Why Fibre Matters for Your Gut, Mood, and Mental Health
When Mental Health Support Starts in the Gut
When we talk about mental health, we often focus on stress, hormones, or emotional load - and rightly so. But there’s another important piece that’s often overlooked: the health of your gut.
One of the most powerful (and underestimated) ways to support gut health is through fibre. Not by following the latest fad diet or health trend, but by making consistent, nourishing choices that support both your digestive system and your nervous system.
If you’ve been feeling anxious, flat, foggy, or emotionally unsettled, fibre may be part of the foundation your body is quietly asking for.
What Is Fibre, Really?
Fibre is a type of carbohydrate found in plants that the body doesn’t digest in the usual way. Instead of being broken down and used by our bodies for energy, fibre moves through the digestive system largely intact, playing a key role in gut function, blood sugar balance, removing toxins and waste products from the body and promoting microbial health (feeding the microbes in our gut).
What makes fibre particularly important for mental wellbeing is its close relationship with the gut microbiome - the community of bacteria that influences inflammation, neurotransmitter production, health of gut cells and communication between the gut and the brain.
The Gut–Brain Connection
The gut and brain are in constant conversation via the gut–brain axis. This communication pathway involves nerves, hormones and immune signals. The signals can go from your brain to your gut, which you may notice as nerves resulting in an urge to go to the toilet, excitement causing ‘butterflies’ or ongoing stress reducing appetite. Or they can go from the gut to the brain, for example gut inflammation causing brain fog or low mood, or certain species of gut microbes contributing to feelings of anxiety.
A large proportion of serotonin (a neurotransmitter involved in mood regulation) is produced in the gut. When the gut environment is supported and the beneficial microbes are fed the fibre they need to thrive, the signals sent to the brain tend to be calmer and more balanced.
Fibre supports us by:
Feeding beneficial gut bacteria;
Supporting the production of short-chain fatty acids including butyrate, acetate and propionate;
Improving the gut lining and barrier function which helps to reduce inflammation, positively impacting mood and brain function;
Helping regulate blood sugar, which influences anxiety and energy; and
Removing excess oestrogen from the body to keep it in balance - too little or too much of which can impact our mental health.
This is why fibre is increasingly recognised as part of a whole-person approach to mental health, as well as for overall health, of which there are many other benefits too many to mention in this article.
The Different Types of Fibre
Not all fibre works in the same way - getting a varied intake from different sources supports the gut more effectively than focusing on one type alone. It is important to remember though, the foods in each fibre category contain a mix of different fibres which is why it is worth mixing it up. For example, green kiwi fruits are a great source of both soluble and insoluble fibre, but as they have a slightly higher amount of insoluble fibre, they are often found on that list.
Soluble Fibre
Soluble fibre dissolves in water and forms a gel-like substance in the gut. It helps slow digestion, softens stools (great for constipation) and supports blood sugar stability - an important factor for mood and anxiety.
You’ll find soluble fibre in foods such as:
Oats
Chia seeds and flaxseeds
Apples, pears, citrus fruits and berries
Legumes like lentils and chickpeas
Stable blood sugar can help reduce feelings of irritability, shakiness, and emotional reactivity.
Insoluble Fibre
Insoluble fibre adds bulk to the stool and supports regular bowel movements, playing an important role in digestive comfort and function.
Sources include:
Whole grains
Nuts and seeds
Vegetables like broccoli, carrots, and leafy greens
Fruits like kiwi fruits (even better with the skin on), grapes, strawberries, raspberries and blackberries berries
Fruits and vegetables with their skin on, including apples and pears
Regular digestion supports the body’s natural detoxification pathways (removing waste products from the liver in stools), which can indirectly influence how we feel mentally and physically.
Prebiotic (Fermentable) Fibre
Prebiotic fibre is a type of fibre that feeds beneficial gut bacteria, such as Bifidobacterium. Prebiotic fibre includes fructans and inulin and is fermented by these bacteria, creating health promoting compounds as a result, such as short chain fatty acids. These can have all sorts of benefits for mental health, including reducing inflammation, producing calming neurotransmitters, lowering cortisol levels and stabilising blood sugar balance resulting in better sleep.
Foods rich in prebiotic fibre include:
Onions, garlic, and leeks
Asparagus
Bananas (especially slightly underripe)
Oats
Legumes
These fibres help create a gut environment that supports mental and emotional wellbeing over time, and would make a great addition to your daily routine.
Resistant Starch
Resistant starch is a type of carbohydrate that acts like fibre, resisting digestion in the small intestine and instead travelling to the large intestine, where it feeds beneficial gut bacteria. Like prebiotic fibre, it supports the production of short-chain fatty acids (in particular butyrate) which helps promote a healthy gut lining, reduce inflammation and support the gut–brain connection. Resistant starch has also been shown to support blood sugar regulation, which can play an important role in emotional stability and anxiety.
Foods containing resistant starch include:
Cooked and cooled potatoes, rice and pasta
Oats
Beans and legumes including lentils and chickpeas
Slightly underripe bananas
Introducing these foods gently and consistently can help nourish the gut in a way that feels grounding rather than demanding.
Fibre and Mental Health: What the Research Is Showing
Emerging research continues to show links between dietary fibre intake, gut diversity, the role of SCFA’s and mental wellbeing (Dalile et al., 2019; Loughman et al, 2021). Diets rich in a variety of plant foods tend to be associated with lower levels of anxiety, depression and overall improved mental health (alongside a healthy diet and lifestyle).
This doesn’t mean fibre is a solution on its own. Mental health is complex and influenced by many factors, however, fibre provides an important foundation, especially when paired with adequate energy intake, protein, beneficial fats, movement and nervous system support.
Gentle Ways to Increase Fibre
If your fibre intake has been low, increasing it gradually is key. Too much too quickly can cause bloating or discomfort, which can feel discouraging. You want to eventually aim for 25-30g fibre each day in-line with Australian recommendations (https://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/dietary-fibre), but start small and work your way up.
You might begin by:
Adding one extra serve of vegetables or fruit each day;
Eat fruits and vegetables without removing the skin for added fibre (where possible) - such as carrots, sweet potatoes, kiwi fruit, apples and pears;
Including some oats, seeds, or legumes in your meals a few times a week;
Drinking enough water alongside fibre-rich foods to avoid constipation; and
Focusing on variety and colour rather than quantity - try adding in a new food every few days to keep it interesting and expose your gut to a variety of different fibres.
Consistency matters more than getting it ‘right’.
Bringing It All Together
Getting enough fibre shouldn’t be about setting yourself rules and targets. It’s about nourishment that supports your body’s ability to cope, regulate and recover from whatever life throws at you. When your mental health feels fragile, the most supportive approach is often the simplest one, and consistency is key. Don’t set yourself unachievable targets, just make one small step in the right direction each day - it will add up over time, trust me!
If you’re unsure how to support your gut and mental health in a way that feels realistic and aligned with your life, personalised nutrition support can help you build a nourishing and sustainable foundation, without adding pressure or making life more complicated. Contact me using this link to see how I can help you.
References
Dalile, B., Van Oudenhove, L., Vervliet, B., & Verbeke. K. (2019). The role of short-chain fatty acids in microbiota–gut–brain communication. Nature Reviews Gastroenterology & Hepatology, 16(461–478). https://doi.org/10.1038/s41575-019-0157-3
Loughman, A., Staudacher, H. M., Rocks, T., Ruusunen, A., Marx, W., Apos Neil, A. O., & Jacka, F. N. (2021). Diet and Mental Health. Modern Trends in Psychiatry, 32(100-112). doi: 10.1159/000510422. PMID: 34032648.
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