Stress Is Your Gut Microbiome’s Worst Enemy

Stress is an unavoidable part of modern life, often striking at the worst moments: whether it’s a last-minute work task, unexpected news, or a chaotic commute. It’s tempting to dismiss stress as just part of modern life, but learning to manage it is more important than you might think. Here’s how stress can negatively impact your gut – and how you can mitigate its effects!

How Stress Impacts Gut Health

Stress influences gut health in profound ways. When your body enters fight-or-flight mode, the sympathetic nervous system (SNS) redirects blood flow away from the gastrointestinal tract to vital organs like the heart and lungs¹. This can lead to:

• Digestive Discomfort: Stress inhibits gut muscle function, causing indigestion and stomach discomfort.
• Increased Cortisol Production: Elevated cortisol levels increase stomach acidity, reduce intestinal mucus production, and heighten the risk of inflammation.
• Gut Microbiome Imbalance: Chronic stress can disrupt the balance of beneficial bacteria in your gut, leading to microbial imbalances that contribute to gastrointestinal disorders.

Stress Eating and Its Consequences

Stress often triggers cravings for high-sugar, salty, and fatty foods. These dietary changes can:

• Increase Proteobacteria levels in the gut, which are linked to inflammatory bowel disease (IBD) and metabolic disorders.
• Reduce Bacteroidetes populations, weakening gut barrier functions and promoting inflammation².

This shift in microbial balance can exacerbate gastrointestinal issues and contribute to chronic inflammation.

The Link Between Stress and IBS

Stress-induced changes in the gut-brain axis are closely associated with Irritable Bowel Syndrome (IBS). Studies show that:

• Psychological distress is common among IBS patients, with 40–60% experiencing psychiatric disorders such as anxiety or depression³.
• Research reveals that IBS patients have altered microbiota functions, including reduced antimicrobial peptide resistance and increased bile acid transformation⁴.

These disruptions highlight how stress can trigger or worsen IBS symptoms.

Gut Health, Anxiety, and Depression

The gut microbiome plays a critical role in mental health. Stress-related inflammation in the gastrointestinal tract releases cytokines that influence brain function through the gut-brain axis. Key findings include:

• Elevated levels of inflammatory markers like TNF-a and IL-6 are linked to anxiety and depression symptoms⁵.
• Gut dysbiosis (microbial imbalance) contributes to chronic inflammation, which has been observed in individuals with depressive disorders⁶.

Improving gut health may help alleviate anxiety and depression by reducing inflammation.

Does Stress Cause Bloating?

Yes, stress can lead to bloating through several mechanisms:

1. Increased Gut Sensitivity: Stress can make your gut more sensitive, causing you to feel bloated even if you haven’t eaten a large meal. This is partly due to the connection between your brain and gut, often referred to as the gut-brain axis. Stress can heighten gut sensitivity, leading to discomfort.
2. Slower Digestion: Stress is considered an “acute threat to homeostasis.” Thus, your digestive system may slow down under stress. This is because the body prioritizes immediate survival, redirecting blood flow away from the digestive organs to more essential areas like the muscles and heart. This can result in slower gastric emptying, leading to a build-up of gas, food, and waste in the stomach and intestines, which contributes to bloating.
3. Gut Microbiome Imbalance: Stress can disrupt the balance of beneficial bacteria in your gut, causing an overgrowth of harmful bacteria or yeast. This imbalance can lead to fermentation of food in the intestines, producing excess gas and causing bloating.
4. Changes in Breathing Patterns: Stress often leads to shallow or rapid breathing, which can result in swallowing air (known as aerophagia). This extra air can get trapped in your digestive system, leading to bloating and discomfort.
5. Increased Cortisol: Stress triggers the release of cortisol, the body’s primary stress hormone. High cortisol can affect the balance of fluids in the body and alter gut motility, both of which can lead to bloating.
6. Digestive Disorders: Chronic stress can exacerbate existing digestive conditions such as irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), or inflammatory bowel disease (IBD), all of which commonly cause bloating as a symptom.

Probiotics for Stress Relief 

Certain probiotics can rebalance the microbiota while alleviating stress-related symptoms:

1. Lactobacillus (L.) Plantarum

Found in fermented foods like kimchi and sauerkraut, this strain reduces pro-inflammatory cytokines and improves memory while lowering stress.

A randomised controlled trial⁷ (RCT) assessed the effects of the probiotic strain Lactobacillus (L.) plantarum in alleviation of stress and anxiety among adults. Half of the participants consumed L. plantarum while the rest were given a placebo for 12-weeks. The study found that the L. plantarum group had a significant reduction in pro-inflammatory cytokines levels, enhanced memory and cognitive traits (such as social emotional cognition) and most importantly reduced stress and anxiety symptoms. This probiotic strain is commonly found in many fermented foods such as brined olives, sauerkraut, sourdough and Korean kimchi. It is also very easy to find in a probiotic supplement.

2. Bifidobacterium Adolescentis

This strain enhances brain-derived neurotrophic factor (BDNF) expression in the hippocampus, reducing anxiety and depression symptoms¹.

Studies⁸ have found that the probiotic strain Bifidobacterium adolescentis exerted anxiolytic and antidepressant effect by rebalancing the gut microbiota and lowering inflammatory cytokines. This probiotic strain also elevates brain derived neurotrophic factor (BDNF) expression in the hippocampus. This is crucial as an impaired BDNF system often increases the likelihood of developing anxiety disorders.

Consider incorporating these probiotics through supplements or fermented foods for better gut health. 

Dietary Tips for Gut Health

These are some simple diet and lifestyle tips to help maintain your gut microbial balance and prevent or reduce symptoms of anxiety and depression:

1. Ensure that your diet has sufficient dietary fiber: Dietary fiber is fermented in our colon to produce short-chain fatty acids (SCFAs), which is the main energy source of gut microbes. Eating enough dietary fiber helps increase microbial diversity and maintain a healthy microbial balance. It is usually recommended to consume around 25-30g per day, which can be easily done by incorporating a fiber-rich food in each meal.
2. Cut back on processed foods high in sugar: Foods high in sugar can worsen anxiety symptoms by promoting the growth of harmful bacteria in the gut. The next time you are feeling stressed, try to reach for some natural sugars instead such as apples, bananas or coconut yogurt.
3. Manage stress levels by engaging in exercise and meditation: Low-intensity exercises such as walking increase levels of the feel-good hormone serotonin. Meditation can also help to calm the mind and help to increase serotonin and decrease cortisol levels, which is responsible for feelings of stress and some of that gut inflammation!

Take Home Message

It is important to nurture both our microbiome and mental health, since they are continuously influencing each other in a continual cycle. Improving gut health and managing stress can be achieved by following some of the gut-healthy diet and lifestyle tips we’ve shared. Feeling overwhelmed could be your gut telling you to take another look at your diet and activity levels.