Bifidobacterium lactis and the science behind advertising claims in people
What it found
Only four trials in people backed up the claim that Bifidobacterium lactis speeds up gut transit.
None of the trials supported the immune defence claims made for Lactobacillus casei.
What they found
Studies in people
Gut transit time
Four trials in people found that Bifidobacterium lactis shortened the time food takes to move through the gut. These were the only studies rated as strong evidence by the authors.
Immune system markers
Trials in people looking at Lactobacillus casei measured things like immune cells and antibodies in blood or saliva. The authors say none showed real clinical benefits matching the advertising claims.
Stool frequency
Several trials in people found no difference in how often participants went to the toilet when taking Bifidobacterium lactis compared to a control product.
Other findings
Company website studies
The company website listed 47 studies, but only 12 met the strict criteria the authors set. Of the 35 website studies left out, most tested sick people or measured unrelated effects.
Funding sources
In 7 of the 16 included trials, the company declared it paid for the research. In several others, the company supplied the product or an author was linked to the firm.
What the authors conclude
- They conclude there is not enough scientific proof to back the health claims advertised for these products, especially for Lactobacillus casei.
- They advise policymakers to tighten rules so companies cannot use weak evidence in food advertising.
- They suggest doctors should be aware of how much trust shoppers place in these marketing messages.
How it was done
Companies advertise fermented milk drinks as boosting immunity or improving digestion. The authors wanted to check if the science actually supports those messages, and whether company websites show the full picture.
They searched medical databases for human trials testing these two specific bacteria in healthy people. They found 16 randomised controlled trials matching their criteria and compared them with 47 studies listed on the company website.
What it can’t tell you
- These trials looked only at healthy people, so they cannot show what happens in someone who is ill.
- A trial can show cause and effect for what it measured, but many of these studies relied on people reporting their own symptoms, which can be influenced by expectations.
Who paid
- Authors work at
- University of Alicante, Spain; University of Alicante, Ecuador
The paper
- Title
- Does the scientific evidence support the advertising claims made for products containing Lactobacillus casei and Bifidobacterium lactis? A systematic review
- Type
- Systematic review
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Meléndez-Illanes L, González-Díaz C, Chilet-Rosell E, Álvarez-Dardet C (2016). Does the scientific evidence support the advertising claims made for products containing Lactobacillus casei and Bifidobacterium lactis? A systematic review. Journal of public health (Oxford, England). doi:10.1093/pubmed/fdv151Free full textPubMed 26515088DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error