It is well known that a healthy diet includes fiber, but what exactly is fiber and why is it important?
“Fiber is an undigestible carbohydrate found in many of the foods we eat every day including fruits, vegetables, grains, legumes and nuts,” says senior clinical dietitian Grace Whitmer.
There are two types of fiber: soluble and insoluble. These fibers impact digestion in different ways. Soluble fiber makes stool thicker by creating a gel in the intestines that slows down digestion. Insoluble fiber makes stool thicker, which can speed up digestion and make it easier to pass.
The benefits of fiber extend far beyond the bathroom, however.
"Fiber can also help keep blood sugar stable by slowing digestion, help lower blood cholesterol by binding to cholesterol to eliminate it from the body and help with weight management by keeping us full longer after a meal,” Whitmer says.
Read on for eight tips on how to reach your daily fiber intake.
Understand your fiber needs
The first step in meeting your daily fiber intake is to understand your unique needs.
Sex plays a large role in determining daily fiber intake requirements. Whitmer notes the general recommendations for daily fiber intake are 25 grams for women and 38 grams for men, but these numbers are simply estimates.
Cancer is another factor that can affect daily fiber intake recommendations. Because cancer patients may experience digestion issues caused by factors including the number and size of tumors, treatment, medication, fluid intake and chronic diseases, it can be hard to tell whether fiber intake recommendations are being met.
Whitmer notes that every MD Anderson patient has access to a registered dietitian who can aid in deciding how much fiber is appropriate.
“Your registered dietitian can help you determine if fiber is an area that you can work toward improvement or if there are other factors outside of fiber intake that are primarily affecting your bowel function,” Whitmer says.
She offers several suggestions for keeping track of fiber intake. The first is to keep track of your fiber intake on a nutrition app. Another option for those who are less concerned about hitting a specific number is simply to examine their stool. Whitmer says the goal should be a daily bowel movement that is soft but formed and passes relatively easily without strain or pain.
"This may vary a little bit from person to person,” she says. “Some may have more than one bowel movement per day or miss a day here and there but still have healthy bowel function and adequate fiber intake.”
Get fiber from food first
When seeking out fibrous foods, it can be tempting to head straight to the supplement aisle. But many foods are excellent sources of fiber. Whitmer recommends trying to meet your recommended daily fiber intake through whole foods first.
Whole foods, or foods that are unprocessed or minimally processed, are healthier options than their processed or ultra-processed counterparts because they contain fewer additives such as sodium, sugar or preservatives.
“It is always ideal to try to get all the nutrients we need from our food, especially since whole foods often provide other health benefits, as well,” she says.
It can be beneficial to increase fiber intake slowly to monitor how your body responds.
“I would counsel a patient to start with adding one serving of fiber-containing food at a time so that your gut bacteria have time to adjust to digesting the increase in fiber,” Whitmer says.
It can also be useful to determine whether you are consuming soluble or insoluble fiber sources, as they impact digestion differently.
Whitmer says that most fruits, vegetables and grains contain a combination of both types of fiber, with insoluble fiber usually found in the skin, seeds and hulls of plants, as well as in raw veggies and leafy greens. Meanwhile, soft fruits like bananas or apples without their peels tend to be higher in soluble fiber.
“I think what surprises patients the most is not what foods contain fiber but how different types of fiber can have such a significant positive or negative effect on bowel function,” Whitmer says.
One of the benefits of consuming more insoluble fiber is that it can increase bowel regularity, especially for those struggling with constipation. However, that benefit can be lost if you aren’t drinking enough water.
“Without adequate fluid, the fiber may actually lead to more constipation,” Whitmer notes.
While there is no magic rule on how much water to drink, our experts recommend about nine cups of fluid a day for women and 13 cups a day for men.
Add fiber to your breakfast
Jump-start your daily fiber intake by enhancing your usual breakfast with fiber-rich foods.
“People don’t often think about adding veggies to breakfast, but you can start your day with more fiber by adding beans or sweet potatoes to your eggs, or including nuts and berries in your oatmeal,” Whitmer says.
Take eggs, for example. While eggs don’t contain any dietary fiber, the Dietary Guidelines for Americans lists a cup of sweet potato as having 6.3 grams of fiber, while a half-cup of cooked black beans is listed as having 7.5 grams. While those are large servings, even a smaller number of fibrous add-ons can help you get closer to your dietary goals.
Another fiber-filled breakfast addition? Nut butters, including peanut and almond butter. Both options serve as easy fiber upgrades to breakfast dishes such as toast, oats or smoothies.
Modify your favorite dishes
One of the most daunting parts of any dietary change is worrying you won’t be able to consume your favorite meals and snacks. But when it comes to fiber, the process is far more about adding than subtracting.
“Instead of thinking you have to change your entire diet, start by looking at where you can add fiber to meals and snacks you already consume,” says Whitmer, noting this might look like choosing brown rice over white rice, or whole wheat bread over white bread.
Eat lots of different sources of fiber
Variety is the spice of life, and it is also key to enhancing your fiber intake. Instead of simply focusing on increasing the amount of fiber in your diet, focus on increasing the types of fiber in your diet.
"If your goal is to increase variety, you will also end up increasing overall fiber intake as well,” says Whitmer, who has been trying to increase fiber variety in her own diet. To do so, she has been starting her morning with overnight oats that contain rolled oats, peanut butter, chia seeds, ground flax seeds, banana and milk.
“I consume a good amount of fiber, but it tends to be from the same sources every day,” she says. “I was excited about this recipe because it includes five different fiber sources."
Consider fiber supplements if you can’t get enough fiber through food
If you are having trouble increasing the amount of fiber in your diet through foods, a dietitian or doctor may recommend a fiber supplement.
There are a wide variety of fiber supplements on the market, as well as a variety of reasons supplementation may be recommended. For example, fiber supplements can help thicken stool after an ileostomy, while they may also be recommended to those who have allergies or food intolerances, says Whitmer.
“A registered dietitian can help you evaluate if you need to modify the fiber in your diet and may recommend a supplement if needed,” Whitmer says.