Nutrition for Menstrual Health: PCOS to Endometriosis
How food can support your cycle, iron levels and inflammation, from the four menstrual phases to PCOS and endometriosis, with portions, timings and swaps.
By Reece Douglas · Founder, FreshPlate
Diet does not cause or cure PCOS or endometriosis, but what you eat can change how heavy, painful or draining your cycle feels. Three levers matter most: iron to replace what you lose, steady blood sugar to calm hormone swings, and anti-inflammatory foods to take the edge off pain.
This guide covers the four phases of the cycle, then the needs of PCOS and endometriosis. Evidence for individual foods is modest, so we stick to what is well established.
What are the phases of the menstrual cycle and how does nutrition fit in?
The cycle has four phases: menstrual, follicular, ovulatory and luteal, and your nutritional priorities shift modestly between them. The best-evidenced need is iron during the period itself. Most other phase-by-phase advice (often called cycle syncing) is sensible eating rather than proven science, so treat it as a framework, not a rulebook.
A cycle averages 28 days, but 21 to 35 is common. Day one is the first day of bleeding, so the phase lengths below are approximate.
Menstrual phase (days 1-5): replace iron and ease cramps
Bleeding drains iron, and heavy periods can lead to iron-deficiency anaemia. The NHS recommends 14.8mg of iron a day for women aged 19 to 49. Pair iron-rich foods with vitamin C, which improves absorption of plant iron.
- Lean red meat, 2-3 portions a week — haem iron is absorbed far more readily than plant iron
- Lentils, chickpeas and beans — about 3-4mg of iron per cooked 150g portion, better absorbed with a vitamin C source
- Fortified breakfast cereal — often supplies a third or more of daily iron per serving, so check the label
- Oily fish — omega-3 fats may help reduce period pain
- Ginger tea — modest evidence for easing cramps, and harmless in food amounts
Follicular phase (days 6-13): build energy with protein and fibre
Oestrogen rises and energy often returns. Eat protein at each meal, plus plenty of vegetables, wholegrains and fermented foods such as live yoghurt or kefir, which support gut health and help clear used hormones.
Ovulatory phase (days 14-16): fibre and fluids
Oestrogen peaks briefly. There is no special diet for these days, but fibre from vegetables, oats and pulses supports the bowel in clearing excess oestrogen. Aim for 30g of fibre a day, the UK recommendation for adults, and drink enough that your urine stays pale.
Luteal phase (days 17-28): steady blood sugar and magnesium
Progesterone rises, then both hormones fall before your period. Appetite often increases, and PMS symptoms such as mood dips, bloating and cravings can appear. Slow-release carbohydrates (porridge, wholegrain bread, sweet potato) and magnesium-rich foods help keep blood sugar and mood steadier.
- Pumpkin seeds, almonds, cashews — a 30g handful gives roughly 80-150mg magnesium; adult need is about 270-300mg a day
- Wholegrains with protein — slower glucose release than refined carbohydrates, so fewer crashes
- Calcium-rich foods — dairy or fortified alternatives; calcium supplements have been studied for PMS, though results are mixed
- Less salt and alcohol — both can worsen bloating and low mood
How much iron do you need if you have heavy periods?
Women aged 19 to 49 need 14.8mg of iron a day, and heavy periods can push your real need higher. Heavy bleeding means soaking through a pad or tampon every one to two hours, passing clots larger than a 10p coin, or bleeding for more than seven days. If that sounds familiar, ask your GP for a blood test; food alone may not correct iron deficiency.
Tiredness, breathlessness on stairs, pale skin, headaches and hair shedding can all signal low iron. Do not start iron supplements without a test, because too much iron is harmful. Our guide to how nutrients are absorbed explains why timing and pairing matter.
- Iron-rich food with vitamin C — do — a squeeze of lemon or a handful of peppers with lentils or spinach noticeably boosts absorption of plant iron
- Tea or coffee with meals — limit — tannins can cut iron absorption sharply, so leave about an hour either side of iron-rich meals
- Calcium supplements or large dairy portions with the iron meal — limit — calcium competes with iron for absorption
- Liver — limit — very high in iron but also in vitamin A, so avoid it if pregnant or trying to conceive
- Iron tablets without a blood test — avoid — excess iron can be harmful, and you may mask an underlying cause
Vegetarian and vegan iron
Plant iron is absorbed less efficiently than iron from meat, so aim a little higher on food sources. Lentils, tofu, pumpkin seeds, dried apricots, fortified cereals and wholemeal bread all help. Vegans should also check vitamin B12, since low B12 causes similar tiredness; see our guide to B12 deficiency signs and vegan sources.
What should you eat if you have PCOS?
If you have PCOS, a diet that keeps blood sugar steady is the best-supported approach, and losing even 5-10% of body weight, where weight loss is appropriate, can improve cycles and insulin resistance. PCOS involves higher androgen levels and often insulin resistance, so the aim is to blunt big glucose spikes rather than cut out whole food groups.
NICE and the NHS do not endorse one named PCOS diet. Low glycaemic index eating, a Mediterranean-style pattern and portion awareness all have reasonable evidence. Our list of blood sugar control foods is a practical starting point.
- Porridge oats, barley, wholegrain bread — good — slower glucose release than white bread, cereals and sugary snacks
- Lentils, beans, chickpeas — good — protein plus fibre, so smaller blood sugar rises
- Oily fish, twice a week — good — omega-3 fats, with one portion being about 140g
- Non-starchy vegetables, half the plate — good — fibre and volume with few calories
- White bread, sugary drinks, sweets — limit — fast glucose spikes can worsen insulin resistance
- Large portions of refined carbohydrate eaten alone — limit — pair carbohydrates with protein or fat to slow absorption
- Crash diets and long fasting — avoid — they often backfire with rebound eating and offer no proven PCOS benefit
Inositol and supplements: what is worth knowing
Myo-inositol is widely marketed for PCOS, and some small trials suggest it may improve insulin sensitivity and ovulation, but the evidence is not strong enough for UK guidelines to recommend it. Talk to your GP or pharmacist first, particularly if you take metformin or other medication. Our free food–medication interaction checker lets you look up foods and drugs together in seconds.
Can diet help with endometriosis pain?
Diet cannot treat endometriosis, but some people find that anti-inflammatory eating reduces pain and fatigue. The evidence is limited, mostly small studies and patient surveys, so experiment carefully and keep your medical treatment in place. Endometriosis involves inflammation, and omega-3 fats, fibre, fruit and vegetables are the foods most consistently linked with lower inflammatory markers.
Our anti-inflammatory foods list covers the basics. Start with a Mediterranean-style pattern, which is rich in these foods and good for the heart.
- Oily fish, 2 portions a week (about 140g each) — eat — omega-3 fats such as EPA and DHA are linked to lower inflammation
- Fruit and vegetables, 5+ portions a day — eat — fibre and antioxidants, and fibre helps clear used oestrogen through the gut
- Walnuts, flaxseed, rapeseed oil — eat — plant omega-3 (ALA), though conversion to EPA and DHA is limited
- Extra virgin olive oil — eat — the main fat in Mediterranean-style eating
- Processed meat and very high red meat intake — limit — some studies link both with higher endometriosis risk, though evidence is not conclusive
- Alcohol — limit — may raise oestrogen levels and worsen pain for some, and the UK limit is 14 units a week
- Gluten-free or low-FODMAP diets — try only with guidance — some report fewer bowel symptoms, but strict diets risk missing nutrients without support
When bowel symptoms overlap
Endometriosis commonly causes bloating, diarrhoea or constipation, and many people also have irritable bowel syndrome. If gut symptoms are severe, ask for a referral to a registered dietitian rather than cutting foods at random. Elimination diets can leave you short of iron, calcium and fibre, all of which matter for your cycle.
How does FreshPlate help with nutrition for menstrual health?
FreshPlate builds recipes around your conditions, medications and dietary requirements, so a plan for PCOS, endometriosis, heavy periods or all three is generated for you rather than assembled by hand. Tell us if you are vegetarian, gluten-free or avoiding certain foods, and the recipes adapt, with iron, fibre and omega-3 sources built in.
FreshPlate also checks recipes against your prescriptions, for example metformin, the contraceptive pill or iron supplements, and flags timing issues such as tea or calcium close to an iron dose. Our batch cooking guide helps you stock the freezer for days when pain or fatigue make cooking harder.
Frequently asked questions
What are the phases of the menstrual cycle and how does nutrition change across them?
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There are four phases: menstrual, follicular, ovulatory and luteal, and your needs shift modestly across them. Prioritise iron and vitamin C during your period, protein and fibre in the follicular and ovulatory phases, and slow-release carbohydrates plus magnesium in the luteal phase. Only the iron advice is strongly evidence-based; the rest is sensible eating.
Can diet cure PCOS or endometriosis?
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No. Diet cannot cure either condition, but steady blood sugar, omega-3 fats, fibre and vegetables can reduce symptoms for some people. Keep any prescribed treatment in place and discuss major changes with your GP.
What foods help with period pain?
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Oily fish, ginger, magnesium-rich foods such as nuts and seeds, and plenty of fruit and vegetables may help, though effects are modest. Heat and over-the-counter pain relief work faster for most people, and severe pain that disrupts daily life should be checked by a GP.
Should I take iron supplements for heavy periods?
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Only after a blood test confirms you are low. Many people with heavy periods need treatment, but taking iron unnecessarily can cause constipation and, in excess, harm. Your GP can test your ferritin and haemoglobin and advise a dose.
Sources
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