Let’s Investigate Fiber

Fiber. We hear about it all of the time: in TV ads praising high-fiber protein bars and cereals, on supplement bottles at our local pharmacies, and in everyday conversation. But even though we understand that fiber is an important part of a healthy diet, most of us don’t have a clue why. For that reason, we will investigate fiber​​—examining what it is, why we need it, and how we can increase our consumption of fiber.

What is Fiber?

For starters, let’s set some groundwork. According to the Nutrition Source at Harvard’s T.H. Chan Public Health School, fiber is a type of complex carbohydrate that the body cannot digest (2021). This means that fiber passes through our stomach and small intestine, the organs responsible for breaking down food and absorbing its nutrients. 

Dietary fiber is found in most plant products, but not animal products, and comes in two distinct forms: soluble and insoluble fiber. Soluble fiber dissolves in water and other gastrointestinal fluids, slowing down the digestive process and lowering both cholesterol and blood glucose levels along the way. Insoluble fiber does not dissolve in water. This type of fiber is known to have a laxative effect, making us less constipated and softening our stool. Listed below are some examples of whole foods that contain fiber:

Soluble Fiber

  • Barley
  • Lentils
  • Apples
  • Oatmeal
  • Avocados

Insoluble Fiber

  • Whole wheat bread
  • Beans
  • Nuts
  • Cauliflower
  • Avocados

How Much Fiber Do We Need to Eat on a Daily Basis?

At this point you may be wondering: how much fiber should we eat everyday? According to the USDA, women under the age of 50 should eat approximately 25 grams of fiber per day, while men of this age group should eat about 38 grams per day. For context, there is about 3 grams of fiber in 1 medium banana and 5 grams of fiber in 1/2 of a medium avocado—so it’s important to eat lots of whole foods in order to meet our daily fiber needs!

What are the Health Impacts of Fiber Consumption?

Now that we have a basic understanding of fiber, let’s look into some of its health-promoting properties. Along with an abundance of other perks, a 2019 meta-analysis highlighted three of its main proven benefits (Reynolds et al., 2019). 

  1. Fiber is heart healthy and effectively lowers our risk for heart disease.
  2. Fiber lowers blood glucose levels, reducing our risk for diabetes.
  3. Fiber helps to maintain bowel health.

The Bottom Line 

In spite of its known importance, most Americans don’t eat enough fiber. Some ways to increase our fiber intake include:

  1. Swap out white bread for whole wheat bread. Tip: make sure “whole” is the first ingredient on a bread’s nutrition label; just because it’s labeled as multigrain does not necessarily mean it’s whole grain.
  2. Add more fruits and veggies into your meals. For example, add sliced apples to oatmeal for breakfast.
  3. Snack on nuts and fruit. 
  4. Leave the skin on fruits and vegetables, such as apples and cucumbers.

Looking for High-Fiber Meal Inspiration? Here are a few of my favorites:

  1. Breakfast: a bowl of oatmeal with mixed berries
  2. Lunch: black beans, corn, mashed avocado, and cotija cheese in a whole wheat wrap
  3. Snack: an apple, with the skin-on, and peanut butter 
  4. Dinner: coconut lentil curry with brown rice and roasted vegetables

Sources

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