A secret weapon for fending off even the deadliest health threats—from cancer to COVID—may lie within your gut

Even with some huge steps toward recovery, we’re still a long way from being out of the woods from COVID-19. Which means now is not the time to let your guard down. Measures like routine hand-washing, mask-wearing, and vaccination remain as important as ever to help stop the spread.

But like I’m always telling you, maintaining your body’s own natural defenses is just as critical. And new research shows a healthy gut microbiome may actually be one of your greatest allies against the ongoing pandemic…

Of course, this isn’t all that surprising when you consider the fact that some 80 percent of our immune system’s cells originate in the gut. Ultimately, it’s the largest immunological organ there is—and the bacteria that reside there play a critical part in mediating your body’s responses to all sorts of threats—from cancer to COVID-19.

So if you want to stay healthy, you need to have a healthy gut. Today, I’ll give you a refresher on how to achieve that. But first, let’s take a look at what the new research has to say about gut health and COVID…

A leaky gut could leave you vulnerable

As you know, COVID-19 is a respiratory illness. Common, most notable symptoms include breathing problems, dry coughs, and high fevers. But your gut may have a key role in the way that infection plays out.

In fact, autopsies show that the coronavirus can impact the liver, kidneys, heart, spleen, and yes… the gastrointestinal (GI) tract. And when your gut gets involved, it’s usually tied to more severe illness. (Many patients who are hospitalized with COVID-19 also have GI symptoms like diarrhea, nausea, and vomiting.)

Plus, a recently published review established some convincing ties between poor gut health—leaky gut, in particular—and COVID prognosis.1

Leaky gut, or “intestinal permeability,” occurs when the junctions that control what can pass through the small intestine’s lining don’t work properly. This leads to substances that are meant to be excreted (like waste, toxins, and food particles) passing into the bloodstream.

It also makes it easier for COVID-19 to attach to the surface of the digestive tract. In turn, this ramps up the infection’s severity, because these surfaces are rich in ACE2—a protein that the novel coronavirus targets, specifically.

The risks of an imbalanced gut

Older people, as well as people with obesity and diabetes—three prime risk factors for severe COVID-19 infections—are the most likely to have microbiome imbalances.

In fact, research shows that COVID-19 patients have lower bacterial diversity in fecal samples than healthy people. They also have lower levels of beneficial bacteria and higher levels of pathogenic strains. And these beneficial populations stayed low for as long as one full month after infection.2

To reach these conclusions, scientists took blood and stool samples, along with medical records, from 100 hospitalized COVID-19 patients between February and May of last year—and compared it to data they took from 78 people before the pandemic started.

After analyzing stool samples, they discovered that the microbiome composition differed significantly between patients with and without COVID-19, regardless of patient age or treatment—ultimately linking an unhealthy gut to a higher risk of COVID-19 infection and severity.

But that’s not all…

Preventing the cytokine storm before it starts

As I’ve mentioned here before, COVID-19 infection generates inflammatory responses in the body—and in the worst cases, catastrophic responses called “cytokine storms” that lead to tissue damage, sepsis, and organ failure.

And now, researchers found that an imbalanced gut may lead to a higher risk of cytokine storms—along with blood markers of tissue damage, like C-reactive protein.

This suggests that the microbiome mediates the immune response to COVID-19 infection.

But here’s where things get really interesting: These researchers believe that an imbalanced gut is likely implicated in cases of “long COVID,” where symptoms persist for weeks, if not months, after infection.

Of course, being an observational study, it’s too soon to claim a causal relationship between an imbalanced gut and poor COVID-19 outcomes. But given what we already know about the gut’s role in modulating immune responses, it’s not exactly a stretch.

And the truth is, there’s more than enough evidence out there for you to start taking steps to strengthen your microbiome in the fight against COVID-19—and chronic disease in general—starting TODAY.

Start with a safe detox

I always like to start any microbiome rehab plan with a good detox.

Periods of planned, safe detoxification will give your gut the rest and recuperation it needs for optimal function. But don’t worry—unlike many detoxes out there, my plan (which I created for my A-List Diet) isn’t complicated at all.

In fact, so many of my patients have told me their detoxes ended up being much easier than they initially thought. It only takes a week to notice a significant difference in how you feel. And the best part is, it includes food.

I typically recommend this cleanse twice per year to help you eliminate accumulated toxins on a regular basis. I usually follow it in the beginning of January (after the holidays) and at the end of June (to prepare for summer vacation).

But really, there’s no better time than the present to get started. (You can find a quick overview of my detox in the sidebar on page 4—and a more complete guide in my A-List Diet book.)

Feed your friendly flora well

Of course, even outside of your detox windows, it’s imperative that you eat well. After all, what you eat directly influences the health of your microbiome—perhaps more than anything else.

Simply put, you cannot follow the Standard American Diet (SAD) of processed foods, GMO-laced grains, pesticide-covered produce, and way too much sugar. Instead, you must eat healthy fats, high-quality fiber, and absorbable nutrients. And you must get enough salt. (In other words, you should follow a smart eating plan, like my A-List Diet.)

More specifically, I recommend:

1.) Avoiding sugar at all costs.

2.) Filling up on lean protein, healthy fats, a little fruit, and plenty of fiber-rich vegetables.

3.) Eating prebiotic-rich foods, like onions, garlic, leeks, asparagus and artichokes, to nourish your probiotics.

And for an added microbiome boost, you can include foods that contain natural probiotics into your diet as well—like sauerkraut, kimchi, and fermented vegetables.

(For a more detailed discussion on how to help your friendly flora thrive with food, I urge you to revisit my March 2019 newsletter [“EXCLUSIVE: Your ultimate guide to a complete microbiome makeover”]. You can also check out my book, Feed Your Health with Bacteria, found under the “books” tab of my website, www.DrPescatore.com.)

So, now that you know how to properly nourish your gut with food, let’s talk about smart supplementation…

Picking the perfect probiotic

One of the best ways to keep your gut microbiome nourished is with a high-quality, multi-species, live probiotic. Just remember, the key is diversity of strains over quantity.

In fact, ingesting too many of the same type of bacteria can actually wreak complete havoc in your gut and on your body. That’s why products boasting billions of CFUs aren’t actually a good option.

Instead, look for a probiotic that features different strains of friendly flora—along with prebiotics, probiotics, and postbiotics (such as bacteriocins), to help to kill off the bad bugs in your gut. All of these beneficial bacteria have research-supported roles in digestion, detoxification, and immune support.

But to really maximize your microbiome’s health, you don’t want to stop with a daily probiotic… you’ll also want to boost your intake of the sunshine vitamin as well.

Double down on vitamin D

Studies have shown that your microbiome suffers when you don’t have adequate levels of vitamin D. And unfortunately, 80 percent of the U.S. population is deficient.

The good news is, recent studies show that just five weeks of high-dose vitamin D supplementation can significantly reduce populations of certain potentially harmful bacteria in the upper GI tract—all while boosting the richness and diversity of beneficial flora.3-4 (No wonder this nutrient has emerged as a superstar against COVID-19, helping to reduce risk of severe infection and death from the virus!)

As always, start by having your vitamin D 25 OH blood level checked every six months to gain a better understanding of whether or not you’re deficient. (“Optimal” levels are between 80 and 100 ng/mL.) Then, if you’re already achieving optimal levels, I typically recommend a daily dose of at least 50 mcg (2,000 IU) to 125 mcg (5,000 IU). But for less-than-optimal blood levels, I always recommend 250 mcg (10,000 IU) to 375 mcg (15,000 IU) daily.

I also advise taking vitamin D3 with regular doses of pantethine (vitamin B5)—1,500 mg, three times per day. Research shows vitamin D deficiency impacts your gut bacteria’s ability to generate pantethine—resulting in inflammation and immune dysfunction. Replacing both, however, helps to restore a normal microbial population.5

Now, let’s go over the last step in your microbiome-strengthening plan…

The best artillery for your gut’s defenses

A healthy gut lining is essential to a healthy microbiome, for fairly obvious reasons. The mucosal barrier of your GI tract acts as home base to your gut bacteria. And its job is to keep the good guys in—and the bad guys out.

Vitamin A reinforces the junctions of your intestinal walls and ensures proper function of the cells lining your gut. In other words, vitamin A deficiencies can have serious consequences for gut barrier function. That’s why I recommend taking 12,000 mcg (40,000 IU) of vitamin A (as retinol) per day.

I also recommend:

  • Aloe vera leaf extract: 250 mg per day
  • Deglycyrrhized licorice (DGL): 500 mg per day
  • Marshmallow root: 100 mg per day
  • N-acetyl glucosamine: 250 mg per day
  • Slippery elm bark: 200 mg per day

Along with vitamin A, these botanicals and nutrients can help heal a leaky gut and strengthen the mucosal lining of your digestive tract. This extra support is especially important if you’ve struggled with food sensitivities, which can do a number on your intestinal barrier.

At the end of the day, your gut helps keep your entire body running in top-top shape. And when you don’t care for it, the health implications are serious—for common infections and chronic disease. So start nourishing your gut and take back control of your life… in the age of coronavirus, and beyond.

SIDEBAR: Prime your microbiome with my easy A-List Diet Detox

DAYS 1-2: Drink only water and plain herbal teas, consistently throughout the day.

DAY 3: Drink water, herbal teas, and nutritious bone broth. (Note: For my personal recipe, see page 186 of my book, The A-List Diet.)

DAY 4: Drink water, herbal teas, and broths. Eat organic, free-range eggs.

DAY 5: Drink water, herbal teas, and broths. Eat eggs and organic avocados.

DAY 6: Drink water, herbal teas, and broths. Eat eggs, avocados, and nuts. (Note: Skip the peanuts and load up on more nutritious options like pistachios, walnuts, almonds, macadamia nuts. You can have raw or lightly salted—whichever you prefer.)

DAY 7: Drink water, herbal teas, and broths. Eat eggs, avocado, nuts, and light, flaky, wild-caught fish (like cod or halibut).


  1. Heenam Stanley Kim.Do an Altered Gut Microbiota and an Associated Leaky Gut Affect COVID-19 Severity?mBio, 2021; 12 (1) DOI: 10.1128/mBio.03022-20
  2. Yeoh YK, et al. “Gut microbiota composition reflects disease severity and dysfunctional immune responses in patients with COVID-19.”Gut. 2021 Jan11;gutjnl-2020-323020.  
  3. Bashir M, et al.“Effects of high doses of vitamin D3 on mucosa-associated gut microbiome vary between regions of the human gastrointestinal tract.” Eur J Nutr. 2016 Jun;55(4):1479-89. 
  4. DanmeiS, et al. “Vitamin D Signaling through Induction of Paneth Cell Defensins Maintains Gut Microbiota and Improves Metabolic Disorders and Hepatic Steatosis in Animal Models.” Front Physiol. 2016 Nov 15;7:498. 
  5. GominakSC, et al. “Vitamin D deficiency changes the intestinal microbiome reducing B vitamin production in the gut. The resulting lack of pantothenic acid adversely affects the immune system, producing a ‘pro-inflammatory’ state associated with atherosclerosis and autoimmunity.” Med Hypotheses. 2016 Sep;94:103-7.