What is Acidophilus?

Acidophilus is probably the most well-known and well-used species of friendly bacteria, so for those considering a live cultures supplement, they might be under the impression that this is the best option for them. (Read more about live cultures). 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: its full name is written as Lactobacillus acidophilus, sometimes abbreviated to L. acidophilus. It is a naturally occurring bacteria found in the gut, mouth and vagina and has been incredibly well-researched in studies focusing on a number of different areas of health. Due to its numerous health benefits L. acidophilus is commonly found in live cultures supplements, such as our own.

Within the acidophilus ‘species’, there are a large number of specific ‘strains’ (types). One example is 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 Every Day EXTRA and Every Day MAX. Other L. acidophilus superstars include Lactobacillus acidophilus Rosell-52 (in our Every Day, For travelling abroad and For Those On Antibiotics), Lactobacillus acidophilus La-05®, and Lactobacillus acidophilus La-14®   (in our ‘For pregnancy’).

*Acidophilus is a species of bacteria that sits within the Lactobacillus genus. Within the species, there are many different individual ‘strains’.

Acidophilus under microscope
L. acidophilus under microscope

Are all strains of L. acidophilus the same?

All strains of L. acidophilus are part of a genus (or ‘family’) of lactic-acid-producing bacteria called Lactobacillus. Strains from this 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 level.

*Different strains within the same species have different modes of action in the body, so it is important to find the strain that is most suitable for you.

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

What is acidophilus used for?

Lactobacillus acidophilus is a species of lactic acid-producing bacteria. Once they have colonised the gut, they ferment carbohydrates and sugars and produce lactic and acetic acids as a by-product. These acids lower the pH of the intestines, which protects us from pathogen over-growth, and favours the proliferation of ‘good’ or ‘friendly’ bacteria in the gut. In this way acidophilus is beneficial in maintaining a healthy balance of gut flora.

L. acidophilus bacteria prefer to use sugars as their fermentation substrate. This means that they break down sugars as they pass through our intestine. One amazing acidophilus benefit is to people that have certain food intolerances. Where they lack sufficient digestive enzymes to break down components of their food, such as lactose (a sugar found in milk and dairy products) – the bacteria can do it for them.

Beyond these characteristics, which are common to all bacteria within the acidophilus species, most of the known benefits of L. acidophilus are found at ‘strain’ level. For example, Lactobacillus acidophilus NCFM® has very different characteristics and health benefits to Lactobacillus acidophilus La-14®.

*Research into the best acidophilus supplement to take for a specific health condition or symptom, should be carried out at strain level.

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, and your own specific health requirements, which can involve a bit of searching.

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

One of the most highly researched strains of acidophilus is Lactobacillus acidophilus NCFM®, which can be found in our supplements Every Day EXTRA and Every Day MAX, both of which satisfy the above mentioned product quality criteria.

*Do your research before buying an acidophilus supplement. Choose strains that meet your own individual health needs, whilst also satisfying the above quality criteria.

Dosage: how much acidophilus should I take?

This question is a little tricky to answer, as different health symptoms require not only different strains of acidophilus, but potentially different acidophilus dosages. As a general rule I would advise following the clinical trial data as closely as possible. So, if a double-blind, placebo-controlled clinical trial shows efficacy for supporting a condition or symptom that is of relevance to you, I would recommend taking as close to the same daily dosage that was used in the trial as you can. Wherever possible our acidophilus supplements are formulated in this way too, using data and dosage information from the most efficacious clinical trials.

Live cultures come in different ‘formats’, and how you prefer to take your daily dose is a personal choice. You can choose from acidophilus powders, acidophilus tablets, acidophilus capsules and even acidophilus in liquid format. The majority of products on the market are in capsule format, as these are generally found to be easier to swallow than tablets, and have better shelf-stability, and less risk of contamination than loose powders (powders portioned in to individual sachets also avoid the risks associated with loose powders).

Some manufacturers of live cultures use enterically coated capsules, which are said to protect the bacteria inside them from the harsh acidic conditions of the stomach. We however, use robust strains of friendly bacteria that are known to survive at a low pH anyway, so we have no need for enteric coating. This means that our capsules can be opened, and the contents sprinkled on to food or drinks (so long as they are not hot or too acidic) with no loss to product integrity. Even if you open up our acidophilus capsule in this way, you can still be sure that the bacteria will survive and you are getting the full dose. You may like to read the following FAQ: Can I open probiotic capsules?

*Different conditions may require different doses, where possible take a similar CFU (billions) count to that used in clinical trials into your specific health condition.

Are there any side effects from taking acidophilus?

In general live cultures, including those from the acidophilus species, have very few side effects. The majority of people do not experience any negative symptoms from taking an acidophilus supplement. However, everybody is different, and therefore everyone reacts to things differently.

With the introduction of any new live cultures supplement, some people may initially experience mild digestive symptoms, such as: bloating or excess gas. In most cases these symptoms do not last for longer than a few days, and are simply the result of a shift in microbial population and diversity. Mild acidophilus side-effects can simply be a sign that changes are taking place within the eco-system of their gut. 

Whilst mild symptoms may be bothersome, they are for the most part, a positive sign that the ‘friendly’ bacteria are doing their ‘job’, crowding out pathogenic strains of bacteria and competing for space on the gut wall lining.

However, if any side effect is troubling you, or lasts for longer than described, I would always recommend stopping taking the product and contacting the manufacturer for advice. It could be other ingredients in the product that are causing issues, such as a prebiotic fibre. Or, it could just be that the strain of acidophilus is not compatible with your individual microbiome at that time. Always listen to your own body, and respect its uniqueness.

Read our FAQ ‘Do live cultures have side effects?’ to find out more.

*L. acidophilus may occasionally cause mild abdominal discomfort and/or bloating in some people, but this typically only lasts for a few days. If symptoms persist speak to the manufacturer for advice.

How long does acidophilus take to work?

This is a question that everyone wants to know the answer to, but frustratingly there is no ‘one size fits all’ here either! With everyone’s microbiome being as unique to them as their fingerprint, it is impossible to know for certain how long it will take to feel the benefits of taking acidophilus supplements.

We receive wonderful feedback and product reviews from our customers. For some people our supplements have an almost instant effect, whereas for others it can take several weeks or more. It depends partly on the state of a persons’ health to start with and also their compliance with taking the product. Diet, lifestyle and any medications being taken are other factors to consider. In general, I would advise patience. The benefits are well worth it, and your health will thank you for it in the longer term.

*Everybody responds differently, and at different speeds, when starting a new live cultures supplement. Don’t be disappointed if results take a little while, they will be worth it in the longer term.

Shop for acidophilus.

For further research in to L.acidophilus and specific strains within this species healthcare professionals might like to take a look at The Probiotics Database.

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