Probiotic Foods
Fermented foods have become increasingly popular as interest in gut health has grown. Yoghurt, kefir, kimchi, sauerkraut, miso, tempeh and kombucha are often described as “probiotic foods”.
But there is an important distinction that is frequently missed:
A fermented food is not automatically a probiotic food.
Fermentation involves microorganisms, but that does not mean the finished food necessarily contains a probiotic microorganism with a demonstrated health benefit. Processing, storage and the particular microorganisms present can all matter.
That doesn’t make fermented foods unhealthy or uninteresting. Many can be nutritious additions to a balanced diet.
The aim of this guide is to separate fermented foods, foods containing live cultures and foods that contain probiotics with demonstrated health benefits.
What are probiotic foods?
A probiotic is a live microorganism that provides a health benefit when consumed in adequate amounts.
Some foods naturally contain probiotic microorganisms, while manufacturers may also add specific probiotics to foods that are not fermented.
For a food to contain a probiotic, however, the relevant microorganism needs to meet the definition of a probiotic. In practice, that means the microorganism should be identifiable by its genus, species and strain and have evidence supporting a health benefit.
So simply seeing the words fermented, live cultures or gut friendly on a label does not automatically establish a probiotic health benefit.
Fermented foods vs probiotic foods
Fermented foods
Fermented foods are made using microorganisms that transform the food during fermentation.
Examples include:
- yoghurt
- kefir
- kimchi
- sauerkraut
- miso
- tempeh
- kombucha
- some cheeses
- sourdough
- some pickled foods
Foods containing live microorganisms
Some fermented foods still contain live microorganisms when you eat them.
That can be interesting from a nutrition and microbiome perspective, but live microorganisms are not automatically proven probiotics.
Foods containing probiotics
These contain specific probiotic microorganisms for which a health benefit has been demonstrated.
Some foods may also have probiotics deliberately added to them rather than relying on fermentation.
This distinction keeps us from making a much bigger health claim than the evidence supports.
Why not every fermented food is probiotic
There are several reasons.
The microorganisms may not have been studied
A fermented food can contain live microorganisms without researchers having established a specific health benefit from those microorganisms.
Processing may kill the microorganisms
Some foods are fermented and then heated or otherwise processed. If the microorganisms are no longer alive when you eat the food, they are not providing the same benefits as live probiotic microorganisms.
The NIH Office of Dietary Supplements gives sourdough bread and many pickles as examples where processing after fermentation can kill the microorganisms.
The microorganisms may not meet the definition of a probiotic
A food can contain live bacteria or yeasts without those microorganisms having a demonstrated health benefit in humans.
That doesn’t make the food “bad”. It simply means that we shouldn’t automatically call it probiotic.
Yoghurt
Yoghurt is one of the most familiar foods associated with probiotics.
Traditional yoghurt is produced by adding live microorganisms to milk, including organisms such as Lactobacillus bulgaricus and Streptococcus thermophilus. Some yoghurts may also contain additional probiotic microorganisms.
But there is an important distinction between:
live cultures used to make yoghurt
and
a specific probiotic microorganism with a demonstrated health benefit.
So when choosing yoghurt, don’t assume that every product delivers the same probiotic benefits.
What to look for
Probiotic Foods
A useful label may identify the cultures or specific probiotic microorganisms included.
If a product is claiming a particular probiotic benefit, look for information about the microorganism and strain rather than relying only on phrases such as “live cultures”.
Kefir
Kefir is a fermented drink, traditionally made by fermenting milk with kefir cultures.
It contains a mixture of microorganisms and can be a nutritious food.
Kefir is often marketed as a powerful probiotic food, but the microorganisms present can vary between products and preparation methods.
So it is more accurate to think of kefir as a fermented food that may contain live microorganisms, rather than assuming every kefir product provides a clinically proven probiotic effect.
Kimchi
Kimchi is a fermented Korean vegetable dish, commonly made from cabbage and other vegetables with spices.
Fermentation can produce a complex community of microorganisms.
However, kimchi may contain live cultures without necessarily containing probiotic microorganisms with proven health benefits.
Kimchi can still be a nutritious food and a useful way to add vegetables and flavour to meals.
Its value does not depend on being labelled a probiotic.
Sauerkraut
Sauerkraut is fermented cabbage and may contain live microorganisms.
But the same distinction applies here.
Some sauerkraut products are processed in ways that affect whether live microorganisms remain in the finished food. Commercial preparation can therefore produce a very different result from traditionally fermented, unheated sauerkraut.
So if you’re specifically looking for live microorganisms, check how the product has been made and stored rather than assuming every jar provides the same thing.
Miso
Miso is a fermented soybean-based paste commonly used in Japanese cuisine.
It is another food that is often described as probiotic.
However, miso may contain microorganisms associated with fermentation without necessarily containing a probiotic microorganism with a demonstrated health benefit.
It can still be a useful ingredient in a varied diet.
One practical consideration is that miso can be relatively high in sodium, so portion size matters.
Tempeh
Tempeh is made by fermenting soybeans and is widely used as a plant-based protein source.
It can be a nutritious food and a useful source of protein.
But again, fermented does not automatically mean probiotic.
The microorganisms used during production and what remains in the finished product are what matter if you’re specifically interested in probiotic effects.
Kombucha
Kombucha is a fermented tea beverage that has become increasingly popular.
It may contain live microorganisms, but the microbial composition can vary considerably between products.
Some commercial products are also pasteurised or processed in ways that alter their microbial content.
So it’s better not to assume that every bottle of kombucha provides a clinically established probiotic benefit.
A practical point
Probiotic Foods
Some kombucha products can also contain significant amounts of added sugar.
If you’re choosing kombucha as part of a healthy diet, look at the nutrition label rather than buying it solely because the front of the bottle says “probiotic” or “gut health”.
Pickles
Pickles are a particularly good example of why the word “fermented” can be misleading.
Some pickles are genuinely fermented using microorganisms.
Others are made primarily by soaking vegetables in vinegar.
Even among fermented pickles, processing after fermentation can affect whether live microorganisms remain.
So:
A pickle can be fermented without being a probiotic food.
And a vinegar-pickled cucumber isn’t necessarily fermented at all.
Cheese
Some cheeses are produced using microorganisms and can contain live cultures.
However, the presence of microorganisms during cheese production does not automatically mean that the finished cheese contains a probiotic microorganism with a proven health benefit.
Cheese can still be a nutritious food for many people, providing protein, calcium and other nutrients.
Its probiotic status is a separate question.
Sourdough bread
Sourdough is made through fermentation involving a community of microorganisms.
However, the bread is subsequently baked at a high temperature.
That means the microorganisms involved in fermentation do not generally remain alive in the finished loaf in the same way that live microorganisms remain in an unheated fermented food.
Sourdough may have nutritional and sensory advantages, but should not automatically be described as a probiotic foods.
Apple cider vinegar
Apple cider vinegar is another product sometimes marketed for gut health.
It is made through fermentation, but fermentation alone does not make it a proven source of probiotics.
So don’t choose apple cider vinegar specifically because you think it is providing a clinically demonstrated probiotic benefit. it’s actually one of my favourite Probiotic Foods. I have a spoonful every day and never get acid reflux as a result.
How to tell whether a food actually contains probiotics
If you’re specifically interested in probiotics rather than fermented foods in general, look for better information on the product label.
Look for the microorganism
Ideally, the product identifies the microorganism by:
Genus → species → strain
This is much more informative than vague language such as “contains good bacteria”.
Look for a live culture statement
This can tell you that viable microorganisms are intended to be present, but it still doesn’t prove that those microorganisms provide a specific health benefit.
Look for storage information on Probiotic Foods
Live microorganisms can be affected by heat, storage time and processing.
Look for a specific health claim supported by evidence
A product making an evidence-based claim should be able to identify the relevant microorganism or strain behind that claim.
Are fermented foods still good for you?
Absolutely, they can be.
The fact that a food isn’t a proven probiotic doesn’t make it unhealthy.
Fermented foods can contribute nutrients and variety to the diet, and many are enjoyable ways to include vegetables, dairy products, soy foods or other ingredients.
The mistake is not eating fermented foods.
The mistake is assuming:
“Fermented = probiotic = proven health benefit.”
Those are three different concepts.
A better way to think about fermented foods
Instead of asking:
“Is this food a probiotic?”
you can ask:
“Is this a nutritious food I enjoy eating?”
and, separately:
“Does this product contain a specific probiotic microorganism with evidence for the benefit I’m interested in?”
Those questions are far more useful.
Probiotic foods vs probiotic supplements
Food and supplements are different.
Probiotic foods
These can provide microorganisms as part of a normal diet.
The advantage is that you’re consuming a food rather than an isolated supplement, and the food may provide other nutrients too.
The limitation is that the microorganisms and their amounts can vary and may not have been clinically studied for a specific purpose.
Probiotic foods & supplements
Supplements can provide identified microorganisms in controlled amounts.
That can be useful when a particular strain has been studied for a particular purpose.
But supplements are not automatically better than food.
The choice depends on why you’re interested in probiotics and what evidence exists for the product you’re considering.
Can fermented foods improve gut health?
This is a much more complicated question than many headlines suggest.
Researchers are studying how fermented foods interact with the gut microbiome, but the potential effects of fermented foods should not automatically be equated with the effects of specific probiotic strains.
A varied diet containing vegetables, fruit, whole grains, legumes, nuts, seeds and other minimally processed foods also supplies dietary components that interact with the gut microbiome.
So fermented foods can be part of a healthy diet without needing to be marketed as miracle gut-health products.
What about prebiotic foods?
Probiotics aren’t the only way nutrition can interact with the gut microbiome.
Prebiotics are substances that are selectively used by microorganisms in ways that provide a health benefit.
Many prebiotic foods are rich in particular types of dietary fibre and include foods such as:
- onions
- garlic
- leeks
- asparagus
- beans and legumes
- oats
- barley
- bananas
- certain other plant foods
The precise prebiotic effect depends on the food, the component involved and the individual.
For overall gut health, a varied fibre-rich diet is far more useful than focusing on one fashionable food or supplement.
A practical guide to choosing fermented foods
When shopping, consider:
Choose foods you actually enjoy eating.
A fermented food that you enjoy and can include regularly is more useful than an expensive product you dislike.
Look at the ingredient and nutrition labels.
Check added sugars, sodium and other ingredients where relevant.
Don’t assume “probiotic” on the front of the package tells the whole story.
Look for information about the actual microorganisms.
Check whether the food has been heat-treated after fermentation.
Processing can affect whether live microorganisms remain.
Remember that fermented foods are not medical treatments.
Enjoy them as part of a balanced diet rather than expecting them to cure health problems.
Common myths about probiotic foods
Myth 1: All fermented foods are probiotic foods
False.
Fermented foods can contain microorganisms without those microorganisms meeting the definition of probiotics or having demonstrated health benefits.
Myth 2: Kimchi is automatically a probiotic food
Not necessarily.
Kimchi is fermented and may contain live microorganisms, but the specific microorganisms and demonstrated health benefits depend on the product.
Myth 3: All yoghurt contains the same probiotics
False.
Different yoghurts can contain different microorganisms and cultures.
Myth 4: Sourdough bread is full of live probiotics
Generally not.
The baking process kills most microorganisms involved in the fermentation.
Myth 5: Pickles are always fermented
False.
Some are fermented; others are simply pickled in vinegar.
Myth 6: More fermented foods automatically means better gut health
Not necessarily.
Overall dietary pattern matters far more than any single food.
Myth 7: Probiotic supplements are always better than fermented foods
False.
They serve different purposes and need to be considered according to the evidence and the reason for using them.
Probiotic Foods – The bottom line
Fermented foods can be nutritious, interesting and enjoyable additions to a healthy diet.
But fermented food, live cultures and probiotics are not interchangeable terms.
Some fermented foods contain live microorganisms. Some foods have specific probiotic microorganisms added to them. Some foods contain microorganisms whose health benefits have not been demonstrated.
And some fermented foods are processed after fermentation in ways that kill the microorganisms.
So rather than asking whether a food is “probiotic”, ask:
What microorganisms are actually present?
Are they alive when I eat the food?
Have they been identified by strain?
Is there evidence that they provide the health benefit I’m interested in?
That approach gives you a far more accurate picture than the word “probiotic” on a food label.
And perhaps the simplest rule is:
Enjoy fermented foods because they are good foods — not because you expect every one of them to be a miracle probiotic.
Frequently Asked Questions
What foods are naturally probiotic?
Some foods contain specific live microorganisms that may qualify as probiotics, but the answer depends on the microorganism, strain, amount and evidence. Some yoghurts are among the clearest examples, while many other fermented foods are not automatically proven probiotic foods.
Is yoghurt a probiotic food?
Some yoghurt products contain probiotic microorganisms, while others mainly contain the starter cultures used to make yoghurt. Check the product information rather than assuming every yoghurt has the same probiotic properties.
Is kefir a probiotic?
Kefir is a fermented food containing a mixture of microorganisms. It may contain potentially beneficial microorganisms, but the exact composition and evidence can vary between products.
Is sauerkraut a probiotic?
Sauerkraut may contain live microorganisms, particularly when it has been fermented and not subsequently processed in a way that kills them. But live microorganisms do not automatically mean proven probiotic health benefits.
Is kimchi probiotic?
Kimchi is a fermented food and may contain live microorganisms, but it is not automatically a proven probiotic food.
Is kombucha a probiotic?
Kombucha is fermented and may contain live microorganisms, but its microbial composition varies. It should not automatically be assumed to provide a clinically demonstrated probiotic benefit.
Are pickles probiotic?
Some pickles are fermented and may contain live microorganisms, while many commercial pickles are made with vinegar or processed after fermentation.
Is sourdough a probiotic food?
No. Sourdough is fermented, but the microorganisms used during fermentation are generally killed during baking.
Are fermented foods good for gut health?
They can be nutritious parts of a varied diet, but the health effects of fermented foods should not automatically be equated with the effects of clinically studied probiotic strains.
Are probiotic foods better than probiotic supplements?
Not necessarily. Food and supplements serve different purposes. The better choice depends on why you are interested in probiotics and what evidence exists for the product or food.
This article is for general information and should not be considered medical advice. If you have a health condition, take medication, or are considering probiotics for a specific medical problem, speak with an appropriate healthcare professional.
Sources & Further Reading