Fiber is the indigestible portion of plants, and falls under the carbohydrate category of macronutrients. It is important for health, especially for the health of our guts. Keep in mind that not all sources of fiber are created equal. Fiber that has been added back to heavily processed and sugary cereal vs fiber from whole grains, vegetables and fruit, can have a different impact on the body. I think you know which sources are probably more health promoting. An overview of the different types of fiber, the importance of getting enough, how much is enough and which foods are high in fiber is below. Yay, fiber!
What does fiber do?
A lot! Sufficient fiber helps:
- Us absorb and digest food better
- Slow down the digestion of carbohydrates and therefore helps support balanced blood sugar and promotes satiety (feeling of fullness)
- Normalize serum cholesterol levels
- Keep our intestinal pH in balance
- Improve bowel function and may help prevent constipation, diverticulitis, appendicitis, colon polyps and colon cancer, hemorrhoids and varicose veins
- Reduce the risk of heart disease, high blood pressure and certain types of cancer
What are the different types of fiber?
- Soluble Fiber ~
- Dissolves in water
- Is a prebiotic, so is "food" for the healthy bacteria in our guts that gets fermented and creates health promoting by-products
- Has anti-inflammatory effects
- Increases insulin sensitivity
- May help with diseases of the colon, such as Crohn's, Irritable Bowel Syndrome (IBS) and Ulcerative Colitis
- May help protect against heart disease
- Increases satiety (fullness), which can help with blood sugar regulation
- Insoluble Fiber ~
- Does not dissolve in water
- Is typically not fermented by the bacteria in our guts (so is not a prebiotic)
- Provides bulking action to stool
- Increases regularity of bowel movements
- Resistant Starch (RS) ~ is a type of starch that cannot be digested, and is considered a 3rd type of fiber. It is also a prebiotic and is fermented by the healthy bacteria in our guts. RS may also:
- Increase the uptake of minerals from our foods
- Reduce the number of bad bacteria in our guts
- Improve the function of the gut
- Play a role in reducing blood sugar and insulin levels
How much fiber do we need?
It is important to get both soluble and insoluble fiber in our diets every day. Whole food sources usually contain both types, although in differing amounts, so some foods are higher in one type than the other.
Each individual's needs can be different with optimal amounts somewhere between 35 - 50 grams per day. Please note: if you want to increase your fiber intake, take it slow, as a big jump in fiber intake can lead to gas and discomfort.
Which foods are high in fiber?
Fiber containing foods usually contain both soluble and insoluble fiber, although in different amounts. Here are a few examples:
- Fruits (especially berries)
- Starchy (root vegetables and winter squash) and non-starchy vegetables (asparagus, broccoli, leafy greens, onions, etc.)
- Nuts and seeds (especially flaxseeds)
- Some legumes and whole grains (Note: may need to limit if blood sugar balance is an issue)
- Sources of resistant starch include:
- Unripe bananas
- Onions and garlic
- Jerusalem artichokes
- Potatoes and rice that have been cooked and then cooled
- Taro root
- Tapioca flour
- Some legumes
Bauman, Ed, PhD., Friedlander, Jodi, N.C. (2015). Therapeutic Nutrition Part 1. Penngrove, CA: Bauman College.
Kresser, Chris, LAc. (2013). Your Personal Paleo Code. New York, NY: Little, Brown and Company Hachette Book Group.
Lipski, Elizabeth, PhD, CCN, CHN (2013). Digestion Connection. New York, NY: Rodale.