While there’s no secret ingredient or perfect way of eating to prevent illness, choosing nourishing foods can help keep your immune system strong.
Healthy lifestyle habits—including getting adequate sleep, engaging in daily joyful movement, practising stress management techniques such as breathing or meditation, and spending time outdoors—allow your immune system to function at its best. Forming habits around meal planning and incorporating a variety of whole foods that provide protein, probiotics, vitamins, and minerals into your diet is another important way to strengthen your resistance to illness during cold and flu season.
The immune system is your natural protector against infection-causing pathogens like viruses and bacteria that you encounter in your day-to-day life. This incredibly sophisticated network of organs, tissues, cells, proteins, and signalling molecules is continuously monitoring your body and taking action when necessary to keep you healthy. The immune system includes lymphoid tissue distributed throughout the body, physical barriers, specialised cells, complement proteins, antibodies, and chemical signals of your innate (non-specific) and acquired (specific) immunity.
FIRST LINE OF DEFENCE
Having healthy physical barriers as a first line of defence means it’s important to support your skin, the mucous membranes of your gastrointestinal and genitourinary tracts, and the lining of your respiratory tract, as these vulnerable areas come in direct contact with the external environment. Adequate protein and hydration are important for supporting these membranes, as is ensuring you have good bacteria (probiotics) by including fermented foods in your diet. Probiotics help talk to your immune cells to balance their action and protect against the colonisation of harmful bacteria in your gut. Fermented foods containing probiotic bacteria including sauerkraut, kimchi, kefir, and kombucha are thought to fight infections by affecting gut pH, producing antimicrobial chemicals, and activating cells that modify the immune response.
Cells of your immune system include both non-specific patrolling white blood cells and memory cells that produce antibodies to fight disease-causing invaders that make it inside your body. Your immune cells produce different chemical signals that have a variety of roles including attracting other immune cells to mount an attack, altering blood vessels to allow the passage of cells to the infected area, signalling the formation of a barrier to reduce the spread of infection, and inducing fever when necessary. These chemical mediators are part of your body’s inflammatory response and contribute to feelings of fatigue and general malaise during illnesses.
VITAMINS AND MINERALS
Vitamin and mineral deficiencies can profoundly impair the immune system, so keeping them at optimal levels in your body is vital for proper immune function.
Vitamins A & D
Vitamins A and D play a role in strengthening mucus membranes and encourage more diverse probiotic communities in the gut. They also regulate the expression of tight junction proteins on intestinal cells (imagine Velcro holding the cells tightly together) and support the development of cells of the innate immune response.3 Carotenoids are a highly coloured group of plant pigments that have antioxidant properties, and some, like beta carotene, are converted to the active form of vitamin A when consumed. They have been shown to enhance the function of several types of white blood cells and increase the antiviral properties of immune system mediators. Food sources of carotenoids with Vitamin A activity include:
- green leafy vegetables
- green, orange, and yellow vegetables such as bell peppers
- sweet potatoes
- carrots
- broccoli
- winter squash
- cantaloupe
- mangoes
- apricots
The sunshine vitamin (vitamin D) is produced through a process involving your skin, liver, and kidneys when you get 10–15 minutes of direct sun exposure. Seasonal infections like influenza usually present around late fall and winter, when serum vitamin D levels will be at their lowest for most people who do not live within 30 degrees of the equator. Vitamin D receptors are found on almost all immune cells, and they regulate both the innate and acquired immune responses to fight infection and prevent excessive inflammation. Food sources of vitamin D include fortified dairy and fatty fish, and for those living in areas with long winters and less sunlight, a vitamin D supplement can help you achieve your daily requirement.
Vitamin C
Vitamin C has anti-inflammatory and antioxidant properties and is helpful for both resisting and fighting infections. It contributes to immune defence by supporting your skin and mucosal barriers, as well as your immune cell function directly by accumulating in white blood cells and enhancing their ability to travel to areas where they are needed to fight infection. Taken continuously, vitamin C hasn’t been proven to prevent illness but may decrease the duration of a cold by about 10 percent, and symptoms may be milder when taken in doses of at least 1 g per day.7 Common sources include:
- citrus fruits
- strawberries
- kiwi
- cantaloupe
- bell peppers
Vitamin C supplements can also be helpful for choosy eaters and come in convenient chewable gummies for kids.
Zinc
Generally, a well-rounded diet is sufficient to supply the required balance of minerals, including magnesium, iron, copper, and selenium, to help support the immune system. Zinc in particular helps to produce certain white blood cells involved in fighting viral infections and can positively influence, or even prevent, the course of disease.8 Good sources include:
- beef
- eggs
- cashews
- pecans
- beans
- fortified grains
I’M SICK, NOW WHAT?
If you or your child does pick up a pesky bug, some general guidelines to follow for a swift recovery include:
Add Garlic
Include garlic for its antimicrobial properties. You can add a chopped-up clove to soups or stews, or odourless capsule forms are another great option if you’re not a fan of the strong taste.
Increase Your Fluid Intake
Soups, herbal teas, nourishing bone broths, and water are essential to stay hydrated, prevent constipation, and help thin secretions. During upper respiratory infections, if secretions are thick and dry, they become more difficult to expel and can lead to lingering coughs and trouble sleeping. Try adding herbal immune support such as astragalus root, shiitake mushrooms, reishi mushrooms, burdock root, or ginger root to either broths or teas for an extra boost.
The bottom line is we must eat healthy to be healthy.
