From the Guidelines
Serotonin levels in the gut decrease during the premenstrual and menstrual phases of the menstrual cycle, which can lead to digestive symptoms such as bloating, constipation, diarrhea, and abdominal pain. This fluctuation is influenced by sex hormones like estrogen and progesterone, which affect serotonin production and function in the gut 1. Estrogen generally enhances serotonin activity, so when estrogen levels drop before menstruation, serotonin levels also decline. The relationship between serotonin metabolism and gastrointestinal motility is well-established, with alterations in serotonin (5-Hydroxytryptamine (5-HT)) metabolism influencing changes in gastrointestinal motility 1. High levels of serotonin are reported in patients with IBS-D, and low levels in IBS-C, highlighting the importance of serotonin in regulating digestive processes 1.
Some key points to consider:
- About 95% of the body's serotonin is produced in the gut, where it regulates digestive processes including motility and secretion
- Maintaining regular physical activity, adequate hydration, and consuming foods rich in tryptophan (the precursor to serotonin) like turkey, eggs, cheese, and nuts may help stabilize gut serotonin levels
- Mindfulness practices or stress reduction techniques can also help manage gut symptoms, as stress can further disrupt serotonin balance in the digestive system
- The fluctuation in serotonin levels during the menstrual cycle can contribute to common digestive symptoms many women experience before and during their periods, such as bloating, constipation, diarrhea, and abdominal pain.
Key factors that influence serotonin levels in the gut during the menstrual cycle include:
- Estrogen and progesterone levels, which affect serotonin production and function
- Gastrointestinal motility, which is influenced by alterations in serotonin metabolism
- Diet and lifestyle factors, such as physical activity, hydration, and tryptophan intake, which can help stabilize gut serotonin levels.
From the Research
Serotonin Levels in the Gut During Menstrual Cycles
There is limited research directly addressing the changes in serotonin levels in the gut during menstrual cycles. However, studies on irritable bowel syndrome (IBS) provide some insight into the role of serotonin in the gut.
- The gut contains a large amount of serotonin, which plays a key role in intestinal secretory, sensory, and motor function 2, 3.
- Serotonin signaling is involved in the pathophysiology of IBS, and alterations in serotonin metabolism may contribute to the development of IBS symptoms 2, 3, 4.
- Research on IBS has shown that serotonin levels can be altered in patients with IBS, with some studies suggesting an increase in serotonin levels in the blood of IBS patients 5.
- The serotonin reuptake transporter (SERT) regulates the intracellular reuptake of released serotonin, and abnormalities in SERT function can alter enteric serotonergic signaling, leading to gut dysfunctions 4.
Implications for Menstrual Cycles
While there is no direct evidence on the changes in serotonin levels in the gut during menstrual cycles, the existing research on IBS and serotonin suggests that hormonal fluctuations during the menstrual cycle may influence serotonin levels and gut function.
- Hormonal changes during the menstrual cycle can affect the gut-brain axis, leading to changes in gut motility, secretion, and sensation 3, 6.
- The relationship between serotonin and the menstrual cycle is complex, and further research is needed to understand the potential implications for gut health and IBS symptoms 2, 3, 4, 6.