Gut Health and Hormones: How They Affect Each Other

If your digestive symptoms get worse at certain points in your cycle, or if hormonal conditions seem to affect your gut, that connection is real. Your gut and your hormones are in constant two-way communication — and understanding that relationship opens up some genuinely useful levers.

How your gut influences hormones

The oestrobolome

A specific collection of gut bacteria called the oestrobolome helps regulate oestrogen levels in the body. These bacteria produce an enzyme that influences how oestrogen is processed and either reactivated or removed. When the gut microbiome is imbalanced, oestrogen metabolism can be disrupted — leading to either too much or too little circulating oestrogen. This is an active research area with implications for PMS, perimenopause and certain hormonal conditions.

Cortisol and the gut-brain axis

Your gut and adrenal glands communicate through the gut-brain axis. Chronic stress raises cortisol, which disrupts gut bacteria, increases gut sensitivity, and slows digestion. It runs both ways: a struggling gut can keep the stress response elevated. This is part of why stress shows up as digestive symptoms — and why calming the gut can measurably affect the stress response. See the gut-anxiety connection.

Thyroid hormones

Your thyroid regulates gut motility significantly. An underactive thyroid (hypothyroidism) commonly presents with constipation and bloating; an overactive thyroid can cause diarrhoea and urgency. Some research also suggests gut bacteria affect thyroid hormone conversion. Persistent, unexplained digestive changes — especially new constipation in adults — are worth getting medically assessed, including thyroid function.

How hormones affect your gut

Oestrogen and progesterone directly affect gut motility and gut sensitivity. This is why many women notice clear digestive changes across their cycle:

• After ovulation, rising progesterone slows gut motility — constipation and bloating increase
• Just before and during menstruation, prostaglandins can cause cramping, diarrhoea and urgency
• During perimenopause, declining oestrogen changes gut bacteria composition and sensitivity

“Is it gut or hormones?” is often the wrong question — it's usually both. See our guides on period bloating and gut health for women over 40.

What supports both gut health and hormonal balance

Fibre and plant variety

Fibre feeds the gut bacteria that help process hormones. A varied, plant-rich diet is one of the best-supported levers for both. See the best foods for gut health.

Fermented foods

A diverse microbiome regulates hormones more effectively. Fermented foods help maintain that diversity. See probiotics vs prebiotics.

Managing stress and sleep

Chronic cortisol elevation harms both gut health and hormonal balance. Movement, sleep and stress management are physiologically relevant here, not just general wellness advice.

When to see a doctor

If you suspect a hormonal condition — thyroid issues, PCOS, endometriosis, perimenopause — is affecting your digestion, or if gut symptoms are new and don't respond to dietary changes, a proper medical assessment is the right move. Gut and hormonal health increasingly need to be considered together.

My free 7-day anti-bloat plan is a gentle starting point for everyday gut support, and the 30-Day Gut Reset builds the full foundation.

General information. Please see a doctor for hormonal conditions or concerning symptoms.

Frequently asked questions

Can gut health affect oestrogen levels?

Yes — specific gut bacteria (the oestrobolome) play a role in how oestrogen is processed and circulated. An imbalanced microbiome can disrupt this, affecting oestrogen levels and related symptoms.

Can thyroid problems cause bloating?

Yes — an underactive thyroid slows gut motility, commonly causing constipation and bloating. Persistent, new-onset digestive changes without a clear cause are worth getting a thyroid check.

Why is my digestion worse before my period?

Rising progesterone in the luteal phase slows gut motility, leading to more constipation and bloating. Both are hormonally driven and normal for most people. See period bloating.