The gut is home to trillions of microorganisms that play an important role in overall health. An imbalance in the gut microbiota can lead to many chronic diseases. There are several factors that can disrupt the gut microbiome and create gut dysbiosis. Understanding what affects gut health can help prevent conditions like irritable bowel syndrome, inflammatory bowel disease, obesity, and more.
Diet
Diet is one of the biggest influencers of the gut microbiome. An unhealthy diet high in processed foods, sugar, and unhealthy fats can reduce microbial diversity and feed harmful bacteria. This increases inflammation, reduces immunity, and contributes to leaky gut.
Too Much Sugar and Refined Carbs
Eating a diet high in sugar and refined carbohydrates like white bread, pasta, and pastries can damage gut health in several ways:
– Feeds pathogenic bacteria – Sugar is a preferred food source for harmful bacteria like Clostridium difficile. This allows them to proliferate and take over, suppressing beneficial bacteria.
– Damages gut barrier – Sugar can damage the intestinal lining and cause leaky gut syndrome. This allows toxins, microbes, and undigested food particles to enter the bloodstream triggering inflammation.
– Weakens immunity – Refined carbs and added sugars reduce immunity by lowering white blood cell counts and activity. This makes it harder to fight off infections from invading microbes.
Too Much Saturated Fat and Trans Fats
Diets high in saturated fats like red meat, butter, and full-fat dairy can alter the gut microbiome by:
– Increasing inflammation-causing bacteria like Bilophila wadsworthia.
– Reducing levels of beneficial bifidobacteria species.
This can increase intestinal permeability and the risk of conditions like inflammatory bowel disease.
Trans fats found in fried and processed foods have been shown to decrease microbial diversity and increase mortality in animal studies.
Too Little Fiber
Most Americans only get around 15 grams of fiber per day instead of the recommended 25-30 grams. Fiber feeds beneficial bacteria species like Bifidobacterium and Lactobacillus that produce short-chain fatty acids.
SCFAs reduce inflammation, improve gut barrier function, and protect against obesity. Low fiber diets have been linked with a loss of microbial diversity and increased risk of diseases.
Food Additives
Common food additives like emulsifiers, artificial sweeteners, and nanoparticles are added to improve texture, flavor, and shelf life but may harm gut bacteria.
For example, the artificial sweetener sucralose has been found to reduce beneficial bifidobacteria and lactobacilli. The emulsifier carboxymethylcellulose has been shown to damage the protective mucus layer in the gut.
Micronutrient Deficiencies
Diets low in omega-3 fatty acids, magnesium, zinc and other micronutrients can starve beneficial bacteria. This may allow harmful species to thrive causing inflammation and impaired immunity.
Medications
Many commonly used medications have been shown to alter the gut microbiome. These include:
Antibiotics
Antibiotics are designed to kill pathogenic bacteria but also wipe out beneficial microbes in the process. This can leave the gut vulnerable to dysbiosis and overgrowth of antibiotic-resistant bacteria like Clostridium difficile.
Repeated use of antibiotics disrupts the gut microbiome long-term and has been linked to increased risk of diabetes, obesity, IBD, and colon cancer.
PPIs
Proton pump inhibitors like Prilosec and Nexium reduce stomach acid production. This changes the gut environment allowing bacteria like Enterococcus, Streptococcus and E. coli to overgrow and cause infections.
Long-term PPI use has been associated with small intestine bacterial overgrowth (SIBO), increased risk of IBD and enteric infections.
NSAIDS
Common pain medications like ibuprofen and aspirin can damage the intestinal lining leading to leaky gut. This allows bacteria and toxins to enter the bloodstream triggering widespread inflammation.
NSAIDs may also reduce levels of Faecalibacterium prausnitzii and other beneficial bacteria that produce anti-inflammatory compounds.
Birth Control
Hormonal contraceptives like the pill appear to lower levels of Lactobacillus species. This can increase vaginal and bladder infections in women. The depletion of lactobacilli may also contribute to intestinal permeability and inflammation.
Antidepressants
Antidepressant medications like SSRIs can alter levels of beneficial bacteria like Bifidobacterium and Lactobacillus. This may be linked to increased intestinal permeability and psychiatric symptoms in some cases.
Chronic Stress
Psychological stress negatively affects gut health in several ways:
– Alters gut motility – Stress delays gastric emptying and speeds up colonic transit time impacting nutrient absorption. This can cause diarrhea or constipation.
– Increases inflammation – Stress hormones like cortisol turn on genes that increase inflammatory cytokines, NF-kB, and lipopolysaccharides.
– Damages gut barrier – Stress increases intestinal permeability allowing bacteria and toxins to enter the bloodstream.
– Reduces beneficial bacteria – Stress exposure is associated with lower levels of lactobacilli and bifidobacteria species.
– Encourages pathogen overgrowth – Stress allows more opportunistic and pathogenic bacteria like clostridia, E. coli, and salmonella to colonize.
Managing daily stress through yoga, meditation, exercise, social connection, nature exposure, and good sleep hygiene can help heal the gut microbiome.
Infections
Bacterial, viral, fungal, and parasitic infections can all disrupt the gut microbiota:
SIBO
Small intestinal bacterial overgrowth involves excessive amounts of bacteria growing in the small intestine. This leads to malabsorption, diarrhea, bloating, and weight loss.
SIBO has been associated with increased intestinal permeability, neuroinflammation, and anxiety symptoms in some patients.
Parasitic Infections
Parasites like giardia, cryptosporidium, blastocystis hominis, and entamoeba histolytica directly damage the intestinal lining and provoke an immune response.
This can cause symptoms like diarrhea, bloating, cramping, fatigue, and nutritional deficiencies. Certain parasites may increase risk of IBD by dysregulating the immune system.
Candida Overgrowth
Candida albicans is a yeast normally found in the gut microbiome but it can overgrow after antibiotic treatment. Excess candida causes leaky gut, inhibits nutrient absorption, and triggers widespread inflammation.
Viral Gastroenteritis
Stomach flu caused by norovirus, rotavirus and adenovirus can acutely disturb the gut microbiota. It takes around 4 weeks for microbial diversity to recover after viral gastroenteritis.
Poor Sleep
Not getting enough quality sleep has been shown to reduce microbial diversity and richness in the gut microbiome.
Lack of sleep also increases intestinal permeability, inflammation, insulin resistance, and stress hormones – all of which negatively impact the gut.
Aim for 7-9 hours of quality sleep per night to support a healthy microbiome. Consider melatonin, stress management, and sleep hygiene habits if you have ongoing insomnia.
Environmental Toxins
Many environmental chemicals and heavy metals have been found to harm the gut microbiome:
| Toxin | Effect on Gut Bacteria |
|---|---|
| Arsenic | Reduces microbial diversity, increases Proteobacteria |
| Cadmium | Lowers Firmicutes, increases Bacteroides |
| Lead | Disrupts short-chain fatty acid metabolism |
| Pesticides | Oxidative stress, inflammation, leaky gut |
Minimizing exposure to heavy metals, pesticides, plastics, and other environmental chemicals may help support a healthy microbiome. Eating organic produce when possible is a good start.
Lack of Exercise
Regular exercise helps improve microbial diversity, increase SCFA-producing bacteria, and reduce inflammation in the gut.
Sedentary lifestyles have been linked to lower bacterial richness, impaired gut barrier function, higher endotoxemia, and increased risk of obesity, diabetes, and IBD.
Aim for 150 minutes of moderate activity or 75 minutes of vigorous activity per week. Weight training and HIIT are great options. Yoga and tai chi can help reduce stress hormones.
Smoking
Tobacco smoke alters the gut microbiome in several negative ways:
– Reduces microbial diversity
– Lowers levels of Bifidobacterium
– Increases inflammation-promoting bacteria
– Damages intestinal barrier function
– Increases intestinal permeability
This helps explain the strong links between smoking and inflammatory bowel diseases like Crohn’s disease. Quitting smoking and avoiding secondhand smoke exposure may help restore a healthy gut microbiome.
Excess Alcohol
Drinking too much alcohol frequently can harm the gut in multiple ways:
– Triggers gut inflammation and Damages intestinal lining
– Alters gut motility leading to diarrhea or constipation
– Encourages growth of pathogenic bacteria
– Reduces levels of beneficial Bifidobacterium
– Increases intestinal permeability and endotoxemia
The occasional drink is probably fine but limiting alcohol to 1 drink per day for women and 2 for men helps avoid dysbiosis. Take a few alcohol-free days per week to support gut health.
Aging
As we get older, the gut microbiome tends to become less diverse with lower numbers of beneficial bacteria like Bifidobacterium and higher amounts of pro-inflammatory species.
Aging is also associated with increased intestinal permeability, reduced nutrient absorption, and higher inflammation.
Supporting gut health with prebiotics, probiotics, and a Mediterranean style diet rich in plant fiber becomes increasingly important as we get older. Staying physically active also helps.
Radiation and Chemotherapy
Cancer treatments like radiation and chemotherapy reduce microbial diversity, wipe out beneficial species, and allow potentially pathogenic bacteria to thrive.
Chemotherapy disrupts the mucus layer and damages the intestinal lining causing inflammation and leaky gut. This contributes to side effects like diarrhea, nausea, and weight loss.
Focus on nutrient-dense, whole foods nutrition. Take digestive enzymes with meals. Restore the microbiome with probiotic and prebiotic foods after treatment.
Gastric Bypass Surgery
Dramatic changes to gut anatomy from bariatric surgery alters the microbiome by:
– Reducing bacterial richness and diversity
– Increasing proportions of Lactobacillus and Escherichia
– Lowering concentrations of Roseburia and Faecalibacterium prausnitzii
These changes may contribute to common post-surgery issues like SIBO, malnutrition, and diarrhea. Support gut adaptation by slowly adding fiber back to the diet after surgery.
Thyroid Disorders
Hypothyroidism slows down digestion and transit time leading to bacterial overgrowth and constipation issues.
Hyperthyroidism speeds up transit which can cause abnormal flora, irritable bowel symptoms, and bacterial infections.
Getting thyroid hormone levels balanced with medication, nutrition, and lifestyle changes may help optimize the gut microbiome.
Conclusion
Many aspects of modern life disrupt the balance of microbes in our gut microbiome. This dysbiosis contributes to numerous chronic inflammatory and metabolic diseases.
Focusing on whole foods nutrition, managing stress, exercising, sleeping well, and avoiding environmental chemicals can help support a healthy gut microbiome as we age. Work with a functional medicine practitioner to identify and address factors specific to your health history.