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Overview

1. Why yoghurt is so interesting to researchers
2. How the new study was designed
3. What the researchers found
4. What the gut microbiome might have to do with it
5. Why an earlier study makes the picture even more interesting
6. What does this mean in everyday life?
7. What the study cannot prove
8. The gut microbiome and healthy ageing
9. Frequently asked questions
10. Conclusion

Why yoghurt is so interesting to researchers

For many people, yoghurt is simply part of breakfast. It may be served with oats, berries or muesli without attracting much attention. From a scientific perspective, however, this familiar food contains a surprising amount of biology.

Yoghurt is not simply milk with a different texture. It belongs to a group known as fermented foods. During production, microorganisms carry out much of the transformation: specific lactic acid bacteria convert lactose, the naturally occurring sugar in milk, into lactic acid.

This lowers the pH and changes the properties of the food, creating yoghurt’s characteristic texture and slightly tangy taste.

This fermentation process also connects yoghurt with one of the most fascinating areas of modern nutrition science: the gut microbiome.

Trillions of microorganisms live in our digestive tract, including a wide variety of bacteria. These organisms do far more than simply accompany digestion. They process components of our food, produce their own metabolic compounds and interact continuously with the intestinal lining and immune system.

What we eat therefore does not only provide nutrients for our own cells. It also influences a complex microbial ecosystem living inside us.

This relationship between diet, microorganisms and long-term health is receiving increasing scientific attention.

A study published in Nutrition & Diabetes in July 2026 analysed data from 9,405 adults aged 50 and over. The researchers wanted to know whether the consumption of yoghurt, prebiotics or probiotics was associated with the frequency of reported colorectal cancer diagnoses.

Probiotics are live microorganisms, such as certain bacteria, that may provide a health benefit when consumed in adequate amounts.

Prebiotics, by contrast, are substances that microorganisms can use. In simple terms, they provide suitable nourishment for certain microbes in the gut.

The study produced a notably strong result:

Among people with relevant consumption, the statistical odds of a reported colorectal cancer diagnosis were around 50% lower. In simplified terms, this means that the statistical chance of a reported diagnosis was lower in this group than in the comparison group.

That sounds like a powerful finding. But does it mean that yoghurt protects against colorectal cancer?

No. The study found a correlation, or statistical association, but it could not demonstrate causation.

Causation would mean that consuming yoghurt, prebiotics or probiotics was itself responsible for the lower frequency of reported colorectal cancer diagnoses.

The result is still scientifically relevant. It adds to a growing field of research investigating how diet, gut bacteria and long-term health may be connected.

How the new study was designed

For their analysis, the researchers used data from one of the best-known health surveys in the United States: the National Health and Nutrition Examination Survey, usually abbreviated to NHANES.

NHANES is not a single clinical trial. Instead, thousands of people are regularly asked about their diet, lifestyle and health and undergo medical assessments. Over time, this creates an extensive dataset representing the US population.

The current analysis used information collected between 2001 and 2020.

A total of 9,405 adults aged at least 50 met the researchers’ inclusion criteria. After applying the statistical weighting used in NHANES, the authors reported that this sample represented approximately 37 million US adults.

The analysis focused on three dietary factors:

• yoghurt
• probiotics
• prebiotics

The researchers then compared these dietary data with participants’ recorded medical histories, including whether they reported ever having received a colorectal cancer diagnosis.

How did the researchers account for other lifestyle factors?

One of the biggest difficulties in nutrition research is that people do not eat one food in isolation.

Someone who regularly consumes yoghurt may also eat more fibre, smoke less, follow a different overall diet or have a different lifestyle from someone who does not eat yoghurt.

The researchers therefore adjusted their statistical models for a wide range of possible influences. These included age, sex, income, education, smoking, body mass index, total energy intake, fibre intake, red meat consumption and several health indicators.

The observed association remained after these statistical adjustments.

What exactly did the researchers find?

After statistical adjustment, the reported odds ratio was 0.50.

That may sound highly technical, but the basic principle is relatively straightforward.

An odds ratio of 1.0 would indicate no statistical difference between the groups.

An odds ratio of 0.50 means that the odds of a reported colorectal cancer diagnosis were approximately half as high in the group with yoghurt, prebiotic or probiotic consumption as they were in the comparison group.

That is a noteworthy association.

It is important, however, to interpret the finding correctly. The roughly 50% lower statistical odds represent a clear and scientifically interesting relationship. They provide another reason to investigate whether yoghurt, prebiotics and probiotics may be relevant within the wider context of gut health.

At the same time, the analysis demonstrated an association rather than a proven protective effect. We cannot conclude that yoghurt prevents colorectal cancer. We can say that the finding is sufficiently notable to justify closer scientific investigation.

What might be happening in the gut?

To understand why yoghurt and other fermented foods are so interesting to microbiome researchers, it helps to consider the trillions of microorganisms that live in our digestive tract.

Not everything we eat is completely broken down and absorbed in the small intestine. Some dietary components, including different types of fibre, continue into the large intestine.

There, they encounter gut bacteria capable of processing them further. In doing so, these microorganisms produce new substances that can interact with our own cells.

Among the most intensively studied are the short-chain fatty acids, often abbreviated to SCFAs. These compounds are produced when certain gut bacteria ferment carbohydrates and fibres that our own digestive enzymes cannot fully break down.

One of these short-chain fatty acids is butyrate.

Butyrate is particularly interesting because it serves as an important energy source for cells lining the large intestine. Researchers are also investigating its role in maintaining the intestinal barrier and regulating local immune and inflammatory processes.

In simple terms, every meal feeds not only our own body but also the microorganisms living in our gut.

This is why modern nutrition research is increasingly interested not only in which nutrients we consume, but also in what our gut bacteria subsequently make from them.

One important limitation remains: the current NHANES analysis did not directly examine participants’ gut microbiomes.

The processes described above therefore provide a biologically plausible explanation for why diet, the microbiome and gut health could be connected. They do not prove that this particular mechanism caused the association observed in the study.

Why an earlier study makes the picture even more interesting

The new findings do not stand entirely alone.

In 2025, researchers published a large prospective analysis involving 132,056 participants from the Nurses’ Health Study and the Health Professionals Follow-up Study.

Unlike the NHANES analysis, participants in these cohorts were followed over an extended period. During follow-up, the researchers documented 3,079 new cases of colorectal cancer.

What made the study particularly interesting was that the researchers did not simply ask how much yoghurt participants ate and who later developed colorectal cancer.

They went one step further.

For a proportion of the tumours, they examined whether Bifidobacterium could be detected. Bifidobacteria are a group of bacteria that occur naturally in the human gut and are frequently studied in microbiome research.

A noteworthy pattern emerged: higher long-term yoghurt consumption was particularly associated with a lower occurrence of certain colorectal tumours in which Bifidobacterium was detected.

No comparably clear association was observed among tumours without this bacterial finding.

The precise mechanisms remain uncertain. Yet this is exactly what makes the research so interesting: scientists are beginning to unravel how food, microorganisms and our own cells interact.

The more scientifically useful question is therefore not simply, “Does yoghurt protect against colorectal cancer?”

It is: What role might fermented foods and the gut microbiome play within the complex processes that influence long-term gut health?

What does this mean in everyday life?

What can we reasonably take from these findings?

They do not provide a reason to view yoghurt as a medical “protective food”. They do, however, fit into a broader picture emerging from nutrition research:

Health is rarely determined by one food in isolation. The wider dietary pattern matters.

1. Natural yoghurt can be part of a balanced diet

Natural yoghurt provides nutrients including protein and calcium. Fermentation also gives it its characteristic bacterial cultures.

People who tolerate yoghurt well can include it as part of a varied diet. Natural yoghurt may be preferable to some flavoured or dessert-style products, which can contain substantial amounts of added sugar.

2. Fibre is at least as important

Supporting a diverse gut ecosystem is not simply a matter of eating fermented foods. It also depends on which substrates reach microorganisms in the large intestine.

This is where fibre-rich plant foods become particularly relevant. Vegetables, pulses, wholegrain foods, fruit, nuts and seeds provide a range of components that are not always completely digested in the small intestine.

Some of these components reach the large intestine, where particular bacteria can ferment them and produce compounds including short-chain fatty acids.

3. The combination may be more interesting than any single food

A simple example would be natural yoghurt served with oats, berries, nuts and seeds.

This combines a fermented food with several plant foods and different sources of fibre.

That probably reflects our current understanding of gut health more accurately than searching for one supposed “superfood”. The gut microbiome itself thrives on variety.

4. Diet complements screening — it does not replace it

However interesting the new findings may be, a balanced diet cannot replace medical screening and early detection.

Regular yoghurt consumption does not make colorectal cancer screening unnecessary. Diet and screening are separate components of long-term health care.

What are the limitations of the current study?

The approximately 50% lower statistical odds are a clear and scientifically interesting result. To understand them properly, however, we also need to recognise what the study design can and cannot show.

The study captured an association, not a long-term sequence

The research was a cross-sectional analysis. In simplified terms, researchers examined dietary habits and medical history within an existing dataset.

This makes it difficult to establish with certainty which factor came first.

For example, it cannot be completely ruled out that an existing diagnosis may already have changed someone’s diet.

Researchers call this reverse causation: rather than diet influencing disease, the disease may have influenced dietary behaviour.

Dietary data are never perfectly precise

Some of the information was based on questionnaires and self-reported data.

This is common in large nutrition studies, but it introduces a degree of uncertainty. Few people can recall perfectly what they have eaten over several weeks and in exactly what quantities.

Yoghurt was not considered in isolation

The main analysis considered yoghurt, prebiotics and probiotics together.

We therefore cannot conclude that yoghurt alone was responsible for the observed association. The result applies to this combined group of dietary factors.

The gut microbiome and healthy ageing: the bigger picture

In the end, this wider biological context may be even more interesting than the individual colorectal cancer statistic.

The gut microbiome is not a static system. Its composition can change throughout life, influenced by diet, medication, physical activity, environment and many other factors.

Researchers are increasingly investigating how the microbiome may relate to healthy ageing. They are examining how shifts in microbial communities may be connected with metabolism, immune function, inflammatory processes and age-related conditions.

Many of these relationships are not yet fully understood. What is becoming increasingly clear is that we cannot view the human body entirely separately from the microorganisms that live within it.

Through our diet, we provide nutrients not only to our own cells but also to a microbial ecosystem containing trillions of organisms.

This is one of the most fascinating developments in modern nutrition science. The question is no longer only which nutrients a food contains, but also what happens to those nutrients in the gut and how the resulting compounds may relate to long-term health.

FAQ: Yoghurt and gut health

Is yoghurt good for the gut?

Yoghurt is a fermented food containing characteristic bacterial cultures. How strongly an individual product influences the gut microbiome depends on factors including the specific cultures present, processing methods, the wider diet and individual biology.

Does yoghurt reduce colorectal cancer risk?

The current study cannot establish that. It found a statistical association between consuming yoghurt, prebiotics or probiotics and lower odds of a reported colorectal cancer diagnosis. Because of the study design, this cannot be interpreted as proof of a protective effect.

Which is better for the gut: probiotics or prebiotics?

They have different functions. Probiotics contain live microorganisms, whereas prebiotics provide substrates that particular microorganisms can use. For long-term gut health, the overall dietary pattern is likely to matter more than any single component considered in isolation.

Which type of yoghurt is best?

Natural yoghurt without large amounts of added sugar can be incorporated into a balanced diet. Combining it with fibre-rich foods such as oats, berries, nuts and seeds may be particularly useful from the perspective of dietary variety.

Can yoghurt replace colorectal cancer screening?

No. Nutrition and medical screening serve different purposes. Recommended screening should be attended regardless of personal dietary habits.

Conclusion: an everyday food and an extraordinarily complex biological system

The new NHANES analysis provides another intriguing indication of a possible connection between diet, the gut microbiome and long-term gut health.

Among 9,405 adults aged 50 and over, yoghurt, prebiotic or probiotic consumption was associated with approximately 50% lower statistical odds of a reported colorectal cancer diagnosis.

That is a noteworthy result.

At the same time, the study design cannot tell us whether consumption was responsible for the difference.

The most useful conclusion is therefore not:

“Eat yoghurt and prevent colorectal cancer.”

It is:

Our diet and gut microbiome are closely connected, and fermented foods such as natural yoghurt can form part of a varied, fibre-rich and balanced dietary pattern.

Perhaps this is the most interesting message behind the research:

Every meal nourishes not only our own body. It also influences trillions of microorganisms that form part of our biological system.

The more we understand this relationship, the clearer it becomes why nutrition can rarely be reduced to one nutrient or one individual food.

References