Gut health is such a big topic at the moment, and we often focus on the things that positively impact your gut, but here we’re exploring what can negatively impact it. Your gut is the 9-metre-long digestive tract from your mouth to your colon, which is the home to trillions of beneficial bacteria, commonly known as your gut microbiota. These bacteria are impacted by daily habits, either negatively or positively, which can have a knock-on effect on our overall health. 

Sleep

There is a mutual relationship between sleep and gut health, as poor sleep impacts gut health as much as poor gut health impacts sleep. A lack of sleep causes release of the stress hormone, cortisol, which can lead to gastrointestinal permeability issues; this means toxins can then enter the bloodstream from the intestine, resulting in bloating and inflammation. 

A lack of sleep can also affect dietary food choices, as the hormones ghrelin (the hunger hormone) and leptin (the satiety hormone) which regulate hunger signals, can be thrown off balance. People often reach for highly processed, sugary foods for a quick energy boost, which can negatively impact gut health due to the sugar content as sugar can feed the pathogenic bacteria (bad bacteria). 

Melatonin is the sleep hormone, but also plays a role is gastrointestinal mobility. When melatonin levels are off balance, gut mobility is impaired which can lead to gastroesophageal reflux disease, otherwise known as acid reflux. Also, staying up late can mean eating too close to bedtime, leaving the body to digest and absorb food whilst you’re sleeping, which it should be resting and recuperating. This may lead to a restless night of sleep, further impacting in your gut microbiota. 

Artificial sweeteners

Diet products or sugar-free items often contain artificial sweeteners, which are synthetic sugar substitutes that have been shown to impact the gut microbiota. A study showed that 6 artificial sweeteners and 10 sport supplements approved by the FDA were toxic to the gut of mice (1). However, this study was performed on rodents, not humans, but the evidence is still emerging. 

Artificial sweeteners are often consumed unknowingly, as they are in many products such as toothpaste, chewing gum and sweets. Artificial sweeteners can induce glucose intolerance and insulin resistance in some cases, which is a problem from type 2 diabetics, as they can’t control their insulin levels. They can cause host of other problems due to an imbalance of the good bacteria, leading to dysbiosis which can contribute to IBS or IBD (2).

Artificial sweeteners are also much sweeter than sugar, so people often use more of it than they would of the sugar equivalent. This can change your taste receptors, leading to you wanting sweeter foods, and in turn adding more sugar to your diet. 

High sugar diet 

A high sugar diet is a diet which is consistently above the recommendations for sugar intake, 30g a day. Things that contribute to the recommendation include sugar, honey, maple syrup and high-fructose corn syrup. This can increase inflammation in the body as well as metabolic and cardiovascular diseases.

Pro-inflammatory properties can be increased with a high refined sugar consumption, which may increase gut permeability. Diets high in sugar can be lacking in fresh fruit, vegetables and wholegrains which are required to support gut diversity. A high sugar diet may also be associated with a low fibre intake, high fat and salt intake which can further negatively impact the gut microbiota (3).  

Stress

It is common to feel nerves in your stomach in the form of ‘butterflies’ due to the connection between the gut and the brain. This is the gut-brain axis which can cause digestive issues, such as flatulence, bloating or even IBS. 

The stress hormone cortisol can negatively impact the gut microbiota too. From an evolutionary perspective, when our body sees a stress and thinks we need to run away, digestion will be halted, and blood will flow to the heart and muscles to allow us to fight off the stress. A chronic stress response a daily basis can lead to long-term digestive problems.

Over exercising and HIIT 

Going to the gym too often or doing excessive HIIT, such as running, may be causing more harm than you think. The body perceives this as stress, causing blood to flow to muscles, not the gut, due to cortisol and adrenaline release. After your workout, your digestive system will still be impaired, leading to gut symptoms.

Sufficient exercise is considered 30-60 minutes, 4-6 days a week. Taking a day off exercise to allow your body to rest is crucial and its importance is often overlooked. Low-intensity exercise such as weightlifting or going for a brisk walk are gut-friendly ideas of exercise you can do to still get some endorphins. 

Mouthwash

The digestive tract starts with your mouth, so optimising oral health can affect gut health. There are lots of bacteria living in our mouth, collectively known as the oral microbiome. 

Many mouthwashes are antibacterial, so they kill both good and bad bacteria in the mouth. The oral microbiota has been linked to systemic diseases such as diabetes and cardiovascular disease through the disruption of nitric oxide (4). 

Take home messages

1. Avoid eating 2-3 hours before bedtime as this causes a burden on your gut, instead of allowing it to recuperate. 
2. Long-term use of artificial sweeteners can impact your gut microbiota and may increase sugar cravings. 
3. A high-sugar diet may increase pathogenic bacteria in the gut. 
4. Stress causes impaired digestion due to the gut-brain axis. 
5. Lots of exercise can lead to poor blood flow to the gut, resulting in digestive discomfort. 

The oral microbiome can impact the gut microbiome, so optimising this can help with gut health. 

Although people lead very busy lives, prioritising sleep can help with many factors of health. Stress can be limited by incorporating things like mindfulness, yoga and meditation, as chronic high levels of stress can impact your gut. Ensuring you have a varied diet with lots of prebiotic and probiotic foods as well as lots of fibre will increase your gut microbiota diversity. Try limit your sugar or artificial sweetener intake by snacking on fruit and swapping fizzy sugary drinks with water and berries.