COVID -19 Boosting your immune system to fight the coronavirus: what you need to know

Supplements

Could taking vitamins, minerals, or other supplements help protect you from COVID-19? Contrary to what you might read on the internet, this is a question that can’t be answered definitively. Here’s what we do know about certain supplements that reportedly have immune-boosting properties.

Vitamin C

For decades, Vitamin C has been used to help prevent the common cold. Among other functions, this vitamin can help maintain healthy skin that provides a barrier to germs and other harmful invaders. In addition, some — but not all — studies suggest it may improve the function of certain white blood cells that fight infection.

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 In addition, there is conflicting evidence about the potential mortality benefits of high dose Vitamin C for patients with sepsis, the most severe form of systemic infections.

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While it’s unclear whether taking a Vitamin C supplement is beneficial for COVID-19, for most people there’s no harm in taking up to 2,000 mg per day (the upper limit set by the National Academy of Medicine).

For smokers and high-risk individuals, it’s definitely worth considering. Vitamin C is water-soluble, so your body will excrete whatever you don’t need into your urine. However, at very high doses, Vitamin C may cause diarrhea or increase the risk of kidney stones (especially in men), so be sure not to exceed 2,000 mg daily.

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Vitamin D

As both a hormone and a vitamin, Vitamin D plays a number of important roles in health.

In recent years, people have taken very high doses of Vitamin D with the intention of boosting immunity. But is this an effective tactic? A 2017 systematic review of 25 randomized trials found that taking a Vitamin D supplement seemed to have a mild protective effect against respiratory-tract infections in most people, but provided much greater protection in those who were very deficient in Vitamin D.

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If your Vitamin D levels are low, you may have a better chance of staying well if you supplement with 2,000 IU per day (or more, with medical supervision). Many — perhaps even most — people are deficient in vitamin D.

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 So it’s probably wise to take a Vitamin D supplement right now, especially if you’re at increased risk for COVID-19.

Of course, your body can make Vitamin D on its own when your skin is exposed to sunlight, so try to get some sun whenever you can. How much sun depends on the time of year and your location. A good starting point is 15 minutes of exposure to a large body part (such as the torso or back). Just remember to avoid sunburns, as excess sun exposure carries its own risks.

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Zinc

Zinc is a mineral involved in the white blood cell response to infection. Because of this, people who are deficient in zinc are more susceptible to cold, flu, and other viruses. One meta-analysis of seven trials found that supplementing with zinc reduced the length of the common cold by an average of 33%.

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 Whether it could have a similar effect on COVID-19 isn’t yet known.

Taking supplementary zinc may be a good strategy for older people and others at increased risk. If you decide to take zinc, make sure to stay below the upper limit of 40 mg per day, and avoid administering nasally, due to the risk of olfactory complications.

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Turmeric

Turmeric is a spice commonly used in Indian and Asian cuisine, including curries. It contains a bright-yellow compound known as curcumin, which emerging research suggests might enhance immune function.

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 However,there isn’t any convincing evidence showing that it helps fight viral infections yet.

On the other hand, adding turmeric to your food adds flavor, and taking a curcumin supplement is unlikely to cause any harm in otherwise healthy people. If you have any medical conditions — especially if you take blood thinners — check with your doctor before supplementing with curcumin.

Echinacea

Echinacea is an herb that can reportedly help prevent the common cold. But is this reputation well-deserved? A recent systematic review of randomized trials found that echinacea may possibly have a mild protective effect against upper-respiratory infections but doesn’t appear to reduce the length or severity of illness.

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 While it’s impossible to say whether it might offer any protection against COVID-19, it appears to be safe to take on a short-term basis. If you’re at high risk, you may consider taking it for the next several weeks.

Garlic

Garlic, a popular and pungent herb with a characteristic aroma, is widely believed to have antibacterial and antiviral effects, including helping to fight the common cold.

A 2014 randomized controlled trial did find that people who took a garlic supplement had fewer colds and recovered more quickly from colds than people who didn’t take garlic.

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 Although this is encouraging, this is just one study. Other high-quality trials are needed to confirm whether garlic is truly beneficial for the common cold or other upper-respiratory infections. For now, enjoy garlic for its zesty flavor and unmistakable aroma rather than counting on it to boost your immunity during the coronavirus pandemic.

Nutrition

Fruits, veggies and seeds

Getting plenty of fruits, vegetables, and seeds is a common recommendation seen on many sites, but the evidence is inconclusive if it truly helps. In one often-quoted study, elderly volunteers were randomized to less than two or greater than five daily servings of fruits and vegetables.

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 They found the group with the higher fruit consumption had a better immune response to the pneumonia vaccine but not to the tetanus vaccine.

Another claim is that “eating the rainbow” and getting “adequate phytonutrients” improves immune function and reduces infection risk. Unfortunately, “eating the rainbow” and getting “adequate phytonutrients” are poorly defined terms, and such messages are usually compromised by being based on nutritional epidemiology studies heavily impacted by the underlying diet (i.e mostly in high-carb diets) and healthy-user bias.

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Therefore, we cannot conclude that any one specific food will improve your immune function. However, as with many other potential health benefits, it makes sense to stick to a diet that provides adequate essential nutrition and is rich in minimally processed natural foods. It may not be more complicated than that.

Refined carbs and sugars

Laboratory evidence suggests sugar may impair white blood cell function, but no credible evidence shows eating it makes you get more infections.

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 However, other evidence suggests acute rises in blood sugar may increase risk of infections and complications.

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 Therefore, it would make sense that we want to limit these blood sugar elevations. Refined carbohydrates and simple sugars are two of the biggest offenders for blood sugar spikes and therefore should probably be avoided.

This is different than saying studies show avoiding these foods results in fewer infections. (We don’t have that evidence.) Plus, as we have mentioned many times, it’s difficult to isolate the effect of one food since any food’s effects have to be studied within the context of the underlying diet (i.e. standard American diet vs. a low-carb diet).

However, one simple solution is to use the measurement of your own blood sugar as a guide. If higher blood sugar is associated with more complications, it makes sense we want to limit that.

We suggest measuring your blood sugar either with a regular glucometer or, even better, with a continuous glucometer (CGM) if you have access to one. If the foods you eat cause your blood sugar to rise above 140mg/dl (7.8mmol/L), consider eating something different.

Studies show that a low-carb, moderate protein, higher fat diet effectively reduces blood sugar and can even reverse type 2 diabetes.

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 We don’t have proof that this will “boost your immune system,” but it may help keep blood sugars in check which may be associated with decreased infectious risk.

Chicken soup/bone broth

Treating colds and the flu with chicken soup may be the most popular urban myth of all time. Surprisingly, it may not be 100% a myth.

One study showed chicken soup “inhibited neutrophil migration,” which the authors suggest could improve our ability to recover from infections.

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 However, this is one of those instances where laboratory findings may not translate to clinical improvements such as fewer or less serious infections. But it’s hard to argue with a tasty homemade soup with chicken, a few low-carb veggies, and plenty of real salt. Immune booster or not, it sounds like a great meal for a wintery day in self-isolation. We chalk that one up to good self-care.

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Fasting

With all the focus on how certain foods affect your immune system, you may also wonder, what about fasting? One study in mice showed that fasting, or more specifically refeeding after a fast, restored immune function that had been suppressed by chemotherapy.

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 During the fasting period itself, however, it appeared to impair the immune system. In addition, the beneficial response to refeeding may be lessened in the elderly.

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These are very important caveats. Over the long term, intermittent fasting and refeeding may boost the immune system. However, during an acute pandemic, where the immediate risk of infection is higher than usual, it may not be a good time to try fasting, given the potential for a temporary decrease in immunity.

This may sound surprising for those who have heard the phrase, “starve a fever.” The theory is that humans have evolved to not feel hungry and purposely avoid food during an acute illness as a protective mechanism, which may in turn limit nutrients the virus needs to replicate. To be clear, this is all conjecture without any quality supporting evidence.

Other evidence suggests that ketones are beneficial for immune function, and perhaps that could be why some recommend fasting.

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 But considering all of the data together, if that were the case, you would likely be better off eating a keto diet and not fasting.

Based on the limited data available, we suggest not fasting longer than 36 hours during the outbreak of the coronavirus, especially if you are older than 60 years old. It’s logical that you can continue with shorter-duration time-restricted eating, although there is no data on this either.