What is Acidophilus?

Acidophilus is probably the most well-known and well-used species of friendly bacteria, and so if you are considering a live cultures supplement, you might be under the impression that this is the best option for you. However, first it’s important to understand what acidophilus actually is, and to distinguish between acidophilus and other kinds of good bacteria.

Acidophilus taxonomy diagram
Taxonomy diagram

What is 'acidophilus'?

Acidophilus is a species of bacteria from the Lactobacillus genus, and its full name is written as Lactobacillus acidophilus, sometimes abbreviated to L. acidophilus. It is also a naturally-occurring bacteria in the gut, and has been incredibly well-researched in studies focusing on a number of different areas of health.

Within the acidophilus species, there are also a number of specific strains (types), such as Lactobacillus acidophilus NCFM®, which is perhaps one of the most widely researched strains of bacteria in the world, and certainly the most extensively researched strain of L. acidophilus. You can find this strain in our ‘For every day EXTRA Strength’ and ‘For every day MAX’. Other L. acidophilus superstars include Lactobacillus acidophilus Rosell-52 (in our ‘For every day’, ‘For travelling abroad’ and For Those On Antibiotics) and Lactobacillus acidophilus La-05®.

Acidophilus under microscope
L. acidophilus under microscope

Are all strains of L. acidophilus the same?

All strains of L. acidophilus are part of a family of lactic-acid-producing bacteria called Lactobacillus. Strains from this family, or 'genus', tend to be the most widely used in live cultures supplements due to their versatile nature. But not all strains within the L acidophilus species have the same properties, so when looking at live cultures supplements, it is best to compare them at strain level, as opposed to merely species or genus. Different strains within the same species will have different modes of action in the body, and it is important to find the strain that is most suitable for you.

Healthcare practitioners can find out more about L. acidophilus on the Probotics Database, on Probiotic Professionals.

How do I find the best acidophilus?

This really depends on what is meant by ‘best’! In terms of suitability, it’s a case of finding the right strain to suit you, which can involve a bit of searching.

However, there are a few key ways to ensure that the supplement in question is of a high quality. Firstly, it should have sufficient scientific evidence to support its safety and survival to the gut. Secondly, don’t be drawn in by huge billion counts. Higher billions does not necessarily equal higher quality – it’s much more important to get the right strains, even if they’re in lower quantities. Lastly, check it has a 'time of expiry' guarantee as opposed to a 'time of manufacture' guarantee, as this means the contents are guaranteed until the supplement goes out of date, rather than just at the time of manufacture (as numbers can decrease after this point).

One of the most highly researched strains of acidophilus is Lactobacillus acidophilus NCFM®, which can be found in our supplements ‘For every day EXTRA Strength’ and ‘For every day MAX’, both of which satisfy the above criteria.

Authors: Dr Aisling Dwyer MB BCh BAO (Medicine, Surgery and Obstetrics), MSc (Personalised Nutrition)​, Dr Kate Stephens PhD Food and Microbial Sciences; Gut Microbiology (University of Reading), BSc Medical Microbiology