Gut health and stress in women:

Many women between 30 and 55 juggle work, home, children and often elderly parents as well. When this mental load lasts for months, the body stays on alert and the gut suffers. Bloating, constipation or diarrhea, slow digestion, fatigue and low mood appear. This happens because the brain and gut are connected by a network of nerves, hormones and bacteria called the gut-brain axis. Stress hormones, CRH and cortisol, slow down the stomach, make the colon more irritable and change gut bacteria. Cortisol also diverts tryptophan toward a chemical pathway different from the one leading to serotonin. And about 90% of the body's serotonin is produced in the gut. Women are more exposed: they carry a heavier caregiving load, have a more sensitive stress system and cycle hormones that act on the belly.

What mental load is

Mental load is the work nobody sees. It isn't doing the grocery shopping, but remembering that the milk is running out. It isn't taking the child to the pediatrician, but knowing the vaccine is due in March, booking the appointment and making sure someone takes them.

Sociologist Allison Daminger of Harvard University studied this work in 2019. She divided it into four stages: anticipating a need, identifying the possible solutions, deciding, and monitoring that everything went well. Major decisions, such as buying a home, are often made together. Anticipating and monitoring, however, almost always remain on women's shoulders, even in couples who consider themselves equal.

Think of a computer with thirty windows open. None of them, on its own, weighs much. Together they slow the machine down, heat the processor and drain the battery. The brain of someone carrying the mental load works in a similar way, because it never fully switches off.

The Italian figures confirm the picture. According to the International Labour Organization, women spend 5 hours and 5 minutes a day on unpaid care work, against 1 hour and 48 minutes for men. That is 74% of the total. A study published in 2025 in Archives of Women's Mental Health linked this invisible work to more stress, more depression and more burnout in mothers.

The gut-brain axis, explained simply

The gut has its own nervous system, with hundreds of millions of neurons. This is why it is called the "second brain". The two brains talk to each other constantly, in both directions, through four channels:

• the vagus nerve, a kind of direct phone line between belly and head;
• hormones, especially stress hormones;
• the immune system, much of which lives around the gut;
• the microbiota, the billions of bacteria that inhabit the gut and produce substances able to send signals to the body.

When life runs smoothly, this dialogue stays balanced. When stress lasts too long, the messages become distorted.

What happens to the belly when stress doesn't switch off

The first alarm starts in the brain

Faced with a problem, an area of the brain called the hypothalamus releases CRH, the hormone that switches on the stress response. CRH sets off a chain that reaches the adrenal glands, above the kidneys, and triggers cortisol production.

For the body, this is a valuable system. It helps you escape a danger or get through a difficult day. The trouble comes when the alarm stays on for weeks or months. That is what happens with mental load: the brain keeps receiving danger signals even though the "danger" is just an endless to-do list.

Stress and motility: it's not a simple blockage

You often hear that cortisol "blocks" the gut. This is only partly true, and it is worth understanding how it really works.

Under stress, the body behaves as if it had to flee. Nobody starts digesting lunch while running from a dog. This is why the stomach empties more slowly and the small intestine slows down too. From this come the feeling of heaviness after eating, nausea and a swollen belly.

The colon, the last stretch, often does the opposite and speeds up. Anyone who has rushed to the bathroom before an exam or a job interview knows this well. Studies show that this double action depends on two different "locks" on which CRH acts. One slows the stomach, the other pushes the colon.

When stress becomes chronic, the rhythm falls apart. Some women lean toward constipation, others toward diarrhea, and many alternate between the two. Cortisol does not work alone. Together with adrenaline, it keeps the body in "flight" mode and takes space away from the "rest and digest" mode, which is the one in which the gut works best.

A barrier that becomes less tight

The intestinal wall is like a brick wall held together by mortar. It lets digested food through and keeps bacteria and irritants out. With chronic stress, the mortar loosens.

Research shows that CRH activates certain defense cells, the mast cells, which release inflammatory substances. In animals, cortisol also contributes to increased permeability. The result is a low-grade background inflammation, which makes the belly more sensitive and can worsen bloating and pain.

The bacteria change too

Prolonged stress reduces the diversity of the microbiota and the number of beneficial bacteria. Picture a garden: with little care and a lot of drought, some plants disappear and weeds take over. A poorer microbiota produces fewer protective substances for the intestinal wall. It also sends different signals to the brain.

Cortisol and serotonin: why mood also passes through the belly

Serotonin is made mostly in the gut

Serotonin is famous as the "feel-good hormone". Few people know that about 90% of the serotonin in the body is produced by special cells in the gut, the enterochromaffin cells. In the gut, serotonin has a very practical job: it tells the muscles when to contract to move food along.

A study published in Cell in 2015 found that certain gut bacteria help these cells produce serotonin. Fiber plays its part too. Bacteria ferment it and produce fatty acids that stimulate production. When the microbiota suffers, therefore, gut serotonin can suffer as well, and regularity with it.

An important clarification

The serotonin made in the belly does not reach the brain, because it cannot cross the barrier that protects it. The brain makes its own. The two systems do influence each other, though: the belly sends signals along the vagus nerve, and brain and gut use the same raw material.

Tryptophan and the two building sites

Making serotonin requires tryptophan, an amino acid that comes from food. Tryptophan is like a truck full of bricks that can go to two different building sites. The first is the one for serotonin and melatonin, the sleep hormone. The second is called the kynurenine pathway.

Even in normal conditions, most of the tryptophan goes to the second site. Cortisol, however, activates an enzyme in the liver called TDO, which sends even more trucks down that road. Inflammation does something similar with another enzyme. Less tryptophan is left for serotonin. Some researchers describe a possible vicious circle: more stress, less serotonin, less brake on stress.

In practice, for a woman under pressure for months, this can mean a more irregular belly, lighter sleep and a more fragile mood. Three signals that are often treated as separate problems.

Why women are more exposed

Women suffer from irritable bowel syndrome more often than men. A large analysis published in The Lancet Gastroenterology & Hepatology in 2020 reports 12% of women against 8.6% of men. The reasons are several, and they add up.

The load is heavier. More hours of care and more mental work mean a stress alarm that stays on longer, including evenings and weekends.

The stress system reacts differently. In animal studies, CRH receptors in females respond even to small amounts of the hormone and adapt less when stress becomes intense. Females also have fewer receptors that act as a brake on cortisol, so they switch it off more slowly. These are laboratory data still to be confirmed in humans, but they point in the same direction as what is observed in people.

Cycle hormones act on the belly. The gut has receptors for estrogen and progesterone. In the second half of the cycle, when progesterone is high, the gut tends to slow down. Shortly before menstruation, hormones drop, and cramps and loose stools become more frequent. When stress adds to these changes, symptoms get stronger. Perimenopause, with its hormonal swings, can also make the belly more temperamental.

The most common signs and when to see a doctor

The gut under stress makes itself felt in many ways:

• a bloated belly that gets worse over the course of the day;
• constipation, diarrhea or an alternation between the two;
• slow digestion and a feeling of heaviness after meals;
• pain or cramps that ease after going to the bathroom;
• fatigue, disturbed sleep, irritability.

Some signs, however, must always be checked by a doctor, without blaming stress: blood in the stool, unexplained weight loss, anemia, fever, symptoms that wake you at night, symptoms that appeared after age 50, relatives with colon cancer, celiac disease or inflammatory bowel disease.

What you can do every day

There is no switch that turns stress off. Some habits, however, help the gut-brain axis find its rhythm again.

1. Eat sitting down and at regular times. The gut loves routine. A lunch eaten standing at the computer reaches the belly like a meal "on the run".
2. Increase fiber a little at a time. Vegetables, fruit, legumes and whole grains feed the bacteria that support gut serotonin. They should be introduced gradually, together with plenty of water, to avoid worsening bloating.
3. Breathe slowly. Inhale counting to four and exhale counting to six, for five minutes. The long exhale stimulates the vagus nerve and shifts the body toward "rest and digest" mode.
4. Move every day. Half an hour of walking helps the gut work and lowers tension.
5. Protect your sleep. Cortisol should be low in the evening. Screens, work emails and to-do lists before bed keep it high.
6. Share the load, not just the tasks. Asking "can you take the child to the dentist?" is not enough. The whole task has to be handed over, including remembering it and booking it. This is the part that weighs most on the mind.