Formulating with Fiber

As Hamlet might have put it, had he been a product developer in modern times, “To add fiber or not to add fiber, that is the question.”

Increasingly, formulators of functional foods and beverages are turning to fiber to help address the fact that the average American consumes only 14 g/d of this critical nutrient, compared to the 25 to 38 g/d recommended in the U.S. dietary guidelines.

There are many great natural food sources of fiber, including fruits (oranges, cantaloupe, grapefruit, papaya), vegetables (zucchini, lima beans) and grains (brown rice, oat bran); but, people still complain they can’t tastefully meet the dietary reference intake (DRI). Actually, the average person just may not have a desire or may not be motivated to eat the fruits, vegetables and grains they should to keep their body running smoothly. Product developers must therefore be realistic and recognize the need to continually add fiber to processed products.

Dietary fiber consists of the remnants of edible plant cells, polysaccharides, lignins and associated substances resistant to (hydrolysis) digestion by the alimentary enzymes of humans. This definition describes compounds such as pectin, gums, oligosaccharides, lignins, cellulose, hemicellulose, modified celluloses and mucilages. Fiber can also be described as digestion-resistant or non-digestible, or soluble or insoluble.

Dietary fiber has value in product formulations for food and dietary supplement products because it provides significant health benefits and functional value. At the same time, there are several important factors to consider, such as flavor, texture, viscosity and cost.

Health Benefits

Fiber is easy to talk about in marketing copy because of its physiological role in the body. Non-digestible fiber passes through the gastrointestinal (GI) tract undigested, reaching the colon. Fibers may be either partially or completely fermented, depending on the type of fiber and organisms available in the colon. If the fiber is not fermented, it will be released in the feces. Even if not fermented, fiber improves bowel function and regularity, reduces constipation, and helps to remove toxins. If the fiber is fermented, it performs those functions plus other health benefits. These include:

Depending on the form and dose, particular sources of fiber have published scientific studies supporting claims such as “supports the gastrointestinal tract and its function”; “supports regularity”; “helps to maintain normal blood lipids”; and “aids normal blood sugar levels in healthy people”. If fiber is going to be used in a functional manner with a claim, other ingredients in the product should also promote health.

Source Drives Function

There are many different sources of fiber available for product formulation. It is important to determine the purpose of the product and how it will be delivered, since soluble and insoluble dietary fibers are so different in formulation related to functionality.

Flavor, texture, viscosity and water-binding capacity, color and cost need to be considered. The solubility, density and particle size are also important. In addition, if combining the fiber with other ingredients, it is important to look at how they will function together. Viscosity will determine whether fiber is appropriate to add to beverages; however, newer soluble, non-gelling fibers are available.

Different forms of fiber include brans from corn, wheat, rice, oat and soy; cellulose; apple and citrus fiber; arabinogalactan; alginate; inulin; and resistant psyllium and starch. Wheat, soy and oat fiber contain phytic acid, which has been shown to bind to some minerals such as calcium, iron and zinc. Coconut fiber is a newer source, which doesn’t contain phytic acid.

Some types of fiber have been positioned to reduce the fat and oils in baked goods, cakes, nutritional bars and muffins, without affecting taste or texture. These fibers improve moisture and emulsification and have an affinity to draw moisture, making them ideal for applications such as salad dressings, sauces and meat fillings. Snacks such as baked tortilla chips have added fiber and provide a healthier profile of ingredients. Even confectionery products may be fortified with dietary fiber. Dietary supplements may include a significant serving size of fiber, delivered via capsules, powders or wafers.

Recently there have been various companies selling fiber products that contain other ingredients such as vitamins, minerals and botanicals. If you chose to formulate these types of combinations, ask the supplier for their research regarding nutrient and drug interaction and impact on absorption. Fiber reduces transit time in the gut, so vitamins, minerals and prescription drugs oftentimes should not be consumed with it or they may not get absorbed properly.

There is also an unmet need for fiber-enhanced products for consumers who restrict carbohydrates from their diet. While low carb diets may serve a health need, they are often high in protein and fat, and deficient in fiber. Many of these consumers are vigilant about the number of calories they consume from carbohydrates daily. Their belief system may be that fiber is a carbohydrate, therefore it should be restricted on a low carb diet.

However, although classified as a carbohydrate, fiber may be partially digestible (digestion-resistant) or non-digestible, and may be used in low carb formulations. It is dependent on the type of fiber and its effects on blood glucose or insulin. This information needs to be communicated to consumers since they may not be aware of the physiological role and effect of non-digestible dietary fiber. 

Judi Quilici-Timmcke, M.S., is the president of Q-Tech Services Inc. and a product formulation specialist. She worked previously as vice president for R&D for Weider Nutrition, and was the head of product development at Rexall Showcase International Quilici-Timmcke (www.JudiQ.com) holds a master’s in dietetics and exercise physiology.