It famously helps to cleanse the system of toxins—and even affects how your genes operate, according to California researchers.
New Study: 90% of Americans Are Lacking in This Cancer-Preventing Nutrient
Published on Jan. 21, 2025
You already know that eating enough fiber is one crucial way to keep your digestive system moving and your belly feeling balanced. But a team of biology and cancer researchers at Stanford University are making a compelling argument that fiber’s benefits go way further.
A January 2025 study published in the journal Nature Metabolism has revealed that as fiber passes through the gut without breaking down, it can actually alter gene expression—making cancer, specifically of the colorectal region, less likely.
The researchers explain that’s because fiber stimulates the gut to produce short-chain fatty acids. Two common types of short-chain fatty acid are propionate and butyrate, which the researchers found affected cell proliferation and cell death—two important factors underlying cancer risk. “We found a direct link between eating fiber and modulation of gene function that has anti-cancer effects,” explained Michael Snyder, PhD, Stanford W. Ascherman, MD, FACS, professor in genetics.
Dr. Snyder added that this could speak to upward trends of digestive-related cancers in recent years: “It is generally the case that people’s diet is very fiber poor, and that means their microbiome is not being fed properly and cannot make as many short-chain fatty acids as it should.”
This study backed up a comprehensive 2023 meta-analysis published in the journal Nutrients, which also highlighted how epidemiological research has “consistently demonstrated the significant role of dietary factors in preventing cancer, with dietary fiber being of particular interest.” In particular, that research team, based in China, said their findings indicated that a high intake of dietary fiber is associated with a reduced risk of 11 types of cancer: Esophageal, gastric, colon, rectal, colorectal adenoma, breast, endometrial, ovarian, renal cell, prostate, and pancreatic cancers.
So how much fiber do you need? The U.S. Department of Agriculture (USDA) recommends that among adults under the age of 50, women should aim for 25 grams of fiber per day, while men should opt for a daily intake closer to 38 grams. However, less than 10% of the American population eats enough fiber in their diets. In fact, according to the 2020-2025 Dietary Guidelines for Americans, 97% of women and 90% of men eschew fiber-rich foods like beans, peas, nuts, whole grains, cruciferous vegetables, and avocados, resulting in inadequate levels.
While you can’t guarantee safety from cancer by simply eating well, fortifying your diet with fiber-rich foods could help you lower your risk. Loading up your plate with more plant-based foods is a great way to start, but you can also check nutrition labels and discuss supplementation with your doctor for a more targeted approach to upping your intake.
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