Dietary fiber, a plant-based carbohydrate not digested or absorbed by the body, is present in most unrefined plant foods such as vegetables, fruits, legumes, and grains. Animal products do not contain fiber.
Nonie Gandhi, a dietitian at the Nancy N. and J.C. Lewis Cancer & Research Pavilion, explains that fiber helps cleanse the body of waste and also plays a role in managing cholesterol levels and hormones like estrogen. She notes there are two types of fiber: soluble and insoluble.
Soluble fiber dissolves in water and forms a gel-like substance as it moves through the digestive system. “Soluble fiber is the best source for decreasing cholesterol and supporting healthy digestion and immune health,” Gandhi says. Insoluble fiber does not dissolve in water but still undergoes fermentation by gut bacteria. It supports regular bowel movements and adds bulk to stool while maintaining intestinal pH.
Many foods provide both types of fiber, but Gandhi suggests focusing on overall intake rather than worrying about distinctions between them. “Most people need to increase their fiber intake in general,” she says. “More than 90 percent of Americans are not meeting their fiber needs.”
The recommended daily amount is 25 to 35 grams; Gandhi encourages aiming for 30 grams per day. She adds: “Instead of worrying about number of grams though, most people benefit from including a fiber source at all meals and snacks. It sounds daunting if you’re not used to thinking about fiber, but it’s doable. Have fruit with breakfast; make sure you are getting vegetables at lunch and dinner; choose whole grain products or plant foods as snacks.”
Common sources include vegetables such as broccoli, Brussels sprouts, artichokes, okra, peas; fruits like pears, apricots, dried figs; avocado; beans; sweet potatoes; flax and chia seeds; bran cereals; oatmeal; lentils; and whole grains.
Gandhi points out that while whole foods are preferred sources of fiber for her patients’ diets—and for gut health—fiber supplements can be useful if someone struggles to consume enough from food alone.
She recommends increasing dietary fiber gradually to avoid discomfort: “If you eat a meal really high in fiber that you aren’t used to, you may experience gas or bloating.” She adds this reaction is normal and usually decreases over time as the body adjusts.
Gandhi also highlights the importance of hydration when increasing dietary fiber: “The more fiber you eat, the more water you need because the fiber is going to absorb some water.”
A diet rich in fiber offers several benefits beyond digestive health—it can help with weight management by promoting fullness after meals and can moderate blood sugar levels. Fiber’s most recognized effect is supporting bowel regularity and helping remove waste from the body—a process that can also lower cholesterol.
Recent research has identified additional cognitive benefits linked to dietary fiber intake. As part of bacterial fermentation in the gut, short-chain fatty acids such as butyrate are produced. Gandhi explains: “Butyrate has been shown to enhance learning capabilities and memory.” She adds that moderating blood sugar levels throughout life may reduce dementia risk according to studies from organizations like the National Institutes of Health and Harvard University.
Fiber consumption also supports serotonin production which affects mood, memory, sleep quality, and cardiovascular function.
“A high-fiber diet in general has been shown to reduce your risk of a lot of chronic conditions,” Gandhi says. “And now we are seeing its positive effects on our cognition as well.”
St. Joseph’s/Candler provides healthcare services across more than 30 counties in southeast Georgia and South Carolina’s Lowcountry region (official website). The organization includes facilities such as St. Joseph’s Hospital and Candler Hospital (official website), offers specialized care including cancer treatment (official website), heart health services (official website), women’s services (official website), neurosciences (official website), advanced surgical options (official website), maintains Magnet status for nursing excellence (official website), focuses on compassionate care guided by faith (official website), and supports community health through outreach programs addressing local needs (official website).
