We’ve all heard about the importance of fiber to our health and digestion, but there are different kinds of fiber that play distinct roles and have varying effects on your health.
Fiber is a non-digestible carbohydrate that offers many health benefits. Many of us fall short of the daily recommendations for fiber: The average American consumes 15 grams/day, compared to the recommended 25 or 38 grams/day for women and men, respectively.
High-fiber diets can help protect against diseases like Type 2 diabetes, heart disease and even certain types of cancer. Many of fiber’s health-promoting qualities likely have to do with the foods fiber is inherently found in. Foods with dietary fiber — like fruits, vegetables, nuts, legumes and whole grains — also contain other nutrients including vitamins, minerals and phytochemicals that benefit our health.
SOLUBLE VS. INSOLUBLE FIBER
There are two main types of fiber: soluble and insoluble. Soluble fiber attracts water, and can dissolve in it. It forms a “jelly like” substance in your small intestine, slowing digestion and helping to keep you full longer. Soluble fiber can also be great for helping to lower cholesterol, by increasing the rate of bile excretion, thereby preventing the recycling and reabsorption of cholesterol in the body. Soluble fibers include beta glucans (found in oats, barley and rye), pectins (found in fruit, veggies and beans), gums (seeds, seaweed) and inulin-containing foods (chicory, onion, processed foods).
In contrast to soluble fiber, insoluble fiber is better known for its effect on helping with bowel consistency. Insoluble fibers, like those found in wheat bran, vegetables and whole grains, contribute bulk to help foods pass more quickly through the digestive system.
We know that the natural soluble and insoluble fiber in foods is health promoting. Research shows that soluble fiber, like that found in oatmeal, legumes and certain fruits and vegetables, can lower total and LDL cholesterol while also reducing the risk of heart disease. The National Cholesterol Education Program Expert Panel recommends consuming 10–25 grams of soluble fiber per day to help lower blood cholesterol.
NATURAL VS. ADDED FIBER
Natural fiber refers to the fiber found intrinsically in foods like fruits, vegetables, whole grains, cereal bran and flours. Processed and packaged foods, like bars, cereals and oatmeal, often contain added fibers, which can be isolated and/or synthetic. Critics argue that adding isolated fiber to products doesn’t account for the nutritional deficiencies and phytochemicals that may be lacking compared to sources of natural fiber.
The FDA has recently refined the definition of dietary fiber, declaring that added fiber can be listed as dietary fiber on food labels only if they met the “beneficial physiological effect to human health” criterion. The FDA reviewed 26 different fiber-containing ingredients used in processed foods to determine if they have any health benefits associated with them to come up with this new definition.
Only seven non-digestible carbohydrates currently meet the existing dietary fiber definition, including beta glucan soluble fiber, psyllium husk, cellulose, guar gum, pectin, locust bean gum and hydroxypropyl methycellulose (found in many gluten-free foods). The FDA has set compliance dates ranging from July 2018–July 2019 for manufacturers to conform to the new labeling.
READ MORE > WHAT 33 GRAMS OF FIBER LOOKS LIKE
THE CASE AGAINST PROCESSED FOOD
While processed and convenient foods with fiber may be a dietary complement for people who aren’t getting enough fiber, those relying on processed sources will likely be lacking in many of the other nutritional qualities of natural fibers. Another thing to be aware of is the presence of other ingredients, like added sugars and starches, that may be in those processed foods.
A protein bar with added fiber may contribute to your daily fiber intake, yet whether that fiber has the same health-promoting properties as those found in a pear remains questionable. The natural fiber in the pear would be absorbed with intact synergistic minerals, vitamins and phytochemicals.
Nonetheless, if you’re working to increase your fiber, do it gradually. A good starting place is to add about 5 grams per day, accompanied by plenty of water, to avoid digestive discomfort.