Bifidus Actiregularis, Bifidus Regularis, Bifidus Digestivum, Bifidobacterium Lactis and its variants are marketing names generated by Danone (known in the United States of America as Dannon) for one of the specific bacteria it uses in its “Activia” range of yoghurt products.
According to a reply received from Dannon by the Writerious blog, Bifidus Regularis (and therefore presumably all the variations of Bifidus…) is a proprietary strain of Bifidobacterium.
The source of “Bifidus” is from the intestinal bacterium Bifidobacterium animalis, a kind of bacteria found in the large intestines of most mammals, including humans. “Actiregularis” is an invented word, the first half of which which emphasises the active nature of the bacteria. In common with with Bifidus Regularis, the “regularis” part emphasises being “regular” and the “is” at the end suggests a scientific derivation. The bacteria is known as Bifidus Actiregularis in UK marketing materials and Bifidus Regularis in marketing materials from the USA.
Bifidus Actiregularis used to be called Bifidus Digestivum in UK marketing materials. “Digestivum” is an invented word which uses “digestive” as a root to suggest beneficial effects on digestion, combined with the latinate ending “um” to suggest a scientific derivation.
It is known as Bifidobacterium Lactis in Canadian marketing materials, where Lactis uses the Latin root for milk (“lac” / “lact-“) and “is” to suggest a scientific derivation.
It is known as “Digestivum Essensis” in German and Austrian marketing materials. These are both invented words, the first emphasising digestion and the second emphasising the “essential” nature of the nutrition, using latinate endings to suggest a scientific derivation.
The name of the bacteria changes from country to country and over time, to reflect differences in marketing strategy and consumer behaviour. One suggestion for the change in the UK from Bifidus Digestivum from Bifidus Actiregularis is that Bifidus Digestivum was so ridiculed it become a liability – do a Google search for Bifidus Digestivum to see the results.
The scientifically correct name for the bacteria is “Bifidobacterium animalis DN 173 010”.
The BBC has recorded an excellent radio programme about gut bacteria, including a discussion of the fundamental uncertainty about the very specific advertised claims for probiotics.