Probiotics Explained – What Are Probiotics?

Probiotics are by now generally well-known. Thanks in particular to the efforts of yoghurt marketers, most people are aware that probiotics may offer some health benefit to them, whether in digestive terms or for general good health.

But beyond this vague understanding and notions of ‘friendly bacteria’, genuine knowledge is thin on the ground. Just what are probiotics? And why do we think they might be good for us?

Here is a quick primer to help you understand probiotics, and how they may benefit your health.

What Are Probiotics?

The marketing phrase ‘friendly bacteria’ (or ‘good bacteria’) is actually not far off the mark.

Probiotics are micro-organisms that confer health benefits to their host. Micro-organisms much like the bacteria that we blame for illness, but with that crucial difference – they benefit the host rather than attack it.

Most commonly found in the gut, and sometimes known collectively as ‘gut flora’, probiotics aren’t essential for our health, but may offer some health advantages. We are all born with gut flora which changes as we go through life.

Just as with ‘bad’ bacteria, there are millions of different strains that all have different effects on us. However, when approaching probiotic supplements or probiotic enriched foodstuffs, the most common strains are Lacti acid bacteria (LAB) and Bifidobacteria.

Why Take Probiotics?

We are encouraged to supplement our diets with probiotics for two reasons: to aid digestive health (preventative or as treatment) and to strengthen our immune systems.

The weight of evidence favours the former. Although research into probiotics is still relatively young, the most promising studies lie in treating digestive health issues such as inflammatory bowel disease (IBS).

For example, in one study ( Dr. Gerald Friedman found that administering a daily multi-strain probiotic in 84 IBS patients progressively reduced daily occurrences of diarrhoea over a 28 day period.

Another ( found significant effects in using probiotics to help reduce antibiotic associated diarrhea in infants.

Using probiotics to help maintain a healthy immune system broadly rests on two theories.

The first is that the right probiotics (such as LAB) help to create a more acidic environment in the gut, whereas harmful bacteria prefer a more alkaline environment.

The second is simply a case of ‘the more good bacteria you have, the less space there is for bad bacteria’. Healthy gut flora takes up space and nutrients that would otherwise be used for harmful pathogens to thrive.

How to Take Probiotics

Probiotics occur naturally in some foods, most notably in dairy products such as yoghurt and cheese. That’s why it’s nearly impossible to find a yoghurt on the supermarket shelves that is not ‘probiotic’ – regardless of whether it has had active culture artificially added. All yoghurts are to some extent probiotic.

Alternatively, probiotics can be taken as a dietary supplement. There are different strains available, corresponding to the different known effects, so do some further research or consult a qualified nutritionist to be sure you’re taking the right strain for you.


Nick Lewis is a health writer specialising in natural health issues, including probiotics. If you would like more information about probiotics visit

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