Rates of colorectal cancer are rising dramatically in younger adults in the United States, and experts think our gut health may be to blame.
California researchers have identified a possible link between a toxin in the gut known as colibactin and the increase in cancer cases in people under the age of 50.
Colibactin is produced by harmful species of gut bacteria, including the common foodborne illness E. coli. The toxin can inflict damage on colon cells, leading to colorectal cancer, now the second-most common cause of cancer deaths in the U.S.
“Not every environmental factor or behavior we study leaves a mark on our genome,” Ludmil Alexandrov, a professor at U.C. San Diego and a member of the school’s Moores Cancer Center, said in a statement. “But we’ve found that colibactin is one of those that can. In this case, its genetic imprint appears to be strongly associated with colorectal cancers in young adults.”
More than 158,000 new colorectal cancer cases and 55,000 deaths are expected this year, according to the American Cancer Society. But there are steps to help prevent harmful colibactin, experts say.
Understanding how colibactin effects the gut is half of the battle. Trillions of species of bacteria live in the human gut. At six months old, E. coli is highly prevalent, but that changes as people age.
About 20-30 percent of adults have strains of E. coli that can produce colibactin, Christian Jobin, a microbiome researcher at the University of Florida, previously told NPR. But not everyone with colibactin develops colorectal cancer and cancer related to colibactin is more uncommon in Africa and Asia than in the U.S. and Western Europe.
Researchers don’t yet know why that is, but Jobin said that “some of these E. coli that produce colibactin are influenced by diet, inflammation and medication.”
He theorized that how people are born, breastfeeding, the use of antibiotics and whether children were fed ultraprocessed foods could be factors.
“All of these factors are known to substantially affect the microbiome and there is some evidence they may impact this [colibactin producing] bacteria, but we really need to investigate each one carefully,” said Jobin.
Researchers at U.C. San Diego noted that many cancers may originate from microbial or environmental exposures long before a person is diagnosed with colorectal cancer.
“It might not be just about what happens in adulthood – cancer could potentially be influenced by events in early life, perhaps even the first few years,” said Alexandrov.
For infants, a healthy gut is essential to ensure that the nervous system, immune system and digestive tract are healthy. The first few weeks and months are “critical,” according to Chicago’s Children’s Healthcare Associates.
Parents can accomplish this by breastfeeding, feeding their children foods packed with healthy bacterias, using formula fortified with gut-balancing probiotics and giving infants skin-to-skin contact. Breast milk is packed with good bacteria and bacteria on the skin can be transferred to infants, helping build up a healthy gut.
Make sure to avoid giving an infant any nonessential antibiotics, too.
“Antibiotics can knock out a raging ear infection and cure strep throat, but they can kill off beneficial gut bacteria at the same time. Use these drugs only when needed, not for viral infections like colds, flu, and many ear and sinus infections,” Stanford Medicine says.
For adults, the advice is similar. Consuming just one serving of probiotic-rich foods like yogurt, pickles, sauerkraut and sourdough bread can help increase levels of good bacteria in the gut and destroy harmful bacteria by producing acid, according to the Children’s Hospital of Philadelphia. These foods also fight the harmful inflammation that cause chronic diseases like cancer.
Adding plenty of anti-inflammatory fiber to the daily diet is beneficial, too. Fibrous foods like bell peppers, bananas, oats and asparagus serve as a prebiotic: food for the good bacteria in your gut. Fiber may protect against a range of harmful bacteria including E. coli, researchers at the U.K.-based University of Cambridge said.
Getting just three to five grams of prebiotics each day has been shown to be beneficial to gut health, according to Texas’s Lubbock Gastroenterology.
Staying hydrated and keeping active will work to prevent constipation and have a positive effect on the gut microbiome, according to Harvard Health.
People who are sedentary have fewer health-promoting species of bacteria, a 2017 study in Spain showed. But the federally-recommended 150 minutes of moderate exercise a week is enough to see a positive impact on gut health, according to Australia-based research from 2023.
Drinking water helps produce mucus that guards our digestive tract, Harvard says. Women should drink around 11.5 eight-ounce cups, while men need 15.5, the Mayo Clinic says.
Mice on low-carb diets had thinner layers of that mucus, allowing more colibactin to reach colon cells, according to a University of Toronto study conducted last year.
But, eating fiber led to lower levels of E. coli and less DNA damage. “Now we are trying to find out which fiber sources are more beneficial, and which are less beneficial,” postdoctoral fellow Bhupesh Thakur said.
