Dr Jenna Macciochi's top 5 tips for immunity

What actually is the immune system?

Although we speak about our immune system as though it is one thing, it's actually a beautifully complex collection of multiple different types of cells (called white blood cells of which there are many, many types), tissues like the gut and organs including the bone marrow, spleen, lymph nodes. It can be found everywhere in the body but tends to be clustered at the barriers to the body - for example the digestive tract and lungs - where there is greatest exposure to our environment. It also includes things like mucus and the microbiota (good bacteria found on us and in us) as these work together with immune cells to protect us.

Rather than a binary switch that we want to turn on, 'boost' even, it's more like a set of rheostats that need balancing, not boosting. Switching on when appropriate and off again when not needed.

Should we start focussing on building a healthy immune system in autumn to safeguard ourselves for winter?

I'd say that taking care of your immune system should be a priority for life and longevity, not just for the seasonal colds and flu (or the latest pandemic). Infection protection is only part of what our immune system does. It's also our main cancer surveillance system, it's involved in growth, healing and repair, recovery from exercise, tolerating benign things in our environment (like potential allergens), how well we age, pregnancy and even mental health.

What factors can compromise our immune system?

There are a plethora of things that can influence our immunity, some we can control and some we can't. Things like genetics, how we are born and fed as babies (c-sections/vaginal, breast/bottle), our gender, our age, our geographical location.

But also, things like how much muscle mass and fat mass we carry, our overall diet pattern (specifically things like micronutrient status, fibre, omega 3 fats and protein), sleep, stress, gut health and exercise.

People often talk about boosting one's immune system, but is it right that this is a confused notion and in fact we don’t want a boosted or overactive immune system?

Yes, this is exactly right, there is no scientific way to boost your immune system (except maybe through a vaccine or specific medication). Because immune responses are designed to make a hostile environment for a germ or toxin that could hurt the body, it means there is often collateral damage to our delicate tissue and organs too. If your immune system over-shoots (e.g. in acute respiratory distress seen in Covid) or acts inappropriately (for example in autoimmune diseases or allergy) it can cause us harm.

What can we do instead to maintain a healthy immune system?

We can't change certain factors that influence our immunity like genetics and how we were born, and there is no single factor in isolation that will help your immunity, but we can aim to take a 360 approach to our health.

Top 5 tips for a healthy immune system

1. Diet

Aim to eat well consistently to avoid nutritional deficiencies. Focus on a food first approach as many important immune nourishing nutrients can't be found in a pill form (e.g. polyphenols) or don't work as well when they are in a supplement.

Food also comes conveniently packaged with fibre which feeds your gut bugs. Your microbiota has a huge influence on the overall health of your immune system. In terms of diet we need to focus on fibre, in the UK we are just not eating enough fibre, we should be aiming for 30 grams a day and 30 different plant foods in a week, including a diversity of colours across fruit/veg/beans/pulses/legumes/whole grains.

Not consuming enough protein is one of the main causes of immune deficiency worldwide so that’s really important too, as are good fats, which we use to resolve inflammation. Oily fish is a great source of these good fats.

Hydration is important to the mucus barriers of the body e.g. like those found in our gut and lungs as it keeps this mucus at a good consistency to help prevent germs from getting in. It's also important to the lymphatic system that we stay hydrated. The lymph is the circulatory system for immune cells to move around the body and perform a surveillance role. It also detoxes and removes metabolic waste products from our cells, tissues and organs, taking them to the liver for disposal. It also transports nutrients around the body.

2. Don't consistently over or under consume calories.

This is because mounting an immune response is energetically costly, and our immune system is intimately entwined with our metabolism. It has special ways of sensing how much food we are consuming. If we are under eating calories consistently then this could have a negative impact on our ability to fight infections, not to mention it could also leave us deficient in important nutrients like protein which is also key to making immunity molecules like antibodies. On the other hand, if we are consistently over consuming calories, this excess energy has to be stored. Much of it may end up as what we call visceral adipose tissue - the fat around our waist and also in-between our organs. These fats cells can become enlarged when we consistently eat too much and this create a metabolic stress and causes unnecessary inflammation (known as meta-inflammation) by our immune system.

3. Quality and Quantity of Sleep

Sleep is really key in the functionality of our immune system. Melatonin that we produce when we go to sleep is very restorative and anti-inflammatory. There is not a magic number for everyone, but best is to maintain a consistent bedtime and wake time. Aim to get between 7-9 hours sleep per night.

4. Movement

Aim to exercise regularly but it is also important just to move your body regularly throughout the day and break up sedentary periods.

We should aim to include regular cardio into our week, but this could be a gentle walk and doesn't have to be something high intensity. Resistance training is extremely important to immune health especially as we age. We lose muscle mass from our 30's and muscle is very rejuvenating to our immune system.

Remember to recover as hard as you train. Not fuelling your workouts properly or overreaching by doing too much can be detrimental to your immune system

5. Stress-Management

Take care of your stress, we underestimate the physical impact of stress. People don’t really consider the negative effect stress can have on your immune function. It might often feel stress is psychological, but it's always biological. There's lots of stress chemicals that are released into our bloodstream when we feel really stressed, whether that's short term e.g. we're about to get hit by a bus, or an ongoing work-related stress.

There's going to be different chemicals and hormones being released in our body, one of the key ones being cortisol (which is known to be immune suppressive and can cause it to deregulate over prolonged time) because evolutionary when we’re running for our life and we’re really stressed, cortisol will turn off the immune system so that it helps us have energy available to save ourselves in that moment.

If we’re constantly stressed, this is when we can really leave ourself open to infection.