Lactobacillus reuteri grounded in evolution

Around four billion years ago the earth saw the emergence of its first forms of life – bacteria. Since then, these single-cell organisms have “populated” our planet. The reason they have been able to survive for such an incredibly long time – despite dramatically varying conditions such as volcanic eruptions and ice ages – is their fantastic ability to adapt. Research on bacteria and their importance for our health has literally exploded in recent years and new theories and insights are being published at a furious rate.

Research has shown that Lactobacillus reuteri is a species of bacteria that has developed a mutualistic relationship with its specific host over millions of years. In other words, throughout evolution certain strains of Lactobacillus reuteri have made their home in the specific environment that is found in the human gut. In some of us they still reside there today, while most others have insufficient levels.

Lactobacillus reuteri is one of few bacteria that has co-evolved with humans since the beginning of time, and because of that it is adapted to its host. L. reuteri is among the first bacterial species to become naturally established in the normal microbiota of the newborn.



The researcher Ivan Casas was fascinated by what he called the circle of life, how essential bacteria are transferred from parent to offspring and where the unique Lactobacillus reuteri was one bacteria that the mother should pass on to her child. In Peru he finds the strain Lactobacillus reuteri Protectis in the breast milk of an Indian mother. This became the starting point for BioGaia. Read more


The origin of Lactobacillus reuteri

The first strain of Lactobacillus reuteri (L. reuteri) for human use, L. reuteri DSM 17938, was isolated in 1990 from the breast milk of a Peruvian mother living in the Andes. The commercial name is L. reuteri Protectis. Other human strains from BioGaia are L. reuteri ATCC PTA 5289 and ATCC PTA 6475. L. reuteri ATCC PTA 5289 used in oral health products was isolated from the oral cavity of a Japanese woman with remarkably good dental status and L. reuteri ATCC PTA 6475 was isolated from breast milk in Finland.

L. reuteri species have been isolated from

  • Breast milk
  • The vagina
  • The mouth
  • The stomach
  • The small intestine
  • The large intestine
  • Feces

All our commercial strains are of human origin, naturally colonize humans, and are therefore more likely to actually have a positive effect on human health. Even an indigenous bacterium like BioGaia's L. reuteri Protectis should be taken on a regular basis, to reach high enough levels to achieve proper colonization and have a good effect.


Dosage and colonization

Based on clinical data 100 million CFU per day has been chosen as a safe and efficient dose of L. reuteri Protectis for humans. Further, since L. reuteri colonization is transient, dosing should be maintained to ensure adequate and stable L. reuteri levels in the gastrointestinal tract. Colonization of L. reuteri Protectis has been shown throughout the entire human gastrointestinal tract using biopsies technique.


Effect and safety

BioGaia’s probiotic products with L. reuteri are among the most scientifically well-documented probiotics in the world with regard to both efficacy and safety. To date the efficacy and safety of BioGaia’s different strains of L. reuteri have been documented in 184 clinical studies in 15,500 people of all ages. Results have been published in 159 papers in scientific journals (February 2018).

Safety has been proven in preterm babies, infants, children, healthy adults and immune compromised adults. No serious adverse effects have been observed up to the maximum tested dosage of 10 billion CFU per day, meaning 1000 times the recommended daily dose.


Lactobacillus reuteri is considered safe as it fulfills the following criteria

  • Human origin
  • Named and classified according to correct taxonomy
  • Manufactured under controlled conditions to eliminate contamination
  • Safety is avaluated and documented on target population
  • Harbors no toxins or transferrable antibiotic resistance genes