Understanding the Types of Dietary Fiber

The first thing to know: Fiber is not just one thing. Fiber is a diverse group of compounds that each behave differently in your body. Knowing which types of fiber you’re getting can help you optimize your digestion, metabolism, and personalize your gut health.

Here’s a breakdown of the main fiber categories recognized by nutrition science, including the functional fibers used in ALF products.

Soluble Fiber (aka Regular Fiber)

Soluble fiber dissolves in water to form a gel-like substance. This slows down your digestion, helping to regulate blood sugar levels and can reduce LDL (“bad”) cholesterol. This is also what gives foods like oatmeal and beans their thick texture when cooked.

• β-Glucans (Beta Glucans): Found in oats and barley; clinically proven to lower cholesterol
• Inulin: A plant-based prebiotic fiber that supports gut bacteria
• Pectins: Naturally occurring fibers in the cell walls of fruit; thickens jams and promotes fullness
• Gums: Gel-forming plant exudates such as guar gum or gum arabic

Key benefit: Promotes satiety, supports cholesterol and glucose balance.

Insoluble Fiber

Insoluble fiber doesn’t dissolve in water. Instead, it adds bulk to your stool and helps food move through your digestive system efficiently. This type of fiber is essential for maintaining regularity and preventing constipation.

• Cellulose: Structural fiber in vegetables and grains; resists digestion
• Lignin: Found in seeds and woody plants; provides texture and bulk
• Hemicellulose: A mix of plant polysaccharides that absorb water and support intestinal health

Key benefit: Supports regular bowel movements and digestive comfort.

Fermentable / Prebiotic Fiber

Fermentable fibers are digested not by you, but by your gut microbes. They’re considered prebiotics — meaning they selectively feed beneficial bacteria like Bifidobacterium and Lactobacillus, which in turn produce short-chain fatty acids (SCFAs) such as butyrate that nourish the colon and support immune health.

• Inulin: A well-studied prebiotic fiber found in plants such as chicory root and Jerusalem artichoke
• GOS (Galactooligosaccharides): Found in beans and milk; enhances microbiome diversity
• Resistant Starch: Present in cooked and cooled potatoes or rice; supports insulin sensitivity

Key benefit: Feeds gut microbes and promotes a healthy microbiome ecosystem.

Functional Fiber (FDA-Recognized)

Functional fibers are isolated or synthetic fibers that have been proven through clinical studies to provide health benefits. The U.S. Food and Drug Administration (FDA) officially recognizes certain fibers in this category for their roles in cholesterol management, glycemic control, and digestive support.

• Psyllium: A gel-forming husk fiber that helps regulate cholesterol and bowel habits
• α-Cyclodextrin (Alpha Cyclodextrin): A ring-shaped plant-based fiber derived from starch, clinically shown to support healthy lipid metabolism and blood sugar response. This is the active ingredient in ALF Cyclodextrin.

Key benefit: Clinically validated for metabolic and digestive health improvements.

Specialized Fibers

Beyond the common categories, some fibers have unique chemical structures or biological activities that make them “specialized.” These fibers may influence fat absorption, immune function, or gut barrier integrity.

• Chitosan: A marine-derived fiber that can bind dietary fats in the digestive tract
• Arabinoxylan: A hemicellulose component of wheat bran that supports prebiotic fermentation
• Psyllium (Husk Fiber): A dual soluble/insoluble fiber used in many digestive supplements

Key benefit: Provides targeted or specialized physiological effects beyond general digestion.

Takeaway

Dietary fiber is a family of compounds that work together to support metabolism, gut function, and overall health. ALF focuses on functional cyclodextrin fibers because they combine the benefits of traditional fibers with targeted and clinically validated physiological effects.

So soluble and insoluble fibers build your foundation, and functional and prebiotic fibers take it further.