NEW YORK, Jan 15: Despite the well-known benefits of fiber for a healthy diet, only 7% of Americans consume the recommended daily amount. A new study from Stanford Medicine highlights the crucial role fiber plays in reducing cancer risk by influencing gene activity.

When we eat fiber, the bacteria in our gut break it down into short-chain fatty acids, such as propionate and butyrate. Researchers at Stanford examined these byproducts and discovered that they can modify histones—proteins that package DNA—making it more accessible and influencing gene expression. This alteration can suppress cancer-promoting genes and activate tumor-suppressor genes in specific conditions.

“We found a direct link between eating fiber and modulation of gene function that has anti-cancer effects,” said Michael Snyder, a Stanford genetics professor. “We think this is likely a global mechanism because the short-chain fatty acids produced during fiber digestion can travel throughout the body.”

Snyder’s team studied the effects of propionate and butyrate on healthy and cancerous colon cells, as well as intestinal cells in mice on fiber-rich diets. They found that both fatty acids could suppress cell growth, promote cellular specialization, and trigger programmed cell death, especially in cancer cells. These processes are vital in controlling the abnormal cell growth that is characteristic of cancer.

“By identifying the gene targets of these important molecules, we can better understand how fiber benefits our health and what goes wrong during cancer,” Snyder explained.

Snyder’s research was published in Nature Metabolism last week. With colorectal cancer rates rising, particularly among younger individuals, Snyder recommends increasing fiber intake as a means of improving health and reducing cancer risk.

In addition to its anti-cancer benefits, fiber is known for promoting regular bowel movements, stabilizing blood sugar, lowering cholesterol, and supporting heart health. The American Heart Association suggests getting 25 to 30 grams of fiber daily from food sources, but most Americans only consume about 15 grams per day.

“It’s generally the case that people’s diets are very low in fiber, which means their microbiome isn’t properly nourished and can’t produce enough short-chain fatty acids,” Snyder noted. “This is not good for our health.”

To help increase fiber intake, registered dietitian nutritionist Stephanie Schiff from Northwell’s Huntington Hospital recommends the following five fiber-rich foods:

Beans, peas, and legumes: black beans, navy beans, lentils, split peas

Fruits: avocados, raspberries, blackberries, pears, apples

Vegetables: broccoli, asparagus, artichokes, Brussels sprouts

Nuts and seeds: chia seeds, flax seeds, pumpkin seeds, almonds