Part 1: Good Gut “Bugs”
How to promote a healthy gut microbiome – and help your body fight cancer.
There are trillions of reasons why we should carefully consider basic lifestyle choices like whether or not to exercise and what to eat, and they’re sitting right in our gut: they are the innumerable bacteria, or microbes, that make up the microbiome of our gastrointestinal tract.
Individually, each microbe’s ability to influence your health is minuscule. But there is great power in numbers. This mega-population of gut bacteria, accounting for about eight pounds of our body weight, has a significant effect – on health, on disease, and even on how well certain treatments work – that scientists are still only beginning to understand.
One of those scientists, a pioneer in microbiome studies, is Johns Hopkins molecular biologist Karen Sfanos, Ph.D., whom I recently interviewed for the Prostate Cancer Foundation’s website. She is very interested in the microbiome’s influence on prostate cancer development, progression, and resistance to hormonal therapy in metastatic disease.
If you have prostate cancer, you already have plenty to think about. Is it weird to start thinking about your gut microbiome, too? Absolutely not, Sfanos says. “It is 100 percent appropriate to think about the microbiome. There’s good evidence to show that what you eat and whether or not you are sedentary, especially as a cancer survivor, can profoundly influence outcomes in lots of different ways.”
Exercise isn’t just about muscles and cardio: our gut bacteria benefit from it, too. When we exercise, our gut bacteria respond by making more formate. “Formate is a metabolite that helps in so many things,” says Sfanos: “new research in mice with melanoma has shown that it even boosts the response to checkpoint-inhibitor drugs. The mice that exercised produced more formate than sedentary mice.” Exercise stimulated the gut microbes, which produced more formate, which boosted the immune system, which then responded better to immunotherapy drugs.
What can we do to improve our microbiome? We could try to load up on “good bacteria,” but even this is a moving target with a great deal of variability. Bifidobacteria, found in many probiotics aimed at “gut health,” are probably helpful, as is Akkermansia muciniphila. But there’s also an interplay happening all the time in the gut, a balance of bacterial heroes and villains. It may be as important to have fewer “bad” bacteria strains as it is to have more “good” ones.
It’s also good to have a bacterial melting pot – many different kinds of bacteria mingling in the gut. “With probiotics, you are literally taking one or a few bacteria in super-overabundance,” notes Sfanos, “assuming they’re even alive – because you don’t know what you’re actually taking. Supplements aren’t regulated like drugs. Basically, you’re introducing an overabundance of something that might potentially be beneficial, but that is not going to top a healthy diet. It may be more important to have a diverse collection of gut bacteria strains than it is to have an over-abundance of particular ‘good’ ones.”
Also, she adds, “everybody’s microbiome is different. Everybody’s makeup of good vs. bad bacteria is different. More important is what you can do as a human being to promote the good.”
So how can we, microbially speaking, light a candle rather than curse the darkness? The goal, Sfanos says, is not so much to acquire the right bacteria but to encourage our bodies to make their own supply, and there are two major ways to do this: exercise and diet. Yes, there are widely available prebiotics and probiotics. “But at the end of the day, you cannot supplement your way out of an unhealthy diet.”
Fiber: The number one thing that promotes the good gut bugs is dietary fiber; 25 grams a day for females and 38 grams for males.” And here again, it is possible to buy fiber supplements, but it’s better to get this fiber in your daily diet from green leafy vegetables, fruits, beans and legumes, bananas, popcorn, and whole-grain cereals. To learn more about a prostate cancer-fighting diet, click here. “Fiber lowers inflammation.” In many diseases, including prostate cancer, inflammation is known to make cancer more likely to develop – or, if cancer is present, to make it more aggressive.
Fermented foods: Fermented foods like sauerkraut, kimchi and yogurt, contain “the types of bacteria, like Lactobacillus, that do the good things in your gut – like control pH levels, which are important in terms of preventing growth of pathogens (disease-causing bacteria or viruses) in the gut.” In fact, she notes, Maria Branyas Morera – a Spanish woman who was verified as the oldest living person when she died in 2024 at the age of 117 – ate yogurt three times a day, and was found to have high levels of Bifidobacterium. But she also exercised regularly and ate a Mediterranean diet.
Fatty fish: Fatty fish, rich in omega-3 fatty acids, and fish oil capsules derived from them, are good for the heart. They also seem to promote a good microbiome, says Sfanos. Among other benefits, they increase the gut’s production of known anti-inflammatory molecules, such as short-chain fatty acids. “The production of anti-inflammatory molecules helps prevent systemic inflammation, a condition that is linked not only to cancer development, but also to cancer progression and worse outcomes.” What are these fatty, oily fish? They include salmon, sardines, anchovies, herring, and mackerel.
Sleep: Sleep is not just good for the body; it’s good for the microbiome that dwells therein. “Sleep regulates cortisol, the stress hormone, and other hormone levels,” says Sfanos. “And it turns out that the gut microbiome has its own circadian rhythm. Not getting enough sleep can throw that off.” The result is disruption to the gut’s ability to maintain healthy digestion and balance its interactions with the immune system and even the nervous system, leading to inflammation and disease.
Avoid: Sugars, processed meat, and prepared food that has a bunch of ingredients with names that are difficult to pronounce. “Excess sugar is not only linked to obesity – a known cancer risk factor – but is also associated with factors that contribute to systemic inflammation,” says Sfanos. “Processed meats are known to contain carcinogens that are linked to prostate cancer risk.” If you don’t recognize them, chances are that your gut microbiome won’t, either.
In addition to the book, I have written much more about prostate cancer on the Prostate Cancer Foundation’s website, pcf.org. As Patrick Walsh and I have said for years, Knowledge is power: Saving your life may start with you going to the doctor, and knowing the right questions to ask. I hope all men will put prostate cancer on their radar. Get a baseline PSA blood test in your early 40s, and if you are of African descent, or if cancer and/or prostate cancer runs in your family, you need to be screened regularly for the disease. Many doctors don’t do this, so it’s up to you to ask for it. Note: I am an Amazon affiliate, so if you do click the link and buy a book, I will theoretically make a small amount of money.
© Janet Farrar Worthington
