Improving Immunity During Cold and Flu Season

Happy Autumn, League of Wildness!

Yesterday was the first day of fall in the northern hemisphere 🍁I love this time of year but it also tends to bring an increase in illnesses. Cold and flu season tends to run from fall through spring, and also includes things like mono, strep throat, ear infections, and stomach bugs. 

We tend to resign ourselves to this “sick season” without realizing there are things we can do to prime our immune systems for the fight. I practice these things frequently and rarely get sick. The last time I was sick enough to have a fever was in 2016. When I do get under the weather, it rarely lasts more than 1-2 days.

What can you do to enhance the function of your immune system to make cold and flu season less miserable? 🤔

Vitamin D

Vitamin D is a necessity for a strong immune system. You probably already know that vitamin D is made by our bodies as a result of exposure to sunlight. But if you live in a northern latitude, the times of the year your body can make vitamin D via sunshine are limited by the low angle of the sun. Meaning, even if you spend a lot of time outdoors on sunny days, your body still won’t make vitamin D because the sun is too low in the sky. If you live north of 37 degrees latitude, you would likely benefit from vitamin D in the winter. In the US, this means anyone north of a line from southern California, Arizona, Oklahoma, Arkansas, and South Carolina. If you live in Europe this includes almost everyone!

It is ideal to get your vitamin D level tested by your doctor so you know if you need to supplement and how much. I live just shy of 48 degrees north, and I take supplements from October through April because during those months, the sun is not high enough in the sky for my body to make vitamin D even though I am outdoors often. The lack of sunshine also has a major impact on my mood during those months. I noticed that come November, I started feeling tired and moody and it was due to the lack of vitamin D. Supplementing made a big difference. 

It is possible to increase your vitamin D intake through nutrition to a degree. Natural foods containing higher levels of vitamin D are salmon, tuna, mackerel, and sardines. Some foods have vitamin D added to them such as milk, juice, oatmeal, and breakfast cereals. Usually, they will specify that they are fortified. I cannot drink milk and generally avoid eating “fortified” foods as they are often highly processed and contain a lot of sugar.

Limit Soap Use

Soap has a very important function in our lives. The understanding that soap could prevent disease was a major discovery that improved our health and life span immensely. But these days, we tend to use too much of it. Soap is a detergent which means it breaks down the fatty membranes of cells. If soap comes in contact with bacteria or a virus, it will destroy the cells, which is great! Unfortunately, it also means that soap destroys the healthy bacteria that live on our skin which act as our first line of defense against germs. A healthy skin microbiome also protects against skin infections and allergens as well as communicating information to our internal immune system.

You absolutely want to wash your hands if you are touching raw meat, after you use the bathroom, and during other necessary times. But if you constantly use detergent or antibacterial soap on your entire body every day, you are basically killing all of the healthy bacteria on your skin which take weeks to repopulate. This means that if you use soap every day on your whole body, your population of healthy skin bacteria is quite low. There are soaps that are more friendly to the skin biome, but I prefer just to use soap only when I need to, like on my feet because I am often barefoot.

A few things that can help:

Avoid antibacterial soaps in most circumstances. Sometimes they are necessary, such as for people in certain lines of work. But most of us do not need to be using these soaps regularly. 

Limit how often you use hand sanitizers. Covid saw us buying up every available bottle, and like antibacterial soaps, they do have their uses. But over-using them can be detrimental to our healthy skin biome.

Take shorter showers in tepid water. Or give cold showers a try! Long, hot showers might feel amazing some days, but they tend to strip our skin of its lipid barrier which can lead to infections, rashes, dry skin, ance, and other issues.

Consider skipping the soap once in a while. Unless you are working outdoors or in a strenuous job, you likely can get away with washing the important zones with a gentler soap and avoiding it entirely on the rest of your body. 

Limit how often you use abrasives, like skin scrubs and loofahs.

Look for soaps that don’t contain sulfates. Several studies have shown that soaps containing sulfates signifncantly decrease the population of healthy skin bacteria.

Eat plenty of  fiber
Fiber is another major factor in healthy immune function. Studies have demonstrated that our immune system health has a lot to do with our gut health and fiber plays a major role. According to nutritional experts, we should be getting 25-35 grams of fiber a day. Most of us get a lot less than that. Indigenous populations in many regions eat upwards of 75 grams or more per day, by comparison.

There are two different types of fiber: soluble and insoluble. They can actually be broken down further, but for the most part, this is what we want to keep in mind. Fiber is a carbohydrate that is not digested. It serves a few functions as it moves through our digestive system. Soluble fiber dissolves in water and increases the bulk of the waste moving throughout the digestive track. Insoluble fiber does not dissolve in water and acts as a broom that collects random bits from our intestines and sweeps them out. Examples of soluble fiber include legumes, avocados, broccoli, brussel sprouts, pears, apples, seeds, nuts, barley, and whole oats. Examples of insoluble fiber include whole grains like quinoa and whole wheat, along with green beans, cauliflower spinach, berries, and sweet potatoes.

When the cold weather comes, I love to see how many healthy foods I can add to soups or curries. I make a batch to last the week and eat it every day. This makes it easy to add sweet potatoes, leafy greens, legumes, and healthy spices like ginger and turmeric into one meal.

A few other things that can improve immunity

Exposure to fresh air and sunlight. Both activate our immune T-cells which are the fighting cells of our immune system. Exposing our bodies to microbes that are present in the air and which come from soil, trees, and natural bodies of water also helps to keep our immune system functioning well.

Avoid or limit ultra-processed food and alcohol. These foods and beverages take a lot of effort for our bodies to process which results in less focus going to building immunity. Excessive alcohol intake impacts all the cells in the body and because it is a toxin, the body immediately shifts all attention to processing the alcohol, delaying focus on other processes including the immune system and digestion.

Manage your stress.
Chronic stress produces excess cortisol which has a major impact on immune system function due to creating inflammation. Practice controlling your stress levels by utilizing breathing and meditation exercises, working out, spending time in nature, listening to music, or whatever else works for you to calm your stress response. Any time you can focus on something to slow your thoughts and your breathing down, it is beneficial. Like many people, my mind tends to have an endless stream of thoughts, but I can slow it down by spending time in nature, doing “stream of consciousness” writing exercises, and making a point just to slow down my breathing. 

Exercise. In addition to managing stress, exercise promotes a healthy immune system. Strenuous workouts canl temporarily lower your immunity, so make sure you space those out so you give your body time to recover. Those same workouts also boost immunity later. Walking is also a great way to get out and knock off several benefits at once! 

Connect with people you enjoy spending time with. Our relationships with others impact our immune function as well. Take a walk or a hike with your partner, kids, or friends. Enjoy a good meal together. Have a date night. Connecting with people reduces our stress levels. Spending time with others also exposes us to more microbes which help train our immune systems to recognize germs and build immunity to a variety of things. 

We often believe that cold and flu season means we can look forward to numerous illnesses and missing days of work or school. There is a lot we can do to boost our immunity by just moving our bodies more, getting outdoors, spending time with people we care about, and adjusting our diets. We don’t have to resign ourselves to weeks of illness every year.

Are there any tips or tricks that have worked for you to reduce the frequency or severity of illness? I’d love to hear about what works for you!

A few resources:
This site has a map showing you where the latitude cut-off is for the sun angle to produce vitamin D in our bodies.

This offers some detail on the types of fiber, what they do, what foods to eat, and expands on the types of fiber as well

A study on the link between social relationships and immune function


Some interesting info on the skin biome andhow  it interacts with the gut biome

Have a wild fall weekend!


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