The Importance of a High-Fiber Diet (& How to Boost Your Intake)

What is fiber? 

By definition, dietary fiber is a form of non-digestible carbohydrates that comes from the plants we eat. Fiber comes in two forms, soluble and insoluble. 

Soluble fiber primarily comes from the inside part of plants and gets its name from being soluble in water. Soluble fiber is fermented by the bacteria in our gut and forms a gel-like substance that plays an essential role in regulating the rate of digestion.

Insoluble fiber comes from the skin of plants and is not soluble in water or fermented by bacteria. Insoluble fiber forms the bulk of our stool, which helps keep everything moving as it should. 

But what does all of that mean for our health? 

How fiber keeps us healthy:

Gut health 

When fiber is fermented by the bacteria in our colon, by-products called short-chain fatty acids are formed. These short-chain fatty acids offer us a variety of benefits ranging from supporting our immune system and digestion, regulating inflammation, and the brain-gut connection. Insoluble fiber promotes healthy bowel movements by providing bulk to our stool to prevent loose stool and absorbing water to keep our stool soft enough to pass and thus prevent constipation. High-fiber diets can also help to prevent the formation of hemorrhoids or diverticular disease. 

Heart health

Soluble fibers help manage healthy cholesterol levels. The soluble fiber binds to the cholesterol molecules in the small intestine, thus preventing their absorption. The role of soluble fiber in lowering cholesterol helps to prevent the development of coronary heart disease. 

Blood sugar management 

Soluble fibers form a gel-like substance in our gut and help to slow down the absorption and digestion of carbohydrates. This supports a steady release of glucose into the bloodstream and helps to lower insulin demand in the body. 

Weight management

Soluble fiber helps to make our stomach content viscous, which slows gastric emptying (the movement of food from our stomach to our intestines). This helps us feel satisfied by our meals and also can help reduce weight. 

Cancer and other chronic illnesses 

Generally speaking, fiber supports a healthy microbiome, which thus supports the prevention of chronic illnesses. The short-chain fatty acids produced via the fermentation of fiber play an important role in disease prevention. One of these short-chain fatty acids, called Butyrate, has anti-cancer properties which include inhibiting cell growth and promoting apoptosis (cell death) in cancerous cells. Studies have also shown that a high-fiber diet decreases the risk of colorectal cancer. 

How much fiber do we need, and how can we get it?

About 95% of Americans and 91% of those in the UK are not meeting the daily recommended intake of dietary fiber, missing their fiber goals by nearly half. The recommendation for healthy adults is 14 grams of fiber for every 1,000 calories, which comes to anywhere from 25 to 38 grams of fiber per day. The best way to achieve this goal is to eat a variety of plant foods, including vegetables, legumes, fruits, whole grains, seeds, and nuts. Variety allows you to consume adequate amounts of both soluble and insoluble fiber, as well as other nutrients like vitamins, minerals, and phytonutrients. The following is an example of what foods you could incorporate in daily meals and snacks to meet fiber intake requirements:

Breakfast: ½ cup of raspberries (4g fiber) , ½ oz pumpkin seeds (2.6g fiber). You could incorporate these into your breakfast in a yogurt bowl, oats, smoothies, or even on top of pancakes.

Snack: 2 cups of popped popcorn (3.8g fiber). 

Lunch: Whole wheat tortilla (2.9g fiber), ½ cup black beans (7g fiber), 1 bell pepper (2g fiber). You could incorporate these foods into a burrito, and even add extra fiber by slicing the bell peppers and dipping them in hummus.

Snack: Apple (4.8g fiber) and peanut butter (2g fiber).

Dinner: 1 cup broccoli (5.2g fiber), which you can pair with your favorite sources of protein and carbs, like pasta and chicken or rice and fish.

Total: ~34g of fiber

Check out a comprehensive list of fiber-rich foods here.

TL;DR Fiber is important in not just our gut health, but also our heart health, blood sugar management, weight management, and disease prevention. You can meet your fiber intake goals, 14g for every 1,000 calories, by eating plant foods like vegetables, fruits, seeds, nuts, and whole grains.

Words by Madeline Peck, RDN, CDN, Huel nutrition team