L. Reuteri Yoghurt: What It Is, How It's Made and Does It Work?

L. reuteri yoghurt is milk fermented long and warm with a Lactobacillus reuteri culture instead of the two starter cultures that define yoghurt. It is a kitchen ferment with a following, not a tested food: no clinical trial has measured what eating it does, and the species' record comes from defined strains at stated doses in drops and capsules. This page is one spoke of the Wellgard probiotics guide.

Evidence at a glance

• Trials of home-made reuteri yoghurt: none.
• Trials of the species: colic, a 2024 pooled analysis in babies;⁷ bone, two trials of 90 and 239 women;^{8, 9} gut survival, one study of 19 adults.⁴
• Largest single trial: 239 women aged 50 to 60, two years, no difference from placebo.⁹
• Strongest measured outcome: daily crying in colicky babies, 64.66 minutes less with one specific strain.⁷

Sources checked on 17 October 2026.

What is L. reuteri yoghurt?

L. reuteri yoghurt is a home-made fermented milk: pasteurised milk, or a plant milk, inoculated with a culture that names Lactobacillus reuteri, usually with a spoonful of inulin to feed it, and held near body heat for a day or more, where ordinary yoghurt takes a few hours at a higher heat. The result is a tart, set or semi-set milk eaten by the bowl and used to seed the next batch.

The bacterium is a lactic acid species found in the human gut, urinary tract, skin and breast milk; its formal name is now Limosilactobacillus reuteri, and a culture may carry either name.³ The foods that carry it are on which foods contain Lactobacillus reuteri.

Is L. reuteri yoghurt really yoghurt?

Not in the standards sense. UK law reserves "yoghurt" for a milk product but names no cultures.¹ The international Codex standard for fermented milks does: yoghurt is the pair Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, at least 10 million live starter cells per gram to the end of shelf life.¹ A milk fermented with L. reuteri alone has neither culture. In the standard's terms it is a fermented milk; "yoghurt" is its kitchen nickname. The one live-culture claim authorised in Great Britain, improved lactose digestion, belongs to those two cultures; none is authorised for L. reuteri or for any live culture in a capsule.²

Is L. reuteri yoghurt a probiotic?

It contains live cultures; "probiotic" is a word the law guards. Scientists define a probiotic as live micro-organisms that, in adequate amounts, confer a health benefit,¹⁰ so UK and EU food law treats the word as a health claim, and no live culture has one authorised.² A home ferment with an unknown cell count fails the "adequate amount" test anyway. This blog says live cultures.

What does the long fermentation do to the bacteria?

It grows them, but nobody has counted a home batch. The published counts are laboratory ones: coconut milk fermented with L. reuteri held about 35 million to 370 million live cells per millilitre after 30 days in the fridge, depending on the strain.⁶

The cells reach the gut alive. In an open study of 19 adults given 400 million live cells of one strain a day for 28 days, the stomach lining of 8 of the 10 healthy volunteers and the duodenum of all 10 carried the species afterwards, against 1 and 3 before.⁴ The stay is temporary: a 2015 review calls ingested lactobacilli transient, present while eaten and fading afterwards.⁵ Neither study measured a symptom.

Does L. reuteri yoghurt work?

No trial has asked. The claims for the yoghurt borrow from trials of defined strains in other forms. In babies under three months with colic, a 2024 pooled analysis of randomised trials found daily crying 51 minutes shorter on live cultures overall and 64.66 minutes shorter with one specific L. reuteri strain given as drops.⁷ In 90 women aged 75 to 80 with low bone density, a year of one strain at 10 billion live cells a day meant shin-bone loss of 0.83% against 1.85% on placebo;⁸ the same strain in 239 women aged 50 to 60 for two years made no difference to bone loss.⁹ None measured bloating, bowel habit or digestive comfort in adults, testosterone, skin or weight. Trial by trial: what Lactobacillus reuteri does.

The SIBO claims run the other way. Small intestinal bacterial overgrowth is diagnosed and managed by a doctor, and no trial has given any L. reuteri product to people who have it. The one study linking the two is a 2018 case series of 30 people with gas, bloating and brain fog, all taking live cultures: 68% had SIBO, and symptoms eased in 23 of the 30 once the cultures stopped and antibiotics were given.¹¹ Anyone with diagnosed SIBO or unexplained bloating asks a GP first.

What do people report?

Reports from makers, not findings from a study. The taste is described as tarter and sharper than shop yoghurt, sometimes fizzy, with a sour rather than sweet smell; a batch that smells rotten or shows mould is binned. Texture runs from thick-set to thin; separation into curds and whey is common. Some report wind, bloating or looser stools in the first days; pooled across 36 randomised trials in 9,312 adults, live cultures caused no more adverse events than placebo, mild gut symptoms being the usual complaint.¹²

Is L. reuteri yoghurt safe to make at home?

For a healthy adult who follows the rules for home-made chilled food, the record shows nothing alarming; the rules matter more because the ferment is held warm for so long. Use pasteurised milk and clean equipment, and follow the Food Standards Agency's chilling guidance: a fridge between 0 and 5°C, cooled food into the fridge within one to two hours, and leftovers eaten within 48 hours or frozen.¹³ No test of a home batch says how long it keeps.

The NHS puts pregnant women, newborn babies, people whose immune system is weakened by a condition or a treatment, and older people at higher risk from listeria, and names unpasteurised milk and dairy made from it among the foods that carry it.¹⁴ The NHS pregnancy page lists unpasteurised dairy among foods to avoid, and a Cochrane review of live cultures taken in pregnancy found pre-eclampsia more common in the women who took them, so a midwife or GP decides.^{15, 16} The safety reviews add the seriously ill, anyone in hospital with a central line and premature babies, after case reports of bloodstream infections from live cultures.¹⁷ Nothing here is for babies: a health visitor or GP decides anything a baby is given. Full list: who should take care with live cultures.

What we don't know

• No trial has measured what eating home-made L. reuteri yoghurt does to any symptom or measure.
• No published count exists for the live cells in a home dairy batch.
• No trial has given any L. reuteri product to people with SIBO.¹¹

Frequently asked questions

Where can I buy L. reuteri yoghurt in the UK?

Almost nowhere ready-made. A few shop yoghurts add L. reuteri to the two standard cultures and name it on the ingredients panel.¹ Makers start from a culture sold for the purpose or an opened live-culture capsule naming the species, and seed each batch from the last.

How much L. reuteri yoghurt should I eat a day?

No trial sets an amount. The adult bone trials gave 10 billion live cells a day as a capsule;⁸ a bowl of ferment carries an unmeasured number. A serving a day is what people report.

When is the best time to eat L. reuteri yoghurt?

No trial compares times of day for L. reuteri in any form. The evidence on live cultures and meals is on morning or night for live cultures.

Is L. reuteri yoghurt good for lactose intolerance?

The authorised wording is "live cultures in yoghurt or fermented milk improve lactose digestion of the product in individuals who have difficulty digesting lactose", for the two yoghurt cultures at 100 million live cells per gram.² A reuteri ferment carries neither culture and is untested in people who struggle with lactose.

Sources

1. Regulation (EU) No 1308/2013, Annex VII Part III, retained in Great Britain: reserves "yogurt" (the regulation's spelling) for milk products, cultures undefined; legislation.gov.uk, in force 16 October 2026. Cultures and count: Codex Standard for Fermented Milks, CODEX STAN 243-2003, adopted 2003, revised 2008 and 2010.
2. EFSA NDA Panel. Scientific opinion on live yoghurt cultures and improved lactose digestion, 2010; authorised in Great Britain under Commission Regulation (EU) 432/2012. doi:10.2903/j.efsa.2010.1763.
3. Mu Q, et al. Role of Lactobacillus reuteri in human health and diseases. Review, 2018. PubMed 29725324.
4. Valeur N, et al. Colonization and immunomodulation by Lactobacillus reuteri in the human gastrointestinal tract. Open biopsy study, 19 adults, 28 days, 2004. PubMed 14766603.
5. Derrien M, van Hylckama Vlieg JE. Fate, activity, and impact of ingested bacteria within the human gut microbiota. Review, 2015. PubMed 25840765.
6. Mauro CSI, Garcia S. Coconut milk beverage fermented by Lactobacillus reuteri. Laboratory study, two strains, 30 days chilled, 2019. PubMed 30906043.
7. Vaz SR, et al. Probiotics for infantile colic: is there evidence beyond doubt? Pooled analysis of randomised trials, infants under 3 months. Acta Paediatrica, 2024. PubMed 37962097.
8. Nilsson AG, et al. Lactobacillus reuteri reduces bone loss in older women with low bone mineral density. Randomised trial, 90 women, 12 months. Journal of Internal Medicine, 2018. PubMed 29926979.
9. Gregori G, et al. Randomised trial of one Limosilactobacillus reuteri strain and early postmenopausal bone loss, 239 women, 2 years. JAMA Network Open, 2024. PubMed 38865129.
10. Hill C, et al. Consensus statement on the scope and appropriate use of the term probiotic. Expert consensus, 2014. PubMed 24912386.
11. Rao SSC, et al. Brain fogginess, gas and bloating: a link between SIBO, probiotics and metabolic acidosis. Case series, 30 people with brain fog and 8 without; no funding, 2018. PubMed 29915215.
12. Liao W, et al. Probiotics for the prevention of antibiotic-associated diarrhea in adults. Pooled analysis, 36 randomised trials, 9,312 people, 2021. PubMed 33234881.
13. Food Standards Agency. How to chill, freeze and defrost food safely. Guidance, 18 December 2017. gov.uk.
14. NHS. Listeriosis. nhs.uk/conditions/listeriosis. Page last reviewed 10 November 2023.
15. NHS. Foods to avoid in pregnancy. nhs.uk/pregnancy/keeping-well/foods-to-avoid. Page last reviewed 15 June 2026.
16. Davidson SJ, et al. Cochrane review of live cultures given in pregnancy against gestational diabetes, 7 trials, 1,647 women; pre-eclampsia in 4 trials, 955 women, 2021. PubMed 33870484.
17. Doron S, Snydman DR. Risk and safety of probiotics. Safety review, 2015. PubMed 25922398.

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