Olive Oil for Constipation: What the Trials Actually Measured
Olive oil for constipation is one of the oldest kitchen suggestions there is: a spoonful in the morning, taken neat or stirred into something warm. The appeal is obvious — most people already have a bottle, and it feels gentler than a laxative. But "people say it works" is not the same as "it has been tested", and the tests that exist are fewer, smaller and more specific than most articles admit. This piece sets out each human trial we could find, what it measured, in whom, and where its limits sit — then what the NHS suggests first, and when a GP, not a food, is the right next step.
For our own oil, see our cold-pressed organic Marrakech olive oil.
The Short Answer
- Olive oil is a food, not a constipation treatment. What exists is a handful of small trials in specific groups.
- The largest is a 2025 double-blind trial by Joukar and colleagues in 140 adults with chronic constipation at one clinic in Rasht, Iran: two tablespoons a day of extra virgin or refined olive oil for four weeks. Symptom scores fell in both groups and further with extra virgin — but there was no no-oil group.
- A 2015 double-blind trial by Ramos and colleagues in 50 haemodialysis patients found olive, flaxseed and mineral oil all improved symptom scores over four weeks, with no significant difference between them — and only 16 people took olive oil.
- The other two trials are narrower still: 110 heart-surgery patients compared with usual care, and 40 toddlers who had olive oil ointment rubbed on the tummy — not swallowed.
- The NHS starts with fibre, fluids, movement and a regular toilet routine, and lists blood in your poo, unexplained weight loss or a sudden change in bowel habit as reasons to see a GP.
Does Olive Oil Help With Constipation? The Direct Answer
Nobody can give an honest flat yes. Four small human trials have measured olive oil in people with constipation — Iranian outpatients, haemodialysis patients, heart-surgery patients and toddlers — and symptoms improved in each. But no trial that gave the oil by mouth compared it with a blinded dummy, and every study was short and narrow.
That matters because constipation often shifts on its own, and people who know they are being studied tend to report feeling better. A placebo group is how researchers separate the oil from those effects; for olive oil taken by mouth, that trial has not been done. The published work is consistent with olive oil helping some people as part of their diet, and none of it is strong enough to call it a proven treatment.
The Trials at a Glance
Every human trial we found that measured olive oil and constipation directly is below. Joukar and colleagues' 2025 trial in 140 Iranian adults, published in the Caspian Journal of Internal Medicine, is the largest and the only one to compare two grades of olive oil.
| Study | Who took part | Design and size | What was given | Main limit |
|---|---|---|---|---|
| Joukar et al., 2025, Caspian J Intern Med | Adults with chronic constipation, one clinic in Rasht, Iran | Double-blind randomised trial, 140 analysed | Two tablespoons a day, raw: extra virgin vs refined olive oil, 4 weeks | No no-oil group; polyphenols not measured; single centre |
| Ramos et al., 2015, J Ren Nutr | Adults on haemodialysis with constipation | Double-blind randomised trial, 50 people (16 on olive oil) | Olive, flaxseed or mineral oil from 4 ml a day, 4 weeks | Tiny groups; no placebo; kidney-failure population |
| Bahrami et al., 2025, J Complement Integr Med | Adults having coronary bypass surgery, Qazvin, Iran | Randomised trial, 110 people | 30 ml extra virgin olive oil a day with food, around surgery, vs usual care | No dummy oil, so not blinded; post-surgery only |
| Arman-Asl et al., 2021, Adv Exp Med Biol | Children aged 1–4 with functional constipation | Pilot placebo-controlled double-blind trial, 40 children | 85% olive oil ointment rubbed on the abdomen twice a day vs paraffin ointment, 4 days | Applied to skin, not eaten; 4 days; pilot size |
The 2025 Iranian Trial: Extra Virgin Versus Refined
Joukar and colleagues recruited adults diagnosed with chronic constipation by a gastroenterologist, using the Rome III criteria and a colonoscopy, at a clinic in Rasht in 2021; people whose constipation had another medical cause were excluded. Each took two tablespoons of olive oil a day, raw and on its own, for four weeks, without knowing which oil they had.
In this double-blind trial of 140 adults, Rome III symptom scores fell from 11.27 to 3.47 with extra virgin oil and from 11.37 to 7.74 with refined oil. By week four, 59 of 70 people on extra virgin oil reported normal stool types (Bristol types 3 or 4), against 17 of 70 on refined oil.
Reading the full paper rather than the abstract, three details stand out. The extra virgin oil was a high-polyphenol product its producer supplied at a reduced price. The authors did not measure polyphenols in either oil, which they name as a limitation. And five people who dropped out early because they disliked the taste were not counted in the analysis.
The Haemodialysis Trial: Olive Oil Against Mineral Oil
Ramos and colleagues ran a four-week double-blind trial in 50 constipated adults on haemodialysis, published in the Journal of Renal Nutrition in 2015, assigning them to mineral oil (17), olive oil (16) or flaxseed oil (17) from 4 ml a day. Scores improved in all three groups — from 10.3 to 3.2 with olive oil — and the difference between oils was not statistically significant.
The authors concluded olive oil was as effective as mineral oil in this group. The fairer reading of a 16-person arm with no placebo is that olive oil improved alongside an established laxative oil, in groups too small to detect a modest difference. People on dialysis live with dietary restrictions most readers do not share, and should talk to their renal team before changing what they eat.
Surgery Patients and Toddlers: Two Narrower Studies
Bahrami and colleagues randomised 110 adults having coronary bypass surgery in Qazvin, Iran, to 30 ml of extra virgin olive oil a day with food, from the day before surgery to 30 days after, or usual care. Constipation and pain scores fell more with the oil, but without a dummy oil participants knew what they were getting, and the result applies to recovery from major surgery, not everyday constipation.
Arman-Asl and colleagues' 2021 pilot trial in 40 children aged one to four is often cited as evidence for giving children olive oil. In fact the children had an ointment containing 85% olive oil rubbed onto the abdomen twice a day for four days, against a paraffin ointment; stool frequency improved more with olive oil, and no side effects were reported. It says nothing about oil given by mouth.
What the Trials Did Not Test
- A placebo by mouth. No oral trial used a blinded dummy, so the size of any real effect is unknown.
- The best dose. Amounts ranged from 4 ml to 30 ml a day; none compared doses.
- Timing. No trial tested morning versus evening — our article on olive oil before bed covers why the hour has not been shown to matter.
- Everyday constipation. Participants had diagnosed chronic constipation, kidney failure or heart surgery, or were toddlers.
As for how oil might help, fats are generally thought to soften stool and ease its passage, and the Joukar authors suggest polyphenols may play a part — untested, since they were not measured. Our guide to olive oil polyphenols explains what those compounds are.
What the NHS Suggests First, and When to See a GP
The NHS describes constipation as not having had a poo at least three times in the last week, or pooing less often than usual. Its first-line advice:
- Gradually increase the fibre in your diet — for example wheat bran, oats or linseed.
- Drink plenty of water and other fluids.
- Keep a regular toilet time and do not delay when you feel the urge; resting your feet on a low stool can help.
- Move more — a daily walk or run.
The NHS advises seeing a GP if constipation is not getting better, keeps coming back, or comes with blood in your poo, weight loss without trying, constant tiredness, tummy pain or a sudden change in how you poo. If a medicine may be the cause, a GP or pharmacist is the right person to ask.
If You Include Olive Oil, Keep It Sensible
- A tablespoon carries around 120 calories, so two a day is a real addition unless it replaces another fat. Our guide to how much olive oil per day sets out what the large studies used.
- Eating it on vegetables, pulses or wholegrain bread brings the fibre the NHS recommends along with the oil. If you prefer it neat, see our guide to drinking olive oil.
- A large dose of fat can worsen heartburn for some people — see olive oil and acid reflux. For the wider digestive picture, see olive oil and gut health.
- If you have gallbladder problems, kidney disease, a prescribed low-fat diet, or are pregnant, check with your GP before taking oil in spoonful doses.
The Honest Objections
"The refined group improved too — isn't this just fat, or placebo?" Possibly, in part; without a no-oil group nobody can say. What the Joukar trial does show is a clear difference between two grades under double-blind conditions.
"One clinic, a supplier discount, four weeks — that is thin." It is. The authors state the funders had no role in the trial, but this is a starting point for research, not a settled answer.
"Why not just take a laxative?" For persistent constipation a pharmacist or GP may recommend one, and that advice comes first. Olive oil belongs in the diet, not in place of being assessed.
Why Sidr & Stone
If you eat olive oil, the one practical pointer from this research is grade: in the only trial to compare them, extra virgin and refined oils did not behave the same. That is not a claim about our oil — no trial has tested it — but it is why we care how ours is made.
- Sidr & Stone's olive oil comes from one single estate — our own family-owned farm on the plains outside Marrakech, Morocco — with every step from tree to bottle under our control and no blending across origins.
- The grove is rain-fed, with no irrigation; the trees take what the season gives.
- It is organically grown, with no synthetic fertilisers, pesticides or herbicides; certification is in progress, as disclosed below.
- It is a limited single-harvest batch, picked when the fruit is ready and cold-pressed within hours of harvest to preserve flavour, aroma and polyphenols.
- It is unfiltered extra virgin olive oil, so natural sediment may settle — normal for an unfiltered oil.
- It is 100% natural: one ingredient, olive oil, nothing added.
- It comes in 500ml dark glass with a gold label, which helps protect the oil from light.
- Sidr & Stone gives 10% of profits to charity, with fulfilment in the UK, EU, and US.
We will not tell you Sidr & Stone is the best olive oil for constipation — that is exactly the kind of claim this article warns against. What we will say is that our oil is single-estate Moroccan, rain-fed, organically grown and cold-pressed within hours of harvest. We have not yet published lab figures for polyphenols or acidity, so we make no claim about them.
Frequently Asked Questions
Does olive oil help with constipation?
Small trials suggest it may help some people, but none is conclusive. In the largest, a 2025 double-blind trial of 140 adults in Iran, symptoms improved with both extra virgin and refined olive oil over four weeks, more with extra virgin, with no no-oil comparison. Persistent constipation needs a GP.
How is olive oil thought to work on the bowel?
Fats are generally thought to soften stool and ease its passage, and some researchers suggest polyphenols play a role. Neither has been confirmed in the constipation trials.
How much olive oil did the trials use?
From 4 ml a day in the haemodialysis trial to 30 ml a day in the heart-surgery trial; the largest used two tablespoons. No trial compared doses.
Is extra virgin better than regular olive oil for constipation?
In the one trial that compared them — 140 adults, four weeks, double-blind — extra virgin scores improved more than refined. Polyphenols were not measured, and it is a single study.
Is Sidr & Stone olive oil better for constipation than other olive oils?
We make no such claim, and no trial has tested our oil. It is single-estate, organically grown, unfiltered extra virgin oil, cold-pressed within hours of harvest.
Can I give olive oil to a child who is constipated?
Speak to a GP or health visitor first. The only children's trial, 40 toddlers over four days, used an ointment rubbed on the tummy — not oil by mouth.
Where can I buy Sidr & Stone olive oil?
Our cold-pressed organic Marrakech olive oil is on pre-order from a limited single-harvest batch, with estimated shipping from November 2026 and fulfilment in the UK, EU, and US.
Is olive oil a medicine?
No. Olive oil is a food, not a medicine. It has a long traditional history — including being honoured in the Prophetic Sunnah — and a substantial body of modern research, particularly around polyphenols, cardiovascular health, and the Mediterranean diet pattern. It can be a worthwhile part of a healthy routine, but it does not cure diseases and is not a substitute for medical care. Be cautious of any olive oil marketed with specific disease-cure claims.
Final Thoughts
The evidence on olive oil and constipation is more interesting than sceptics allow and much thinner than enthusiasts claim. Four small trials in four specific groups all saw symptoms improve; none tested oil by mouth against a blinded dummy, and the best of them compared two olive oils rather than olive oil with nothing.
The honest conclusion is modest. Olive oil is a good food to eat generously, extra virgin is a sensible choice when you do, and none of it replaces fibre, fluids, movement — or a GP when something has changed. For what to look for on a label, see our guide to choosing a quality olive oil.
Our cold-pressed organic Marrakech olive oil — single-estate, rain-fed and pressed within hours of harvest — is available to pre-order from the current single-harvest batch, with fulfilment in the UK, EU, and US.
Our extra virgin olive oil is grown organically on our own single-estate farm on the plains outside Marrakech: we control every step from tree to bottle, and no synthetic pesticides, herbicides or fertilisers are used. It is not yet certified organic — certification is in progress, and we will publish it as soon as it comes through.
Pre-Order Sidr & Stone Organic Marrakech Olive Oil — Limited Single-Harvest Batch →
Disclaimer: This article describes published research on olive oil and constipation at the time of writing; research findings may change, and readers should check current sources. Olive oil is a food, not a medicine, and is not a substitute for medical treatment of any condition. For any health concern, consult a qualified medical professional.