What are Probiotics?

Dr Kate Stephens PhD Food and Microbial Sciences; Gut Microbiology (University of Reading), BSc Medical Microbiology

Probiotics are microorganisms that are thought to be beneficial to the human host. The digestive tract is home to trillions of microorganisms. Some of these are good for us, some are harmful and some are neutral. The term 'probiotics' describes the beneficial microorganisms which take on a number of tasks. The main one is to crowd out harmful bacteria in order to keep your gut healthy. With around 70% of your immune system based in your gut¹, gut health is a key factor to our overall wellbeing. To learn more, read gut health - all you need to know.

Probiotic strains under the microscope - from left to right: B. lactis BB-12, L. acidophilus LA-05 and B. infantis Rosell-33

Probiotics are also known as friendly or good bacteria. But if we're being specific, it's worth pointing out that some probiotics are actually yeasts!

What do probiotics do?

Probiotics are thought to support immune health by stimulating the body’s natural defences, and by lining the intestines with a protective layer of friendly bacteria that bars pathogenic substances in the gut from harming the body. As two-thirds of the body's immune system is managed in the gut, it may be important to keep one's probiotic levels high.

Research shows that probiotics support digestive health by producing specific enzymes needed in the digestion of food and aiding the break down of food substances.

Probiotics are also believed to improve the absorption of vitamins & minerals into the bloodstream, and even produce B complex vitamins & vitamin K.

What are probiotic strains?

Not all probiotics are the same. Research shows that different probiotic strains can help support different areas of health. But what exactly is a strain? A strain denotes a type of bacteria - and informs us on a very specific, in-depth level (more specific, than a species, for example). Take a look at the image below to understand the context of genus, species and strain.

It's important to look at the strain level, as comparing different species is like comparing cats & dogs!

GENUS: A genus is a biological classification of living organisms. The term comes from the Latin genus meaning group. A genus contains one or more species. Examples of common probiotic genera include Bifidobacterium and Lactobacillus.

SPECIES: ‘Species’ refers to a type of microorganism existing within a genus or family. For example, acidophilus is the name of a species within the Lactobacillus genus.

STRAIN: A probiotic ‘strain’ is a genetic variant or subtype of a species. Different probiotic supplements contain different strains, which may be classified under the same species and genus. However, one acidophilus is not equal to another acidophilus. It’s the strain level that matters when you choose a probiotic in order to help with a specific health condition. If you're looking to take a probiotic, make sure to look out for robust, well researched strains when choosing the right for you.

After all, when choosing a dog there is a difference between embarking on life with a Labrador or a Dachshund.

What happens when you have an imbalance of bacteria in the gut?

Disruptions to the good bacteria in the gut can compromise our health. The resulting imbalance of good and bad bacteria is known as ‘dysbiosis’ and can result in poor digestion, lowered natural immune health and a large variety of conditions such as:

Low Energy Levels
Poor Immune Health
Gas or Bloating
Food intolerances or Allergies
Acne and/or Eczema
Indigestion, Heartburn
Constipation or Diarrhoea
Irritable Bowel Syndrome (IBS) symptoms

Clinical trials and extensive research have shown that probiotic supplementation may be an effective way of supporting a healthy gut. Find out more by reading: How do probiotics work?

What’s the difference between Probiotics and Prebiotics?

Whereas probiotics are the beneficial microorganisms themselves, prebiotics are a source of food for probiotics and help them grow, multiply and survive in the gut. For more information, take a look at our article: What are Prebiotics?

Probiotics and health concerns

The Probiotics Database provides more detailed information on some of the most researched strains in the world, and explores the clinical research behind different strains, for different circumstances. Health professionals can view the Probiotics Database on the Probiotic Professionals site. When it comes to research on probiotics, generally speaking the bulk of the gold-standard clinical trials suggest that probiotics can help to support gut health. However, emerging fields of research include a huge variety of health concerns, such as weight loss, skin health and even mental health. Research into probiotics is growing at an exponential rate - so probiotics remain an exciting field to watch.

Is there a difference between live cultures and probiotics?

Whilst live cultures and probiotics are often used as synonyms, strictly speaking they are not exactly the same thing. We love live cultures and fermented foods and drinks such as kimchi, kombucha and kefir. Recipes to make your own fermented foods are on trend and these are indeed thought to contain live cultures which may help to support a healthy gut. However if we take the definition that probiotics are microorganisms that are proven to have health benefits on the human body, then it's worth pointing out that live cultures found in foods and drinks are not usually clinically trialled, and therefore cannot be linked to a specific health benefit. There is also rarely a guarantee of the types or numbers of live cultures found in a fermented foods. It may therefore be more accurate to refer to most fermented foods as containing 'live cultures', and reserve the term 'probiotics' for foods and supplements that have been clinically studied in humans and proven to have health benefits. For more information on this topic take a look at the Food Myth.

What is the microbiome and what influences it?

Our body is host to trillions of microorganisms, also known as microbes. The collective term for these microbes (bacteria, viruses and fungi) which call our body their home, is the microbiota. All the genes inside these microbial cells are referred to as the microbiome. Each human being’s microbiome is completely unique and has a profound effect on the anatomical, physiological and immunological development of the host.

Factors that can disrupt the balance of our microbiome:

Exotic travel
High sugar intake
Processed food / junk food
Contraceptive pill
Stress
Indigestion of pesticides/pathogens
Caesarean birth/bottle feeding
Age
Low diversity / low fibre diet
Medicines / antibiotics

What is the best probiotic to take?

If you are thinking about taking a probiotic or prebiotic and are unsure where to start or what to take, ask for help from a specialist. Choosing the right one should depend on the specific health concerns you have, as different types of probiotics have been shown to help support different areas of health.

Infographic: Probiotics - All You Need To Know