Health – Fight infection this winter

People commonly take supplements to “boost” their immune system, but the therapeutic claims for these products are often vague and unsubstantiated.

Here is my attempt to negotiate the maze of myth, wishful-thinking and developing evidence related to how we fight infection. 

First of all, recurrent illnesses are not necessarily a sign of immune deficiency. We’re exposed to thousands of bugs every day, and some of them are bound to get through our first lines of defence, and some people are just at higher risk due to their jobs (think teachers, caregivers), age (preschooler and elderly) and lifestyle. A few mild illnesses a year are normal, even if in quick succession. 

The typical symptoms of a cold are actually due to your immune response (inflammation of the mucous membranes causing runny nose, cough, sneezing and sore throat), not to the virus itself. Theoretically, then, “boosting” your immune system could make you feel worse. 

What we want to do is improve your immune accuracy, that is, the ability to neutralize threats selectively, without collateral damage to normal tissues. And how can we measure that? The answer currently is “not very well”. 

We can count white cells, but there is a wide range of normal and it doesn’t tell us much about how they are functioning. Measurements of the different types of immune cells are available. However, they only become important when we are assessing severe immune deficiency syndromes, like AIDS, or the effects of immune suppressant drugs. 

There is a solid body of evidence for some surprisingly mundane factors contributing to immune accuracy:

• Not smoking 
• Feeding the good bacteria in your gut. I have commented on this in a previous column, but your tummy does best with adequate fibre and a reasonable intake of probiotics (live organisms that you can consume through fermented foods, like natural yoghurt)
• Gardening. Exposure to healthy soil gives contact with lots of beneficial bacteria
• Moderate daily exercise 
• Stress reduction and a positive attitude to life
• Normal vitamin D levels. Most people in sunny Auckland have adequate levels, but shut-ins, people who routinely cover most of their bodies and those with very dark skin may be at risk. There is no benefit from supplementation for most of the population. 

And if you do get sick, “listening to your body” is important. Not rushing back to work, getting adequate fluids, rest, and sleep all contribute to an efficient immune response. 

Despite a long-held belief, vitamin C does not prevent colds, but may mitigate symptoms and duration a bit. In addition, zinc 75mg daily from the onset of the illness can shorten the course. There is also some evidence that ginger (best eaten fresh) and turmeric have immune benefits and are certainly safe.

Finally, regular flu and Covid vaccines.. Exposure to a tiny amount of known strains gives worthwhile protection for both these illnesses, which we are going to have to live with for the foreseeable future.