We talked to a handful of registered dietitians to get the lowdown on the different types of fiber (i.e., what they are and what they do) and compiled their best advice for making sure you get what you need every day. “Soluble fiber dissolves into a gel-like substance that is important to help capture and remove toxins and cholesterol from the body,” explains registered dietitian Amy Shapiro, M.S., R.D., CDN. Insoluble fiber is not digested by the body or absorbed into the bloodstream. Instead, it forms the “weight” and “bulk” of stools in the body, acting as a broom of sorts by sweeping waste along and aiding evacuation. Both forms can help you feel full by creating volume in the digestive tract that lets your brain know you’ve eaten, but each also has specific benefits tied to how your body handles them. According to the Journal of Cardiovascular Nursing, soluble fiber also bolsters heart health by decreasing total and LDL cholesterol levels3. Additionally, it’s a great tool for achieving and maintaining a healthy weight. Soluble and highly viscous fibers block the absorption of fats and increase the viscosity4 of food in the digestive tract, which promotes satiety (i.e., makes you feel full for longer). But soluble fiber has some indirect effects, too. Soluble fiber that is also fermentable (not all soluble fibers are), also known as prebiotic fiber, is an excellent source of food for the bacteria that live in your gut. When these prebiotic, fermentable fibers get to the colon, the bacteria feed on them, creating short-chain fatty acids5, or SCFAs, like butyrate, acetate, and propionate (bioactive gut metabolites and a form of postbiotics). These SCFAs provide energy, support metabolism, regulate blood sugar levels, and bolster healthy inflammatory responses6. Although there is more research on viscous (soluble) fiber and healthy body composition8, insoluble fiber may also help you maintain your desired weight. In one study from The American Journal of Clinical Nutrition, participants that swapped their low-fiber breakfast cereal for a cereal high in insoluble fiber9 had improved appetite regulation and ate fewer calories throughout the day. That said, some mostly-soluble fiber foods include: However, according to a 2017 scientific review from the American Journal of Lifestyle Medicine, the average American eats only 16 grams of fiber12 per day—a far cry from the recommended intake. While there are no specific recommendations for how much of that should be soluble versus insoluble fiber, most health experts recommend including a variety of foods in your diet to make sure you’re getting both types. Low fiber intake can lead to problems like suboptimal bowel movements, extra weight, and sluggishness, but it can also create gut, heart, and immune health issues down the road. And since fiber is found in some of the most nutrient-dense foods (e.g., fruits, vegetables, whole grains, and legumes), falling short on your fiber needs could mean that you’re missing out on other important nutrients, too. RELATED: How Much Fiber You Need Per Day + How To Increase Your Intake “Add more plants to your diet,” says Shapiro. “Try to incorporate plant foods (whole grains, nuts, seeds, fruits, and veggies) at every meal. That can be oats or a smoothie at breakfast, salad at lunch, trail mix or fresh fruit for a snack, and cooked veggies at dinner.” To make sure you’re getting adequate amounts of both types of fiber, Nichole Dandrea, M.S., RDN, registered dietitian and author of The Fiber Effect, takes it one step further: “Shoot for at least three colors, if not more, per meal, choosing from green, red, purple, yellow, orange, blue, and tan,” she says. To translate that into food, think broccoli, tomato, cabbage, squash, carrots, blueberries, and oatmeal, respectively. For example, a fiber-full meal might look like a grain bowl with farro, broccoli, radish, carrots, and red onion. In addition to eating more vegetables, you can also make the foods you’re already eating more fiber-rich with a few small tweaks. “An easy, convenient way to increase fiber in one’s diet is using ground flaxseeds and chia seeds,” Carrie Kirkland, R.D., L.D., a bariatrics dietitian at Morrison Healthcare, tells mindbodygreen. “They are both versatile ingredients with minimal texture and taste. Two tablespoons of chia seeds have eight grams of insoluble fiber and two tablespoons of ground flaxseeds contain four grams of fiber. If you’re struggling with dietary fiber intake, try adding them to your yogurt, smoothies, protein shakes, or cottage cheese.” Kirkland warns against flavored fiber powders that have a lot of added sugar (something that you definitely don’t want). It’s important to read your supplement labels and make sure you’re only getting the good stuff. Avoid any fiber supplements with the following ingredients, which are all fancy names for sugar: Upping your fiber intake slowly gives the bacteria in your gut time to adjust to the new food source. Eating too much fiber (especially soluble fiber) too quickly can create excess gas and lead to uncomfortable side effects, like bloat, stomach upset, and suboptimal bowel movements. “Try increasing fiber intake by five grams each week, and make sure to drink plenty of water,” Dandrea suggests. “If you’re increasing your fiber intake with beans, be sure to soak them overnight first to reduce gas-forming compounds. Cooking them with a pressure cooker and a piece of kombu seaweed can also help to reduce the gas-forming compounds.” The best way to make sure you’re meeting your needs is by including a variety of plant-based foods (like colorful veggies, nuts, and seeds) in your diet and adding a premium fiber supplement (like mbg’s organic fiber potency+) to your routine for additional support. If your diet is really low in fiber now, make sure you’re increasing your intake gradually (i.e., over the course of several weeks), so you don’t experience any unwanted digestive side effects as your body adjusts. She has written twelve books and has had more than 2,000 articles published across various websites. Lindsay currently works full time as a freelance health writer. She truly believes that you can transform your life through food, proper mindset and shared experiences. That’s why it’s her goal to educate others, while also being open and vulnerable to create real connections with her clients and readers.
