The Food You MUST Eat to Protect Yourself from COVID-19

Updated: Apr 16, 2020

Wouldn't it be nice to know whether particular foods could protect you more against the coronavirus?

Actually, when you eat the right foods, you CAN strengthen your immune system...

...which can then help you fight (off) any virus more effectively.

Here you are going to find out EXACTLY, which foods you should include to get you the best protection...

...and which one you should avoid.

Do you know about the 5 crucial, science based lifestyle factors to protect yourself from COVID-19?

You can read it here.

The 5 diet related key points that can strengthen or weaken your immune system







You've been told to eat your vegetables while you were growing up. Your parents told you something along the line:"Vegetables keep you healthy and strong."

Was that even scientifically correct?

It appears our parents were all natural born scientists.

Vegetables can indeed keep us healthy and strong.

They can keep you healthy and strong in a variety of ways actually, but this article will focus on the effects they have on our immune system.

There is a very interesting compound found in one kind of vegetable:

What vegetable is that?

Cruciferous vegetable

How important is this compound?

It is of such importance that:

It is REQUIRED to maintain a large population of immune cells. (1), (2), (3)

Guess what you need immune cells for?

These immune cells are important in fending off little critters, that would like to use your intestine as a gateway to host all kinds of illegal activities. These immune cells are basically little policemen patrolling along the lining of your intestines.

The worst part?

If they are lacking, it also increases the risk of intestinal damage, due to the possible presence of unfavorable microbes, comparable to hooligans, who are up to no good and like demolishing stuff.

An easy to understand analogy to put things in perspective:

Cruciferous vegetables contain an abundance of something called 'I3C', which you can compare to the abundance of tax you pay.

Then that I3C ends up in your digestive tract and gets oxidized and then condensed into a compound called 'DIM'. (4)

This trajectory is similar to:

Your tax money ending up into a government agency that handles your taxes, where your money gets 'oxidized' and 'condensed' into different departments.

DIM is just one such department: Department of Internal Money making.

What DIM does is activate a receptor called AhR, which is in charge of the maintenance of the immune cells mentioned earlier. (4)

You can compare this to:

The 'department of money making' using some of the money to pay public services, like the police department. AhR is basically the salary for the little patrolling policemen in your intestine.

In other words, you need to eat your cruciferous veggies, otherwise your internal police department will go on strike.

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What are cruciferous vegetables?

Cruciferous vegetables are vegetables of the family Brassicaceae such as:

Cauliflower, mustard greens, cabbage, kale, spinach, garden cress, bok choy, choy sum, broccoli, Brussels sprouts and similar green leafy vegetables, excluding lettuce.

Bottom line:

A daily serving of cruciferous vegetables gives you tons of nutrients on top of enhancing your immune system.

The produce aisle with all its beautiful green vegetables is your best friend and it deserves your attention.

So, next time you're in the supermarket... the name of Zeus, don't prioritize toilet paper and then forget all about the greens.

This act of blasphemy is simply unforgivable.


A great claim has been made by scientists:

Many kinds of mushrooms have the potential to provide us with the next generation of antibiotics, to reduce environmental pollution, and even produce our fuel.

That's not all:

They even go as far as stating they are one of the great untapped resources of nature. (5)

That sounds amazing, but:

Can our little fungi friends boost our immune system, while simultaneously taking care of pollution?

Mushrooms can offer a host of health benefits and have ANTIVIRAL AND ANTIBACTERIAL PROPERTIES on top of that. (6), (7)

They do seem magical...

Unless you are intolerant.

In that case the only trips you will be taking are to the restroom. More about intolerances under "Microbiome".

How can mushrooms improve our immune response to viruses?

Mushrooms have 2 ways to do that:

  1. By supplying you with prebiotics to feed your microbiome (more on prebiotics under "Microbiome")

  2. By increasing secretory IgA (8)

If you remember from "5 Ways to Protect Yourself from COVID-19, Hardly Anyone Talks About, But SHOULD" almost all infections are initiated at the moist or mucosal surfaces.

Where are these surfaces located?

In or on your eyes, nose, mouth and the inner lining of your digestive tract.

And what does secretory IgA do?

Secretory IgA protects these mucosal surfaces...

By neutralizing viruses and preventing them from playing cliffhanger on the surface. (9), (10)

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At least one of the compounds in mushrooms, called beta glucan, is responsible for the ability to increase secretory IgA, as lots of trials have demonstrated beta-glucan supplements can do exactly that.

There could be other compounds involved, but what is clear is:

Mushrooms can enhance immune response to viruses and foreign invaders. (8), (11), (12), (13), (14)

But that's not all:

They also show immune enhancing effects among cancer patients during chemotherapy:

"How to Prevent and Treat Cancer with Vegetables, Fruits and Mushrooms"

The immune system of cancer patients is particularly vulnerable during these treatments. (5), (6)

Nutritional yeast: a health food?

Beta glucan derived from 2 different mushrooms have even been licensed as successful drugs in Japan. (15)

Beta glucan is also found in yeasts such as nutritional yeast.

Nutritional yeast is commercially sold and often touted as a health food, due to its beta glucan content.

It may have favorable effects in this form as well, but there is a big problem here:

It's not easy to find unbiased research.

Unbiased means that the studies aren't funded by the (supplement) companies that stand to gain from positive outcomes.

Bottom line:

If you like or tolerate mushrooms, try to include some into your diet.

Have them at least a few times a week.

Whole foods like mushrooms are preferred over nutritional yeast:

They contain the 'immune booster' beta glucan and countless of other nutrients on top of that.


Micronutrients, like vitamins and minerals, are essential nutrients the human body can't do without.

They are involved in an amazingly wide range of processes:

  • metabolism of carbohydrates, fat and protein;

  • cell development;

  • genomic stability;

  • DNA synthesis and repair;

  • and more. (16)

You may be thinking:

"If they're so important, they can surely impact immunity."


Micronutrient deficiencies impair immune defenses, (17) making you more susceptible to infections, regardless of what age you are. (18)

You may be wondering then:

"Should you take multivitamin and mineral (MVM) supplements then just to cover your bases?"


Large-scale studies show that MVM supplements produce little harm or no harm in the short run. (19)

But in the long run...

They might actually slightly increase your risk of cancer and cardiovascular disease.

So, why so many people blindly take multivitamin supplements then?

Misleading commercials and placebo effects are to blame for that, simply because consumers haven't been properly informed. (19)

Bottom line:

Simply taking a MVM supplement to cover your bases is not necessarily a good idea.

It depends on your diet pattern and your overall gut health (what you absorb).

It also depends on the supplement and its dosage.

Therefore, it's better to get professional advice from a certified nutrition expert.

If you'd like to check possible deficiencies you might have yourself, you could also track your nutrients for several days with an online food calculator like Cronometer.

Basically, you only have to enter the foods you eat and Cronometer calculates your vitamin and mineral intake for you.

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What you should most definitely do:

Focus on the things that contain these micronutrients in their natural form:


Differences between foods

Almost all foods contain some vitamins and minerals.


Certain foods impact immune response more than others.

Maybe that's because these foods contain a host of other nutrients or phytochemicals as well.

These nutrients may not be essential in the same way as vitamins and minerals are, but they can still be beneficial. (20)

What foods are we talking about?

Foods that are not only rich in vitamins and minerals, but also have favorable effects on your immune response, are:

Fruits and vegetables.

In 1983, they already realized that a greater fruit and vegetable consumption lead to a reduced risk of getting a cold. (21)

Effects on people with higher risk

In older people higher intake of fruits and vegetables improved immune function and showed a better response to a vaccine they were administered with. (22)

Does age matter?

The older you get, the more your immune response to the coronavirus, that causes COVID-19, weakens.

That's one of the reasons most fatalities among people infected with the coronavirus were older than 60 years. (23)

Another more vulnerable group, pregnant women, also benefits from a higher intake of fruits and vegetables:

Pregnant women are more resistant to respiratory infections during pregnancy. (24)

COVID-19 is a respiratory tract infection.

What's the impact on other people who are at higher risk?

Even if we look at a variety of people with a variety of conditions on a large scale:

Fruits and vegetables are clearly associated with improved immune responses. (25)

Bottom line:

Instead of rushing out to stock up on toilet paper, focus on the produce aisle...

Or get yourself some frozen veggies, frozen berries, etc.


The microbiome is, by far, the most important topic to cover in regard to immune health, but also many other health topics.

You may be wondering:

"Why is it only mentioned now"?

Because the previous mentioned topics all mentioned foods that are the base of a healthy microbiome. More about this in a minute...

When we refer to microbiome in this article, we are talking about the bacteria in the GI tract, or gut. (26)

The microbiome plays a very important role in the health of your immune system.


Important is an understatement.

To put things in more perspective:

The number of bacterial cells in the human body EXCEEDS the number of human cells! (27)

Isn't that remarkable?!

We are more microbe-human-hybrid beings than we are in fact human beings.

Not surprising, that your friendly intestinal flora can stimulate and develop different components of your immune system.


It acts as a protective barrier, preventing pathogens from setting up shop in your gut.

It starts right after birth when a 'barrier' of microbiota is formed.

The big question now is:

How do you take care of your microbiome?

For newborns and infants breast milk contains beneficial bacteria and it feeds the beneficial bacteria as well, resulting in a healthy population of bacteria and promoting the development of the immune system. This may help also prevent conditions, such as eczema and asthma, common among young children. (28), (29)


If you are able to read this, chances are you are not living off breast milk.

There are other ways, thankfully, to tend your inner garden.

Your diet

Diet has a major impact on the composition of your intestinal microbiota and your immune status.

Gut bacteria can directly influence immune and epithelial cells by producing a compound called short chain fatty acids (SCFA's). (1)

Your intestinal epithelial cells are the physical barrier that separates your gut from the outside.

The good part?

This barrier prevents harmful bacteria and substances from getting through.

The scary part?

It is only a single cell layer thick! (30)

That means:

You need some really good mechanics in there to take care for this single cell layer.

SCFA's are these little mechanics.

SCFA's maintain these fragile epithelial cells and promote intestinal IgA (remember?) responses...

...contributing to the protection of foreign invaders. (31)

Bottom line:

You need to feed your bacteria well so they can produce little mechanics that can repair and maintain your most important defense barrier.

How do bacteria produce SCFA's?

They produce SCFA's mostly from different non-digestible carbohydrates, such as fiber.

Foods that contain carbohydrates often contain a variety of different non-digestible carbohydrates.

We call these compounds that feed our friendly flora: PREBIOTICS. (32)

In what foods can we find prebiotics?

In vegetables and fruit, whole grains, legumes, nuts and seeds. And let's not forget our previously discussed friend mushroom, which hosts an abundance of prebiotics.

If you are considering a low carbohydrate diet...

Realize that one of the more common species of beneficial flora, Bifidobacterium Bifidum, harbors specific carbohydrate transporters allowing them to protect the epithelial cells. (33)

Food intolerances

There can be one problem when it comes to food...

No matter how healthy it is.

If you have an intolerance or allergy towards a specific food...

Instead of improving your health and immune system...

They can have an opposite effect.

How is that possible?

Food intolerances or food allergies can cause inflammation and weaken your immune system instead. (34)

What's the cause?

The causes of food intolerances can be multifold.

If your intestinal health is impaired, that could lead to food intolerances even by itself. (34) Sadly, it's pretty common.

"What can I do about it?"

Good question.

If you are aware what foods you are sensitive to, exclude them from your diet for the time being and keep feeding your microbiome with a variety of foods, that you can handle.

Foods you are sensitive to and cause you digestive discomfort, itchy skin or other symptoms, can be reintroduced slowly over time, similar to the protocol commonly use among low FODMAP diets.


FODMAPS are a group of sugars that are not completely digested or absorbed in our intestines.

The FODMAP diet, developed by Monash University, is about minimizing high FODMAP foods for several weeks, followed by a slow and careful reintroduction over the course of several weeks to several months.

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Food allergies

Food allergies are not the same as food intolerances.

They can't be treated the same way:

A food allergy is a direct response of the immune system to a food, which negatively impacts your health. (35)

More on this in a future article.

More magic

There are several other things your good bacteria can produce, that can contribute directly and indirectly to an enhanced immune response.

They can even produce vitamins, of which you already know, are a key factor in shaping a good immune system. (1)

Prebiotics can feed the bacteria that help and produce a soothing balm for your insides.

Probiotics are live, beneficial microorganisms (mostly bacteria), which are often sold in supplement form or used to make, for instance, yogurt or pickled vegetables.

Fermented foods

Different kinds of yogurt have become increasingly popular over the years.

Yogurt is usually made from dairy.


Nowadays it is made from a variety of foods such as:

  • Soy

  • Almonds

  • Cashew

  • Coconut

The probiotic bacteria are the key in making yogurt.

Another type of fermented food is gaining popularity:

Fermented vegetables like sauerkraut or kimchi.

They also contain probiotics, but they are slightly different...

Fermented vegetables are fermented with naturally present microbes.

Therefore, they may be more suitable for our microbiome, provided that they are raw and not pasteurized or heated.


Don't go overboard on serving sizes, especially when you're just starting out, because it's very powerful stuff.

Probiotic supplements?

Probiotic studies have shown promising results in respect to our immune system. (36)

Perhaps you're wondering:

Should I take probiotic supplements?

Excellent question.

Whether to take probiotics in supplement form or not, to give your immune system a little boost, is a complicated issue unfortunately:

It depends on your individual microbiome and which species and strains of beneficial bacteria are possibly lacking.

That's not all...

Many factors, such as age, hormonal perturbations, diet composition and supplement intake, antibiotic therapies, lifestyle, disrupted circadian rhythm (natural day and night rhythm) and physical activity all have an impact on your gut microbiome! (37), (38)

Antibiotics deserve to be emphasized:

Antibiotics can have such a drastic effect on your microbiome.

The good part?

They can be life-saving in some cases...

The bad part?

Antibiotics are also able to cause LASTING CHANGES, disrupting intestinal harmony by wiping out beneficial microorganisms.

This can lead to all sorts of health problems, including weakened immunity. (39)

Let's simplify it with an image:

During and after an antibiotic course, a multiple strain probiotic is often recommended, because antibiotics can cause diarrhea. (40), (41)

Not only that:

You can reduce the damage caused by the antibiotics by frequently reintroducing beneficial bacteria, that may otherwise get hurt in the line of duty.

This getting hurt may feel like getting blasted by a nuclear bomb for some bacterial strains, so they need some help or reinforcements down there.

Bottom line:

  1. Always take care of your microbiome by incorporating the foods in your diet that support it: whole grains, legumes, vegetables, fruits, mushrooms, nuts and seeds.

  2. Fermented foods are great to incorporate into your diet, but build up slowly.

  3. When taking antibiotics, it serves to take a multistrain probiotic alongside with them.

  4. Take them a few hours apart.

  5. After finishing your course of antibiotics keep taking the probiotics, until you finish the bottle or batch.


If antibiotics are the nuclear bombs for our friendly little troops, alcohol is one of those small little bombs, that do some damage, albeit significantly less.

After that little bomb has dropped, ground troops are more able to regroup and do some damage control, taking care of the wounded and rebuild.

Whereas, after a nuclear bomb has dropped...

They would like to do all these things, but they can't because their bodies have become disintegrated.

Bottom line:

Alcohol can reduce the total numbers of your intestinal flora.

That's a bad thing, because:

They are needed for healthy gut immunity.

How does alcohol manage to do that?

Alcohol disrupts the relationship between the microorganisms and the intestinal immune system.

And the worst part?

Alcohol damages your gut lining, or the epithelial cells, leading to holes forming in the barrier function. (42)

Bottom line:

Like mentioned above, troops can regroup and rebuild, but the more little bombs land, the more holes will form in their defences and the more helpless they will become.

In this case that means:

Frequent alcohol consumption will more negatively affect gut immunity.


Diet has a big impact on how your immune system operates.

A healthy microbiome is the most important component in forming a healthy immune system.

Our friendly flora requires food in the form of vegetables, fruit, legumes, whole grains, mushrooms, nuts and seeds in order to produce the substances that protect our gut and thus strengthen our immunity.

Some of these foods have special immune enhancing qualities, like cruciferous vegetables and mushrooms.

Other kinds of beneficial foods are foods that supply live probiotics, like:

  • Fermented vegetables

  • Different kinds of yogurts

Finally, keep in mind the things that can be harmful:

  • Individual food sensitivities, even of healthy prebiotic-rich foods, can negatively impact your immune system.

  • Alcohol is harmful to your gut lining and your friendly microbes.













































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