Can we really ‘boost’ our immune system to fight COVID-19?


To date, the 1918 Spanish flu pandemic has the unenviable tag as the most humanly devastating in history, infecting more than 500 million people, and killing at least 50 million people worldwide. Unfortunately, the pandemic also came with opportunities for self-styled chemists and medics to make regular appearances in the news media, with alarming and sensational headlines.

Sadly, not much has changed in 2020. Even though the COVID-19 pandemic is separated from the Spanish flu by more than 100 years, with a commendable advancement of scientific discoveries, there are still thousands of so-called medical remedies floating around. The current theme by the herbal and other drug peddlers is “boosting” the immune system.

And as always, social media is inundated with nutritional advice. This time, we’re being advised to seek out foods rich in Onions, Garlic, Antioxidants, Zinc and Vitamin C, while “nutritional and medical experts” are also peddling nutritional products such as probiotics.

According to another “nutritional expert”, green tea and cayenne pepper can even provide better protection against COVID-19 than face masks – albeit, a bold and questionable claim, considering that some face masks reduce your risk of coronavirus infection by a factor of five.

“Boosted” immunity doesn’t exist

Unfortunately, the idea that nutritional pills or supplements or some wellness habits provide a shortcut to a healthy immune system is a myth. In fact, the entire notion of “boosting” one’s immune system doesn’t have any medical or scientific meaning or relevance.

For a start, there are three main barriers to infection, which also provide the three keys to unravel the concept of immediate immunity. These are the mucus membrane, the airways, and the skin.

Once the virus succeeds in going past these defences, then you have to induce the ‘innate’ or non-specific immune response, which primarily consists of cells, physical and chemical barriers. The innate immune system is elicited first, but does not retain memory of previous responses. The main purpose of the innate immune response is to rapidly fight off the invading pathogen(s) in the body.

When that is not enough, then the adaptive immune system kicks in. This response involves Lymphocytes (B-cells and T-cells) and antigen presenting cells (B-cells, dendritic cells and macrophages). While the innate immune response is immediate, the adaptive immune response is not (takes a few days or weeks to emerge).

However, the effect of the adaptive immune response is long-lasting, and is sustained long-term by memory T cells.   Importantly, the adaptive immune system is pathogen-specific, so for example, a T-cell specific to SARS-CoV-2 will not respond to common cold or the measles virus. Eventually, almost all viral infections will trigger adaptive immunity.

The current usage of the term “boosting the immune system” presumably denotes making these responses stronger or more active.

In actual fact, you don’t want to make the immune system more active.

If you take the symptoms of the common cold – fever, body aches, copious amounts of phlegm – these symptoms aren’t actually caused by the virus itself. Instead, they’re part of the innate immune response that are triggered purposefully by the body.

In this case, the rise in temperature that comes along with fever helps to create an uncomfortable environment for the virus to replicate, the aches are by-products of the inflammatory cytokines that run through your veins telling immune cells what to do and where to go (perhaps also signalling the brain to slow down and allow the body to recover), and the mucus helps to flush out the pathogen.

The mucus and chemical signals are part of inflammatory responses, which is the real indicator of a healthy immune response. But since this biochemical process is exhausting, you wouldn’t want to have it in an overdrive. And most viruses, including SARS-CoV-2, will trigger it anyway. What this means is, if any of the various “immune-boosting” supplements being advertised today had any impact on the immune system, they would give you almost nothing extra but a runny nose and more phlegm.

Furthermore, making the adaptive immune system generally “more active” could also be extremely unwelcome. For example, allergies occur when overactive immune cells treat even innocuous antigens, such as pollen, as though they are extremely harmful. Each time they find the pollen, they trigger the innate immune response too – itchy eyes, lots of sneezing, and general malaise. This is probably not what the advocates of these remedies have in mind.

But let’s give the advocates of the “immune system boosters” the benefit of the doubt, and assume they mean that their products can enhance the immune response – rather than literally “boost” it. The overarching problem with these claims, however, is that they don’t have any grounding in evidence. So what are these claims based on? – and is there anything that can help support the immune system?

For healthy individuals, forget the supplements – except vitamin D

Many multivitamins claim to help “maintain healthy immune function” but research indicates that multivitamins don’t work in already healthy people, and some may even be harmful.

Let’s take vitamin C. The health effects of this antioxidant have been hyped ever since Linus Pauling (a two-time Nobel Prize winner) became fascinated with its ability to fight the common cold. After extensive studies on vitamin C, he started taking 18,000 mg per day – around 300 times the recommended daily dosage!

There is however very little evidence to support the claim that vitamin C can fight off colds and other respiratory infections. Indeed, a review by Cochrane – an organisation noted for objective and unbiased research – reported that in adults, vitamin C administration at high doses after the onset of symptoms, showed no consistent effect on either the duration or severity of common cold symptoms. Since then, various infectious disease experts and nutritional immunologists from prominent labs around the world have asserted that vitamin C supplements aren’t beneficial unless you are immune-deficient!

Let’s look at vitamin D. In the advanced world, most people already have enough vitamins from their diets, unless they are restricted.  The only exception may be that of Vitamin D, in which case taking vitamin D supplement wouldn’t be a bad idea.

Several studies have linked low vitamin D levels to more severe symptoms and increasing risk of respiratory infections, as well as in the development of autoimmune diseases such as Lupus erythematosus and Arthritis. Many immune cells can actively respond to vitamin D, and it’s believed to play an essential role in both innate and adaptive immunity.

Ironically, it has been estimated that about a billion people worldwide have insufficient vitamin D. With the current lockdown in many countries because of COVID-19, it’s understandable that even less sunlight exposure could lead to more deficiencies.

It must, however, be pointed out that high doses of one nutrient can create deficiencies of other nutrients needed by the immune system. For example, whereas zinc is essential for immune function, high doses of zinc supplements taken over extended periods can cause a deficiency in copper, which is also essential for proper immune system function.

It is also worth noting that studies in cell culture or laboratory animals only provide a foundation for potential tests in humans, not recommendations for immediate action in humans. For example, onion or garlic contains natural antioxidants and phyto-compounds that may enhance immunity, however, as noted by the World Health Organization (WHO), “There is no evidence from the current COVID-19 outbreak that eating garlic has protected people from the new coronavirus.”

Should we stock antioxidants?

Perhaps a more appropriate question is – do antioxidants help at all? The answer here is slightly more complicated. As part of the inflammatory immune response, white blood cells (T-lymphocytes) release toxic oxygen compounds.

These can either kill viruses and stop them from replicating, or damage healthy cells, which can lead to cancer, thereby wearing out the immune system in the fight. To stop this double-edged sword from “cutting”, the body elicits the release of antioxidants. These help to control the “aberrant” oxygen compounds in order to keep our cells safe.

Free radicals are seen as important signals within cells because they “switch on” the body antioxidant defences, but excessive levels of (or “boosting”) free radicals can also damage cells and promote inflammation. In general, short-term inflammation is part of the body’s mechanism to clear an infection, however, if inflammation builds out of control, it could create cellular damage that is difficult to reverse.

The main danger is that, if you are worried about COVID-19, which is related to oxidative stress and inflammation, you may be tempted to assume, “if some is good, then more is better,” to fight the disease. Current evidence, unfortunately, doesn’t prove this. Fortunately, we get some of our reserves of these antioxidants from our diets (egs. carrots, strawberries, blueberries, turmeric etc.)

There’s currently an ongoing trial to see if antioxidant supplements might help the recovery of COVID-19 patients. However, the trial is just one of several others hunting for potential treatments for COVID-19. What do we know currently? – despite several years of research, not a single peer-reviewed, placebo-controlled, double-blind study on humans has demonstrated that high doses of antioxidants can “boost” the immune system, or treat or prevent viral infections like COVID-19 in humans.

Probiotics may or may not help

According to the homeopaths and fitness experts, probiotics is much more than a sweet drink made from fermented tea. Social media is trending with outrageous and deceitful claims about the product, including that it can even treat AIDS. Some websites are also propagating another unthinkable falsehood that it can cure COVID-19.

Probiotic drinks contain beneficial microorganisms which are concentrated in foods, drinks, or pills but the therapeutic potential is less clear because no studies have proven that the drink which has these microorganisms in high enough concentrations is even considered one.

One review found that probiotics significantly reduced upper respiratory tract infections. When administered to school children, they also slightly reduced school absences. The authors concluded that even though they could be better than placebo treatments, the overall quality of the available evidence was low. There is therefore no hard evidence that probiotics can protect you from COVID-19.

So what has been proven to work?

Admittedly, quite a number of these myths are innocuous, but the danger is that one could have a false sense of security.

Nutritional supplements aside, there are a number of approaches one could use to support the immune system. They aren’t especially attractive, but have been proven to work. More so, they don’t require parting with your hard-earned money: get enough sleep, destress, exercise, fill your mind with good thoughts, limit alcohol intake, and eat a balanced diet.

Ultimately, you need to picture your immune system like your car’s engine, which needs petrol or diesel to run. Adding more petrol or diesel to your fuel tank would not enable the car to run any more powerfully than the engine capacity allows. Like the fuel for your car, a balanced and healthy diet is critical for your immune system to keep functioning, however, this doesn’t mean you can overload it with nutrients to super-charge your immunity. The only sure way to improve your immunity to certain pathogens is though vaccination.

The idea of “boosting” the immune system should therefore not be our focus and preoccupation. Staying healthy means maintaining an immune system capable of attacking harmful pathogens, including bacteria and viruses. Needless to say, an immune system in over-drive would only result in chronic inflammation, allergies and autoimmune diseases. There are however some people who have weakened immune systems due to age, sickness, surgery or malnutrition, who may benefit from immune-nutrition. There is still much to learn in nutritional immunology

What’s the take-home message?

There is currently no evidence to indicate that you can “boost” your immune system with a nutrient supplement, however, healthy eating and other lifestyle choices can contribute to a healthy immune system. Reduce, the work your immune system has to do to protect you. You can:

  1. Indulge in some form of physical activity daily.
  2. Go to bed at a time that will get you enough sleep for sustaining a strong immune system.
  3. Eat a balanced diet
  4. Maintain a healthy weight.
  5. Destress by using walks or other tools to cope with fear and anxiety.

For protection against COVID-19, following frequent hand washing with soap (or sanitizers with at least 70 percent alcohol), following social distancing recommendations, plus the wearing of masks is key.

As for nutrition, focus on nutrient-rich plant foods. Limit sugar-sweetened and fizzy drinks, red meats, “fast foods” and alcohol intake. These nutritional recommendations, if made as a blueprint would go a long way in helping your immune system protect you against COVID-19.

>>>Stanley Moffatt is a Professor in Virology, Molecular Medicine and Nanotechnology at Regent University College of Science and Technology, Accra

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