Study compares 8 probiotic products' efficacy

Empty stomach: Probiotics professor clarifies findings of efficacy study


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Lead author: “I think that the headlines in the papers do rather misrepresent the principal findings of the study..."
Lead author: “I think that the headlines in the papers do rather misrepresent the principal findings of the study..."

Related tags Probiotic

A soon-to-be-published UK study has questioned the efficacy of several on-shelf probiotic products after testing eight including giants Yakult and Danone – but the lead author tells us its key findings have been distorted in the press.

The University College London (UCL) School of Pharmacy researchers led by professor Simon Gaisford used an artificial gut employing pig gastric fluids for the tests that suggested liquid-based products were better than those that were freeze-dried in keeping probiotic strains alive in product formulations, and in the gut and intestines.

Professor Gaisford said that the levels of ‘probiotic survivors’ that made it from product, to gut, then into the intestine, did raise questions about efficacy in some products, but that the reporting had missed the key conclusion that empty stomach consumption was best.


“I think that the headlines in the papers do rather misrepresent the principal findings of the study…that the most likely chance of success would be if the patient took the product on an empty stomach to minimise gastric emptying time,”​ professor Gaisford told NutraIngredients.

The porcine gut simulation, ex-vivo study meant, “absolute number counts need to be treated with caution, as is always the case with plate counting.”

“The study showed that some products did show viable bacteria following exposure to gastric fluid. Symprove performed the best in our tests, but Actimel, Yakult and #VSL3 also looked capable of delivering live bacteria and Bio-kult had some viability over short - less than 10 min - gastric residence time."


But only Symprove, #VSL3 and Actimel delivered projected efficacious doses inside of the 12 hours in the gut-intestines after which they would expect to be expelled from the body. Some did not meet their label claims in the study that will soon be published in Beneficial Microbes​ journal.

One product – barley fluid probiotic formulation Symprove – met all three primary endpoints, while Probiotics International-owned Bio-Kult, which fared less well, called for a strain recount as it officially failed all three endpoints along with Align, Bio Balance and Probio7.

This provoked broadsheet publications like The Daily Telegraph ​to run stories like ‘Why claims for good bacteria drinks may be difficult to stomach’.

The 3 endpoints

  • Probiotic content versus label claim
  • Survival in the gut
  • Bioavailability in the bloodstream

Yakult pointed to its regulatory approval and more than 100 human studies conducted on its products including some that showed, survival of Yakult’s unique strain through the human gut at a high level, during the period of intervention and for a few days afterwards.”

“This characteristic (strain survival) is mentioned in Yakult’s advertisements in the UK, as approved by the relevant regulatory authorities.”

Danone informed us, "studies showed that there is a high transient increase in the levels of L. casei CNCM I-1518 in the ileum (final section of small intestine) and faeces".

Measurement matters


Bio-Kult said the strain formulation of its product was too complex for the pig gut simulation to accurately gauge.

“Bio-Kult is a broad spectrum probiotic containing 14 strains of bacteria from 5 genera and includes the unique strain Bacillus subtilis PXN 21…”​ brand owner Probiotics International Ltd. (Protexin) said.

Protexin said the strain, linked to a reduction in colic in children, which was contained in “large quantities”​ in Bio-Kult, was not picked up by the assay at all.

Surveys indicate 6 out of 10 British household regularly consume probiotics. The market there is estimated at over €250m.

Probiotics are most strongly linked in the scientific literature for boosting immune systems, reducing gastro issues like irritable bowel system (IBS) and reducing antibiotic associated diarrhoea (AAD) but have also been associated with skin, brain and even sports performance benefits. 



Beneficial Microbes (ahead of publication)

Comparative survival of commercial probiotic formulations: Tests in biorelevant gastric fluids and real-time measurements using microcalorimetry’

Authors: S. Gaisford, M. Fredua-Agyeman 

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