Eating More Of This May Alter Your Genes To Fight Colorectal Cancer, Study Finds

Eating a fiber-rich diet is linked to numerous health benefits1: improved regularity, a healthy gut microbiome, blood sugar balance, and weight management. More and more research also shows that high fiber intake is protective against colorectal cancers (including colon cancer). 

In fact, researchers of a new study published in Nature Metabolism investigated how gut bacteria changes (from fiber) help fight cancer cells in the colon2. Here’s what you need to know. 

The role of short-chain fatty acids

Before diving too deep into the details of the study, let’s quickly go over the relationship between fiber, short-chain fatty acids, and health. 

Now, fiber is not digested by the human body—so it goes through the GI tract relatively unscathed. However, beneficial bacteria in your gut microbiome (aka your colon) can feed on and ferment the soluble, prebiotic fiber you consume. This fermentation process produces compounds called short-chain fatty acids (SCFAs). 

SCFAs are a type of fat that’s really only produced by gut bacteria—it’s not a type of fat found in food. 

Propionate3 and butyrate4 are two SCFAs that have anti-inflammatory properties, improve the integrity of the gut barrier (protecting against a leaky gut), reduce cholesterol, and support the gut-brain axis. 

This new study was one of the first to show how these SCFAs may influence cancer. 

Why SCFA may have cancer-fighting abilities 

Several different experiments were conducted as part of this study. 

Some were cellular experiments and involved exposing untreated and treated colorectal cancer cells to propionate and butyrate in addition to normal cells. 

There was also an animal component to analyze the effects of SCFAs on mouse intestines. 

Overall, researchers found that both propionate and butyrate SCFAs altered the gene expression (the epigenetics) in both the human cells and the mice. 

Because while your DNA doesn’t change, lifestyle can influence whether certain genetic signals are turned on or off. In this scenario, the epigenetic changes occurred in genes that code for cell differentiation, growth, and apoptosis (programmed cell death). 

These processes play crucial roles in either maintaining healthy cell growth or disrupting the uncontrolled proliferation typically seen in cancers.

What’s more, butyrate exhibited dual effects: It seemed to promote normal cell function while inhibiting the growth of colorectal cancer cells.  

While this is a cell study, and more research in humans to analyze this effect, it sheds light on one of the potential mechanisms behind why fiber supports colorectal health. It also supports large-scale human studies that show those with the highest dietary fiber intake had a reduced risk of certain types of colorectal cancers. 

How to get more fiber

The thing is, about 95% of people in the U.S. aren’t eating the recommended amount of fiber a day (about 25-38 grams5). The average fiber intake hovers around 16 grams a day. So, even if you eat a lot of fruits and veggies every day, there’s a good chance you’re still falling short on fiber. 

Some high-fiber foods to add to your diet (or eat more consistently) include: 

To specifically increase the amount of prebiotic fiber in your diet, you should also consider a supplement. Fiber supplements can be quite helpful as they provide beneficial amounts of research-backed fibers. It's hard—or impossible—to get enough through the diet alone (like guar beans). 

Many powdered fiber supplements provide 6+ grams of fiber per serving and mix easily into foods or beverages. Not sure where to start? Here’s a comprehensive list of expert-vetted fiber supplements.

The takeaway

Fiber plays so many important roles in health yet is widely under-consumed. Adding more fiber to your diet through foods and supplements is a great way to improve your overall health and gut health. 

And just a few small tweaks to your meals and snacks can significantly bump up your daily fiber intake (more tips on how to do that here).