Common Reasons Your Gut is Fermenting (And How To Soothe It)



While fermentation is the magical process that transforms a few raw ingredients into limitless varieties of beer and wine, there is another way that fermentation can be less welcome in our lives – gut fermentation!


What is gut fermentation?


Trillions of bacteria living in your intestines love to get first dibs on your food.  They especially love carbohydrates, feeding on the fibre and when they do, they produce gas as a waste product.  In small amounts, this is a perfectly normal process and mostly goes unnoticed.  But when fermentation starts happening to excess, you really know about it!


Why does gut fermentation become a problem?


The friendly bacteria in your gut play a part in digesting your food, absorbing nutrients and protecting your gut from more harmful microbes.  Normally there are fewer friendly bacteria in your small intestine, but in both the large and small intestines, these bacteria can overgrow.


Imbalances in the types of bacteria, either too much or too little, can create an unfavourable gut environment, and what is living down there may start to produce too much gas.  This gas often gets stuck for a while, causing trapped wind.


Trapped wind in your intestines activates nerves which sense the increased pressure as discomfort.  More gas can lead to increased swelling, which can feel quite painful.  If you’ve ever felt that your tummy is swollen but firm, that is called distension.


This sudden pain and in some cases distension, can be concerning, embarrassing, and cause anxiety as your mind may start to imagine more serious causes of your pain.


And speaking of embarrassing, the gas must go somewhere.  So, this invariably leads to flatulence, burping, or even halitosis.  Not fun!


For some people, a heightened nerve sensitivity in the gut can also lead to more discomfort and more pain than seems proportionate to what you’ve eaten.  Let’s explore why that might be happening:


Common causes of fermentation in the gut:


  • The gut environment – antibiotics and certain medications such as acid blockers or proton pump inhibitors (most commonly omeprazole) can dramatically affect your microbiome, leading to dysbiosis.Dysbiosis is an imbalanced gut microbiome where bacteria that tend to keep the peace are overwhelmed by other types of bacteria that like to gate-crash and cause havoc.  Lifestyle factors such as stress, ageing and lack of sleep can also disrupt the balance.


  • High FODMAP foods – many carbohydrate-based foods contain fermentable sugars known as FODMAPs for short (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) and bacteria love them.
    There is a long list of foods under this category, but typical trigger foods include garlic, onions, beans, chickpeas, wheat, lentils and milk.The more you eat of these foods across the course of a day, the more gas, bloating and other symptoms may start to creep in.Sadly, many women I work with have eliminated these foods due to their symptoms but are then missing out on the valuable nutrients they provide.


  • Sugar – the easier it is for the sugar to be released from foods, the more likelihood there is for fermentation to occur. So, the more processed carbohydrates are (think white pasta, white bread, white rice, added sugar), the more likely to cause unwelcome symptoms!


  • Emulsifiers – I call these washing up liquid in the gut. These additives are added to many manufactured food products such as drinks, dressings, meats and plant-based milks to mix water-based and oil-based ingredients together.


Oil is often added to allow dairy alternative milks to be frothed up to create a ‘barista’ version. I am not a fan of sunflower or rapeseed oil where they simply don’t need to be.


Some studies have linked health risks (particularly regarding Inflammatory Bowel Disease) with the regular use of emulsifiers, such as carboxymethylcellulose, polysorbate 80 and carrageenan.  These additives may alter the delicate balance of the gut microbiome, as well as contributing to leaky gut and inflammation.


First, a word on FODMAPs

A low FODMAP diet is often recommended to alleviate symptoms associated with gut fermentation.  While this may work short term, it doesn’t deal with the underlying cause of your bloating – an imbalanced microbiome.  And removing foods from your diet for too long can further add to the problem.


In fact, although lots of foods might be triggering gas, the more varied your plant-based food intake can be, the more you will promote balance in the gut and reduce your symptoms in the longer term.


So, if reducing high FODMAP foods feels like the only step that will give relief in the short term, my advice is to try this regimen only for between 2 and 6 weeks maximum.  And preferably under professional guidance to help you keep your food intake balanced and reintroduce trigger foods successfully.



How to soothe and reduce symptoms:

  1. Self-care & rest – when gas and bloating hit, self-care and rest may be the best first response. Consider any combination of gentle movement (think slow, restorative yoga, stretches or walking), meditation, a warm bath, a hot water bottle, peppermint or fennel tea.


  1. Practice mindful eating and chew well – chewing is the first stage of digestion because your saliva contains an enzyme called amylase, which starts to break down carbohydrates. And the act of chewing mechanically breaks down your food into smaller pieces to help things along.


Which is why if you’re used to eating on the go or when stressed, you don’t feel so good afterwards!  While the act of slowing down your eating can really help to digest your food well, you can take this one step further by eating mindfully too.


Tuning in to all the senses as you eat, especially sight, touch, taste and smell may very likely provide a mindful experience of the food you are eating.  Plus, you may find that you notice you are full sooner and stop.  Less food to digest means less to ferment, and better portion control – win/win!


  1. Minimise trigger foods – this does not mean cut them out (although in the case of refined sugar, minimal is better), but know that they are dose dependent and tend to have a cumulative effect. So, if you are including high FODMAP foods such as lentils, beans, onions and chickpeas, limit the amount you eat in one day.


Carbohydrates are common culprits, so make sure you focus on including plenty of protein, a variety of vegetables and healthy fats at most meals and add a small carbohydrate portion to complement. When carbohydrates such as pasta are the main focus of your meal, there is more likelihood of fermentation.


  1. Use a slow cooker or pressure cooker – for meats and beans especially, this cooking method helps to soften food for better digestion and gives your gut less work to do!


  1. Minimise grazing – in the gaps between eating, your digestive tract uses a wave of muscular contractions to push partially-digested food through the digestive tract. This helps stop food sitting in your gut too long, helping to reduce gut fermentation.


These muscular contractions also help to prevent bacteria from the large intestine back-flowing into the small intestine adding to the problem.  It’s a bit like having an internal road sweeper, clearing up all the debris.

Give your digestive system a break to do this regular sweep.  You can help this process by keeping to three satisfying meals per day and avoiding snacking.


  1. Limit drinking with meals – even water. Too much liquid dilutes stomach acid and slows digestion.  This may especially affect digestion of proteins, leaving protein-heavy meals sitting in your stomach for longer.  Protein putrefaction means fermentation (think rotting smell).  The answer is NOT to avoid these foods, but to ensure they are being digested well. Keep fluids at least 20-30 minutes away from meals and only sip if you need to while eating.


  1. Work around medications – although medications such as antibiotics and omeprazole can be important where needed, they can compromise your gut health, especially when used long-term. Ask your medical practitioner for a medication review.




If you’d like to understand more about the dose dependency of fermentable foods, my free masterclass 3 Steps To Control Your Gut (And Still Eat Your Favourite Food) goes into more detail.



Jane Barrett is a registered nutritionist and expert in digestive health helping women & children with digestive issues take control of their health through food. She offers support through meal plans, online courses & personalised 1:1 programmes on Zoom.