can normally do. And similarly, nothing specific in our diet has been conclusively proven to help prevent, or manage, a COVID-19 infection. It really all comes down to just eating healthy. Doctors and scientists agree that the best way to keep your immune system in shape, and protect yourself from any infection, is to get good sleep, chill out, and eat your damn fruits and veggies. 

That’s been the bite for today. Stay hungry.