Why the female gut functions differently

Digestive problems? Women are twice as likely to be affected as men! This is because hormones, the gut-brain axis, and the microbiome are closely linked, so says Prof. Dr. med. Julia Seiderer-Nack. The specialist in internal medicine and sought-after expert on gut health explains in her new book "Women Have a Different Gut", among other things, the connection between the gut and diseases like endometriosis, IBS, or PCOS, why a microbiome-friendly diet is important - and which hacks can help alleviate symptoms.

Why are more than 70 percent of those affected by IBS female?

That's a good question, which we have asked far too little in medicine so far and to which we still have too little knowledge - gender health gap says hello. It is often argued that women go to the doctor more often, speak more openly about digestive complaints compared to men, and therefore are more often diagnosed with IBS.

Women are also attributed more stress or psychological burdens, which are often a quick explanation for female-typical pain conditions such as migraines, fibromyalgia, or IBS. What we have so far paid too little attention to, however, are measurable scientific differences between men and women in the gut, which could provide us with new perspectives for understanding and also treating IBS.

How do I actually recognize that I am suffering from IBS?

An irritable bowel is first and foremost a diagnosis of exclusion - so if I have suffered from constipation, abdominal pain, diarrhea or bloating for a long period of time, laboratory values, stool samples, and a gastroscopy and colonoscopy must be used to rule out other conditions such as an infection, celiac disease or chronic inflammatory bowel disease behind these symptoms. If the bowel is organically healthy in these examinations and the patient still has these symptoms, such an irritable bowel is likely.

What are the differences between male and female intestines?

Women's intestines are not only squeezed together by the uterus and slightly longer, but often also more relaxed: the food pulp is moved through the intestinal loops more slowly, which is why we are more prone to constipation. We also have a different intestinal microbiome, i.e. a different composition of bacterial species in the intestine, and show differences in the strength of our immune defenses, e.g., after infections or in autoimmune diseases.

And very importantly: The intestine is also influenced by female sex hormones, whether in terms of transport speed or in terms of pain perception. Women more often show increased pain sensitivity in the abdominal area (visceral hypersensitivity), which can play a role not only in endometriosis but also in irritable bowel syndrome and can be influenced by hormone levels.

© GU Verlag

Prof. Dr. med. Julia Seiderer-Nack, specialist in internal medicine and expert on intestinal health.

How do female hormones affect the intestine?

Female sex hormones can also act on the intestine via receptors - for example, we know that the hormone progesterone slows down the transport speed of food in the intestine, so the intestine becomes sluggish and prone to constipation. We observe this not only during pregnancies but often also in the second half of the menstrual cycle.

On the other hand, estrogen also affects our pain perception - and thus also how strongly we perceive signals from an irritated bowel. In addition, there is a close interaction with tissue hormones such as histamine and prostaglandin. Therefore, it is not surprising that some patients experience increased bowel problems depending on the cycle, or the bowel can become more irritable during phases of hormonal change (e.g., menopause).

What do conditions like PCOS and endometriosis have to do with the intestine?

On the one hand, we observe that about 20-30% of all patients with PCOS and endometriosis also have an "irritable bowel" at the same time - this naturally raises suspicion and suggests an influence of hormone balance and the microbiome on inflammatory processes. And indeed, science shows us that patients with PCOS often have a leaky gut; in patients with endometriosis, we often find a changed composition of the intestinal microbiome, which is probably also related to hormone levels and inflammatory processes.

"Women Have Different Intestines", GU Verlag

What exactly is the gut-brain axis and what does it do?

The gut-brain axis is not a thick cable in our body. The term describes the complex and mutual communication between the nervous system of the gut and the central nervous system, that is, our brain. These two systems are in constant exchange via hormones, neurotransmitters, signaling substances, and also the autonomic nervous system.

A good connection is not only important for regulated digestion, but it also has far-reaching effects - for example, on our emotions, stimulus processing, immune system, or hormone balance. Interestingly, 90% of the communication goes from the gut to the brain, so what the gut and its microbiome have to say is indeed relevant for our headquarters in the head.

What does the perfect, healthy microbiome look like?

Science cannot clearly answer this question to this day, as this ecosystem and its effects on our health are too complex. However, we know that a high diversity of species in our gut is important and associated with health, and we also don't want disease-causing or inflammation-promoting bacteria in the gut. For example, we also know that some bacterial species are particularly important: for our immune system, the gut barrier, or the formation of anti-inflammatory fatty acids.

How does the gut microbiome change during menopause?

The gut microbiome develops into a largely stable ecosystem in the first three years of life, but with the onset of puberty, differences in composition appear between the male and female microbiomes under the influence of hormones.

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And we know today that the microbiome changes again during menopause, for example, in species diversity, but also in the occurrence of different species. Interestingly, after menopause, the female microbiome becomes more similar to that of men again. Researchers suspect that these change processes and the resulting altered formation of metabolic products could also be related to the increased risk of cardiovascular diseases, obesity, and osteoporosis.

What does a reconstructive diet for the microbiome and gut barrier consist of?

A diet rich in fiber is crucial for a healthy and diverse microbiome. It means consuming at least 30 grams of vegetables, whole grains, and fruits per day. A plant-based, fiber-rich diet is a good foundation, just like an anti-inflammatory approach with high-quality omega-3 fatty acids and avoiding industrial ultra-processed foods. The latter can harm the gut barrier and microbiome due to their many additives and unhealthy fats.

Foods naturally containing valuable bacteria such as lactobacilli and bifidobacteria, i.e., those that are probiotic, are also helpful for the microbiome. Examples include kefir, natural yogurt, sauerkraut, beetroot, or fermented vegetables.

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