“Boost your immune system”. But what does this mean?


COVID is a pandemic that is scaring the ordinary members of public. And this is entirely understandable. An invisible foe capable of crippling people regardless of age, race, wealth across the globe, with seemingly no cure in sight. It is natural to try and prepare yourself in case you get the infection. Many articles and whatsapp forwards are promoting substances to “Boost your immune system”. But what does this mean?


As we discussed in a previous blog about plasma exchange, your body’s immune system is an amazing mechanism that can recognise invading organisms and target them for destruction. It does this with the help of white blood cells (of which there are many types) and production of antibodies. Its importance is evident in diseases that destroy our immune system, such as leukaemia, chemotherapy, and also auto-immune disorders in which the immune system causes damage by accidentally damaging the body itself, for instance in rheumatoid arthritis, lupus, Type 1 Diabetes and more.

So we have a way to deal with the coronavirus. Then we should boost this right? Boosting the immune system is exactly what we need. A great idea in theory, but one that fails in execution. Because the phrase “boost the immune system” has no meaning. What are you trying to achieve here?

Do you want to make more white blood cells? Well, in leukemia you have hundreds of thousands more white cells, but it is a cancer that can damage your bones.

Do you want these white cells to be more aggressive? Well, that’s what auto-immune disorders are, an overly aggressive immune system that acts without control, and destroys your own functioning organs.

What about a strong response against the virus? An immune system that responds excessively will pump out chemicals that recruit more white cells, increase blood flow to the infected area to recruit more white cells, which in turn produce more chemicals, etc etc. This positive feedback loop can result in the excessive production of these chemicals that makes your blood vessels too dilated and leaky, forcing fluid into the tissue, tanking your blood pressure, reducing the amount of oxygen reaching your cells and in severe instances causing death. This “cytokine storm” is actually one of the proposed mechanisms by which COVID-19 can cause respiratory failure, as the leaky blood vessels cause fluid to pool in your lungs, making it more difficult to breathe.

Do you see the problem here. “Boost the immune system” is a useless phrase that doesn’t actually mean anything. In the body everything is kept in a very fine balance. Swaying excessively towards an extreme results in a disease. That’s exactly what we want to avoid. And now to the second half of the problem.


There have been lots of foods that have been proposed to boost the immune system. All sorts of herbs, spices, natural extracts, fruits, vegetables, vitamins, drinks, everything under the earth has been proposed by one person or another. Some claim to have special properties, others claim to reduce inflammation (this is particularly egregious as the immune system itself causes an inflammatory process in order to target invading pathogens. You cant boost a system by stopping its actions).

In a way, they are right. The best way to “boost” is to be healthy. A healthy, varied diet that provides you with all the necessary substrates to produce the cells that keep you healthy. Excessive sugars and fats in your diet (and in your blood) will damage these cells, reducing their efficacy. Exercise triggers signalling pathways within cells and throughout the body that reduce excessive sugars, fats, and keep the body in the right balance to function properly. This is of course a massive oversimplification of metabolic disease and inflammatory processes that occur with diabetes, obesity and poor diet. But the end result is still the same.

It is not by taking one substance, one magic food or one simple cure that we can prepare for COVID. It is instead by putting in the effort to eat a varied, healthy diet, reducing your sugar and fat intake, and maintaining regular exercise, even if it is an hour walk a day. Quick fixes do not exist in medicine, as much as every doctor wishes it to be true.

Dr Rajan Choudhary, UK, Chief Product Officer, Second Medic Inc