Winter has come, and we're undoubtedly excited about the holiday season. But wait — what if you get sick? None of us want a viral infection like influenza or a simple flu ruining our festive spirit. Fortunately, help is just around the corner. Let's talk about these superheroes: nutritious foods to boost our immunity.
Some foods, such as citrus fruits, berries, pomegranates, kefir, yogurt, and so on, have regulatory and supportive effects on the immune system.
These substances are generally micronutrients, such as vitamins and minerals, but also antioxidants and anti-inflammatory and antimicrobial compounds like polyphenols, flavonoids, and polysaccharides.
It is important to add these foods to our diet to protect ourselves from diseases and keep our immunity strong in winter.
What is immunity?
Our bodies have an immune system to protect us against harmful organisms, medically referred to as 'pathogens.' 'Pathos' comes from Ancient Greek, meaning 'to suffer' and 'disease.' The suffix 'gen' at the end of the word gives the meaning of 'producer.' So, literally, our immune systems work to protect us from 'disease producers.'
The immune system in the human body is a complex system of various immune cells, antibodies, and physical barriers that prevent pathogens from entering or causing disease.
The immune system works not only against pathogens but also against any allergens, toxins, or environmental pollutants.
The first line of defense involves physical barriers, such as skin and mucosal surfaces, including the nose, stomach, bowel, etc. We also call this defense mechanism innate immunity. We all have it from birth and it prevents harmful organisms or substances from entering our bodies. But what if they get in?
Having a strong immune system does not mean not having any infections — it means your body knows how to deal with infections. It is also natural that microbes or harmful substances enter our body from the outside. We just need to have a good enough immune system to prevent these microorganisms from making us sick.
This is where adaptive immunity comes into play. Since our infancy, our immune system identifies every foreign substance that enters our body and learns how to deal with it. For this purpose, it produces special immune cells and secretions. Many functional foods help our immune system at this point.
Immune-boosting properties can be listed as antioxidant, antitumor, antiviral, antibacterial, and antifungal effects. However, an overreaction of the immune system is also harmful. For example, allergies and intolerances are the overreaction of the immune system to certain substances. Therefore, immune regulation is also important, and some foods support this.
Immune-boosting foods for winter
The field of medicine has two basic approaches to a particular disease: to prevent or to treat. Foods can show both effects with the bioactive components they contain. Studies show that these foods, namely nutraceuticals, can be at least as effective as drugs (pharmaceuticals). A great deal of research has been done on the bioavailability and distribution of nutraceuticals when they are converted into tablets or pills.
1. Citrus fruits for vitamin C and polyphenols
If we are talking about 'winter' immunity, we should definitely start by mentioning citrus fruits. Since they are the main winter fruits, they are easy to find. Additionally, they're not only very effective, but also very delicious.
Citrus fruits include vitamin C and bioactive polyphenols like hesperidin, neuritin, and naringin. While vitamin C sustains the integrity of immunological barriers and supports the function of the immune cells, polyphenols show anti-inflammatory effects and reduce inflammatory markers.
This combination leads to a regulated and effective immune defense against pathogens.
2. Kefir and yogurt for probiotics
We mentioned the mucosal barrier function in the prevention of infections above. Probiotic and prebiotic foods come into the stage now. We know that healthy microbiota, the microorganisms living in our body, especially in the gut, help us a lot to sustain body health. They aid in maintaining mucosal integrity in our bowels, which prevents pathogens or harmful particles from leaking into the body.
Products like kefir and yogurt include healthy bacteria to build a good microbiota. That's why it is better to include 1 or 2 portions into your daily diet.
3. Pomegranate for anthocyanins and ellagic acid
Pomegranates are another famous winter fruit. They are rich in bioactive compounds and are known for their strong antioxidant and anti-inflammatory content, particularly polyphenols, such as anthocyanins and ellagic acid.
You can even see pomegranate-originated supplements for immunity because of these bioactive compounds. But, if you consume it as a fruit, you don't need to buy such products, plus, you are able to get the fiber content of pomegranate seeds when you consume it as a whole fruit.
4. Garlic for allicin
Garlic is a traditional supplement for winter infections. Your grandparents might have suggested you consume garlic if you were under the weather. But it is also scientifically true! Garlic has a special compound called allicin. Allicin is a sulfur-containing compound released when garlic is crushed or chopped. That's why garlic has a unique smell.
Studies showed that garlic has antimicrobial properties against pathogen bacteria and viruses and immune-enhancing effects with its allicin content.
5. Red-purple fruits for resveratrol
Another famous supplement compound is resveratrol. You may see or even use resveratrol supplements in effervescent tablets or pills for when you have the flu. But, if you knew that red fruits contain a great source of resveratrol, would you prefer those supplements or opt for delicious berries, red grapes, or plums?
6. Oats and mushrooms for beta-glucan
You might be confused when you see oats and mushrooms together for one bioactive compound. Yes, they are quite different foods, but they are both great sources of beta-glucan — a polysaccharide found in cereals or the cell walls of fungi.
Research showed that beta-glucans can help activate the immune cells and increase their pathogen-killing abilities like phagocytosis.
Bonus: chocolate for happiness
Yes, it is true! Dark chocolate is also one of our power foods for winter. It contains several health-promoting components like polyphenols, procyanidins, and theobromines that positively modulate the immune system.
But beyond that, chocolate makes us happy. It contains a precursor to the happiness molecule serotonin called tryptophan. Tryptophan is one of the essential amino acids and a building block for serotonin synthesis. When you consume chocolate, the tryptophan in it can contribute to the production of serotonin in the brain.
Also, imagine eating Christmas chocolates with your family, or a piece of chocolate with your warm coffee while you are catching up with friends. This is what is important about food. We do not always use it as a nutrient source — sometimes, we feed our souls by incorporating it into our traditions, special days, and happy moments.
We know from thousands of scientific studies that chronic stress has detrimental effects on our immune system by suppressing its function. There is evidence to suggest that positive emotions and a sense of well-being can have beneficial effects on the immune system by lowering stress levels.
Thankfully, we have a great variety of foods to protect our bodies from infections during the winter, and the ones we mentioned above are good and effective examples of these functional foods. As long as you choose a balanced lifestyle and diet to protect your physical and mental health, you can enjoy the winter to your heart's content.
How can I boost my winter immunity with foods?
You can easily support your immune system by incorporating nutrient-rich options such as fresh fruits and veggies. Many bioactive species are in plant-based foods. Additionally, it is important to get enough protein. If you are not vegan or vegetarian, you can get lean protein from animal sources and support your microbiome with dairy products.
How do I stay healthy in the winter?
Staying healthy in winter may require a little bit of effort compared to warmer months. You should dress appropriately for the weather, stay active, and get sufficient sleep to support your overall well-being. Also, you can try to get enough sunlight by going for a walk if it is possible in the place where you live. If you live where winters are generally dark, it may be beneficial to talk to your doctor and take a vitamin D supplement.
Can winter cause the flu?
While winter itself doesn't cause the flu, the cold weather creates conditions that may contribute to the spread of flu viruses.
- Journal of Food Biochemistry. Immunity boosting nutraceuticals: Current trends and challenges.
- Foods to deliver immune-supporting nutrients. Current Opinion in Food Science.
- Dark chocolate: An overview of its biological activity, processing, and fortification approaches. Current Research in Food Science.