A growing body of research underscores the undeniable link between diet and long-term health outcomes, revealing how food choices can influence gene function. A recent study from Stanford Medicine, published in Nature Metabolism today, identifies how fiber intake directly impacts gene expression through epigenetic modifications. The study highlights the anti-cancer effects of fiber digestion byproducts, adding to the mounting evidence that diet plays a crucial role in disease prevention.

Fiber is a fundamental component of a balanced diet, yet less than 10% of Americans meet the minimum recommended intake. The Stanford researchers traced how the two most common short-chain fatty acids produced by fiber digestion—propionate and butyrate—alter gene expression in human cells and mouse intestines. They discovered direct epigenetic changes in genes responsible for regulating cell proliferation, differentiation, and apoptosis, all key factors in cancer prevention.

“We found a direct link between eating fiber and modulation of gene function that has anti-cancer effects, and we think this is likely a global mechanism because the short-chain fatty acids that result from fiber digestion can travel all over the body,” said Michael Snyder, PhD, Stanford W. Ascherman, MD, FACS Professor in Genetics. “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 is not doing our health any favors.”

The study findings are particularly relevant in light of rising colon cancer rates in younger adults, prompting new discussions about the interplay between diet and cancer treatment. “By identifying the gene targets of these important molecules we can understand how fiber exerts its beneficial effects and what goes wrong during cancer,” Snyder added.

While these findings emphasize the role of fiber in disease prevention, they also highlight a concerning trend in low- and middle-income countries (LMICs), where dietary habits are shifting toward unhealthy, processed foods. As economies develop, traditional high-fiber diets rich in whole grains, legumes, and fresh produce are being replaced by ultra-processed, calorie-dense foods that lack essential nutrients. This nutritional transition mirrors patterns seen in high-income nations, where fiber consumption remains alarmingly low and diet-related diseases, including obesity, diabetes, and cancer, continue to rise.

The consequences of this dietary shift in LMICs are already apparent. Urbanization and globalization have made processed foods more accessible and affordable, leading to an increase in diet-related non-communicable diseases. The growing preference for refined carbohydrates, sugary beverages, and unhealthy fats has been linked to a surge in obesity and metabolic disorders in countries that previously had low incidences of such conditions. Without intervention, these trends could further burden healthcare systems that are already struggling to manage infectious diseases and malnutrition.

Addressing this issue requires a multi-faceted approach. Public health initiatives must prioritize nutritional education and emphasize the benefits of fiber-rich diets. Governments should also consider regulatory measures such as food labeling reforms and taxes on unhealthy foods to curb the widespread consumption of processed items. Moreover, policies that encourage the availability and affordability of high-fiber foods, particularly in urban areas, could play a vital role in reversing this trend.

As research like the Stanford study continues to shed light on the long-term health impacts of dietary choices, it becomes increasingly clear that fiber deficiency is not just a Western problem. The implications extend globally, particularly in LMICs where rapid dietary transitions are taking place. Recognizing the power of diet in shaping genetic function underscores the urgency of promoting fiber-rich nutrition as a cornerstone of preventive healthcare.