Probiotics: what are they?

‘Probiotics are live microorganisms that, when administered in adequate amounts confer a health benefit on the host’ (World Health Organisation).

There has been a dramatic increase in probiotic use worldwide in recent years to the point where it is now one of the most commonly consumed supplements, but what is the conflicting science around it?

Well, our gut plays an essential role in the digestion and absorption of the food we eat, and this is assisted by the many bacteria that live there. When we are born this gut bacteria, or gut flora, is passed to us during birth, and as we grow; genetics, age, lifestyle and most importantly our diet add to this flora.

Did you know that gut bacteria also plays a role in immune defence, and approximately 70% of our immune system is located in our gut (crazy right?!) Therefore, hundreds of years ago, scientists began to question whether they could improve health and immune function by modifying and replacing harmful microbes/bacteria, with useful microbes or ‘good bacteria’. Some of these ‘good bacteria’ you might recognise from advertisements where they refer to their food product containing ‘L. casei cultures’, or ‘Bifidobacterium genera’. 

Studies have demonstrated some effectiveness of probiotics in reducing the risk or symptoms of travellers’ diarrhoea, respiratory tract infections, IBS, inflammatory bowel disease, and ulcerative colitis when taken correctly. However, a lot is still unknown and therefore the European Food Safety Authority is yet to approve them for widespread medical use.

 Why might you consider taking a probiotic?

With continued investigation into the necessity and effectiveness of probiotics, we are still learning how they might impact our health. All humans have different diets and genetic backgrounds, therefore have different gut bacteria make up, another thing that makes us all unique! For this reason, people may respond differently to probiotics.

There are some cases where we have seen progress in proving their effectiveness:

Athletes: The International Society of Sports Nutrition have demonstrated their support for probiotics in certain cases for athletes. Athletes have varying gut microbiota in comparison to other populations due to volume of exercise, and higher protein consumption.

The immune defence decreases when an athlete’s training load is increased. This happens as intense, prolonged exercise – especially in the heat- increases the permeability of our gut making them more susceptible to infection. Therefore, specific probiotic supplementation for athletes has shown to promote healthy immune responses during regular, vigorous training.

Antibiotics: although antibiotics are effective in killing bad bacteria that may give you an infection, they kill the good bacteria also. Therefore, recommendations to consume a probiotic alongside an antibiotic can help maintain levels of good gut flora.

Foreign Travel: foreign travel can introduce your body to bacteria it is not used to.  It can also elevate exposure to pathogens that may induce illness like travellers’ diarrhoea. Taking a probiotic 2-3 weeks prior, during, and 1 week post travel can assist your gut in preventing travellers diarrhoea.

Did you know that many foods we regularly eat are fortified with probiotics?! This includes some yoghurts (Yakult and Actimel yoghurt drinks, Glenisk natural yoghurt), cheese, snacks, nutrition bars, and infant formula. These foods are all sufficient for maintenance of good bacteria and have much lower doses of live microorganisms than supplements. Including some of these in your diet regularly will delight your gut bacteria!

There is emerging evidence to suggest fermented foods are beneficial in providing health promoting bacteria so they might be a nice addition to your diet too! These foods may include; kombucha, kefir milk, sourdough bread and miso soup.

Prebiotics: feed your gut bacteria

Prebiotics are the foods that our gut bacteria thrive on to become healthier and stronger, and therefore influence our overall gut health. They not only feed our good bacteria, but also positively impact the environment that these good bacteria live in. Dietary prebiotics for the most part come in forms of carbohydrates. They cannot be broken down fully by enzymes in our stomach, or intestines. While all prebiotics are fibres, it is not the case that all fibres have prebiotic effects on our gut flora.

Some foods that prebiotics naturally exist in include; asparagus, garlic, wheat, onions, prunes, beans, peas, banana, leeks.

Probiotics in a nutshell

  1. Probiotics are good, live bacteria that live in our gut and play an important role in digestion, absorption, mood and immunity.
  2. Evidence has demonstrated some effectiveness of probiotics in reducing the risk of gastrointestinal disorders such as IBS, travellers’ diarrhoea, respiratory tract infections, inflammatory bowel disease, and ulcerative colitis.
  3. Many foods that we regularly eat have probiotics in them. These include yoghurt, cheese, some milks, and some fermented foods.
  4. Situations where you might consider taking a probiotic supplement include; athletes during vigorous training where immune systems may be tested, during and after a course of antibiotics, and before & during foreign travel.
  5. Don’t forget to feed your healthy gut bacteria with prebiotics i.e. include lots of fruit, veggies and legumes in your diet.

We hope this helped to unravel the evidence surrounding probiotics and when they might be of benefit.