Innate Immunity vs. Adaptive Immunity: Everything You Need to Know
The immune system can be broadly subdivided into two branches: The innate and adaptive immune system. These two immune system branches respond to threats differently to protect your body from infection. To understand how your immune system works, you need to know the difference between these two immune system branches. Let’s look at the innate versus adaptive immune system and what it means for you.
What is Innate Immunity?
Your innate immune system is your body’s first line of defense against disease-causing microorganisms and other noninfectious stimuli, such as trauma and stress. It launches a rapid, non-specific response to foreign substances over minutes or hours after the foreign entity has entered the body. Think of the innate immune system as a form of general or “built in” immune protection. (Source, Source)
The innate immune system prevents harmful microbes from hurting the body by providing several lines of immediate defense. It comprises physical barriers, including the skin and mucous membranes in the respiratory tract and gut. It also includes chemical barriers, such as stomach acid, natural killer cells and phagocytes, and antimicrobial proteins.
Once the innate immune system is activated, it alerts the adaptive immune system, triggering a secondary immune response to bolster the fight against invading pathogens. More on this shortly!
Every person is born with innate immunity. In breastfeeding babies, bioactive compounds in breast milk support the infant’s innate immune system. (Source)
Here’s a brief summary of innate immunity:
- Innate immunity is naturally present in the body.
- It typically offers long-term protection from microbes throughout your lifetime.
- The response time is relatively immediate.
- The immune response is non-specific; it responds approximately the same way to different pathogens.
- Innate immunity can be inherited from our parents.
- It is mediated primarily by cytokines.
- The innate immune system doesn’t have immunological memory.
What is Adaptive Immunity?
The adaptive immune system is also called the "acquired immune system" because it is developed over time when the body is exposed to pathogens. It is the body's second line of defense if pathogens evade the innate immune system and enter the body.
While the innate immune system provides “general” protection, think of the adaptive immune system as the “specialized” immune system. It is slower to respond than the innate immune system. However, it is also more complex, and when it does respond, it provides a dialed-in antigen-specific immune response.
An antigen is a toxin or another foreign substance that elicits an immune response. The adaptive immune system produces specific antibodies in response to antigens. The generation of antibodies allows the adaptive immune system to "remember" substances to which it has been exposed so that if and when it encounters that substance again, it can respond faster. (Source)
The first stage of the adaptive immune response involves the processing and recognizing invading antigens, such as bacteria. Once a foreign antigen has been identified, the adaptive immune system releases specific immune cells designed to destroy the antigen and protect the body. In addition, the B lymphocytes, a type of white blood cell, make antibodies. Antibodies are protective proteins that enable future responses to previously recognized antigens to be faster and more efficient. This feature of the adaptive immune system creates immunological “memory.” Future exposures may, therefore, not cause an individual to get sick or may result only in a mild sickness.
Compared to the innate immune system, the adaptive immune system usually takes several days to mount an immune response to invading pathogens.
Here is a brief summary of the adaptive immune system:
- Adaptive immunity can be acquired from another person or through vaccination.
- It takes days or weeks to develop.
- Adaptive immunity may or may not last for an entire lifetime.
- It is pathogen-specific.
- It is not inherited.
- It is mediated by antibodies.
To make matters even more complex, the adaptive immune system can be subdivided into two branches: Active and passive immunity.
Active immunity is formed by your body when exposed to different disease-causing agents naturally through your environment, causing it to develop an adaptive immune response. Active immunity is more energy-intensive than innate immunity, so your body reserves it for pathogens that cannot be effectively removed by the innate immune defenses. (Source)
Passive immunity is a form of adaptive immunity that refers to the passive transfer of antibodies from one individual to another, such as from mother to baby through breastmilk. Passive immunity can also be transferred by artificial means, such as injecting antibodies to combat disease. An example of this is the monoclonal antibodies used to treat COVID. (Source, Source)
Humoral vs. Cell-Mediated Adaptive Immune Responses
Finally, the adaptive immune system can go one of two routes for killing pathogens after recognizing them: The humoral or cell-mediated response. (Source)
- In the humoral response, your body identifies a foreign antigen and recruits B cells to create antibodies. These antibodies neutralize the foreign antigen and prevent it from infecting your cells.
- In the cell-mediated response, body cells that have already been infected by the pathogen are killed with the help of cytotoxic T cells, a type of white blood cell.
Ways to Support Your Whole Immune System
Many dietary and lifestyle practices support a healthy immune system. Some are specific to the innate or adaptive branches of the immune system, while others benefit both. Here are some tips to get you started!
1. Breastfeed (if you can)
Breastfeeding is beneficial for many reasons. One is that it helps shape both the innate and adaptive branches of an infant's immune system! (Source)
Infants have immature immune systems, placing them at an increased risk of infection compared to older children and adults. Breastmilk delivers nutrients, probiotic bacteria, and bioactive compounds such as antimicrobial proteins from mother to infant that protect the infant against infectious microorganisms while his or her immune system is still developing. For example, human milk oligosaccharides (HMOs) in breast milk bind to pathogens and toxins in the infant's gut, helping to eliminate them from the infant's body. These compounds help shape the infant’s gut microbiota, which ultimately becomes part of his or her innate immune system.
Moms need to support their health to be able to breastfeed. Staying hydrated and nourished and managing stress may help moms breastfeed successfully to support their babies' immune systems.
2. Eat a Whole-Foods, Nutrient-Dense Diet
Diet has a profound effect on your immune function. Research shows that our bodies need many micronutrients for optimal immune function, including zinc, selenium, vitamin A, vitamin C, and vitamin D. In addition, many phytonutrients found in vegetables, fruits, nuts, seeds, herbs, and spices support healthy immune function. (Source, Source)
- Vitamin D
For example, there’s no question that vitamin D is crucial for proper immune function. It regulates innate and adaptive immune systems by stimulating immune function or calming overactive immune responses, depending on what is needed. Vitamin D may also protect against specific infections, such as respiratory infections. (Source, Source)
Our bodies make vitamin D primarily through sun exposure. Diet contributes only a small amount of vitamin D through foods such as egg yolks and fatty fish. Recent research indicates that 40% of U.S. adults have insufficient vitamin D levels, and 22% have a moderate deficiency. Given our largely indoor-oriented lifestyles, most people in industrialized nations may need to supplement with vitamin D to maintain levels in the optimal range of 40-60 ng/mL. (Source, Source)
Zinc is an essential mineral that supports optimal immune function. Zinc supports the normal development of innate immune cells and assists with the production of cytokines, a vital part of the innate immune response. Zinc also fortifies the innate immune system barriers in the respiratory tract and gut, further supporting the innate immune system. (Source, Source, Source)
Zinc also supports adaptive immunity by influencing the growth and function of B cells, the cells responsible for making antibodies, and T cells. (Source)
Research shows that supplemental zinc, especially zinc lozenges, can shorten the duration of the common cold by up to 42%. (Source)
Whole foods rich in zinc include oysters, beef and beef liver, crustaceans such as crab, turkey, chicken, and certain nuts and seeds, such as pumpkin seeds.
- Vitamin C
Vitamin C (ascorbic acid) is another nutrient essential for immune function. It promotes healthy epithelial barriers in the lungs and gastrointestinal tract, part of the body’s innate immune system. Vitamin C also stimulates immune cells to tackle invading pathogens and is a potent antioxidant that can “clean up” excessive inflammation caused by immune system stressors. (Source)
Overall, a diet centered around whole foods, including meat, poultry, seafood, fresh produce, nuts and seeds, legumes, and whole grains, is an excellent step towards supporting healthy immune function.
It is important to note that even the most wholesome diet may lack certain nutrients today due to the nutrient-depleted soil in which food is grown. In addition, modern lifestyle challenges such as chronic stress can deplete the body's nutrients. In addition, pregnant women experiencing nausea and food aversions may have a difficult time meeting their nutritional needs. Together, these factors can make it tricky to acquire all the nutrients your body needs in sufficient amounts solely from food. Therefore, a comprehensive Prenatal Multi or multivitamin supplement may be a smart addition to your routine alongside a wholesome diet. (Source, Source)
3. Keep Moving
A growing body of research indicates that exercise has many beneficial effects on the immune system. Consistent moderate to vigorous exercise may enhance adaptive immunity, improving protection against infections. The muscle contractions involved in exercise can also aid lymphatic drainage; the lymphatic system is an essential component of the immune system where white blood cells and other immune cells are circulated. (Source)
It’s important to note that there’s a “sweet spot” for exercise and immune function. Exercise too little and you’ll fail to reap the immune system benefits; exercise too much and you may suppress healthy immune function. It may take some experimentation to determine the right amount of exercise for your immune system. Listening to your body as you ramp up exercise can help. If your exercise intensity increases to the point where you’re noticing more fatigue or respiratory symptoms, that is a sign that you may need to dial back your activity level. (Source)
4. Manage Stress in Healthy Ways
We can all agree that stress is unlikely to simply disappear from our lives. However, managing our stress healthily is essential for our immune function. Unmanaged stress can hinder normal immune function, making us more vulnerable to immune challenges such as infections and autoimmunity. (Source, Source)
Healthy stress management practices run the gamut, including hiking or running, doing a guided meditation, or writing in your journal. Certain herbs like Holy Basil and Ashwagandha can help your body manage stress. The key is to build a stress management routine that works for you!
5. Prioritize Sleep
It is well established that sleep is vital for a healthy immune system.
Sleep deprivation, or not getting enough sleep, and low-quality sleep, not getting enough restful sleep, are associated with multiple adverse effects on the immune system.
Shockingly, just one night of sleep deprivation significantly reduces natural killer cells, part of the innate immune response, and cellular immunity in humans. While it’s normal to occasionally have a bad night of sleep, the goal is to avoid letting that happen frequently if you want a healthy immune system! (Source)
Certain nutrients and herbs, including L-theanine, magnesium, glycine, and chamomile, can support restful sleep. These natural sleep aids are best used on top of a solid sleep routine that includes a consistent bedtime and wake time, a relaxing pre-bedtime routine, and a sleep environment that is dark, cool, and quiet.
While everybody's sleep needs differ, a good rule of thumb is to aim for 7-8 hours of sleep nightly in a cool, dark, quiet room. Avoid using digital devices the hour before bed, and create a pre-bedtime wind-down routine that helps you relax and prepare for sleep.
6. Try Herbs and Other Immune System-Supporting Nutraceuticals
Last but certainly not least, several herbs and other nutraceuticals, defined as products derived from food with specific health benefits, can provide additional support for the immune system alongside diet and lifestyle.
For example, Elderberry (Sambucus nigra) is a small dark purple berry used for centuries in traditional herbalism to aid the immune system. It contains anthocyanin flavonoids that regulate inflammation and modulate the immune system. Research shows that elderberry reduces upper respiratory tract symptoms and duration of the common cold. (Source, Source)
Prebiotics, ingredients that promote the growth of beneficial bacteria, may also support healthy immune function. Arabinogalactan, a prebiotic derived from larch trees, supports healthy innate and adaptive immune function. It has been found to increase the antibody response to the pneumonia vaccine in adults, an example of adaptive immunity, and bolsters natural killer cell, macrophage, and monocyte activity, an example of innate immune activity. (Source, Source)
Finally, postbiotics are another natural “ingredient” that can support the immune system. A postbiotic is a bioactive compound produced by your gut bacteria as a byproduct of their metabolic activity that benefits your health. Many postbiotics are end products produced by gut bacteria when they break down dietary fibers and prebiotics in your gut. (Source)
It is important to note that many herbs in “immune support” supplements may not be safe to take during pregnancy or breastfeeding. You should always consult with your healthcare provider before taking any herbs or supplements, especially during pregnancy and while breastfeeding.
The Bottom Line on Innate and Adaptive Immunity
There are significant differences between innate immunity and adaptive immunity. While innate immunity is naturally present in the body from infancy onward, adaptive immunity must be developed over time upon exposure to another person or through vaccination.
Once your innate immune system develops in infancy, it usually provides lifelong protection. On the other hand, adaptive immunity can provide short-term or long-term protection against infections.
The good news is that you don’t need to leave your immune function up to chance! By taking proactive steps with your diet and lifestyle, you can support both your innate and adaptive immune systems and become more resilient to potential immune stressors you may face in your life.
Meet the Author
Lindsay Christensen, MS, CNS, LDN, is a functional nutritionist and health writer with a deep passion for functional medicine. Lindsay has her B.S. in Biomedical Science and M.S. in Human Nutrition and is a Certified Nutrition Specialist (CNS) and a Licensed Dietitian Nutritionist (LDN).
Lindsay works as a nutritionist at The California Center for Functional Medicine, where she helps patients with various chronic health challenges, including Lyme disease and autoimmunity. In her private practice, Alpine Fuel Nutrition, she provides holistic nutrition consulting to mountain athletes, including trail runners, climbers, skiers, and mountaineers. She has written for multiple health companies and publications, including Quicksilver Scientific, WellTheory, Paleo Magazine, WellBeing Journal, and Needed.
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