Growing science of the gut-brain axis: Healthy gut “essential to whole-body health”

10 Jul 2023 --- Nutrition brands are highlighting a sustained demand for products that target the gut-brain axis – the bidirectional communication system between the human digestive system and the brain – as research builds a better understanding of the links between the intestinal microflora and other health areas.

Nutrition Insight speaks with experts from Kerry, TriNutra, Nutiani by Fonterra and Roquette to discuss how the gut-brain axis influences overall well-being and its impact on diet and nutrition. 

“Globally, consumers are increasingly taking a holistic approach to wellness and recognizing that gut health affects the entire body, including issues such as weight management, emotional well-being, diabetes, allergies and immunity,” says Dr. Mathieu Millette, scientific director of RD&A for ProActive Health at Kerry. 

“This is reflected in greater consumer awareness of probiotics and their benefits. Furthermore, spore-forming probiotics like [Kerry’s] BC30 are clinically evidenced as safe and effective for taking daily to support digestive health, immune health and protein absorption.”

Morris Zelkha, the CEO of TriNutra, adds: “Consumers increasingly understand that a healthy and balanced microbiome can directly impact their health and well-being. But this topic goes beyond a trend; a healthy microbiome is essential to whole-body health.”

“A healthy gut starts with a nutritious diet and regular light to moderate physical activity. Consumers also know stress can impact the immune system and gut microbiome, challenging their health and well-being. Pairing dietary supplementation with regular exercise and a nutritious diet can make all the difference when fostering one’s microbiome health and well-being.” 

A healthy gut starts with a nutritious diet and regular light to moderate physical activity, says Zelkha.Regulating mood and emotions 
Marshall Fong, the senior global marketing manager for active living at Fonterra, explains that the gut-brain axis is crucial in regulating emotions, mood and behavior. 

“The gut produces and releases various neurotransmitters, including serotonin, dopamine and gamma-aminobutyric acid (GABA). These neurotransmitters are also found in the brain and are involved in regulating mood and emotions.” 

Fong adds that a dysregulation or dysfunction of the gut-brain axis is most notably associated with stress, anxiety and mood. In clinical trials, probiotics have been shown to impact these aspects of mental health positively. 

“Hormones, such as ghrelin and peptide YY, are also released in the gut and can influence appetite, satiety and mood. Additionally, the gut produces stress hormones, including cortisol, in response to stressful situations.”

Nutiani’s probiotic strain HN001 was shown in two placebo-controlled trials to impact mood, anxiety and overall mental wellness in different adult populations, including in perinatal women and people with pre-diabetes, continues Fong. 

“A pilot trial in adults also showed that HN001 positively improves happiness, a result we are currently investigating in a larger placebo-controlled trial.”

Two-way street 
Fong explains that the gut microbiota influences the gut-brain axis by producing neurotransmitters and metabolites, modulating the immune system, maintaining gut barrier integrity and communicating via the vagus nerve. 

“These mechanisms facilitate bidirectional communication, where the gut microbiota can impact brain function, and conversely, the brain can influence the composition and activity of the gut microbiota.”

This bi-directionality of the gut-brain axis means that a disturbance in the complex bacterial communities that make up the microbiota can adversely affect the brain, explains Caroline Perreau, research manager for R&D in nutrition and health at Roquette. 

“In this state of microbiota dysbiosis, the pathways involved in the gut-brain axis are dysregulated, leading to altered permeability of the blood-brain barrier and potentially neuroinflammation. This can contribute to developing mental disorders like stress, anxiety, depression and sleep difficulties.” 

“The connection is equally impactful in the other direction too, with evidence suggesting that mental or emotional disturbance influences the appearance of metabolic and functional bowel disorders, such as irritable bowel syndrome.”  

She emphasizes that a detailed understanding of the gut-brain axis – and the mechanisms involved in its expression – is essential for successfully preventing and treating a wide range of health conditions. 

Studies have linked the gut microbiome to heart and brain health, weight management and diabetes.“Changes in the gut microbiome can also impair the modulation of the immune system, disrupt gut motility and sensitivity and lower intestinal permeability. The gut microbiota influences the gut-brain axis in a myriad of ways. So in many respects, the health of our gut bacteria directly correlates with our sense of well-being.” 

Consequences of gut microbiome imbalances
Millette says that the gut microbiota – which comprises trillions of microorganisms, including bacteria, fungi, viruses and protozoa living in the intestines – impacts many areas of health, including digestion, immunity and the absorption of nutrients from food. 

Probiotics that diversify the gut microbiome have been expanding in their areas of application, most recently targeting symptoms of “long-COVID.”

“Studies have linked a diverse gut microbiome to improved heart and brain health, weight control and a reduction in the risk of diabetes.” 

He also explains that an imbalance of microorganisms in the gut – microbial dysbiosis – can be caused by “everyday stressors” such as antibiotics and other medications, hormonal changes, poor diet, illness, aging, stress and travel. 

“Reduced microbial diversity may make the gut more prone to infection. An inefficient digestive system has also been associated with over- or under-stimulation of the nerves carrying information from the gut to the brain. It could be linked to a range of conditions, including depression and anxiety.” 

Probiotic sports nutrition
In sports nutrition, Zelkha highlights that the gut-brain axis directly influences athletes’ health status, as previous research has reported that athletes training for a marathon experience a deterioration in their global mood state. 

“Runners and other athletes whose athletic activities cause significant physical and psychological stress levels are more susceptible to upper-respiratory tract complaints and infections.” 

He adds that a clinical study on TriNutra’s proprietary black seed oil ThymoQuin showed that the product helped contribute to a healthy microbiome, which is linked to immune health and overall mental well-being in endurance athletes. 

“ThymoQuin-supplemented runners also showed higher levels of Streptococcus thermophilus and lower stress hormone exposure (cortisol) – both of which are objective markers related to stress response, immune vigilance and psychological mood state across the gut-immune-brain-axis.” 

Pro- and prebiotics are both linked to their effects on gut microbiota and digestion.Impact of a healthy diet 
Maintaining a healthy gut microbiota through good dietary choices, prebiotic supplements, and other interventions is an effective way to improve gut-brain axis function and promote an all-around happier body, argues Perreau. 

She explains that the composition and activities of the gut microbiota are heavily influenced by diet, particularly nutrients that escape digestion in the stomach and small intestine and reach the colon primarily intact. 

“These nutrients are then fermented in the colon, affecting the microbiota makeup, functions and overall colonic environment. 

“The result is the production of beneficial metabolites, including neurotransmitters, cytokines or hormones which impact mood regulation, behavior and cognition. Some have a local impact on the enteric nervous system, and others can enter the bloodstream, thus being able to affect other organs and different parts of the nervous system.”

She continues that it is widely accepted that a varied diet, rich in vitamins, minerals, beneficial fats and fiber, is critical to supporting a healthy microbiota and, in turn – the brain. 

“A growing body of literature suggests that prebiotic fiber can be efficient in improving cognitive variables, thereby adding credence to the gut-brain connection.” 

According to Innova Market Insights, F&B and supplement launches with gut-brain axis claims increased 2% over the last five years (2018 to 2022), with claims tracked in the baby and toddler categories growing 66% and brain health claims increasing 83% at the same time.

At the recent Vitafoods event in Geneva, Switzerland, Nutrition Insight spoke to Aptar CSP Technologies on its new technology innovations for the probiotics market, including packaging innovations to conveniently deliver powder- and oil-based probiotics in beverages. 

By Jolanda van Hal, with additional reporting from William Bradford Nichols