Dr. Vliet’s Health Tip: Has YOUR Gut Bifidobacteria Been Devastated by COVID? Find Out What to Do About It!

Dr. Hazan published research that found that within three years after taking the COVID vaccine bifidobacteria went down to zero. This is much longer than the “temporary” disruption reported earlier in the pandemic. Dr. Hazan recently posted that “killing bifidobacteria with new technology like mRNA shots is not something that can be easily fixed…and this keeps me up at night.”

Dr. Hazan’s findings are profoundly alarming for several reasons:

1. Bifidobacteria play critical roles in many aspects of our total health, including immune function and also the production of critical neurotransmitters like serotonin. The COVID illness and especially the COVID shots, devastate the gut bifidobacteria, which explains why there has been an explosion the last 5 years in diseases that result from loss of Bifidobacteria: Alzheimer’s, Parkinsons, Crohn’s, autoimmune disorders, depression/anxiety, autism and even cancers.
2. More than 70% of Americans have had at least one COVID shot, and very few physicians are teaching their patients about the shot damage to the gut bacteria, or what to do about it.
3. People who did not get the COVID shots are still at risk of bifidobacteria destruction if they had the COVID illness, which means an estimated 40-50% of Americans who had the illness are at risk from the consequences of losing bifidobacteria. Again, few doctors are telling patients about this connection or what to do about it.

These are the three big reasons we prepared this Health Tip and guide
to action steps you can take on your own now to restore your gut health!

Loss of gut bifidobacteria was first discovered by Dr. Sabine Hazan in patients receiving the COVID vaccine.  In doing laboratory analysis of stool (fecal) specimens, she found that patients’ microbiome had changed pre and post vaccination.  Oddly, it was only a certain group of microorganisms, the bifidobacteria species, that were destroyed by the COVID shots.  Dr. Hazan presented four patients’ data in a poster presentation to the American College of Gastroenterology that showed 90 days after the vaccine their Bifidobacteria dropped from nearly a million to near zero.

Dr. Hazan also found an even more alarming change in the microbiome of babies born to COVID-vaccinated mothers.  These babies had no bifidobacteria,  when it is normal for newborns to have Bifidobacteria make up 90% of the microbiome. The vaccine that was marketed to the public as supposed to be improving your immunity was actually killing the very Bifidobacteria in the gut that your immune system needs to function properly!  And the destruction is not just temporary.  The even more devastating finding is that the destruction of bifidobacteria appears long-lasting, and very difficult to restore.
Dr. Hazan’s research makes it easier to connect the dots between covid vaccine injury and post covid illness syndromes, including gut dysbiosis, now that we know the ramifications of losing bifidobacteria.  I am glad more physicians are finally speaking out, but they are still too few and patients are suffering when they don’t know the cause and are not told what could help!
We describe both what happens when you lose bifidobacteria and steps you need to take now to help restore a healthy microbiome, and replenish lost bifidobacteria!

The Gut-Organ Axis Systems:
The body has several gut-organ axis systems that connect the intestinal microbiome with distant organs and systems via neural, immune, endocrine, and metabolic pathways. These multi-directional communication networks help regulate systemic homeostasis throughout the body that can either

1. protect one’s health in eubiosis (a healthy, balanced gut microbiome characterized by high microbial diversity, a predominance of beneficial microorganisms, and stable, symbiotic interactions with the host), OR
2. destroy one’s health as with dysbiosis (disruption of the healthy gut microorganism balance).  When dysbiosis occurs, it compromises these regulatory networks and leads to systemic health problems across many organ systems.

Gut-immune axis: The Gastro-Intestinal (GI) tract (“gut” or intestines) houses the largest number of immune cells in the body, and microbial exposure trains immune tolerance. This axis maintains systemic immune homeostasis, with disruptions contributing to autoimmune and inflammatory disorders. Dysbiosis leads to chronic immune activation, systemic inflammation, and loss of immune tolerance.  All of these disruptions in turn lead to a marked rise in autoimmune diseases such as the acute COVID-19 induced cytokine storm, and chronic inflammatory autoimmune disorders such as IBS bowel disease, autoimmune thyroiditis, autoimmune pancreatitis , autoimmune testicular and ovarian dysfunction, rheumatoid arthritis, Lupus, MS and others.

Gut-brain axis:  This is the best-characterized gut-organ axis.  It involves bidirectional communication between the gut and brain (central nervous system, or CNS) through the vagus nerve, immune signaling, and hormones, such as cortisol, thyroid, estradiol, testosterone, and insulin. Gut microbes produce neuroactive molecules (e.g., serotonin, GABA, dopamine precursors) which influence mood, cognition, and stress response. Conversely, psychological stress damages the microbiome balance by affecting intestinal barrier permeability and composition of microbes. Dysbiosis is linked with

• Anxiety, depression, cognitive dysfunction, fatigue, and even psychosis seen in post-acute COVID syndrome (long COVID) due to systemic inflammation and disrupted SCFA production affecting neuroimmune regulation.
• Longer-term damage leading to neurodegenerative disorders: Parkinson’s, ALS, MS, dementia (many types, including Jacob-Creutzfeld and Alzheimer’s)

Gut-skin axis:  Communication between the gut and skin occurs through immune,  metabolic, and endocrine pathways. Microbial balance influences systemic inflammation and skin barrier health, while vitamin D metabolism and immune signals travel both directions between the gut and skin. Microbial imbalance increases systemic inflammation contributing to skin conditions like psoriasis, eczema, rosacea, acne, and atopic dermatitis worsened by COVID-19-induced immune dysregulation and the inflammation created by the COVID shots.

Gut-liver axis:  The portal vein connects the small intestine and liver directly. Microbial metabolites (such as short-chain fatty acids and bacterial endotoxins) reach the liver, influencing bile acid recycling, glucose metabolism, and inflammation. Hepatic diseases like fatty liver or cirrhosis often accompany gut microbiome imbalances.  Dysbiosis promotes liver inflammation and fibrosis, is linked to non-alcoholic fatty liver disease (NAFLD), liver cirrhosis, and was a major factor that aggravated liver injury in COVID-19.

Gut-pancreas axis:  The gut microorganisms regulate endocrine functions through metabolites like indole and short-chain fatty acids, which stimulate GLP-1 secretion and insulin release. This axis is central to blood glucose regulation and metabolic balance.​ Disturbances in balance and outright loss of critical microorganisms like bifidobacteria lead to impaired insulin and glucose regulation that contributes to type 2 diabetes mellitus, pre-diabetes (insulin resistance), and lead to bowel inflammation and worsening metabolic control after COVID-19 illness and after the COVID injections.

Gut-kidney axis:  Gut-derived metabolic breakdown products and toxins in urine, including indoxyl sulfate and p-cresyl sulfate, accumulate when kidney function declines, leading to worsening kidney inflammation. On the other hand, altered renal filtration affects gut microbial composition and metabolite circulation.   Microbial toxin accumulation from micro-organism imbalance contributes to systemic inflammation and progression of chronic kidney disease progression, which is commonly worsened in COVID-19 illness and COVID-vax injured patients who may have had only mild kidney impairment prior to the illness or injection.

Loss of Bifidobacterium and Colon Cancer
The loss of Bifidobacterium species increases cancer risk primarily by disrupting gut microbiome homeostasis, which impairs mucosal immunity, weakens the gut barrier, and promotes inflammation—all of which contribute to tumor formation, especially in colorectal cancer (CRC). This is one of a number of possible causes of the markedly increased rate of colon cancer, especially among younger adults not normally at risk for colon cancer, in those who got the COVID injections.

Bifidobacteria produce beneficial metabolites such as short-chain fatty acids (SCFAs) like butyrate that have anti-inflammatory and anti-proliferative effects on colonocytes, which helps maintain the integrity of the intestinal lining and prevent cancerous changes. Studies found significantly lower levels of bifidobacteria in colorectal cancer patients compared to healthy individuals, and experimental models show that these bifidobacteria can inhibit colorectal cancer cell growth by inducing cancer cell death and growth arrest. Basically, the loss of bifidobacteria removes this protective effect, increasing colorectal cancer risk.

The molecular basis for linking the loss of Bifidobacterium to tumor initiation primarily involve disruption of immune regulation, increased chronic inflammation, impaired DNA damage response, and altered oncogenic signaling pathways.  I include this additional background for those interested in more detail on each of these steps.

1. Immune Activation and Immune Evasion:
   • Bifidobacterium species promote antitumor immunity by activating dendritic cells (DCs) and enhancing local immune responses via the STING (stimulator of interferon genes) signaling pathway and interferon signaling. Loss of Bifidobacterium reduces this immune activation, impairing tumor immune surveillance, which facilitates tumor initiation and progression.
   • Bifidobacterium bifidum has been shown to augment immunotherapy by enhancing STING activation and dendritic cell-mediated antitumor immunity. Without this bacterial stimulation, tumors are more likely to escape immune suppression.
2. Chronic Inflammation:
   • The absence of Bifidobacterium can contribute to a pro-inflammatory gut environment.
   • Chronic inflammation leads to production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), which causes oxidative damage to DNA and mutations in epithelial cells, two early events in formation of tumors.
3. DNA Damage and Suppressed DNA Damage Response:
   • Bifidobacterium-produced metabolites (like SCFAs) help maintain integrity of the mucosal barrier and regulate oxidative stress.  Without these critical metabolites, epithelial cells are more susceptible to DNA damage and mutations that lead to cancer.
   • Carcinogenic bacteria can produce toxins or induce ROS that create DNA double-strand breaks and damaging modifications. Bifidobacterium itself isn’t a genotoxin producer, but when bifidobacteria is lost in the gut, overgrowth of harmful bacteria is enabled.  This in turn causes DNA damage, accelerating tumor formation.
4. Oncogenic Signaling Pathway Dysregulation:
   • Bifidobacteria support normal regulation of signaling pathways such as Wnt/β-catenin and PI3K/AKT involved in cell growth and apoptosis.
   • Loss of Bifidobacterium leads to dysregulated signaling, which favors abnormal activation of these pathways that promotes cell proliferation and inhibits apoptosis. All of these are processes essential for tumors to form.
5. Epigenetic Modulation and Metabolite Effects:
   • Bifidobacterium produces beneficial metabolites (e.g., butyrate), which regulate gene expression epigenetically by inhibiting histone deacetylases and promoting tumor suppressor gene expression.
   • Absence of bifidobacteria removes this epigenetic tumor-suppressive modulation, increasing cancer risk.

In summary, loss of Bifidobacterium fosters a tumor-promoting microenvironment by weakening immune defense, increasing inflammation-induced DNA damage, disrupting DNA repair, and dysregulating critical oncogenic signaling.  All of these mechanisms facilitate colorectal tumor formation, growth and spread.

Bifidobacterium species most strongly protective against tumor formation:

• Bifidobacterium longum: This bifidobacteria species has been extensively studied and shows strong anti-cancer properties. It reduces tumor size, reduces precancerous lesions, and reduces inflammation in colorectal cancer models. It exerts these effects through immune modulation, downregulation of oncogenic pathways (PI3K-Akt, MAPK), and promoting beneficial microorganisms like Lachnospiraceae while suppressing cancer-promoting bacteria such as Alistipes.
• Bifidobacterium breve:  This species enhances antitumor immunity by activating T cell effectors, improving responses to immunotherapies, and reducing tumor growth in melanoma models, implying a broader anticancer role beyond colorectal cancer.
• Bifidobacterium adolescentis: This species stimulates production of anti-inflammatory cytokines, promotes regulatory T cells (Foxp3+), enhances innate immune responses against tumors, and shows potential for use in targeted anticancer gene therapy.
• Bifidobacterium bifidum: This species has a role in promoting immune-modulatory molecules like BopA and TagA that enhance dendritic cell stimulation and local anti-inflammatory cytokine production, which contributes suppression of colon inflammation (colitis) and likely colorectal tumor formation.
• Bifidobacterium animalis, subspecies lactis has demonstrated adjunctive antitumor effects when combined with other therapies.

Together, all of these Bifidobacteria species contribute to tumor suppression through immune activation, inflammation reduction, epithelial barrier reinforcement, and modulation of microbial ecosystems and tumor-associated signaling pathways.

Factors Affecting Balance of Organisms in the Gut Microbiome:
Many factors affect the balance of gut microorganisms to disrupt the balance between beneficial and harmful microorganisms. The obvious culprits of course are use of antibiotics, particularly with overuse, as we often see in medicine today.

Medications and antibiotics:

• Antibiotic use drastically reduces beneficial bacterial populations, allowing harmful bacteria to overgrow and disrupt microbial balance, causing many adverse effects. That is the reason it is so crucial to take pro-biotics, such as the more potent TruProbiotic™ Complex  formula after have taken a course of antibiotics.
• Other drugs that cause negative effects on the gut micro-organism balance include proton pump inhibitors (“anti-acid” medicines), NSAIDs, Metformin, laxatives, selective serotonin reuptake inhibitors (SSRIs) and other antidepressants, opioids, beta-blockers, anti-psychotics (e.g., quetiapine), benzodiazepines, and progesterone/progestin medications (used for contraception and for menopause therapy) have all been associated with measurable changes in gut microbial diversity and composition, some with lasting effects even after stopping the medications.

Infections and inflammation:

• Acute or chronic infections, including viral infections like COVID-19, cause immune activation and altered gut mucosa permeability that leads to micro-organism imbalance and overgrowth of unhealthy bacteria.
• Chronic inflammation damages mucosal barriers, favoring growth of detrimental microorganisms and loss of beneficial ones.
• COVID-19 Vaccine and COVID-19 Illness Multiple studies indicate that COVID-19 vaccines “temporarily” alter the gut microbiome and claim they do not cause permanent damage and claim that the significant changes to gut bacteria are typically associated with an actual SARS-CoV-2 infection vs the COVID shots. This is NOT what I see in patients of mine who have had the COVID illness and not the COVID shot, or those who have gotten the COVID shots and then had COVID illness. In fact, I see the opposite situation in my patients: people who have gotten the COVID shots, especially if also receiving boosters, typically have worse “irritable bowel” symptoms of inflammation, diarrhea, bowel dysmotility, intestinal obstruction, and new onset of colon cancers.
• Researchers, in particular gastroenterologist Dr. Sabine Hazan, hypothesize that low bacterial diversity and depletion of Bifidobacterium species lead to all the mechanisms of damage I described above that increase the risk of many different medical conditions, including cancers.
• After COVID shots, many changes in the gut microbiome have been confirmed by stool analysis: chronic inflammation damage, presence of blood and microclots, reduced diversity of microorganisms, loss of specific bacteria, especially major destruction of Bifidobacterium following vaccination

Dietary factors

• Diets low in fiber and high in simple sugars, processed foods, proteins, and food additives (such as emulsifiers and artificial sweeteners) disrupt microbial diversity and promote inflammation in the gut.
• Accidental chemical ingestion (e.g., pesticides on unwashed produce) can also negatively impact gut flora.​

Lifestyle and environmental factors

• High stress and anxiety levels have been linked to microbiome disruption through neuroimmune pathways.​
• Excessive alcohol consumption and smoking also cause microbial imbalance.​
• Exposure to environmental toxins can impair microbiome homeostasis.​

Host factors

• Genetic background, age, immune status, and pre-existing diseases influence susceptibility to dysbiosis. Age-related physiological changes such as reduced gut motility, altered mucus barrier, and compromised epithelial regeneration create a mucosal environment that favors dysbiosis.
• Birth mode (cesarean vs vaginal), infant feeding methods, and aging affect microbiome composition early on and throughout life.

How To Improve Gut Microbiome and Restore Healthy Balance of Microorganisms:
The critical first step in restoring the lost Bifidobacteria is to take the appropriate supplements to boost replenishment of Bifidobacteria in the gut.  It is difficult, if not almost impossible today, to accomplish this with just dietary approaches. 

1. Take Prebiotic and Probiotic supplements: We specifically selected premium quality probiotics for The Truth For Health store that all carry the Bifidobacteria in ample quantities: TruProbiotic™ Complex, a two week course of the formula designed for therapeutic potency to rebuild a damaged gut microbiome after an illness treated with antibiotics or vaccine or long covid symptoms; TruProbiotic™ Daily to maintain a robust, healthy balance in the gut microbiome; TruProbiotic™ Lean, which contains Bifidobacterium animalis B420 that has specific effects to improve metabolism and facilitate weight management, and also boosts immune function.

Let’s look at each of these in more detail:

• TruProBiotic™ Complex contains 18 different strains, including 7 bifidobacteria, which feature a diverse blend of HOWARU® and FloraFIT ® probiotic strains to support a healthy gut microbiome. Each strain is well researched and identity-verified and has been genetically characterized and properly classified for your safety and assurance. These strains were not only selected for their health benefits and complementary actions but also for their viability and stability.  This is designed as a two week course to use after you have to take antibiotics, or have been ill, or have had surgery, and then move to one of the daily maintenance products.
• TruProbiotic™ Daily ideal for individuals seeking a well-rounded supplement to support a healthy balance of intestinal flora, cellular health, and immune health. It features four probiotic strains, including the extensively studied HN019 strain of Bifidobacterium lactis and bifidobacterium longum BI-05, and Saccharomyces boulardii (Sb), a non-pathogenic yeast, to further complement healthy gastrointestinal ecology. Gastro-resistant, vegetarian capsules provide an innovative solution for targeted delivery of sensitive ingredients to the small intestine, as they alleviate exposure to the low pH environment of the stomach.
• TruProbiotic™ Lean features vegetarian, gluten and dairy-free Bifidobacterium animalis subsp lactis B420 well-known for improving gut barrier function, modulating gut microbiome favorably by increasing beneficial microbes such as Akkermansia. In addition, B420 has strong immune regulation function, reduces inflammation markers, and positively influences glucose metabolism.  Bifidobacterium animalis subsp lactis B420 has been shown to assist with healthy body composition, supporting the reduction of body fat mass and promoting less calorie consumption.

Most commercially available probiotics do not have the stability, combination of microorganisms you need, or the reliability in manufacturing that make them as effective as the marketing claims.  Many are just a waste of money.  Remember, it is indeed challenging to produce reliable and stable probiotic supplements that keep the stability of the beneficial bacteria organisms during distribution and sitting on store shelves. It is also challenging to create probiotics supplements that ensure the survival of the good bacteria after they are swallowed and travel through the acids of the stomach to the lower digestive tract to reach the targeted tissue.

Our products have formulas based on careful selection of organisms for the purposes needed and to ensure stability and survivability in the digestive tract to reach the intestines. To improve stability and reliability of the product you buy, all packages of Truth for Health Foundation probiotics in capsule form come in sealed, nitrogen-purged blister packs to serve as protection from heat, moisture, oxygen and other factors proven to compromise the stability of probiotics.

To further support resistance to low pH and the delivery of microorganisms to the small intestines, TruProbiotic™ Daily, and TruProbiotic™ Lean encapsulates the ingredients in gastro-resistant DRcaps™. These uniquely designed, innovative capsule formulations help slow exposure of active organisms to stomach acid, which in turn promotes a more targeted release.

1. The next crucial step, in addition to the proper high quality probiotics, is to restore optimal vitamin C and vitamin D intake.  Both play important roles in maintaining a healthy gut microbiome, though they do so through somewhat different biochemical and immunological mechanisms.
2. Vitamin C Recent studies (2025) show that vitamin C supplementation increases beneficial bacteria, especially Bifidobacterium and members of the Lachnospiraceae family in both healthy and metabolically challenged individuals. These genera are known producers of short-chain fatty acids (SCFAs) like butyrate, which support intestinal barrier integrity and reduce inflammation. Increased Bifidobacteria levels are linked to improved infection resistance and lower systemic inflammatory tone. Vitamin C also acts as a strong antioxidant and immune modulator, reducing oxidative stress in the gut microenvironment. By decreasing reactive oxygen species, it promotes a more favorable milieu for anaerobic commensal bacteria and helps restore microbial balance after dysbiosis (“Refloralization”). Some data also suggest these shifts may influence neurological and cognitive outcomes via the gut–brain axis.
3. Vitamin D influences the gut microbiome both directly through vitamin D receptor (VDR) signaling in intestinal epithelial and immune cells and indirectly through immune and barrier regulation. Moderate vitamin D₃ supplementation has been shown to modify gut microbial composition, increasing diversity and stabilizing community structure over time.  Mechanistically, vitamin D binding to VDR upregulates tight junction proteins, thereby reducing intestinal permeability and protecting against endotoxin leakage and inflammation. It also helps maintain eubiosis by suppressing harmful, pro-inflammatory bacterial species and supporting anti-inflammatory populations. This contributes to enhanced mucosal tolerance and systemic immune balance, which can reduce risk for autoimmune conditions and chronic inflammation.

Together, optimal vitamin C and D levels support gut eubiosis, intestinal barrier strength, and immune regulation, forming a synergistic foundation for metabolic and systemic resilience. I recommend TruC + BioFlav™ which combines high-potency vitamin C with a standardized, full-spectrum, citrus bioflavonoid complex and TruBioD3™ which contains vitamin D3 (cholecalciferol) in convenient soft gels. Vitamin D3 is the bioidentical form of vitamin D synthesized in the body from cholesterol, following activation by the UV rays in sunlight. Both TruC + BioFlav™ and TruBioD3™ are available at the Truth For Health store

1. Dietary approaches

• Eat a high-fiber diet: Fiber serves as prebiotic food for beneficial gut bacteria, increasing microbial diversity. Plant-based foods like vegetables, legumes, whole grains, nuts, and seeds are rich sources of fiber.
• Consume diverse plant foods: Eating a wide variety of fruits, vegetables, nuts, legumes, and whole grains (aiming for 30 different plant foods weekly) supports a broad microbial ecosystem.
• Include fermented foods: Yogurt and kefir (especially from raw milk) as many commercial products do not contain bifidobacteria, kimchi, sauerkraut, tempeh, and kombucha provide live beneficial bacteria (probiotics) that can enhance gut microbial balance.​
• Limit processed and sugary foods: High intake of sugar and ultra-processed foods can promote dysbiosis by feeding harmful bacteria and increasing gut inflammation.

1. Lifestyle factors

   Stay well hydrated: Adequate water intake aids digestion and supports regular bowel movements, maintaining gut microbial abundance.​

• Eat slowly and chew thoroughly: This improves digestion and reduces discomfort such as bloating, aiding a healthy gut environment.​
• Engage in regular physical activity: Exercise has been shown to promote microbial diversity and gut health.
• Manage stress: Chronic stress can negatively impact gut microbiota, so stress reduction techniques may benefit gut balance.
• Limit unnecessary medication use: Avoiding overuse of antibiotics and other medications that disrupt the microbiome supports recovery and stability.

CAUTION: As always, we urge you to avoid supplements without checking knowledgeable sources to evaluate your medical situation, proper lab tests to verify what is needed, and to make sure to avoid adverse interactions with prescription medicines and other supplements you take.
All Truth for Health Foundation Products Meet or Exceed cGMP Quality Standards, the highest quality standard for supplements sold in the USA.

For more information, references from studies are listed in the Product Data Sheets for each product, available on our website.  Under medical practice regulations, we are unable to answer individual medical questions or make specific individual supplement recommendations for people who are not established patients of Dr. Vliet’s independent medical practice.

I encourage you to consider our other natural medicines with our top quality, cGMP-compliant professional formulas for TruImmune™Boost, TruNAC™, TruImmunoglobulin,™ TruC with BioFlav™ (Vitamin C with complete Bioflavonoids), Tru BioD3™, TruZinc™, TruMitochondrial ™Boost and TruProBiotic™ Daily to replenish critical bifidobacteria depleted by COVID shots, viral illnesses, and antibiotic therapy.

To Your good health and improving resilience!
Elizabeth Lee Vliet, MD

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