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Dietary fiber (also called roughage or bulk) is a type of carbohydrate found in plant foods. It is mainly present in fruits, vegetables, legumes, and whole grains. The body cannot digest or absorb fiber, and it passes relatively intact through the gastrointestinal system. 

Fiber is best known for preventing constipation, but it provides a number of other health benefits as well. Unfortunately, most Americans don’t eat enough fiber. Please continue reading to find out how much dietary fiber you should eat every day. We will also list some fiber-rich foods that can help you reach your daily fiber intake goals.

Types of Fiber: Soluble vs. Insoluble Fiber

Soluble fiber dissolves in water and forms a gel-like substance. It helps to lower blood glucose and cholesterol levels. Examples of soluble fiber-rich food include legumes such as peas and beans, vegetables such as cauliflower and carrots, fruits like apples and citrus fruits, and whole grains like oats and barley. 

Insoluble fiber does not dissolve in water and adds bulk to stool. It helps to prevent constipation and make bowel movements more regular. Sources of food with high insoluble fiber content include vegetables such as cauliflower, green beans, leafy green vegetables, and potatoes, seeds and skins of fruits, whole grains such as wheat bran, brown rice, and whole wheat flour, and nuts and seeds.

Fiber’s Role in Digestion and Overall Health

Fiber plays a key role in slowing digestion of food, improving absorption of nutrients, and promoting the movement of waste (stool) through the digestive system. It also provides food for healthy gut bacteria. Having a healthy population of beneficial bacteria in the GI tract maintains the gut microbiome (the balance between good and bad bacteria in the digestive tract).

Additional health benefits of dietary fiber include aiding weight loss, lowering blood pressure, preventing blood sugar spikes, normalizing blood cholesterol levels, and lowering the risk of diseases such as diabetes, heart disease, and colorectal cancer.

How Much Fiber Do You Really Need?

The recommended daily fiber intake for adults under 50 is 25 grams for women and 38 grams for men. These amounts are based on specific factors, such as:

Age and sex

The daily recommended fiber intake varies as follows:

• Adult women aged 50 years and younger: 25 grams

• Adult women aged 51 years and older: 21 grams

• Adult men aged 50 years and younger: 38 grams 

• Adult men aged 51 years and older: 30 grams

• Children: 14 grams to 31 grams, depending on age and sex

  • Toddlers aged 1 to 3 years: 14 grams

  • Children aged 4 to 8 years: 17 to 19 grams

  • Pre-teens aged 9 to 13 years: 22 to 25 grams

  • Teenagers aged 14 to 18 years: 25 to 30 grams 

Calories Consumed

Dietary guidelines are to eat 14 grams of fiber per 1,000 calories consumed. Therefore, if you are on a 2,000-calorie per day eating plan, your goal should be to eat 28 grams of dietary fiber daily.

Other factors, such as chronic health conditions, medications, and fluid intake, can also affect fiber intake recommendations. 

The Health Benefits of Adequate Fiber Intake

Digestive Health and Prevention of Constipation

Dietary fiber prevents constipation by adding bulk to stool and softening stool, making it easier to pass. By adding bulk, fiber also solidifies loose, watery stools when you have diarrhea. Find out “What to Eat When You Have Diarrhea.”

Eating a high-fiber diet lowers the risk of diverticular disease, hemorrhoids, and bowel cancer.

Cholesterol Levels and Cardiovascular Disease

Soluble fiber lowers total blood cholesterol levels and LDL (low-density lipoprotein) cholesterol, also known as the “bad” cholesterol. High-fiber foods have additional heart-health benefits, such as lowering blood pressure and reducing inflammation. 

Blood Sugar Levels and Risk of Type 2 Diabetes

Soluble fiber can help manage diabetes by slowing the absorption of sugars and preventing spikes in blood sugar. A healthy diet that includes enough soluble fiber can lower the risk of developing type 2 diabetes.

Weight Loss and Healthy Eating

Foods that have high fiber content keep you feeling full longer, thus reducing caloric intake and aiding with weight loss. Additionally, high-fiber foods are less calorie-dense and can help with weight management.

Mental Health

Although the exact mechanism is unknown, it is believed that a high-fiber diet reduces body inflammation that affects the levels of certain brain chemicals. In other words, a high-fiber diet may have a protective effect on mental health, thus reducing the risk for the development of depression. 

High-Fiber Foods

• Whole grain such as rye, oat bran, rolled oats, quinoa, sorghum, barley, brown rice, bulgar wheat.

• Whole fruits such as apples, pears, bananas, strawberries, and oranges.

• Vegetables such as carrots, cauliflower, broccoli, sweet potatoes, beetroot, eggplant, and leafy greens.

• Beans (black beans, green beans, lima beans), green peas, and other legumes.

• Nuts and seeds, such as almonds, pistachios, chia seeds, and sunflower kernels.

What Does 25-30 Grams of Fiber Look Like?

Here’s an example of what a daily meal plan might look like to get the recommended amount of fiber (25-38 grams) per day:

Tips to Include More Fiber In Your Diet

• Add fiber to your diet gradually and see how your body responds. This will give your gut time to adjust. A good way to do this is to add one fiber-containing food to each meal at a time.

• Eat high-fiber foods throughout the day to meet your fiber needs. Loading up on fiber at one meal can cause side effects like gas and bloating.

• Drink plenty of water to stay well hydrated. Most of the benefits of fiber in preventing constipation are lost if you don’t drink fluids. How Much Water Should You Drink a Day?

• Switch to high-fiber alternatives, such as brown bread instead of white bread and brown rice instead of white rice.

• Add fiber to your favorite foods. Love ice cream? Add nuts and berries to add fiber.

• Increase the variety of fiber sources you eat rather than focusing on a few high-fiber foods.

Fiber Supplements vs. Whole Foods

It’s better to get fiber from whole foods (unprocessed or minimally processed foods) first before turning to a fiber supplement. Whole foods are healthier than processed foods because they have a high fiber content and also contain fewer additives such as sugar and salt. Moreover, getting fiber from whole foods as part of a balanced diet gives you additional nutritional benefits in the form of other nutrients.

However, if you cannot get enough fiber from your daily diet, you may need to take a fiber supplement to fill the gap. Talk to your healthcare provider about taking one of the following:

• Psyllium (Metamucil, Konsyl) contains both soluble and insoluble fiber

• Methylcellulose (Citrucel) contains mostly insoluble fiber

• Wheat dextrin (Benefiber) contains mostly soluble fiber

• Calcium polycarbophil (FiberCon) contains mostly soluble fiber

Compare Citrucel vs Metamucil. Which fiber supplement is right for you?

Side Effects of a High-Fiber Diet

Eating too much fiber can lead to side effects such as gas, bloating, abdominal pain, constipation, and diarrhea. In rare cases, it can cause complications such as intestinal blockage. To lower the risk of side effects, make sure you drink enough water and consume fiber. Be sure to gradually increase fiber in your diet. Find out which foods cause constipation.

Consequences of Not Getting Enough Fiber

Not eating enough fiber can put you at risk of developing gastrointestinal conditions such as constipation, irritable bowel syndrome (IBS), and diverticulitis. It can also increase your risk of diabetes, cardiovascular disease, and some types of cancers. 

Inadequate fiber can cause signs and symptoms such as:

• Constipation

• Hemorrhoids

• Tiredness and sluggishness

• Feeling hungry soon after eating

• Difficulty losing weight

• High cholesterol

References:

1. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983

2. https://www.mountsinai.org/health-library/supplement/psyllium#:

3. https://www.niddk.nih.gov/health-information/digestive-diseases/constipation-children/eating-diet-nutrition

4. https://www.usda.gov/media/blog/2015/03/31/online-nutrition-resources-your-fingertips

5. https://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels

6. https://www.mdanderson.org/cancerwise/8-tips-for-reaching-your-daily-fiber-intake.h00-159622590.html

7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7589116/