Irritable bowel syndrome (IBS) has long been described as a condition without a clear cause. Growing research into the gut-brain axis is revealing that IBS is the result of complex signalling between the digestive system, the nervous system, and hormones.
Recent research has focused on a hormone called INSL5, which appears to play a key role in bowel motility and diarrhoea. While it’s common to experience abdominal discomfort and changes to your bowel habits during perimenopause and menopause, these findings help explain why, and when, symptoms may worsen.
The gut–brain axis explained
The gut and the brain are in constant communication. This connection, known as the gut-brain axis, relies on nerves, immune signals, hormones, and the gut microbiome, to keep digestion running smoothly. When this communication is well balanced, the bowel contracts in a coordinated way and sensations from the gut are interpreted accurately by the brain.
In IBS, this signalling becomes disrupted. The gut may become overly sensitive to normal stretching, or bowel movements may speed up or slow down inappropriately. Stress, infection, inflammation, and hormonal changes can all influence this system, amplifying symptoms even when the bowel itself appears structurally normal.
Importantly, this disruption is influenced by emotional and hormonal factors. The brain affects the gut, and the gut feeds information back to the brain, creating a loop that can either stabilise digestion or can prolong symptoms.
Gut hormones and bowel behaviour
Hormones produced within the gut play a crucial role in controlling digestion. They regulate appetite, fluid balance, and how quickly food moves through the intestines. One hormone gaining attention is INSL5, which recent research has linked with increased bowel motility and diarrhoea.
Studies suggest that higher activity of INSL5 may encourage faster transit through the colon, contributing to looser stools and urgency. This reinforces the idea that IBS symptoms are not random, but driven by measurable biological signals that influence how the bowel behaves.
Crucially, gut hormones don’t work in isolation. They interact closely with stress hormones, reproductive hormones, and signals from the nervous system. When one part of this network shifts, the effects can ripple through digestion.
Symptoms during perimenopause and menopause
Many women with IBS notice that their symptoms change over time, particularly during perimenopause and menopause. Oestrogen and progesterone influence gut motility, pain perception, and fluid handling in the bowel. As hormone levels fluctuate, and eventually decline, these regulatory effects become less stable.
During perimenopause, hormone levels can swing unpredictably, which may lead to alternating constipation and diarrhoea, increased bloating, or heightened abdominal pain. Anxiety, sleep disruption, and fatigue (common features of this life stage) can further sensitise the gut-brain axis.
In menopause some women experience slower gut transit and constipation, while others experience diarrhoea and urgency. The underlying IBS hasn’t necessarily worsened, but the hormonal environment supporting gut balance has changed.
Managing IBS
Dietary strategies may help reduce gut stimulation, while gut-directed therapies, such as targeted medications, psychological therapies, or hormone-aware approaches, can reduce sensitivity along the gut-brain axis. For women in perimenopause or menopause, addressing hormonal health alongside bowel symptoms may lead to better overall control.
Book an appointment today to determine the best treatment options for managing your IBS symptoms.
