Fiber is a type of carbohydrate that is not absorbed by the body and it can be found in fruit, vegetables, legumes, and cereals. Adequate consumption of dietary fiber is important to maintain gastrointestinal health and prevent health problems, such as constipation.
Additionally, dietary fiber, especially the soluble kind, helps to regulate blood glucose levels and increases satiety thereby fighting diseases like diabetes and obesity. Therefore, the daily recommended amount of fiber for adults is between 25 and 38 grams.
Health benefits of eating more fiber
In general, the health benefits of fiber are:
- Preventing constipation. Fiber speeds up bowel movements, increases the amount of stool produced, and eliminates it more easily, especially when the fiber is consumed with adequate amounts of water.
- Increasing the body’s sense of satiety. Because fiber is not digested, it creates a type of gel in the stomach, which helps reduce the number of calories ingested and thus facilitates weight loss;
- Helping to regulate blood sugar levels. As the absorption of carbohydrates in the intestines is slower, this makes glucose increase progressively and insulin levels regulate.
- Decreasing levels of cholesterol and triglycerides. Fiber can decrease the absorption of fat and cholesterol in the intestines, which causes them to decrease in terms of concentration in the body on a long-term basis;
- Eliminating toxins that are in the intestines through stool. Fiber also regulates and controls the intestine’s pH;
- Maintaining the health of the gut microbiota and gastrointestinal tract. Fiber feeds the good bacteria that are naturally present in the intestines. As well as promoting the health of the gut microbiota, fiber reduces inflammation, increases body defenses, and avoids the development of intestinal diseases.
In order to really benefit from a fiber-rich diet, the best thing to do is to have high fiber food every day, as a part of all main meals and snacks. Another important aspect of this type of diet is that you need to up your water intake, as water hydrates the fiber and lubricates the intestines, which helps the body to get rid of stool more easily and this prevents constipation.
List of high fiber foods
The following table lists foods that are rich in fiber and the quantities they have:
Quantity of fiber (100 g)
Cooked brown rice
Whole wheat bread
Greens, vegetables, and by-products
Boiled sweet potato
Nuts and seeds
Cooked pinto bean
Types of food fiber
Dietary fiber can be classified as soluble or insoluble. The main difference between them is that soluble fiber dissolves in water, while insoluble fiber doesn’t. Each one has benefits.
Soluble fibers dissolve in water making a gel, and therefore they stay in the stomach and small intestine longer, and make you feel fuller.
In addition, soluble fibers are metabolized and fermented by the good bacteria present in the intestine. This helps to maintain intestinal health and reduce inflammation, preventing the emergence of gastrointestinal diseases, such as Crohn’s disease, ulcerative colitis, irritable bowel syndrome, and colorectal cancer, which is why they can be considered a prebiotic.
These fibers also bind to the fat and sugar present in the food that is in the intestines, helping to reduce cholesterol and control blood sugar.
Pectin and inulin are types of soluble dietary fiber, which can be found in fruit, vegetables, grains, and foods containing oats, wheat germ, barley, and rye.
Insoluble fibers are not dilutable in water and their fermentation in the gastrointestinal microbiota is limited, so when they get to the large intestine they accelerate gastrointestinal transit as they increase the amount of stool and act as a natural laxative. This prevents problems such as constipation, hemorrhoids, and bowel inflammations. They also help eliminate toxins that originate in the intestines.
Some insoluble fibers are cellulose and lignin, which can be found in whole grains, especially almonds, chia and flaxseeds, walnuts, raisins, and fruit and vegetable skins.
Recommended daily fiber amount
Daily intake of fiber should be around 20 to 40 grams per day. One tip to eat more fiber-rich food is up your intake of raw, whole food (e.g. fruit and vegetables with the peel), and avoid refined foods, such as white flour and white rice.
In order to treat constipation, it is important to remember that as well as increasing fiber consumption, you should also increase water intake (plain water or tea without sugar), as water hydrates the fiber in the intestines, which helps stool to move through the tract. Eating more foods with water, such as jelly, orange, and watermelon also helps to prevent constipation that comes from ingesting more fiber but insufficient water.
According to the Academy of Nutrition and Dietetics, the daily recommended amount of fiber varies according to age and gender, as per the following table:
Quantity of fiber in men per 1000 kcal/day
Quantity of fiber in women per 1000 kcal/day
0 to 6 months
Mother’s milk only
Mother’s milk only
6 to 12 months
1 to 3 years old
4 to 8 years old
9 to 13 years old
14 to 18 years old
19 to 50 years old
> 50 years old
How to eat more fiber
Finally, another solution for ingesting more fiber is to supplement all your meals with a source of fiber, such as oats, ground flaxseed or wholemeal wheat bran. You could, for instance, add some oats to a fruit salad, or add some wheatgerm to your yogurt.