Tis the season for all things germy. The good news is that your body is actually designed to fend off these germy invaders. Yep, I’m talking about your body’s immune system. The even better news is that the foods you eat can help support your immune system so that it is better equipped to defend your body against disease-causing microorganisms, or pathogens, that will make you sick.
First, a little lesson on the immune system
The immune system has two types of defense mechanisms:
- Innate – this includes the mechanical barriers that cover the body (a fancy way of saying skin) as well as the cells and chemicals that are the “first responders” to a pathogen that has made it into the body. The innate defense mechanism is also called the nonspecific defense mechanism because all human bodies come equipped with essentially the same innate “system”. It is not specific to your individual body.
- Adaptive – this line of defense provides protection against specific antigens (toxins, bacteria, and other substances that are recognized by the body as foreign) and activates the immune system. The adaptive defense mechanism is also called the specific defense mechanism because these defenses are specific to your body and the encounters it has previously faced with specific antigens. In other words, if your body was previously exposed to a virus, your adaptive immune system knows the virus better and is more equipped to fight it than it was the first time it was exposed.
Within these defense mechanisms are three lines of defense. The first and second lines of defense are innate and the third line is adaptive.
- First line of defense – this includes the skin as well mucous membranes and their secretions (things like your saliva and mucus in your respiratory system)
- Second line of defense – this comes into play if the first line of defense is compromised. It includes cells and chemicals like: phagocytes (specialized white blood cells), natural killer cells (pretty descriptive name: they can kill infected body cells and some tumor cells), your inflammatory response, antimicrobial proteins, and fever (yep, that’s right, a fever is a sign that your body’s defense system is working!)
- Third line of defense – this comes into play if the first two lines of defense are unable to effectively fight an invader. The adaptive nature of this line of defense is why the immunity of a newborn is much lower than that of a young adult – because this line of the young adult’s immune system has had several years to adapt to specific antigens and “learn” how to better fight them, whereas an infant has had little exposure.
Support your immune system through FOOD
Now that you understand generally how the immune system works, you’ll better understand why certain foods support the proper functioning of your immune system:
- Vitamin C – this is the poster child for immunity. Why? because it increases the production of white-blood cells and antibodies (antigen-fighters). What is misunderstood about vitamin C, however, is the thought that more is better. The truth: your body can only absorb so much at a time, so don’t bother with the mega-doses. A good target is 150-200 mg per day. As a reference, a medium orange has about 70 mg.
- Sources: oranges, broccoli, bell pepper, strawberries, leafy greens (spinach, kale, chard), kiwi
- Vitamin D – helps to regulate the innate and adaptive immune responses
- Sources: sunlight (go for a walk outside!), salmon, egg yolks
- Vitamin E – stimulates the production of natural killer cells
- Sources: sunflower seeds, almonds, leafy greens
- Zinc – increases the production of white blood cells and helps white blood cells release more antibodies
- Sources: pumpkin seeds, beans (white, kidney, garbanzo), nuts (almonds, cashews, pistachios
Aim for real food sources of these vitamins and minerals rather than supplements!
Studies suggest that certain other foods benefit immune function
- Probiotics – several studies have linked gut health to overall immune function
- Sources: kefir, sauerkraut (and other cultured vegetables), apple cider vinegar, kombucha, miso
- Adaptogens – adaptogens are a class of plants that are understood to help your body adapt to certain stressors
- Examples: Ashwaganda, Ginseng, Astragalus root, and mushrooms like Chaga, Reishi, and Cordyceps
- Natural “antiseptics” – these foods have natural antibacterial, antimicrobial, and/or antiviral properties and are believed to help fight off certain infections
- Examples: Apple cider vinegar, garlic, coconut oil
Lifestyle choices can also impact immunity
- Hygiene – one of the best things that you can do is so simple: wash your hands! This is arguably the easiest way to prevent illness. If germs can’t get in your body, your body doesn’t have to fight them.
- Sleep – sleep is your body’s chance to rest so that it can go to work protecting you from illness; a lack of sleep disrupts this
- Smoking – smoking decreases the production of natural killer cells and reduces the number of circulating antibodies (remember, we like antibodies, they fight antigens). It also makes for an easier entrance of bacteria into the bronchial and lung tissue by damaging the cilia, which work to keep invaders out
- Exercise – exercise increases body temperature, stimulates the lymphatic system, and reduces stress
- Stress – cortisol is the primary hormone released as part of the stress response, and research has shown that cortisol blocks immune-supporting T-cells from proliferating
Don’t wait until you’re sick to start implementing some immune-friendly choices into your life. Pick one nutrient or habit that seems most approachable for your lifestyle and tastes and keep adding more from there. Your immune system will thank you.
Tortora and Dickerson, Principles of Anatomy and Physiology. 13th edition.
Marieb, Elaine, Essentials of Human Anatomy and Physiology. Tenth edition.