Fiber gets a lot of well-deserved credit for keeping the digestive system in good working order—but it does plenty more. In fact, it’s a major player in so many of your body’s systems that getting enough can actually help keep you youthful.
The trouble is, few Americans consume the amount they should. For people age 51 and older, government guidelines recommend at least 28 grams per day for men and 22 grams for women. But the Department of Agriculture says adults in this age group average just about 16 grams per day.
What Is Fiber Anyway?
Fiber is a carbohydrate found in plant foods: beans, fruit, grains, nuts, and vegetables. Technically, it isn’t a nutrient because it isn’t broken down and absorbed. But that’s what makes it so beneficial.
There are several types of fiber, but they all fall into two broad categories: soluble and insoluble.
Many plant foods contain both, so by eating a variety, you’ll cover all your bases.
How It Keeps You Young
The study mentioned earlier followed over 1,600 healthy adults for 10 years. Those who had “aged successfully” after a decade (meaning they were free of cancer, heart disease, and diabetes, and had good overall cognitive, physical, and cardiovascular function) consumed an average of 29 grams of fiber per day. How is it that this simple substance can have such a powerful effect on health and longevity? It turns out there are many ways that fiber works its anti-aging magic.
Cutting cholesterol. Soluble fiber binds to bile acids, substances produced by the liver that aid in digestion and fat absorption, and it helps your body excrete them. “The body then needs to produce more bile acids, and it pulls cholesterol from the blood to do it,” says JoAnn E. Manson, M.D., chief of the division of preventive medicine at Brigham and Women’s Hospital. A 2016 Cochrane Review of 23 studies found that increasing fiber led to a 7.7 mg/dL reduction in total cholesterol and a 5.4 mg/dL drop in LDL (“bad”) cholesterol.
Controlling weight. Fiber adds bulk, so you feel full faster and stay full longer. And many high-fiber foods are low in calories.
Lowering colorectal cancer risk. A recent report by the World Cancer Research Fund International/American Institute for Cancer Research found that eating 90 grams of fiber-rich whole grains daily could lower colorectal cancer risk by 17 percent.
Reducing inflammation. Chronic inflammation has been linked to many diseases, such as arthritis, certain cancers, and even Alzheimer’s. “Many studies have shown that increased insoluble fiber intake leads to reduced inflammation,” says Qi Sun, M.D., Sc.D., an assistant professor in the department of nutrition at the Harvard T. H. Chan School of Public Health. This may be because other beneficial components of whole grains, such as polyphenols and magnesium, also have anti-inflammatory properties.
Boosting good bacteria in the gut. “Fiber doesn’t digest, it ferments,” Malone says. “By the time it reaches the colon, the fermented material supplies food to help those good bacteria multiply and thrive.” A healthy supply of good bacteria can have far-reaching health effects, such as strengthening the immune system and helping to control inflammation.