Victoria Sampson: Most Replayed Moment: Don’t Brush Your Teeth After Sugar! The Best Oral Care Routine

The host opens with a study in mice that linked an oral bacterium to tumour growth. The transcript renders the bacterium as "fusavector and nucleotum" (later "fuzobacterium"), which is Fusobacterium nucleatum. The guest confirms they know the research. They say this specific bacterium has been shown to accelerate tumour growth in mice and has also been linked to colorectal and breast cancer. The host acknowledges the research is fairly new, then asks whether the health of the oral microbiome has a significant causal relationship with the chance of developing some form of cancer.

I wouldn't yet say causal.

The guest pushes back on the causal framing. They describe most cancers as multifactorial, with many things affecting whether a cancer develops and how aggressive it is. They do treat oral health and certain oral bacteria as risk factors, which they say can increase how aggressive these cancers are and may even play a role in starting them. So the disagreement is one of degree. The host asks about causation, and the guest will only commit to association and risk.

The guest names the evidence that would change their mind. It is research they are waiting to see published, not results they already have. As they describe it, researchers have developed an antibiotic that kills only this bacterium. It will be given to colorectal cancer patients whose tumours carry the bacterium, to see whether it slows progression or improves prognosis. Only if those results come back positive would they call the causal link strong. No trial design, sample size or timeline is given.

for now, I would say that it's multifactorial and it's definitely a risk factor

Asked what causes high levels of the bacterium, and whether it comes from food or lifestyle, the guest lists several factors. Some people are genetically disposed to higher levels, and diet, close contact and inhaled air also play a part.

It's what we eat, it's who we're kissing, it's what we're breathing in.

When the host asks whether their girlfriend carries it, the guest says that is unknown without testing. They then point to testing as a way to see these levels and tailor treatment plans and recommendations. They describe green tea as "extremely effective" at killing the bacterium and call this surprising for something so simple. In a later exchange they credit green tea with being anti-inflammatory, helping with oxidative stress ("basically stress for the body"), and being antibacterial. These claims are not tied to any named study in this excerpt.