Författare: Justin Stebbing Professor of Biomedical Sciences Anglia Rusk

Hard on the heels of impressive research findings that a glass of milk is good for reducing cancer risk, another recent study has highlighted the potential benefits of yoghurt consumption in lowering the risk of certain types of cancer – particularly colorectal cancer.

The number of new colorectal cancer cases among people under 55 has doubled globally in recent years, with diagnoses increasing by nearly 20%. As a consultant oncologist, many people have asked me how their risk can be reduced.

The emerging evidence suggests that regular yoghurt consumption may have a protective effect against certain aggressive forms of colorectal cancer by modifying the gut microbiome, the natural bacteria that live in the gut.

The gut microbiome plays a crucial role in overall health, influencing digestion, immune function and even cancer risk. The gut bacteria can live inside cancer itself, and in general a healthy balance of these bacteria is thought to be essential for maintaining a strong immune system and preventing inflammation, which can contribute to cancer development.

Read more:
Gut bacteria nurture the immune system – for cancer patients, a diverse microbiome can protect against dangerous treatment complications

Yoghurt contains live cultures of beneficial bacteria, such as lactobacillus bulgaricus and streptococcus thermophilus, which can help maintain this balance.

The study found that consuming two or more servings of yoghurt per week was associated with a lower risk of a specific type of aggressive colorectal cancer, which occurs on the right side of the colon and is associated with poorer survival outcomes compared with cancers on the left side.

The study analysed data from over 150,000 participants followed for several decades, indicating that long-term yoghurt consumption may alter the gut microbiome in ways that protect against certain cancers. Researchers surveyed the participants every two years about their yoghurt intake, and measured the amount of Bifidobacterium (a type of bacteria found in yoghurt) in the tumour tissue of 3,079 people within the sample who were diagnosed with colorectal cancer.

While yoghurt did not directly lower the risk for all types of colorectal cancer, those who ate two or more servings of yoghurt per week had a lower risk of developing “Bifidobacterium-positive proximal colon cancer”, a type of colorectal cancer that occurs in the right side of the colon and has one of the lowest survival rates. This new work also validates and builds on previous studies showing similar findings.

Several mechanisms have been proposed to explain how yoghurt might reduce cancer risk. One key mechanism is the modulation of the gut microbiome. Yoghurt’s probiotics can enhance the diversity and balance of gut bacteria, potentially reducing inflammation and levels of cancer-causing chemicals (carcinogens).

Additionally, yoghurt may exert anti-inflammatory effects on the colon lining cells, called the mucosa, which could help prevent cancer development. Improving gut barrier function is another potential mechanism, as yoghurt may reduce gut permeability, which is linked to increased cancer risk.

Choose wisely

Beyond its potential anti-cancer effects, yoghurt offers several other health benefits. Like milk, it is rich in calcium, which supports bone density and may reduce the risk of brittle bones, known as osteoporosis.

Regular yoghurt consumption has also been associated with lower blood pressure and reduced risk of cardiovascular disease. Some studies suggest that yoghurt intake may help prevent type 2 diabetes and other diseases too.

But when incorporating yoghurt into your diet, it’s important to choose wisely. Opt for plain, unflavoured yoghurt to avoid added sugars, which can negate health benefits – for example by causing weight gain, which is a risk factor for obesity and cancer.

Different fermentation processes can result in varying levels of beneficial bacteria, so look for yoghurts with live cultures. Plain, unsweetened Greek yoghurt is generally higher in protein and lower in sugar, while full-fat yoghurt often has fewer processed ingredients than reduced-fat or non-fat variations.

Yoghurt contains all nine essential amino acids, and aside from improving gut health, a serving of plain Greek yoghurt contains 15 to 20 grams of protein.

There are nearly 45,000 cases of bowel cancer every year in the UK, making it the nation’s fourth most common cancer, and third worldwide – but many of these are preventable.

According to Cancer Research UK data, 54% of all bowel cancers could be prevented by having a healthier lifestyle. Smoking, lack of exercise, alcohol, eating processed meat, and poor diet are all significant factors in the development of bowel cancer.

The emerging evidence suggests that yoghurt, particularly when consumed regularly, may play a role in reducing the risk of certain aggressive forms of colorectal cancer. While more research is needed to fully understand these effects, incorporating yoghurt into a balanced diet could be a beneficial choice for overall health.

But as with any dietary recommendation, it’s crucial to consider the broader context of a healthy lifestyle, including a diverse diet rich in fruits, vegetables and whole grains, along with regular physical activity. While yoghurt is not a magic bullet against cancer, it is a nutritious food that can contribute to a healthy diet and potentially offer protective effects against certain cancers.

As research continues to uncover the complex relationships between diet, gut health and cancer risk, incorporating yoghurt into your daily routine may be a simple yet beneficial step towards a healthier life. Läs mer…

Imagine a world where bacteria, typically feared for causing disease, are turned into powerful weapons against cancer. That’s exactly what some scientists are working on. And they are beginning to unravel the mechanisms for doing so, using genetically engineered bacteria to target and destroy cancer cells.

Using bacteria to fight cancer dates back to the 1860s when William B. Coley, often called the father of immunotherapy, injected bacteria called streptococci into a young patient with inoperable bone cancer. Surprisingly, this unconventional approach led to the tumour shrinking, marking one of the first examples of immunotherapy.

William Coley (centre), a pioneer of bug drugs.
Wikimedia Commons

Over the next few decades, as head of the Bone Tumour Service at Memorial Hospital in New York, Coley injected over 1,000 cancer patients with bacteria or bacterial products. These products became known as Coley’s toxins.

Despite this early promise, progress in bacteria-based cancer therapies has been slow. The development of radiation therapy and chemotherapy overshadowed Coley’s work, and his approach faced scepticism from the medical community.

However, modern immunology has vindicated many of Coley’s principles, showing that some cancers are indeed very sensitive to an enhanced immune system, an approach we can often capture to treat patients.

How bacteria-based cancer therapies work

These therapies take advantage of the unique ability of certain bacteria to proliferate inside tumours. The low oxygen, acidic and dead tissue in the area around the cancer – the tumour “microenvironment” (an area I am especially interested in) – create an ideal niche for some bacteria to thrive. Once there, bacteria can, in theory, directly kill tumour cells or activate the body’s immune responses against the cancer. However, several difficulties have hindered the widespread adoption of this approach.

Safety concerns are paramount because introducing live bacteria into a patient’s body can cause harm. Researchers have had to carefully attenuate (weaken) bacterial strains to ensure they don’t damage healthy tissue. Additionally, controlling the bacteria’s behaviour within the tumour and preventing them from spreading to other parts of the body has been difficult.

Bacteria live inside us, known as the microbiome, and treatments, disease and, of course, new bacteria that are introduced can interfere with this natural environment. Another significant hurdle has been our incomplete understanding of how bacteria interact with the complex tumour microenvironment and the immune system.

Questions remain about how to optimise bacterial strains for maximum anti-tumour effects while minimising side-effects. We’re also not sure of the dose – and some approaches give one bacteria and others entire colonies and multiple bug species together.

Recent advances

Despite these challenges, recent advances in scientific fields, such as synthetic biology and genetic engineering, have breathed new life into the field. Scientists can now program bacteria with sophisticated functions, such as producing and delivering specific anti-cancer agents directly within tumours.

This targeted approach could overcome some limitations of traditional cancer treatments, including side-effects and the inability to reach deeper tumour tissues.

Emerging research suggests that bacteria-based therapies could be particularly promising for certain types of cancer. Solid tumours, especially those that have a poor blood supply and are resistant to conventional therapies, might benefit most from this approach.

Colon cancer, ovarian cancer and metastatic breast cancer are among the high-mortality cancers that researchers are targeting with these innovative therapies.
One area we have the best evidence for is that “bug drugs” may help the body fight cancer by interacting with routinely used immunotherapy drugs.

Recent studies have shown encouraging results. For instance, researchers have engineered strains of E coli bacteria to deliver small tumour protein fragments to immune cells, effectively training them to recognise and attack cancer cells. In lab animals, this approach has led to tumour shrinkage and, sometimes, complete elimination.

E coli have been used to deliver cancer tumour fragments to immune cells.
Kateryna Kon/Shutterstock

By exploiting these mechanisms, bacterial therapies can selectively colonise tumours while largely sparing healthy tissues, potentially overcoming limitations of conventional cancer treatments.

Ultimately, we need human trials to give us the answer about whether this works, by controlling or eradicating cancer and, of course, if there are side-effects, its toxicity.

In one study I worked on, we showed that part of a bacterial cell wall, when injected into patients, could safely help control melanoma – the most deadly form of skin cancer.

While we’re still in the early stages, the potential of bacteria-based cancer therapies is becoming increasingly clear. As our understanding of tumour biology and bacterial engineering improves, we may be on the cusp of a new era in cancer treatment.

Bacterial-based cancer therapies take advantage of several unique mechanisms to specifically target tumour cells. As a result, these therapies could offer a powerful new tool in our arsenal against cancer, working in synergy with existing treatments like immunotherapy and chemotherapy. And, as we look to the future, bacteria-based cancer therapies represent a fascinating convergence of historical insight and groundbreaking science.

While challenges remain, the progress in this field offers hope for more effective, targeted treatments that could significantly improve outcomes for cancer patients. Läs mer…