Why is everything you thought you knew about your immune system wrong?

Maybe you’ve heard that consuming plenty of vitamin C will ward off colds, or perhaps TikTok has influenced you to take turmeric or other supplements to boost your immune system. The problem is that these bold claims and quick fixes are complete nonsense. He says there are a lot of myths about immunity Daniel Davisan immunologist at Imperial College London.

In his new book Self Defense: The Myth-busting Guide to Immune Healthhe sets out to challenge these misconceptions. With each technological advance, such as the use of super-resolution microscopy to show how immune cells interact with their targets, the incredible complexity of the immune system becomes clearer, Davis explains.

But he says he does not leave us adrift New worldThis complexity helps us appreciate the importance of the immune system in mental health, makes us aware of lifestyle factors that may compromise our immunity, and improves our ability to distinguish truth from fad.

Helen Thompson: Let’s start with the phrase “immune health” and claim we can boost it. That’s not actually the right way to think about it, is it?

Danielle Davis: Yes, there are many products that say they can “boost” your immunity. But this does not seem entirely true, because although you need your Immune system To be strong against infectious agents, if you just increase their strength in a general way, they may attack healthy body cells and cause autoimmune diseases or allergies. They must act in an organized manner to be able to respond appropriately.

So, is it about wanting to make our immune system “smarter”?

None of these sound ways of talking about immune health are accurate enough. First, each person’s immune system is completely unique and, at the level of your genes, the most unique thing about you. So when we talk about immune health, what we can really talk about are things that have been proven to be true, on average, Helping people, but it’s very difficult to know if that’s something that’s going to help you as an individual or not.

One of the biggest discoveries is that the immune system does not operate in a silo, it is influenced by diet, exercise, and our microbiome. Is it possible to say which lifestyle factor has the greatest impact on immune health?

The thing that has the most obvious impact on our immune health is long-term stress. For the other things you mentioned, there is a lot of evidence, but it is still very difficult to prove causality. But with stress, we have a molecular understanding of what’s really going on.

And he?

When your body feels threatened, it has a fight-or-flight response – the signal goes from the hypothalamus to the pituitary gland to the adrenal gland, which triggers the production of stress hormones – adrenaline. [epinephrine] And cortisol – which helps your body prepare for work. This condition calms the activity of your immune system. This is fine in the short term, like skydiving. When you land, changes occur in the number of immune cells in your blood for about an hour. Then it returns to normal. But if you are in a state of chronic, long-term stress, your cortisol levels remain higher, and this weakens your immune system over a longer period, and becomes a problem.

The reason we’re so confident about how this happens is that if you look at how good your immune cells are at killing virus-infected cells or cancer cells in a lab dish, and then you add cortisol, those cells will be less efficient at killing virus-infected cells or cancer cells. By adding this to the associations we see – how people with long-term stress respond less to vaccines, for example, or how they are more susceptible to infections – it means I can say with confidence that long-term stress affects the immune system.

If I suffer from stress and change my lifestyle, is there any way to measure my immunity to see if it helps me?

It’s still very difficult to prove that doing something to reduce long-term stress helps you. It makes sense that this would happen, but it is difficult to show. In hospitals, they measure white blood cell counts as an alternative [for immune health]. But there are a number of different types of immune cells in the body, and to some extent, every cell in your body is part of your immune system. Therefore, it is difficult to choose a simplified measurement.

I hear experts, often well-known scientists, on TikTok or podcasts, claiming that certain things will help their immunity. Should we believe them?

The example I use is orange juice. I grew up thinking if I had a cold, I would drink some orange juice. I never questioned it. But it turns out This is not true. It goes back to Linus Pauling, who won two Nobel Prizes. He was very popular, he was always on the radio, everyone was listening to him. In 1970, he wrote a book called Vitamin C and colds -It was an instant bestseller. New factories had to be built to keep up with the demand for vitamin C. But this was based on selected data and anecdotal evidence, and was then aggressively promoted in the media.

“
The thing that has the most obvious impact on our immune health is long-term stress
“

The truth is that high vitamin C supplements have no effect on whether you catch a cold. It’s true that people who take high vitamin C supplements have about an 8% reduction in cold duration, but even that is difficult to explain because people who take such high doses may be doing other things in their lives. [that might be the real reason for the shorter duration]. But it’s a myth that’s ingrained in our culture, and it goes back to a very important scholar who has a Biblical approach to telling us something.

Which brings us to today. We need to be careful about anyone’s fantastic success or vision for anything. We need experts, but we also need to question any single voice – the scientific consensus is what we should follow.

Recently, there has been increasing interest in the links between our immune system, inflammation, and mental health. This all sounds great.

The relationship between The immune system and our mental health It’s a really exciting frontier. The initial catalyst was that a group of people who took anti-inflammatory medications to treat rheumatoid arthritis reported feeling better mentally even before their physical symptoms improved. It is a type of medicine that blocks the action of a cytokine – Cytokines are protein molecules produced and secreted by immune cells to communicate with other immune cells.

Another piece of evidence is that people with some mental health conditions have higher levels of inflammatory markers in their blood. A Study of nine-year-old children Who have higher than average levels of IL-6 [a cytokine] They found that when they turned 18, they were more likely to be depressed.

Perhaps the strongest evidence comes from animal testing – if you inject an animal with it [IL-6]The animal will then remain more in a dark area of ​​the cage, not exploring, and not interacting, mimicking mental health conditions.

But we don’t yet have a good way to handle that information. Taking a common anti-inflammatory medication like aspirin or ibuprofen to treat depression doesn’t work. Several small experiments have shown this. Whether cytokine blockade, just as it does in patients with rheumatoid arthritis, helps people with mental health problems, even when they don’tR You have rheumatoid arthritis, it’s not clear yet. In cases where this has been tested, the results so far have been either negative or unclear.

Future research should devise tests to determine People who It might be helpful: Can people with specific mental health conditions and higher-than-average levels of various cytokines in their blood, and perhaps some other markers that have not yet been discovered, be helped by anti-cytokine medications? We don’t know. But the knowledge itself can be encouraging — knowing that if you have a mental health condition, it may be linked to something like your immune system. It’s a really important boundary.

People should ask you all the time what is one thing they can do to improve their immunity. What do you tell them?

There are some answers, but they are not black and white. Long-term stress is a problem. Getting enough sleep is important. But how much and when, for you individually, I don’t know. We know that the microbiome is important, but can I give you something that will definitely make your microbiome better? No, I can’t. These answers may be unsatisfying, but the ultimate strength is knowing that all of this is really hard. There is always more to the story, more nuance. If there’s anything you can gain from studying the immune system, it’s just the wonder of how complex it is.

Topics: