Activia: The importance of strain specificity

The International Scientific Association for Probiotics and Prebiotics (ISAPP) defines probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host”.[1]

However, not all probiotics are the same. Even within the same genus and species, individual strains can operate in distinct ways. Understanding the specific roles of strains, can help us differentiate those which are live cultures and those which are probiotics. For example, understanding the different strains within Activia can help us appreciate how they work together within the fermentation process and how they support health outcomes, like digestive health.[2][3]

Like all living organisms, probiotics are classified within a taxonomy that highlights their shared characteristics and unique properties and provides a uniform and internationally understood nomenclature to simplify understanding.

Probiotics can be identified by their genus, species, subspecies and strain, which are the final four levels in the taxonomy classification system.

While taxonomy differs between animals and microorganisms (for example we might refer to breeds of dogs and strains of bacteria), both help to organise and identify organisms with precision. Just as distinct dog breeds have unique traits, probiotic strains may offer specific health benefits unique to that strain, for example, to help target specific digestive symptoms, like bloating or constipation.

While nomenclature is intended to provide order, sometimes the use of different naming conventions can do the opposite. The strain CNCM I-2494 of Bifidobacterium animalis subsp. lactis is often referred to by different names in publications and within scientific materials. This strain also goes by Bifidobacterium animalis subsp. lactis DN-173-010 and is commercially sometimes known as Bifidus Actiregularis®.

The name containing CNCM and used throughout this website (sometimes as the shortened version B.lactis CNCM 1-2494) refers to the nomenclature used by the Pasteur Institute’s National Collection of Cultures of Microorganisms (CNCM in French), while the name containing “DN” refers to Danone’s own coding identifier for the strain, but they are one and the same.

Strain specificity is crucial to the function of probiotics. For example, Bifidobacterium animalis lactis CNCM I-2494 is a robust, acid-resistant strain that thrives in dairy and survives digestion in sufficient numbers to remain active in the gut.[5-8] Its health benefits, including an improvement in symptoms associated with minor digestive discomfort, are well-documented through numerous clinical trials.[2-3]

A 2014 randomised controlled trial further emphasised the importance of strain specificity. Researchers gave patients on antibiotics one of two commercially available probiotics-supplemented yoghurt drinks that both contained bacteria of the same genus and species of Lactobacillus casei, but of two different strains, Lactobacillus casei Shirota and Lactobacillus casei DN-114001. These two have been particularly well studied for immune support and digestive symptoms such as constipation and diarrhoea. Only the group receiving the Lactobacillis casei DN 114001 strain saw a significant reduction in antibiotic associated diarrhoea.[4]

Choosing the right strain is fundamental, but it’s just the beginning. Healthcare professionals recommending probiotics also need to consider the right amount for the right usage within different populations that have different health conditions and status.[5]

This is where having access to research findings is key. Clinical trials that examine health outcomes in particular populations shed light on how we can recommend probiotics and probiotic-containing foods for specific conditions, such as constipation, diarrhea, and immunity, among others. A product merely stating it contains probiotics or live cultures may not be enough to guarantee specific health outcomes and benefits. Recommendations must be backed by clinical evidence.

Recently the UK Edition of the Guide to Probiotics was published, which includes a list of commercially available probiotic products that are based on peer-reviewed publications. This is a helpful tool that can assist health professionals with decision making regarding appropriate selection of probiotics: Probiotic Chart.

Activia contains five key strains, which together play a vital role in contributing to the fermentation process and delivering targeted digestive benefits and sensory traits (such as texture):

1 - Bifidobacterium animalis subsp. lactis CNCM I-2494 (patented as Bifidus Actiregularis®): Grows well in a dairy matrix and can survive the entire GI tract[6-9] Also helps balance the intestinal microbiota and promotes healthy digestion[2-3].

2 - Lactococcus lactis CNCM 1-1631: A starter culture used in Activia yogurt fermentation, contributing to a creamy texture.

3 - Streptococcus thermophilus CNCM 1-1630: Produces lactic acid, aiding lactose digestion and creating a beneficial environment for other live cultures[10]. While s. thermophilus is a standard yogurt bacterial culture, the strain added to Activia is unique.

4&5 - Lactobacillus bulgaricus (2 strains: CNCM 1-1632 & CNCM 1-1519): Help lower product acidification[11].
Work synergistically with S. thermophilus to bring texture and support lactose digestion[10]. Lactobacillus bulgaricus is a standard yogurt bacterial culture, but the strains added to Activia are unique.