Is it possible to improve your immune system? For most people, the answer is yes. While our immune systems are amazingly good at defending against diseases, right now with COVID-19, it makes sense to take what steps are available to boost our immune systems. So, what lifestyle changes should we consider? What’s proven to work? Does it help to improve your diet? What about vitamins or herbal supplements?

Immune System Overview

First, it’s important to understand that the immune system is a system, not a single entity, and according to Science Direct, it’s “arguably the most complex system in the human body.”(Ref)

Two Sides of Your Immune System

The Innate Immune System

The innate immune system is inherited and is active from the moment you were born. It provides a physical barrier to protect your body and includes your skin, the eye’s cornea, and the mucous membrane that lines your respiratory, gastrointestinal, and genitourinary tracts. These barriers protect against harmful invaders, and when this system recognizes an invader, it goes into action right away by surrounding, covering, and eliminating the invader.

The Acquired Immune System

Your acquired immune system, also called the adaptive immune system, with help from your innate system, makes cells (antibodies) to protect your body from invaders. These antibodies develop after you’ve been exposed to the invader and stay in your body. Acquired immunity creates immunological memory; for example, if you’ve had measles, the acquired immunity is life-long – you’ll never get measles again. In other cases, as with chickenpox, you don’t get lifetime immunity, but after your first exposure, your immune system will recognize the invader and defend against it.

Your acquired immune system changes during your life. There’s a normal age‐related decline in immune functions, referred to as immunosenescence, which explains why older people are more prone to get sick and experience diseases more severely. (Ref) It’s also why vaccines don’t work as well in elderly people. (Ref)

Basic Strategies to Strengthen Your Immune System

It makes sense that if you’re looking to boost your immune system, you should adopt a healthy lifestyle as quickly as possible. Remember that your immune system is a system, and every part of your body functions better when you adopt healthy living strategies including:

  • Choose optimal nutrition
  • Take Supplements
  • Exercise regularly
  • Maintain a healthy weight
  • If you drink alcohol, drink only in moderation
  • Minimize stress
  • Get adequate sleep
  • Laugh!

Nutrition & Your Immune System

You’ve heard the phrase “garbage in, garbage out,” right? That applies to your immune system. If you want your immune system to work well, you need to provide it with good, regular nourishment. A diet of fresh, whole foods with an emphasis on fresh vegetables and fruits is ideal. The bottom line is that there is a correlation between strong immune systems and a good diet. As an example, scientists have long understood that people who live in poverty and are malnourished are more vulnerable to infectious diseases.

As we get older it’s even more important to focus on good nutrition. As we age, we burn fewer calories, but our nutrient needs are the same or even higher than when we were younger. It’s therefore important to focus on choosing foods that are as nutrient-dense as possible.

When we eat healthy food, we become healthy, and if our goal is to optimize our health and boost our immunity, optimal nutrition is key. Optimal nutrition, superior health and a strong immune system come from a diet focused on nutrient-rich foods and fewer calorie-rich foods. Therefore, the foundation of a nutrition plan designed to boost health and immunity consists of nutrient-dense foods.

Photo by cottonbro from Pexels
Photo by cottonbro from Pexels

This means focusing on high-nutrient, natural plant foods: vegetables, fruits, beans, nuts, and seeds. Additionally, if it’s possible, choose organic foods, as organic fruits and vegetables deliver 20-40% more antioxidants than conventional fruits and vegetables. (Ref) At the same time, it’s important to reduce or eliminate foods with low nutrients and foods that are actually toxic to the body.

If you’re like most people, you probably don’t eat enough vegetables to benefit your health and immune system. Maybe considering the current COVID-19 situation, it’s time to change that – especially considering the evidence that a diet focused primarily on consuming vegetables and fruits is the most important factor in preventing chronic disease and premature death. (Ref 1, 2)

Take Care of Your Gut

Over 2500 years ago Hippocrates said, “All disease begins in the gut.” Only in the last 20 years or so has research revealed how correct Hippocrates was. Gut health is critical to overall health. An unhealthy gut contributes to a weakened immune system and diseases including diabetes, obesity, depression, and chronic fatigue syndrome. (Ref 1, 2, 3) On the other hand, brain health is associated with having a healthy gut.

The research also shows that the longest living people have very diverse gut microbiomes (the trillions of bacteria and other organisms living in and on us). (Ref)

Consider this: your gut microbiome contains between one trillion and ten trillion cells, and an adult person’s body has about one trillion cells. So, we are at least as much bacterial as we are human.

Your gut microbiome comprises more than 75 percent of your immune system, and there are several things people commonly do that harm the gut microbiome, including:

  • Having a diet high in refined carbohydrates, sugar, and processed foods
  • Using antibiotics
  • Using medications like birth control and NSAIDs, such as aspirin, Tylenol & ibuprofen
  • Having diets low in fermentable fibers (Ref)
  • Experiencing chronic stress

A major task of your intestine is to form a defensive barrier to prevent absorption of damaging substances from the external environment. (Ref) When your intestinal barrier becomes permeable – you get “leaky gut” – which is a condition in which the lining of the small intestine becomes damaged, causing undigested food particles, toxic waste products, and bacteria to leak through the intestines and flood the bloodstream. Leakage causes an immune response that affects your gut itself and other organs and tissues.

To take care of your gut, the first thing you need to do is avoid things that damage your gut microbiome and damage your intestinal barrier. Beyond that, the most common recommendations include

  • Avoid foods and chemicals that irritate the gut
  • Choose a diet of fresh, whole, nutrient-dense foods, mostly vegetables and fruits
  • Eat a great diversity of foods
  • Eat plenty of fermentable fibers such as sweet potato, yam, almonds, etc.
  • Eat fermented foods like kefir, yogurt, sauerkraut, kimchi, etc.
  • Take probiotic and prebiotic supplements
  • Exercise regularly
  • Manage your stress (Ref: 1, 2, 3, 4, 5, 6)
Image by StockSnap from Pixabay
Image by StockSnap from Pixabay

What’s So Special About Fruits & Vegetables?

Fruits and vegetables contain lots of antioxidants, which are vitamins, minerals, and phytochemicals that help your body both remove free radicals and control free-radical production.

Free radicals are generated both by our bodies and by exposure to X-rays, ozone, cigarette smoke, air pollutants, and industrial chemicals.  A balance between free radicals and antioxidants is necessary for our bodies to function properly. If free radicals overwhelm your body’s ability to regulate them, a condition known as oxidative stress ensues, which triggers a number of diseases.

Most of the degenerative diseases that afflict humanity are related to free radical reactions. These diseases include atherosclerosis, cancer, inflammatory joint disease, asthma, diabetes, senile dementia and degenerative eye disease. (Ref)

It’s because of this potential for free radicals to cause harm that including antioxidants in our diets is so important, since antioxidants assist our bodies in coping with oxidative stress. This approach of consuming dietary antioxidants as functional foods is critical for managing diseases, since antioxidants are the natural enemies of free radicals.

That said, free radicals are not all bad and can help our immune cells and remove damaged cells. The problem with free radicals is that without regular consumption of antioxidants and phytochemicals to keep them in check, they begin to destroy normal tissue.

Not getting enough antioxidants can lead to an excess of free radicals, which creates inflammation and leads to premature aging. Vitamin C, vitamin E, folate, selenium, and alpha-and beta-carotene, as well as various other phytochemicals, have antioxidant effects. The most important sources of natural antioxidants come from routinely consuming vegetables and fruits, beans, nuts and seeds.

Vegetables are especially rich in antioxidants. Eating lots of vegetables - especially green vegetables - is an easy way to get lots of antioxidants into your diet. Antioxidants are minimal from animal products, and absent in processed foods. (Ref 1, 2, 3, 4, 5)

According to Medical News Today, free radicals are connected to:

  • Central nervous system diseases, such as Alzheimer’s and other dementias
  • Cardiovascular disease due to clogged arteries
  • Cataracts and age-related vision decline
  • Age-related changes in appearance, such as loss of skin elasticity, wrinkles, graying hair, hair loss, and changes in hair texture
  • Diabetes
  • Genetic degenerative diseases, such as Huntington’s disease or Parkinson’s

The takeaway? The amount of antioxidants we get is entirely within our control, because when we eat a significant and diverse amount of unprocessed vegetables, our chances of staying healthier and living longer increase. (Ref) The bottom line is that a diet focused on foods containing concentrations of antioxidants is good for you. (Ref 1, 2, 3, 4, 5, 6)

Which Foods Boost Immunity?

Cruciferous Disease Fighters

Cruciferous vegetables such as broccoli, kale, cauliflower, and cabbage are essential disease-fighters because they sustain intestinal immune function. (Ref) The beneficial effects of cruciferous vegetables on human health have been somewhat linked to phytochemicals. They prevent oxidative stress, induce detoxification enzymes, stimulate the immune system, decrease the risk of cancers, inhibit malignant transformation and carcinogenic mutations, and reduce the proliferation of cancer cells. (Ref)

Cruciferous vegetables contain sulfur-containing compounds that are responsible for their slightly bitter flavor. Our bodies break down the sulfur-containing compounds into powerful immune-boosting and anti-cancer compounds that heighten resistance to viral infections, such as COVID-19. (Ref 1, 2)

Image from Peakpx
Image from Peakpx
Image by Monika Schröder from Pixabay


Mushrooms contain many unusual disease-fighting compounds that have been used in folk medicine for centuries and are just beginning to be understood scientifically. What’s important to know is that mushrooms possess many unusual disease-fighting compounds that support our body's ability to react quickly and powerfully to viruses and bacteria. Mushroom phytochemicals contain anti-inflammatory and immune-modulating properties that may also help with autoimmune diseases. (Ref 1, 2)

The compounds found in simple mushrooms have been shown in animal experiments and cell cultures to boost immunity. White, cremini, portobello, oyster, maitake, and reishi mushrooms have all been shown to have anticancer effects. Varieties like shiitake, maitake and reishi are particularly good for staying healthy during the cold and flu season. (Ref 1, 2, 3, 4, 5)

Onions & Garlic

The allium family of vegetables, which includes onions, garlic, leeks, shallots, chives, and scallions, provide a vast array of medicinal benefits, including antiviral, anticancer, anti-inflammatory, antioxidant, and antifungal compounds. Onions contain flavonoids, particularly quercetin, which is an important antioxidant. Interestingly, garlic is among the oldest cultivated plants and has been used as a spice for over 4000 years. (Ref)

Numerous studies show that regular consumption of allium vegetables is associated with a lower risk of cancer. Similar to cruciferous vegetables, allium vegetables contain sulfur compounds, which is what causes you to tear up when slicing onions.  It’s these sulfur compounds that possess medicinal properties, including immune-boosting and antiviral abilities. Garlic, in particular, is probably the most important member of the allium family. (Ref 1, 2, 3, 4, 5)

Onions from Peakpx
Onions from Peakpx
Picture courtesy of Pexels
Picture courtesy of Pexels

Berries & Pomegranates

Berries are rich sources of bioactive compounds with antiviral properties. They possess large quantities of polyphenols (plant compounds that bring health benefits) and polysaccharides (complex carbohydrates essential for healthy nutrition), which stimulate human immune systems through a variety of different mechanisms proven to help with influenza. (Ref 1, 2)

All berries and their juices—including blueberries, blackberries, raspberries, acai berries, goji berries, elderberries, and strawberries—are superfoods. Pomegranates possess antioxidant, anticarcinogenic, and anti-inflammatory properties that may help prevent cancer, cardiovascular disease, diabetes, erectile dysfunction, bacterial infections, and antibiotic resistance. (Ref 1, 2, 3, 4)

How Can Herbs and Supplements Boost Immunity?

Lots of supplements claim to boost our immune system, but the problem is that proving that an herb—or any substance, for that matter—can enhance immunity is very complicated. This is in part due to the complexity of the immune system.

What we do know for sure is that a deficiency in certain minerals and antioxidants can impair your immune system. It is precisely for that reason that the best thing you can do for yourself is to adopt a diet consisting of organic, fresh whole foods, and mostly vegetables and fruits. By doing so, you’ll be getting most of the compounds our bodies need. That said, it doesn’t hurt to supplement with a multi-vitamin.

Scientists don't know, for example, whether an herb that seems to raise the levels of antibodies in the blood is actually doing anything beneficial for overall immunity.

There are a number of supplements I take that research leads me to believe support improved immune function. These include:

  • Amla Powder (Phyllanthus emblica) (Ref 1, 2)
  • Astragalus (Ref)
  • Echinacea (Ref)
  • Ginseng (In particular, Panax Ginseng) (Ref 1, 2, 3, 4)
  • Ginger (Zingiber officinale) (Ref)
  • Glutamine (Ref 1, 2, 3)
  • Green Chireta (Andrographis paniculate) (Ref)
  • Green Tea (Camellia sinensis) (Ref: 1, 2, 3)
  • Magnesium (
  • NAC (Ref 1, 2, 3,)
  • Spirulina (Arthrospira platensis) (Ref: 1, 2, 3, 4)
  • Turmeric (Curcuma longa) (Ref: 1, 2 )
  • Vitamin C
  • Vitamin D (Ref 1, 2, 3)
  • Zinc (Ref)

How Does Stress Affect Your Immune System?

It doesn’t take a scientist or a doctor to prove that there’s a relationship between the mind and the body. Anyone that’s awakened at night with their heart racing from a stressful thought can attest to that.

Not all stress is bad, however. If you think about the “fight-or-flight” response, it’s a natural defense mechanism. So, it’s not short-term stress that’s the problem, it’s chronic, long-term stress that can suppress your immunity, increasing your susceptibility to infections and even cancer. (Ref 1, 2, 3)

Photo by Kat Jayne from Pexels
Photo by Kat Jayne from Pexels

What Works to Manage Stress?

Dozens of studies (Ref 1, 2) demonstrate that mindfulness-based stress reduction (MBSR) techniques such as meditation, breathing exercises, yoga or tai chi help to reduce stress. In general, mindfulness practice involves accepting whatever arises in your awareness at each moment.

Exercise is another great stress reliever, and it’s proven that people that exercise regularly have less stress than those that don’t. (Ref) Regular exercise boosts your confidence, improves how well you sleep, and releases endorphins, your good mood hormones.

There are dozens of approaches to managing stress, and managing stress is one element of ensuring your immune system is working optimally.

How Does Exercise Support Your Immune System?

“Being active has enormous health and well-being benefits. Physical activity is important in the management of long-term diseases, but, it is even more important in the prevention of many other common diseases. I believe that if physical activity was a drug it would be classed as a wonder drug, which is why I would encourage everyone to get up and be active.”

-Professor Dame Sue Bailey, Chair of the Academy of Medical Royal Colleges (AOMC), in the Forward to the AOMC’s report on exercise: (Ref)

Everyone knows that regular exercise is important for healthy living, and it’s not new information: over 2300 years ago, Aristotle said that “a man falls into ill-health as a result of not caring for exercise.” Exercise improves cardiovascular health, lowers blood pressure, helps control body weight, and protects against a variety of diseases. Exercise also contributes to general good health and to a healthy immune system by promoting good circulation, which allows the cells and substances of the immune system to move through the body freely and do their job efficiently.

The amount and type of physical activity you get is related to your health and the strength of your immune system. Virtually all the global health organizations agree that everybody should get at least 30 minutes of moderate physical activity, like a brisk walk, every day. You can mix it up by doing your 30 minutes as 3 10-minute walks but exercising in at least 10-minute blocks is recommended – it’s not considered enough to just walk a few minutes. (Ref 1, 2, 3)

The protective effect of regular moderate exercise is significant – there’s a 40-50% reduction in the number of days people are sick, and exercise can reduce the risk and severity of respiratory viral infection. (Ref)

Studies show that exercise boosts our immune systems, and that moderate exercise is best. (Ref 1, 2, 3, 4, 5, 6)  Heavy exertion lasting longer than 90 minutes should be avoided. (Ref 1, 2) The takeaway is that it’s important to exercise enough to build your immune system, but too much exercise can actually reduce your immune function, as it stresses your body.  As figure 1, Optimal Exercise shows, regular moderate intensity exercise improves the immune response to respiratory viral infections.


It’s also important to diversify your physical activity to include aerobic fitness, strength and flexibility. (Ref 1, 2, 3) As we get older, including balance into your fitness routine is also important, not so much as it relates to immunity, but to prevent falls as we age. (Ref)

To get an idea of what types of exercise you should make a regular part of your lifestyle, see the activity pyramid below (figure 2). The activities at the base of the pyramid should be done daily, and as you go up the pyramid, the activities are less frequent but more intense.

If you’re presently inactive, start with the activities at the base, and as you get stronger and more fit, move up the pyramid. Activities higher up in the pyramid produce many benefits in your aerobic fitness, strength and flexibility.

Exercise Pyramid

There are a few things you can take into consideration, which should be common sense. For example, you can replace daily moderate exercise with running 20-30 minutes, 3 to 4 times per week. The same amount of energy is expended in these two examples, so the health benefits are considered to be the same.

That being said, regular movement is advised – you’ve heard the phrase “sitting is the new smoking.” The more regular movement you get, the better off you are.

Studies also show a correlation between regular exercise and longevity (Ref 1, 2), but it’s important to note that a moderate amount of exercise provides the benefits: too much exercise, or none at all, both aren’t good for you.  With jogging, for example, between 1 and 2.5 hours per week at a slow to moderate pace, 2 or 3 times per week brings the greatest health and longevity benefits.

The ideal amount of exercise to promote longevity is between 7-12 hours of exercise per week (Ref 1, 2).  Dr. Valter Longo, one of the world’s leading experts on longevity, recommends:

  • An hour of fast walking every day
  • At least medium intensity cardiovascular exercise 2.5-5 hours per week
  • Resistance training at least 2 times per week

Here’s the big takeaway, in a quote from Physical Activity in The Prevention & Treatment of Disease:

Physically active individuals run half the risk of dying from cardiovascular disease as sedentary persons of the same age. Physical activity also decreases the risk of having high blood pressure, age-related diabetes and colon cancer. Quality of life is also improved by physical activity due to greater mental well-being and better physical health. There is also strong support for physically active individuals having a lower risk of being affected by brittle bones, bone fractures caused by falls, blood clots, obesity, and mental disorders.

Despite the COVID-19 “shelter-in-place” recommendations, you can still exercise outside, as long as you adhere to social distancing guidelines. Just make sure to keep at least 6 feet from other people. Beyond that, avoid touching handrails or exercise equipment.  Avoid group activities, but it’s okay to go for a hike, run, or bike ride with others, provided you avoid all physical contact and maintain that 6 feet of distance from everyone.

Is Laughter Really Medicine?

We’ve all heard the phrase “laughter is the best medicine,” and it turns out that there’s at least some truth to this notion. Laughter literally triggers healthy physical and emotional changes in your body, strengthening your immune system, improving your mood, and reducing or eliminating your stress.

At an intuitive level, this makes sense. The effects of humor and laughter are numerous: Humor is not only instinctive and a basic human need, but it also is very good medicine. Laughter boosts the immune system, lowers blood pressure, reduces stress hormones, and is linked to healthy functioning organs. (Ref 1, 2, 3, 4, 5)

Photo by Andrea Piacquadio from Pexels
Photo by Andrea Piacquadio from Pexels


We trust that this article has provided you with things you can do to boost your immune system. Does that mean you won’t get sick? Are there any guarantees? Of course not. COVID-19 is a new and terrible virus. What you can take away from this article is that there are a number of things you can do to boost your immune system that are in your control, and if your immune system is functioning even a little better, you might be better able to recover in the unfortunate case that you do get sick.

3 thoughts on “How to Boost Your Immune System”

  1. Thank you Fit after 50 for providing me with such valuable information to keep me fit, healthy and happy! I have a much better understanding of how my body works and what easy remedies to put in place to keep my body and mind as fit as possible!
  2. andy sinsigalli
    Dave, i am looking for a good plant based protein supplement. Any ideas? of the supplements that you have listed i am taking most of them, i exercise a fair amount (six days a week) and am working to maintain a whole food diet. i have cut back dramatically on meat based protein and would like to find a plant based product to keep my macros in order. thanks!

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