Most people need to increase their fiber intake and reduce the amount of added sugars in their diets. Government guidelines recommend a dietary fiber intake of 30g a day as part of a healthy, balanced diet. However, most adults consume only about 20g a day, highlighting the need to find ways to increase fiber consumption.
Fiber Requirements Across Age Groups
While adults should aim for 30g of fiber daily, children need varying amounts depending on their age:
- 2 to 5 year-olds: About 15g of fiber a day
- 5 to 11 year-olds: About 20g
- 11 to 16 year-olds: About 25g
On average, children aged 11 to 18 consume only 16g a day, indicating a significant gap between recommended and actual intake.
Health Benefits of a High-Fiber Diet
Eating plenty of fiber is associated with a lower risk of heart disease, stroke, type 2 diabetes, and bowel cancer. A high-fiber diet promotes regularity with a softer, bulkier, and regular stool pattern. The health benefits of a high-fiber diet, consumed regularly and reaching recommended amounts, are now fairly well-defined.
Digestive Health
Dietary fiber increases the weight and size of stool and softens it, making it easier to pass and lowering the chance of constipation. If you have loose, watery stools, fiber may help make them solid. High fiber diets are more filling and give a sense of fullness sooner than an animal and meat-based diet does. Insoluble fiber maintains bowel movements by absorbing water and softening the stool. Soft stool is easier to pass, thus preventing constipation. They also add bulk to the stools hence prevent the formation of loose stools.
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A high-fiber diet may lower the risk of swollen veins in the anus and lower rectum called hemorrhoids. Eating plenty of fiber also may help lower the risk of a condition called diverticulitis that involves small, inflamed pouches in the colon wall. Prolonged, vigorous contraction of the colon over a long period of time may result in diverticulosis. This increased pressure causes small and, eventually, larger ballooning pockets to form. A high fiber diet increases the bulk in the stool and thereby reduces the pressure within the colon.
Cardiovascular Health
Soluble fibers are the ones that will reduce cholesterol levels when used on a regular basis. Psyllium husk and prebiotic soluble fiber will also reduce cholesterol. They may also reduce the incidence of coronary heart disease. Soluble fiber found in beans, oats, flaxseed, and oat bran may keep the body from absorbing some of the cholesterol in other foods, potentially lowering low-density lipoprotein (LDL), also called "bad," cholesterol levels in the blood.
Blood Sugar Control
In people with diabetes, fiber may slow the absorption of sugar and help improve blood sugar levels. That's especially true of soluble fiber. Soluble fibers slow the absorption and digestion of carbohydrates and lower insulin demand in the body, thereby stabilizing postprandial glucose levels.
Weight Management
High-fiber foods tend to be more filling than low-fiber foods, making you likely to eat less and stay satisfied longer. High-fiber foods also tend to take longer to eat and to be less energy-dense than low-fiber foods. The soluble prebiotic fibers have been shown to turn off the hunger hormones produced in the wall of the gut and to increase the hormones that give a sense of fullness. Soluble fibers make the stomach contents viscous and prolong gastric emptying time, which can help reduce weight, improve BMI, lower body fat, and waist-to-hip ratio.
Cancer Prevention
It is still not certain if a high-fiber diet helps prevent colon cancer. Considerable research suggests that this may occur. Certainly, it makes sense to increase regularity and so speed the movement of cancer-causing carcinogens through the bowel. In addition, reducing a heavy meat diet reduces the bile flow from the liver in a favorable way. This, too, reduces the amount of carcinogens that reach and are manufactured in the colon. Finally, a high-fiber diet, including prebiotic soluble fiber, increases the integrity and health of the wall of the colon. A high-fiber diet is linked with a lower risk of colorectal cancer as well. A review of the entire world’s literature on the effect of fiber on colon polyps and cancer prevention has shown rather clearly that for every 10 grams of fiber added to the diet, there is a 10% reduction in the incidence of colon cancer.
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Gut Health and Immunity
A high-fiber diet changes the bacterial makeup of the colon toward a more favorable balance. For instance, it is known that those people with obesity, diabetes type 2, and inflammatory bowel disease have a predominance of bad bacteria in the colon. This, in turn, may render the bowel wall weak and allow bacteria and, indeed, even toxins to seep through. A high-fiber diet with a modest reduction in animal and meat products may return the bacterial makeup to a more positive balance. Some fiber also serves as food for "good" bacteria in the gut. It's known as fermented fiber.
These bacteria play a major role in keeping the colon wall itself healthy. In addition, these good bacteria produce a very strong immune system for the body. They significantly increase calcium absorption and bone density. They provide other documented benefits.
Longevity
Fiber intake is associated with decreased prevalence of diabetes type 2, coronary heart disease, stroke, and improved immune function.
Types of Fiber
Dietary fiber is a nutrient known as a carbohydrate. Fiber includes the parts of plant foods that the body can't digest or absorb. This makes it different from nutrients such as fats, proteins, and other carbohydrates including starches and sugars. The body breaks down these nutrients and absorbs them.
There are two main types of fiber: soluble and insoluble.
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Soluble Fiber
This type of fiber dissolves in water. It forms a gel-like material in the stomach that slows down digestion. It can help lower cholesterol and blood sugar. Soluble fiber attracts water into your gut and forms a gel-like substance, keeping you full and helping you feel satiated. Once it makes it into the colon, it can serve as a substrate for microbiota, meaning your microbiota can metabolize the food that you digest as well.
Examples of soluble fiber-rich foods include whole foods and fresh produce, such as apples, avocados, bananas, cabbage, broccoli, and cauliflower, as well as legumes, beans, and oatmeal. The best sources of soluble fiber are oats, dried beans, and some fruits and vegetables.
Insoluble Fiber
This type of fiber doesn't dissolve in water. It supports the movement of material through the digestive system and adds bulk to stool. So it can be helpful for people who have constipation or don't regularly pass stool. Insoluble fiber cannot be dissolved and will not contribute to the calories you consume. The body can’t take up energy from insoluble fiber, but it is critical to consume because it’s the bulk of substrate that helps you have a bowel movement, helping to prevent constipation.
Sources of insoluble fiber include whole grains, nuts, and seeds.
Most high-fiber plant foods contain both soluble and insoluble fiber. The amount of each type of fiber varies with the type of plant, such as whether it's a fruit, vegetable, or whole grain. But you can get both types of fiber by eating a variety of fiber-rich foods. To get the right balance of soluble vs. insoluble fiber each day, you should aim for a two-to-one ratio of insoluble to soluble fiber.
How to Increase Your Fiber Intake
It's important to get fiber from a variety of sources, as eating too much of one type of food may not provide you with a healthy balanced diet. To increase your fiber intake you could:
Choose a higher-fiber breakfast cereal: Opt for plain wholewheat biscuits (like Weetabix) or plain shredded whole grain (like Shredded wheat), or porridge as oats are also a good source of fiber. For breakfast, you can easily get the day started well by using a high-fiber, whole-grain cereal. Check the labels. Add fruit such as blueberries and bananas.
Go for wholemeal or granary breads: Choose higher-fiber white bread, and choose wholegrains like wholewheat pasta, bulgur wheat, or brown rice. Always use whole grain or wheat with rolls and sandwiches. Does your fast-food store not have them? Perhaps you look elsewhere.
Go for potatoes with their skins on: Enjoy a baked potato or boiled new potatoes.
Add pulses to meals: Include beans, lentils, or chickpeas to stews, curries, and salads. Add kidney beans, garbanzos, or other bean varieties to your salads. Learn to like legumes. Beans and members of the bean family such as peas and lentils are excellent sources of fiber.
Include plenty of vegetables with meals: Serve vegetables as a side dish or add them to sauces, stews, or curries. Try snacking on vegetables such as cauliflower, broccoli, carrots, and green beans. Salads - adding cooked and then chilled vegetables provide great flavoring to almost any salad. Remember, a cobb salad has lots of cooked corn in it.
Have some fresh or dried fruit for dessert: Choose fruit canned in natural juice. Eat at least five servings of fruits and vegetables each day. Fresh fruit is slightly higher in fiber than canned. Eat whole fruits instead of drinking juices. Dried fruits have a higher amount of fiber than the fresh versions. For example, 1 cup of grapes has 1 gram of fiber, but 1 cup of raisins has 7 grams. While all fruits have some fiber, there are some that are higher than others. Snacks should consist of fruit and/or nuts. Fruit juices should contain pulp. Clear juices such as clear orange, pear, or apple juice contain little fiber and have a lot of fructose. Make snacks count. Whole fruits, raw vegetables, low-fat popcorn without salt, and whole-grain crackers are all healthy choices. A handful of nuts or dried fruits that don't have added sugar also can be a healthy, high-fiber snack.
Keep a jar of oat bran or wheat germ handy.
Cook with brown rice instead of white rice.
Rethink your plate: Reducing the portions of the meat or animal food portion to the side with equal or more portions of vegetables, legumes, and fruits portion always allows for more fiber. There was never anything magic about making the meat or animal food portion the main part of the dinner plate. Eating from smaller plates can, over time, trick your mind and long-term habit of using a dinner plate.
When buying packaged foods, check the Nutrition Facts label for fiber content.
Choose whole-grain bread: Choose breads with at least 2 grams of fiber per serving. On the label, whole wheat, whole-wheat flour, or another whole grain should be first in the ingredient list.
Substitute whole-grain flour for half or all of the white flour when baking.
Fiber Content in Sample Meals
Here's an illustration of how fiber can be incorporated into daily meals:
Fiber at breakfast: Two thick slices of wholemeal toasted bread (6.6g of fiber) topped with one sliced banana (1.4g) and a small glass (150ml) of fruit juice (1.2g) will give you around 9.2g of fiber.
Fiber at lunch: A baked jacket potato with the skin on (4.7g) with around half a can (about a 200g portion) of reduced-sugar and reduced-salt baked beans in tomato sauce (9.8g) followed by an apple (1.2g) will give you around 15.7g of fiber.
Fiber at dinner: Mixed vegetable tomato-based curry cooked with onion and spices (6.6g) with boiled wholegrain rice (2.7g) followed by a lower fat fruit yoghurt (0.4g) will give you around 9.7g of fiber. Bear in mind that fruit yoghurts can sometimes be high in added sugars, so check the label and try to choose lower-sugar versions.
Fiber as a snack: A small handful of nuts (30g), such as almonds, can have around 3.8g of fiber. Make sure you choose unsalted nuts without added sugars.
Fiber on Food Labels
The amount of fiber in any food can depend on how it is made or prepared and on how much of it you eat. All fiber comes from plants, bushes, vines, or trees. Of course, the ones that we eat provide us with fruits, vegetables, and grains.
When reading a food label, choose foods that contain more fiber. As a rule of thumb, choose cereals with 6 or more grams of fiber per serving, breads and crackers with 3 or more grams per serving, and pasta with 4 or more grams per serving. Another strategy is to make sure that a whole-grain food has at least 1 gram of fiber for every 10 grams of carbohydrate. Ignore the marketing on front of the package labels. Just because a bread is labeled "multigrain" or "12 grain" does not mean it is a whole grain. The grains could be refined and the bread may be low in fiber.
Cautions and Considerations
High-fiber foods are good for your health, but adding too much fiber too quickly can lead to gas, bloating, and cramping. Add fiber to your diet slowly over a few weeks. Also, drink plenty of water. Fiber works best when it absorbs water.
Irritable Bowel Syndrome (IBS)
IBS patients need to be careful of the amount of soluble fiber they consume. The reason for this is that, while the good colon bacteria thrive on these fibers and produce health benefits, other gas-forming bacteria may generate excessive but harmless gas and subsequent bloating.
Inflammatory Bowel Disease (IBD)
There is now some information in the medical literature on what type of diet may be harmful and what may help Crohn’s Disease. A reduction in red meat is likely helpful. So is reducing the fat in the diet, including vegetable oils. More importantly, people who had low fiber ingestion in the diet had a greater chance of getting CD. So, a gradual increase in the amount of fiber is likely helpful in hopefully preventing CD. This should always be done in conjunction with the physician. It should be done gradually and should include soluble fibers which fertilize the best colon bacteria. The good bacteria grow and push out the bad ones.
We still do not have strong evidence in the medical literature on what is the best diet for UC. Eating plenty of soluble fiber, including prebiotic fibers will nourish the best colon bacteria. It is hoped that this will result in a decrease in the bad or Firmicutes bacteria.
Other Medical Conditions
In some situations, your healthcare professional may ask you to eat less fiber. This may ease the symptoms of a condition or help the digestive tract heal from a treatment. If you get surgery that involves the intestines or stomach, your healthcare professional may recommend a lower fiber diet afterward for a time.
Conditions such as Crohn's disease and ulcerative colitis inflame parts of the digestive tract. When symptoms flare up, you may need to eat less fiber. Your healthcare professional also may ask you to eat less fiber during a bout of diverticulitis. But once the symptoms of these conditions get better, it's often important to slowly add fiber back into your diet.
Conditions such as Crohn's disease can cause parts of the intestines to become narrowed over time. These narrowed areas are called strictures. If you have strictures, you may need to follow a low-fiber diet. Radiation therapy for cancer can cause diarrhea and narrowing of the intestines as side effects. That's especially true if the radiation is targeted at the stomach area or the pelvic area. With gastroparesis, the stomach empties slowly after eating.