Dietary fiber is an important part of a healthy diet.In the daily diet, whole grains such as oats and brown rice, green leafy vegetables such as spinach and cabbage, various legumes and nuts are the main sources of dietary fiber.Several clinical studies have shown that a high-fiber diet can help reduce weight gain, lower cholesterol and cardiovascular disease, and reduce the risk of colorectal cancer.
After ingesting dietary fiber, the human gut does not absorb it directly. Many people may think that these substances are just helping the gut move and speeding up the excretion of stool.In fact, in addition to effectively regulating the intestinal passage time and promoting bowel movement, intake of dietary fiber has a perhaps more important role:Feed the bacteria in your gut to build a healthy gut microbiome.
The gut flora produces large amounts of short-chain fatty acids (SCfas), such as propionate and butyrate, while breaking down dietary fiber. These short-chain fatty acids have multiple benefits for gut health and have been found to reduce inflammation levels, enhance the gut's resistance to pathogenic bacteria, and act as a source of nutrients for gut cells. A 2023 paper in Frontiers in Immunology found that after feeding mice a high-fiber diet, propionate produced by intestinal bacteria metabolism can activate an immune response against cancer cells and help clear colorectal cancer cells.
Now, a new study in Nature Metabolism finds thatThe anti-cancer effects of dietary fiber may be more 'direct' than previously thought.Researchers at Stanford University School of Medicine further tracked the effects of propionate and butyrate on normal cells and colorectal cancer cells,These short chain fatty acidsIt can directly promote epigenetic regulation, so that genes with anti-cancer effects can function.
Despite a growing body of research demonstrating the importance of dietary fiber for health, unfortunately,Many people's diets are very low in fiber. Data show that the daily intake of dietary fiber is generally insufficient (less than 20 grams) for adults worldwide.This means that many people's gut microbiota is not properly fed and is not producing the short-chain fatty acids it should.
According to the "Chinese Residents Dietary Nutrient Reference Intake (2023 edition)" recommendation, adults over 18 years old should consume 25-30 grams of dietary fiber per day. The American Cancer Society's recommendation is even higher: 30 to 40 grams of fiber per person per day. Taking 30 grams as the standard, it is roughly equivalent to the dietary fiber contained in 500 grams of green leafy vegetables, 100 grams of coarse grains and 250 grams of fruits per day. you are used to eating big fish and meat, are you eating enough dietary fiber?