Your Immune System Is Your Greatest Asset — Here’s How to Care for It

A prescription for living well from a Harvard physician

Dr. Jeffrey Rediger, M.D., MDiv
6 min readMay 5, 2020


Photo: OksanaKiian/Getty Images

You don’t need to spend more than five minutes flipping through TV channels or news articles to see that way too many amygdalas (the fear center in our brains) are on overdrive these days.

Stock markets have plummeted, schools have halted normal operations, and group meetings and social functions are all canceled. As we know, fear and stress can put us into a state of “fight or flight” and elicit a constant state of unease. Not only does this way of being feel bad, it also leaves us more vulnerable to illness and slower to heal. Though we don’t know how long the coronavirus crisis will last, one thing is certain: We can’t stay in a fight-or-flight state for the duration.

So, what will calm your amygdala and build your immunity in a way that renders you less susceptible to illness, at this time when good health is our greatest asset?

We live in a hyper-connected world where there are always going to be pathogens that come into our lives in one way or another. This is not the first time in recent years that we’ve faced a sweeping viral enemy, and it won’t be the last. Vaccinations can be lifesaving when available, but they don’t come close to eradicating the flu, for instance. The development of a coronavirus vaccine will be an enormous step forward, no doubt. However, in the meantime, there is work to be done to care for our bodies. Giving the brilliant, highly specialized cells of your immune system all they need in order to flourish can’t guarantee you won’t get the virus, but will help you build a strong baseline of health and recover faster if you do become sick.

When the body’s immune cells receive the nutrients they need, they function crisply and efficiently, warding off threats and not allowing harmful pathogens to take root.

We have come a long way in understanding pathogens.

One hundred and 60 years ago, we still believed in the spontaneous generation of microbes, including viruses. The word “spontaneous” in this context means “without cause.” We believed that infections appeared in our bodies out of the blue. We also still had more of a tendency to see illness as a moral affliction, a judgment from God.

The French chemist Louis Pasteur helped us take a huge step forward from these lines of thought when, in the 1860s, he definitively proved the existence of germs as the cause of disease. Our takeaway from this discovery was “kill the germ.” Simple, right?

But sometimes simple is too good to be (completely) true and, in this case, there’s more to the story.

At the time of Pasteur’s discovery, a few other scientists were working on a different version of the germ theory. Antoine Béchamp and Claude Bernard were colleagues, and they had concerns. They thought the “kill the germ” approach by itself was a dangerous proposition. They were among the first to talk about what we now call the microbiome, and their argument was that we are surrounded at all times by millions of pathogens, inside and outside our bodies; and that these germs only become invaders when something vital has broken down in our immune systems. They argued that germs are attracted to diseased tissue, but are not the cause of diseased tissue — just as mosquitoes are attracted to stagnant water, but are not the cause of the stagnant water.

Béchamp and Bernard argued that most of the “germs” that live in and on our bodies are actually important and beneficial, even critical for our health and well-being. When the body’s immune cells receive the nutrients they need, they function crisply and efficiently, warding off threats and not allowing harmful pathogens to take root.

In a speech to a group of students and physicians, Bernard declared, “The terrain is everything; the germ is nothing.” He then lifted a glass of water, contaminated with deadly cholera bacteria, and drank it. He didn’t get sick, proving that his “terrain” was as healthy as he claimed it was. He made his point — germs don’t cause disease. Establishing a foundation of health and vitality, free of toxins, and fostering a strong, balanced immune system, he argued, was more important than killing pathogens.

For the past 17 years, I have interviewed people with medical evidence for recovery from incurable illnesses. Like the now disproven idea of spontaneous generation, there’s also nothing spontaneous about spontaneous remission. In cases that were previously considered flukes with no medical or scientific value, there are actually identifiable factors associated with how these individuals created abundant health and vitality in the face of great odds. The healing of their immune systems is a critical part of their stories.

Food is either medicine or poison, depending on what it contains, so you want to eat a clean diet. Don’t over-medicate. Flush your lymphatic system regularly with lots of water. Get plenty of rest.

It turns out that you don’t have a heart problem, a diabetes problem, a blood pressure problem, a cancer problem, or an autoimmune problem as much as you have a chronic inflammation problem. Chronic inflammation is an immune system gone awry, damaging the body it was designed to protect. If you want to decrease the amount of chronic inflammation in your body, then you need to heal your immune system.

You have an amazing immune system, with brilliant cells and cell-subtypes, all of which want to unleash their superpowers and keep you healthy and vital. For that to occur, you need to give your cells the proper conditions. One of the most important things you can do is give yourself real food, mostly plants, and largely eliminate processed foods, sugar, and refined flours from your diet.

Food is either medicine or poison, depending on what it contains, so you want to eat a clean diet. Don’t over-medicate. Flush your lymphatic system regularly with lots of water. Get plenty of rest. Spend time with people you love who make you laugh.

When it comes to the coronavirus and other flu variants: Follow common-sense recommendations like washing your hands — a lot! But also turn off the news and change your focus. The strength of your team of natural disease-fighting cells within your immune system is also directly linked to how you manage stress, how you manage your relationships and past traumas, and even how much you understand your value and invest in living your own authentic, best life. If you make the hard choice to focus on improving these things, you may be astonished with the positive results — for both you and your immune system.

The coronavirus, like so many other seasonal flus and viruses we live with, is probably going to be around for the long haul, and your focus needs to be on building an immune system that can take on all comers. Let’s use the coronavirus threat as impetus for facing a truer reality, using medications and vaccinations wisely, and also doing the hard, deeply gratifying work of building health and vitality from the ground up. Even Louis Pasteur recanted on his deathbed, after a lifetime of fighting. “Bernard was right,” he said, referring to the man who boldly drank the glass of cholera. “The pathogen is nothing; the terrain is everything.”

In the days and months to come, we are going to learn so much more about Covid-19. But now, as we all struggle with our fears and the very real practical consequences of this pandemic, let’s focus on what is within our control, which is quite a lot. Let’s protect ourselves and those we come in contact with; let’s elevate our lives to a whole different order of protection and safety. Let’s do what we can to see this as an opportunity rather than yet another burden.



Dr. Jeffrey Rediger, M.D., MDiv

Dr. Jeffrey Rediger, author of CURED, Medical Director of McLean SE, serves at Caritas Good Samaritan Medical Center, and teaches at Harvard Medical School