At the end of each year, consumer food trends are announced and trendwatchers highlight mental health as a key trend for 2025 and beyond. Both younger and older generations are not only looking to improve their physical health but also their mental health through the consumption of food ingredients and supplements.

Researchers have also become more interested in the interaction between diet and our brain, and they found that the gut and the bacteria that live in it, the so-called microbiota, play an important role. This fascinating crosstalk between the gut, its microbiome, and the brain, is known as the microbiota-gut-brain axis.

One’s mental health refers to a state of well-being that allows you to handle stress, realize your abilities, learn effectively, work productively, and contribute to your communities. It is a fundamental aspect of overall health and well-being. It encompasses more than just the absence of mental disorders and is experienced by everyone differently (1). Your cognition is part of your mental health, and someone with a cognitive disorder or experiencing cognitive decline, is affected in abilities like learning, memory, perception, and problem-solving. To counteract cognitive decline for elderly, or improve cognitive performance in younger generations, people are looking to nutritional solutions. Moreover, prevention becomes more important for aging populations as medications addressing cognitive decline have limited success to date.

The nervous system is an intricate network of nerves and cells that links the brain to different parts of the body. The second largest nervous system can be found in our gut and is called the enteric nervous system (2). This enteric network communicates with the brain about hunger and satiety, as well as emotions like stress and fear. The gut microbiota are all the microbes and bacteria residing in the human gastrointestinal tract. In the colon, bacteria ferment soluble dietary fibers, like inulin type fructans, into short chain fatty acids (SCFAs) such as butyrate, acetate, and propionate, which are beneficial for our health (3). The interaction between the microbiota in the gut and the brain is called the microbiota-gut-brain axis. The connection between the gut and the brain emerged when research showed that people with anxiety and depression more often had an unhealthy microbiome (4).

As mental health and cognition are top of mind for consumers, the food and supplement industry seek to respond to this by including ingredients that might influence mental and cognitive well-being via the gut-brain axis. A group of such ingredients are prebiotics. The International Scientific Association for Probiotics and Prebiotics (ISAPP) defines a prebiotic as ‘a substrate that is selectively utilized by host microorganisms conferring health benefit’ (5). Selectivity implies that only a limited range of microorganisms are affected, which could include one or several microbial groups, but not all. Additionally, a prebiotic must demonstrate a scientifically proven health benefit, supported by well-controlled research trials. ISAPP recognizes inulin, fructooligosaccharides (FOS), and galactooligosaccharides (GOS) as prebiotics. Inulin and FOS can be extracted from the chicory root and added to many types of foods, like cereals, yogurts or snack bars. They can also be found naturally in fruits and vegetables like banana and onions. When the gut microbiota ferment prebiotics like inulin, they make SCFAs and other metabolites, which can (in)directly impact the brain through the immune, endocrine, or other pathways. A healthy immune system that keeps inflammation low, and an effective gut barrier preventing harmful substances reaching the brain, appear to be supported by a healthy gut microbiome (6).

Research on prebiotics and the gut-brain axis is still in its infancy, however, a few studies examining the effect of chicory root fiber on cognition show promise. An initial study showed that intake of 5g chicory inulin over a 4h period affected the episodic memory tasks where the inulin group had greater accuracy on the recognition memory task and improved recall performance (7). In addition, a three-month intake of 16g chicory inulin in persons with obesity was associated with improved cognitive flexibility (8). A longer-term study showed that prebiotic chicory fructans in twins of 60 years or older gave improved cognitive function in relation to associative learning and memory (9). Furthermore, an ongoing long-term trial, PRECODE, in elderly with cognitive decline, is investigating the impact of prebiotics like inulin using functional Magnetic Resonance Imaging (fMRI) with memory tests (10). fMRI has opened new frontiers in neuroscience, as its non-invasive, safe and can help unravel complexities of cognition.

Most research conducted on prebiotics and cognition has been done with people who are cognitively healthy. Studying suboptimal cognition in healthy individuals that may arise due to stress, poor sleep, sedentary behavior, and unhealthy dietary patterns (characterized by low dietary fiber intake), may provide critical windows of opportunity for prebiotics (11).

An easy way to improve the composition of your gut microbiome is by increasing the intake of dietary fibers and prebiotic-rich foods. Numerous natural sources of prebiotics exist; however, dietary supplements offer a convenient and effective means to incorporate the appropriate types and amounts of prebiotics into your diet. Supplements offer a promising and convenient way to enrich one's diet with beneficial proven prebiotics, like chicory root fibers, for the gut microbiome. Industry analysts predict that the dietary supplement segment, for example functional gummies, will experience the most rapid growth in the application of plant-based prebiotics in the coming years.

The microbiota-gut-brain axis is a system whereby the gut, and the microbiota in it, communicate with our brain and might even support our brain function. To keep the microbiota healthy and balanced, you can consume prebiotics like chicory inulin and oligofructose. Scientific studies already show the potential of prebiotics to improve cognition. An easy way to incorporate prebiotics in your diet is via supplements.