The nights are drawing in, and the air is getting crisper. Soon, the leaves will start to turn the color of rust, and we’ll retreat indoors to hibernate by the fire with a mug of something warming. There is certainly plenty to love about the move into fall and winter, but the colder seasons can leave you feeling run down. We take a look at the best advice for how to stay healthy in winter.April 28, 2022 5:30 pm October 12, 2020 2:26 pm
Fall and winter can be a testing time for our immune systems. Along with having to contend with colder temperatures, rain and snow, we are also exposed to the many illnesses which flourish during the cooler seasons.
Bad weather in itself is not to blame for the added pressure on our immune systems around this time of year, but rather the way we tend to live during the colder months.
Luckily, there are a few simple changes you can make to get your immune system in the best possible shape for the winter ahead.
To understand how we can help our bodies defend themselves against winter bugs, first let’s take a look at what your immune system is, and how it works.
What is the immune system?
Put simply, your immune system is the organs and methods your body uses to either keep bugs out of your system, or destroy them if they manage to make their way inside.
The organs that keep bugs out of the body are called ‘barrier organs’. These include your skin, mucous membranes and the acid in your stomach. Their job is simple: don’t let any bugs make it past their defences into your body.
Unfortunately, some bugs do succeed in getting around them. Bugs can enter your body through a wound in your skin, for example, or if you consume a bug that can survive the harsh environment of your stomach acid.
Luckily, your body is ready to mop up any invaders.
Other organs in your immune system, called the ‘lymphoid organs’ or ‘lymphatic system’, attack and kill any bugs that make past your barrier organs. The lymphatic system makes use of a range of different methods to first find the invading bug and then to destroy it. Your bone marrow, lymph nodes and spleen are just a few key parts of your lymphatic system.
Types of pathogens
So what are these organs defending you against?
There are few different types of bugs that can cause problems in the body. Any organism that causes disease is called a ‘pathogen’. You will have heard of the most famous types: bacteria and viruses.
Bacteria are single-celled organisms which can have a spherical, spiral, or rod-like shape. Many of them are perfectly harmless, or even good for us, but a few have the ability to cause disease. Usually, they’re slightly bigger than viruses, but they’re still much too small to be visible to the human eye. Disease caused by bacteria can include strep throat and urinary tract infections.(1)
Viruses – which, thanks to recent global events, we’re all very familiar with – are different in that they need a host to survive and spread around.(1)
Disease-causing viruses inject themselves into your cells and take them over. They effectively hijack the cell and change its function in order to produce lots of copies of themselves. The cell then dies, and the new viruses spread. Viruses cause diseases such as HIV and respiratory illnesses like flu and, unfortunately, coronavirus.
There are also some other, less well-known pathogens: fungi and parasites. Yeast and mould are examples of fungi which can cause disease in humans. Usually, though, they’re less able to make trouble in the body than bacteria and viruses.
In fact, fungal infections are generally only a threat to a person’s life if their immune system is already compromised, for example through chemotherapy.(1)
The final group of major pathogens is made up of parasites such as worms (like tapeworm) or protozoa. These single-celled organisms can also cause disease; Malaria, for example, is caused by a protozoa called Plasmodia.
Given the variety of threats, your body needs a variety of different tactics to make sure you stay healthy.
White blood cells and the immune system
Think of white blood cells (leukocytes) as the soldiers of your immune system.
There are a couple of different types: phagocytes and lymphocytes.
Phagocytes get rid of pathogens by effectively gobbling them up. The phagocyte approaches a pathogen and moves around it until it is fully surrounded, before absorbing the pathogen into itself, where it can be broken down and destroyed.
Lymphocytes destroy pathogens too, but importantly, they can help you body remember them. This means your immune system can react faster to destroy them if they appear again. In the future, your body will be able to neutralize the recognized pathogen before it can cause disease. This is why you can remain immune to some diseases after having been infected in the past.
There are two types of lymphocytes.
B-lymphocyte cells act as sentries, keeping an eye out for any cells that shouldn’t be there. They can’t destroy a pathogen on their own, but if they find one, they send out antibodies which stick to the pathogen and raise the alarm to other cells. Once released, antibodies stay in your bloodstream, ready to react quickly if the pathogen should return.
T-lymphocytes are sometimes called ‘killer cells’ because their job is to track down the foreign cells which the B-lymphocytes have marked, and destroy them.
Cold weather, in itself, doesn’t make your immune system weaker or stronger than it would otherwise be. However, the winter period makes it easier for illnesses to be spread because often we’re sheltering indoors, in close contact with other people who might be carrying the pathogen.
Why winter takes a toll on your immune system
The main factors that can weaken your immune system are age, stress, and eating a poor diet.
Cold weather, in itself, doesn’t make your immune system weaker or stronger than it would otherwise be.
However, the winter period makes it easier for illnesses to be spread because often we’re sheltering indoors, in close contact with other people who might be carrying the pathogen.
There’s also evidence that sunlight is effective at killing off viruses out in the open.(1) Less sunlight in winter means that more viruses are able to survive long enough to latch onto a new host.
So, while the winter season sees many animals preparing their burrows and nests for the toughest time of year, for pathogens, life is about to become much easier.
Eating for immunity: vitamins and minerals
While your immune system is very effective at protecting you from disease, there are a few things you can do to lend a hand. These involve making little changes to your diet, to give the organs involved in protecting you from pathogens everything they need to function healthily.
There are three main groups of foods that you should consider when eating to support immunity. The first is vitamins and minerals. Below are the key micronutrients involved in immunity:
- Vitamin C is a powerful antioxidant, which helps to reduce oxidative damage in the body. But it also plays a crucial role in phagocytosis, the process by which your phagocytes gobble up intruding pathogens.(2) Find it in fruits and vegetables, particularly citrus like bergamot and orange. Or, for a big hit of vitamin C, try sea buckthorn juice. One sea buckthorn berry contains twelve times the vitamin C of an orange!
- Vitamin D is also important for immunity, and deficiency in this vitamin can lead to an increased susceptibility to infection.(3) Stock up by eating hemp seed, tofu and mushrooms. For bonus vitamin D, leave your mushrooms in the sun before you eat them – like us, they’re able to soak up vitamin D from sunlight.
- Zinc, selenium and iron are important minerals involved in your immune response. Deficiency in zinc can reduce the efficiency of phagocytosis, while iron regulates the function of your T-lymphocytes, the ‘killer cells’ that find and destroy pathogens(4). Selenium is also an antioxidant and a deficiency can slow your immune response down, giving pathogens more of a chance to do damage in your cells.(5) Almonds, walnuts and lentils are a great source of zinc, while Brazil nuts pack the highest amount of selenium of any plant source. Iron can be found in dried apricots, spinach, and pumpkin seeds.
Foods for gut health
Given that your digestive system is one of the best ways for foreign bacteria to get into your body, it shouldn’t come as a surprise that more than half the antibody-producing cells in your body reside in your gut. That means it’s incredibly important to look after your gut if you want to keep your immune system healthy.
When it comes to gut health, not all bacteria are bad. Quite the opposite!
There are 100 trillion bacteria living in your gut.(5) Some are beneficial, some less so, but they exist in a delicate balance that keeps you healthy.
If you’re eating for immunity, you want to feed and look after your ‘good’ bacteria, which will naturally keep any ‘bad’ bacteria under control.
There are two types of foods that can help you do this: probiotics and prebiotics.
What are probiotics and prebiotics?
Probiotics are foods which contain live ‘good’ bacteria. The intention is that when you eat them, these extra bacteria reach your gut and boost the numbers of ‘good’ bacteria in your system, contributing to better gut health. Live yoghurt is a popular example of a probiotic.
However, there is some debate about whether the extra bacteria survive long enough in your digestive system to be useful.(7). Generally speaking, if you enjoy eating probiotics like live yoghurt and kimchi, you should keep them in your diet as they may have a positive effect on your gut health.
Prebiotics, on the other hand, are foods which you can’t digest yourself, but which provide a hearty meal for your gut bacteria. To be a prebiotic, foods have to meet three criteria:
- They have to be able to stay in tact until they reach your gut bacteria. That means they can pass through your stomach acid, and that you can’t digest or absorb them yourself.