5 threats to your immune system–and how to fight them | Prof. Daniel Davis MBE

**Jonathan** (0:00)
Welcome to ZOE Science and Nutrition, where world leading scientists explain how their research can improve your health.
Walk into any store, and you'll see rows of supplements claiming to boost your immune system. We all want to avoid being sick during the winter months, so these products can seem tempting. But do any of them really work? And is trying to boost your immune system really a good idea? To help us understand, we're joined today by Daniel Davis, Professor of Immunology and Head of Life Sciences at Imperial College London. He has published 145 scientific papers and authored four best-selling science books. Daniel has researched immune health for 25 years and helped discover the immune synapse which revolutionized our understanding of this system. Today, he'll help us bust some myths about the immune system and explain how immune health is linked with mental health. Most importantly, he'll tell you how to support your immune system. By the end of today's episode, you'll know what you need to do to reduce your risk of catching cold or flu this winter. And just as importantly, you'll know what won't help. Dan, thank you so much for joining me today.

**Daniel Davis** (1:22)
Thanks, Jonathan. It's wonderful to be here.

**Jonathan** (1:24)
I'm aware that our immune system helps to fight off these microbes that are out there in the world trying to infect me and make me sick. And honestly, every time a scientist starts talking about the immune system to me, I end up feeling more confused at the end of the conversation than at the beginning. So I think it's brilliant that we have one of the world's leading experts on the immune system here to hopefully clear this up for me and I imagine for many of our listeners too. So can we just start at the beginning really, which is like, what is the immune system and why is it so challenging to study?

**Daniel Davis** (1:55)
The immune system is very complicated. I'm sure people are very aware of the importance of your immune system in fighting off all different kinds of infections.
It's also important in preventing us from succumbing to other kinds of illnesses, cancer and all sorts of other problems that could arise in our health. It's inherently complicated because it has to fight off all different kinds of possible infections, including infections that have never before existed in the universe. A new type of virus could arise at some point and our immune system has to be able to fight that. So the immune system is there to fight off things that are potentially dangerous, but not attack any normal part of your healthy body. And to some extent, every single cell of you is part of your immune system, because almost all the different types of cells that make up the human body actually have some ability to know when they are infected with a virus, for example, or when they are turning cancerous. So most cells of the body have already some in-built sensory mechanism to detect when they themselves have a problem, and they could signify to other bona fide immune cells that they have a problem. So all of your body is part of the immune system.

**Jonathan** (3:17)
I mean, one thing I heard really clearly was that not only does it have to be incredibly good at attacking sort of these bad things outside, but it needs to be really smart at recognizing whether this is actually part of my body, so it mustn't be attacked. I'm interested that you mentioned that just in the summary. Is that a very important part of what it needs to do in order to be healthy?

**Daniel Davis** (3:37)
Absolutely, because you will know that there are any number of products and ideas telling you how to boost your immune system. And on the face of it, that sounds quite a simple thing that we want to be doing. But having just told you the complexity of what the immune system has to do, a layer of depth in the idea of boost the immune system is immediately impairment. What does that actually mean? If you just somehow boost the ability of your immune system to be very active and start fighting things, then you don't want to do that, because it would inadvertently start attacking things that are part of the normal, healthy body. And that would then cause you problems in itself. So it's important that we understand the complexity and the nuance in what the immune system has to be able to achieve, because already we're at the point where some of the sound bites and clickbait you might come across for do this one thing to boost your immune system, already now we could be questioning what does that actually mean? And I want to just boost my immune system in a very general way to make it more active. I need it to be restrained in some situations, because I don't want the immune system to react against my own body or things that are not particularly harmful to me, which would happen if your immune system started reacting against food or something and gave you an allergic reaction.