IBS affects twice as many women as men. The menstrual cycle makes it worse. No tracker tracked both.
IBS symptoms — bloating, cramping, irregular bowel movements — fluctuate with the menstrual cycle. Progesterone in the luteal phase slows digestion. Prostaglandins during your period trigger diarrhoea. The overlap between hormonal and gut symptoms is real, documented, and completely ignored by mainstream nutrition apps.
How IBS (Irritable Bowel Syndrome) affects what you eat
IBS requires careful management of fermentable carbohydrates (FODMAPs), fibre types, meal timing, and stress. The menstrual cycle overlaps significantly — progesterone slows gut motility in the luteal phase, worsening constipation-predominant IBS; prostaglandins during menstruation trigger gut spasms and diarrhoea. Understanding both cycles simultaneously is the key to managing IBS nutritionally.
What your body needs most
Gentler on the gut than insoluble fibre. Oats, psyllium husk, and peeled fruits are ideal.
Support gut microbiome diversity. Lactobacillus and Bifidobacterium strains are most studied for IBS.
Prevents constipation and supports gut motility throughout the cycle.
Supports gut motility (constipation relief) and reduces cramping.
Reduces fermentable carbohydrates that trigger bloating, gas, and pain in IBS.
Foods to eat more of
Soluble fibre (beta-glucan) that soothes the gut without the irritation of insoluble fibre.
Nutritious without the fermentable carbohydrates that trigger IBS symptoms.
Easier to digest. Cooking breaks down cell walls and reduces fermentable compounds.
Probiotic support. Lactose-free versions avoid a common IBS trigger.
Reduces gut spasms and nausea. Particularly helpful during the menstrual phase.
Clinically shown to reduce IBS cramping and spasm.
Foods to cut back
The primary dietary triggers of IBS bloating, gas, and pain.
Trigger exaggerated gut contractions in IBS — particularly problematic during the period.
Both stimulate gut motility and can trigger diarrhoea-predominant IBS flares.
High-FODMAP sugar alcohols that cause significant gut fermentation.
How your cycle interacts with IBS (Irritable Bowel Syndrome)
IBS symptoms correlate directly with cycle phase. Luteal phase: slower gut motility, more bloating, constipation-predominant symptoms. Menstrual phase: prostaglandins trigger cramps and diarrhoea-predominant symptoms. Oli knows which phase you're in and can inform your food choices accordingly.
Explore cycle nutrition →IBS (Irritable Bowel Syndrome), nutrition and your questions
Why is my IBS worse on my period?
Gastroenterology research describes two hormonal mechanisms colliding. Through the luteal phase, progesterone slows gut motility — the documented cause of pre-period bloating and constipation. Then at menstruation, prostaglandins (the same compounds behind uterine cramps) trigger gut contractions, flipping many women into diarrhoea-predominant symptoms. Studies report around 73% of women with IBS experience this cycle-linked pattern.
What is the low-FODMAP diet and should I try it?
FODMAPs are fermentable carbohydrates (in onion, garlic, wheat, apples and more) that research identifies as triggers of bloating and pain in IBS. The diet, developed at Monash University, is a structured elimination for 4–8 weeks followed by systematic reintroduction — it is not designed to be permanent. Reviews rank it as the best-evidenced dietary intervention for IBS, and guidance consistently recommends doing it with a dietitian.
What foods are safe to eat during an IBS flare?
Low-FODMAP guidance lists gentle, cooked options: oats, bananas, blueberries, rice, cooked carrots or courgette, lactose-free dairy or kefir, and plain proteins like chicken or fish. Trials also support ginger and peppermint (as tea or oil) for calming gut spasm. The common triggers research points to during flares are raw vegetables, fried food, caffeine and alcohol.
Can hormones cause IBS?
Research doesn't show hormones cause IBS, but they clearly modulate it — IBS is diagnosed twice as often in women, studies find symptoms track the menstrual cycle for most, and gut sensitivity changes measurably across cycle phases. This is why tracking cycle alongside food can reveal patterns that food diaries alone miss.
Is coffee bad for IBS?
Studies show caffeine stimulates gut motility, which makes coffee a commonly reported trigger for diarrhoea-predominant IBS — with a compounding effect during menstruation, when prostaglandins are already stimulating the gut. For constipation-predominant IBS, the same mechanism can work in the opposite direction. Dietitians commonly suggest trialling a reduction around the period first, when the research says it matters most.
Important: IBS management often benefits significantly from working with a gastroenterologist and registered dietitian. The low-FODMAP diet is most effective when guided by a professional to ensure nutritional adequacy. This page summarises published research and guidance from the health authorities listed under Sources — it is educational content, not medical advice, and Oli is not a medical provider.