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  • Marissa Mekelburg Functional Medicine Dietitian

How Strong Is My Immune System? A Self-Quiz


It's that time of year again - cold and flu season. It seems like everyone you know is sick, and you're just waiting for your turn. Or maybe you've already been struck down by a virus and are looking for ways to speed up your recovery. Either way, a strong immune system is key to keeping yourself healthy during the winter months. In this blog post, we will discuss how to evaluate just how strong your immune system is (we have a 5-question quiz) and tips to improve it!


If you're new here: welcome! My name is Marissa Mekelburg MS, RDN, CLT, HHP and I am a Digestive Health Dietitian Nutritionist specializing in the personalized nutritional management of GI conditions such as IBS, food sensitivities, and autoimmune conditions. I help people just like you get to the root causes of their health issues and finally feel good again.


As a digestive health dietitian, the number one thing is to acknowledge that 70-80% of the immune system is in our gut. This means that there is an intricate balance between the microbiome, gut health, local gut immune response, as well as systemic immunity. They say that the gut is the key to all health and that is not an exaggeration (1).


With that in mind, you'll be able to read through this guided quiz to assess if your immune system is supported by your lifestyle habits and nutrition...or if there is some room for improvement. Let's dive in.



Strawberry-topped cupcakes next to a gold-colored fork

Photo by Deva Williamson on Unsplash




Question 1: Are you eating a lot of added sugar?


Do you have a sweet tooth? Unfortunately, if you overindulge on sweets and highly processed carbs, it can weaken your immune system.


How? The explanation is that when we over consume sugar, it can lead to dysbiosis (an imbalance of gut flora) which then creates an inflammatory environment and can weaken our immune response (2, 3, 4).


Foods that significantly raise blood sugar – such as those high in added sugars – increase the production of inflammatory proteins like tumor necrosis alpha (TNF-α), C-reactive protein (CRP), and interleukin-6 (IL-6), all of which negatively impact your immune function (5).


So if you find yourself eating a lot of candy, desserts, or processed foods with added sugars (think: sweet drinks, desserts, granola bars, and sweetened yogurt), it can make it harder for your immune system to fight germs.


What counts as "a lot"? The CDC recommends keeping added sugars below 10% of your total calories (6). However, if you’re eating an average of 2,000 calories, that represents 200 calories or 12 teaspoons of added sugars…in other words, ¼ cup of sugar. That’s still a lot! I recommend that my clients keep their added sugars as far below 10% as possible, making progress each week.



Question 2: Are you eating a lot of processed foods?


While there isn't a strict definition of what "processed foods" means, I'm referring to packaged foods that may have a lot of preservatives and ingredients added that can impact gut health, and/or a fair amount of the nutrients removed.


While slicing an apple and dunking the slices in lemon juice is technically "processing", I am actually thinking about the kinds of foods like crunchy packaged snacks with highly refined flour, sugar, dyes, and preservatives, frozen dinners with a bajillion ingredients, and bags of piping hot goodies from the drive through.


Why does it matter?


A diet rich in processed foods can mean there are nutrient deficiencies such as Vitamin A, D, C, and zinc. Each of these nutrients is crucial for a healthy immune system.

Nutrient deficiencies can also contribute to chronic low-level inflammation which goes back to the above conversation about the dangers of a dysregulated innate immune system.


What counts as "a lot"? I recommend that my clients keep the 80/20 guideline in mind: most of the time – 80% or more – choose whole, real foods. And then sometimes – 20% or less – have foods that feel more like a splurge. Over the course of a week, that amounts to about a few meals.



Question 3: Are you eating a lot of Omega-6 fatty acids?


If you're thinking about omega fatty acids, you're probably thinking about omega-3 fatty acids, the kind of essential fats that you find in healthy foods such as salmon and walnuts.


Omega-6 fatty acids are also essential, but we usually have too much of them. More of a nutrient is not always better.


Omega-6 fatty acids are found in many foods, including soybeans and corn (7). As we have more processed foods, they tend to be high in soybean oil and corn oil and so you get a lot of the omega-6 fatty acids. With less processed foods, you’ll reduce your omega-6 fatty acids.


What we need for optimal health is not just measured in a set amount. While these fatty acids - omega-3 and omega-6 - are essential, we need them in an optimal ratio (8). When we have too much omega-6 and too little omega-3 (as is very common in the US) we can have inflammation crop up again.



Question 4: Are you exercising?


I know that it is not going to surprise you that I'm qualifying exercise as "healthy", but it may surprise you to learn that exercise has benefits beyond muscle strength and cardiovascular health. Exercise is actually being studied as a possible modulator of the microbiome; i.e., those who exercise consistently have better gut health. And as we keep learning, gut health is the foundation of all health, including your immune system.


In addition, we know that exercise helps to reduce stress, which is a good thing for the immune system. Stress also impacts the immune system (and not in a good way). More on that in a moment.


How much is enough? First of all, I encourage my clients to find movement that they actually enjoy. Doing something because you should is not going to stick because that is depending on willpower, which won't last. We're human. Instead: work on building a movement routine that brings you joy, in addition to the health benefits. As for me, I love lifting weights, rebounding, using the elliptical, yoga, hiking and walking.


And enough? I recommend starting where you are and building from there. If you’re currently sedentary, start with 20-30 minutes of walking a few times per week and build from there. If you try to jump into a habit of five miles a day, seven days a week, you’ll be more likely to get sore (and possibly injured) and get burnt out. Better to build your habits in a slow and steady manner that will stick. Eventually, the goal is to have 30 minutes of movement most days. Aim for a mix of strength training, cardiovascular activities and stretching, too.



A person walking along a fallen tree away from the camera

Photo by Jon Flobrant on Unsplash



Question 5: How're your stress levels?


If your stress level was registering on a dial, would it be in the red?


Not good for the immune system, I'm afraid!


When we’re stressed, the immune system’s ability to fight off antigens is reduced, making us more susceptible to infection when stressed. The stress hormone cortisol can suppress the effectiveness of the immune system (e.g. lowers the number of lymphocytes).


Stress can also have an indirect effect on the immune system as a person may use unhealthy behavioral coping strategies to reduce their stress, such as drinking, smoking, or eating sugary foods, etc.


(P.S. Alcohol is especially problematic if you have SIBO. I explain in detail here: Alcohol and SIBO: The Dietitians’ Definitive Guide.)



How can you boost your immune system?


As we head into shorter days where we are exposed to less sunlight and are making less vitamin D…and holidays with more alcohol and sugary treats, what can we focus on to help keep our immune system strong?


We can make changes to our daily routine that boost our immune system. You might be surprised at how simple some of these changes can be…with a big immune-boosting impact!


Here is what I recommend!



Include immune-boosting foods and supplements


I recommend that you seek immune-boosting foods as regularly as possible.


Vitamin A helps to protect against infections, increases white blood cells, and supports t-cell function.


Vitamin A is found naturally in (9):


● Fermented cod liver oil

● Liver

● Carrots and other orange vegetables

● Spinach

● Kohlrabi



Vitamin C has antiviral, antibacterial, and antihistamine functions and also boosts antibody production.


Vitamin C is found naturally in (10):


● Papaya

● Red bell pepper

● Strawberries

● Citrus fruit

● Camu camu

● Goji berries

● Incan berries



Vitamin D activated T-cells reduce the severity of autoimmunity, and enable monocytes to kill more viruses. While we can get vitamin D from the sun, the sun is not strong enough in the winter in most places to make much.


Food sources of vitamin D include (11):


● Liver

● Grass-fed butter

● Fatty fish

● Egg yolks

● Fermented cod liver oil


Pro-tip: I recommend getting your vitamin D blood levels checked next time you’re at the doctor’s office. Ideal levels are between 50 and 80 ng/mL.



Zinc and selenium: these two minerals both boost the immune system. Zinc can shorten the duration and severity of the common cold.


You can find these minerals in (12, 13):


● Liver

● Beef

● Oysters

● Scallops

● Lamb

● Oats

● Sesame and pumpkin seeds

● Brazil nuts



Fiber is so important for our immune system; it is not just valuable for regularity. Rather than reach for a supplement, get fiber naturally from:


● Fruits and vegetables

● Whole grains

● Beans, peas, and legumes

● Nuts and seeds



Fermented foods also support gut health and your immune system. Beyond yogurt, live and active cultures can be found in:


● Sauerkraut

● Kefir

● Kombucha (be mindful of added sugar here)

● Miso

● Kimchi



Herbs that can boost your immune system include:


● Elderberry

● Garlic

● Echinacea

● Turmeric



Mushrooms contain a special kind of fiber called beta-D-glucan which can help to improve your immune system. Mushrooms can be enjoyed with your meals, such as shiitake, but you can also get the benefits of mushrooms in the form of a tea, tincture, or powder. Examples of immune-boosting mushrooms include:


● Shiitake

● Maitake

● Chaga

● Reishi

● Turkey tail




a variety of mushrooms on a white countertop with a cutting board, knife, and small wooden spoons.

Photo by Thanh Soledas on Unsplash



Reduce stress


We can’t avoid stress entirely, but a lot of our health has to do with how well we manage and move through stress.


Activities like walking, meditating and deep breathing are all solidly backed by a large body of research (14, 15). Exercising, yoga, and time with friends and family that you enjoy are all ways to reduce stress and boost your immune system (16).


If you haven’t been finding time for movement or connection, stop right now and mark your calendar for a quick walk in the next day or two. And, send a text to a friend you’d like to connect with and schedule a time to do that. Your mood (and immune system) will thank you.



Get enough sleep


Did you know that if you’re not getting enough ZZZs, your immune system pays the price (17)?


Winter is a perfect time to cultivate better sleep habits. It gets dark more quickly and the cold weather is just begging for you to get cozy, have a warm cup of tea (how about a mushroom tea?), and dive into a good book.


Aim to get to bed by 10 pm at the latest. And instead of screen-on-screen time (scrolling on your phone while also watching Netflix), create a winddown routine that might include a warm bath, some gentle stretching, and a good book. You can enjoy some aromatherapy to help relax such as using some lavender essential oil. You can also boost your sleep with specific bedtime snacks, like pistachios: Do Pistachios Help You Sleep? Yes!


Overall, little habits can snowball towards an immune system that is less equipped to fight off viruses and bacteria…or your habits can strengthen your immune system to be able to avoid illnesses as much as possible.



Key takeaways


While there is no single way to measure the strength of your immune system, a self-quiz such as this post can offer a glimpse into how your habits are impacting your health – and immune system – overall.


Cutting back on added sugar, boosting fermented foods, fruits, and vegetables, having adequate vitamin D and sleep, and reducing stress are all foundational habits to support your overall wellness (not to mention, your immune system).


I also know that implementing these habits is far harder than you’d guess. Life is busy and processed foods are so convenient. If you’d like some support with these changes, so that you can make progress with fewer roadblocks (and less frustration!) give me a call! Your immune system will thank you.









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