What are probiotics? A definition
Are supplements or food the best probiotics?
What is probiotics used for?
What are the benefits of probiotics?
Find out probiotics benefits & effects on our gut bacteria & health.
Find out what type of bacteria are probiotic.
What are postbiotics?
What is probiotics? A definition
Probiotics are live bacteria thought to have health benefits when taken.
They are often referred to as “beneficial”, “helpful”, “good” or “friendly” bacteria.
The World Health Organisation definition of probiotics is:-
“live microorganisms which when administered in adequate amounts, confer a health benefit on the host”
How to take probiotics? Supplements or food?
You can take probiotics in several ways:-
– As food supplements
In capsules or powders containing large numbers of live or freeze dried bacteria
Usually several types of bacteria are taken together as a supplement.
– Eat in foods containing freeze dried bacteria
Recently, some foods (like chocolate & granola bars) have freeze dried probiotic bacteria added to them.
What are the best probiotics?
We currently know only a few types of helpful bacteria & yeasts.
The bacteria we currently use as probiotics are mostly from the dairy industry.
Lactic acid bacteria have been used in fermenting milk into yogurt & cheese for centuries.
Lactic acid bacteria can be easily grown & survive in oxygen, so in early experiments, they could be seen & investigated under microscopes in the laboratory.
These are the best known & researched probiotics so far.
Many of the bacteria in our guts & food are anaerobic (meaning that they can’t survive in oxygen).
This means they are harder to grow once they are outside the body – ie. in a laboratory.
There are many more bacteria that could have health benefits, we just haven’t been able to discover them yet.
Future research will use new techniques to investigate anaerobic bacteria
This should uncover new strains of potentially helpful bacteria to use as probiotics.
Fermented foods may contain a wider variety of bacteria
These can contain a wider variety of naturally occuring bacteria than are found in supplements.
If these foods are pasteurised or sterilised for longer shelf life & food safety, the probiotic bacteria will be killed off by the heat.
The effects & benefits of probiotics on our gut bacteria & health
To reach our gut, probiotic bacteria must make it through the stomach acid alive.
It is estimated that about a billion of these probiotic bacteria need to get through intact, to have any effect on our microbiome.
Around 100 trillion bacteria already live in our gut.
They don’t want to give up their hard won home in the gut wall, which allows bacteria to survive, feed and reproduce.
Probiotics pass through our digestive system, they don’t seem to colonise, or survive long term.
Researchers have seen traces of probiotic bacteria in the gut for weeks after they have been taken.
But taking probiotics doesn’t seem to change our normal balance of gut bacteria.
Despite not settling in the gut long term, probiotic bacteria seem to have positive effects on our health
Studies show these probiotic “guests” can boost our immune system by:-
– communicating with the cells & bacteria that live in our gut
– soothing inflammation whilst in transit through the gut.
What are Probiotics good for? What are the health benefits of Probiotics?
Scientists at the International Scientific Association for Probiotics & Prebiotics find strong enough evidence to state that taking probiotics can help:-
– reduce antibiotic associated diarrhea
– reduce the incidence and duration of common colds (upper respiratory tract infections)
– improve mild to moderate IBS (Irritable Bowel Syndrome) and other digestive symptoms
– reduce crying time in colicky but otherwise healthy infants
– manage vaginal infections
Other scientific studies have found probiotics can help:-
– reduce the duration of infectious diahhrea & acute diarrheal illness
– alleviate eczema, hayfever & allergies
– reinforce the gut wall barrier
– restore the microbiome after antibiotics
– lower cholesterol levels in some people
Research continues into exactly how and why probiotics help our health and why effects vary from person to person.
Research into probiotics benefits has varying results
Results from research into taking probiotics is not consistent.
Probiotics benefits vary from person to person, depending on :-
– the unique mix of bacteria in their guts
– how quick their digestive system is
– the acidity of their stomach
The make up of our gut bacteria changes day by day, dependent on what you eat & whether you have had antibiotics or other medicines recently.
So even within the same person, the effect of any probiotic can vary over time.
Different types of probiotic bacteria help some people more than others and no one strain will work for everyone.
This makes it hard to test new probiotics accurately as we can’t clearly compare the effects.
We can’t yet predict how a particular probiotic will effect us.
When one study has good results, it is hard to repeat in further studies.
We don’t yet know how exactly how many probiotic bacteria we personally need to take, which bacteria do what & which strains are most effective for us.
What probiotics are best to take & when?
Finding the best probiotic to take, to work with the unique blend of bacteria in your gut, can be a case of trial & error.
You may need to try several different probiotic supplements to get the health benefits you hope for.
Probiotics don’t take up long term residence in your gut.
– Once you’ve found the right one for you, you’ll need to replenish the helpful bacteria in your gut.
–Take your chosen probiotics regularly to keep your stocks topped up.
Probiotics are safe to take as supplements & eat in fermented foods.
Follow any instructions given on the label for both foods & supplements.
Talk to your doctor first though, if you have a compromised immune system or IBS / other digestive disorders.
What are probiotics? & What type of bacteria are probiotics?
The best known probiotics are lactic acid bacteria, for example, Lactobacilli and Bifidobacteria.
Lactic Acid bacteria break down the sugars in milk (lactose) into lactic acid.
These include types (or strains) of Lactobacillus (such as Acidophilus) & Bifidobacteria.
– Lactobacillus bacteria are found naturally in milk.
They break down (ferment) lactose (sugars in milk)
– Bifidobacteria ferment lactose.
They live in our intestines and are also found in dairy products like milk, yogurt and cheese.
Different probiotic supplements will have different blends & types of bacteria, either live or freeze dried.
Here are some of the common types of bacteria often found in probiotic supplements:-
– Bifidobacterium breve
– Bifidobacterium longum
– Bifidobacterium infantis
– Lactobacillus plantarum
– Lactobacillus paracasei
– Lactobacillus acidophilus
– Lactobacillus delbrueckii subsp. Bulgaricus
– Lactobacillus rhamnosus
– Streptococcus thermophilus
What are Probiotics with Yeast : Saccharomyces boulardii
Saccharomyces boulardii is a type of yeast used as a probiotic
Research has found it can benefit our digestive health.
It is a type of yeast found naturally in lychee fruit & mangosteens.
The yeast is extracted from the fruit and grown in the laboratory, to make Saccharomyces Boulardii probiotic supplements
The future of probiotics
Our current knowledge of probiotics is at an early stage.
Scientific research findings so far are based on relatively small groups of people.
Future research will uncover the effects of different types of bacteria & give a wider range of helpful probiotics with further health benefits.
In the future, by understanding which bacteria are already in our guts, we can start to figure out which probiotic bacteria will best interact with our own unique microbiome, leading to personalised blends of probiotics to work with our unique gut bacteria & deliver specific health benefits.
Researchers also hope to discover better ways to deliver probiotics to the gut (so they can reliably make it through our stomach acid intact).
Postbiotics. What are probiotics & postbiotics?
Postbiotics is a new term used by scientists to describe the chemical & bacterial byproducts produced by our gut microbes when they break down fibre in our gut.
These byproducts (also known as metabolites) can help boost the immune system, reduce inflammation, and change the composition of the gut microbiome.
This article by Professor Tim Spector & Dr Christina Menni explains what are probiotics and postbiotics in more detail.
The Science Bit
The information I share on this site distills the research I’ve read on the microbiome, prebiotics & probiotics.
You’ll find links to the relevant research studies on each page.
I’m not a scientist / dietician / nutritionist. I’m a food lover & home cook, putting microbiome research findings into action in my kitchen.
Find out more about the scientists leading research into the microbiome on the FAQs page