DIETARY FIBERS
Dietary fibers are a diverse group of indigestible plant components, primarily
carbohydrates (polysaccharides) and lignin, that resist digestion by human
gastrointestinal enzymes. Unlike starch and other digestible carbohydrates, fibers
are not broken down in the small intestine. Instead, they pass largely intact into the
large intestine, where some fibers undergo partial fermentation by gut microbiota.
Fibers are classified into soluble and insoluble types, each contributing differently
to digestion, metabolism, and overall health. Because humans cannot synthesize
fibers, dietary intake is essential to maintain gastrointestinal, metabolic, and
cardiovascular health.
CLASSIFICATION OF DIETARY FIBERS
Soluble Fibers
Soluble fibers dissolve in water to form viscous gels. Examples include pectins,
gums, mucilages, β-glucans, and some hemicelluloses.
Physiological Effects:
Slow gastric emptying
Reduce postprandial blood glucose spikes
Bind bile acids to lower serum cholesterol
Insoluble Fibers
Insoluble fibers do not dissolve in water and add bulk to the stool. Examples
include cellulose, lignin, and certain hemicelluloses.
Physiological Effects:
Accelerate intestinal transit
Prevent constipation and hemorrhoids
Maintain gut motility and prevent diverticulosis
Functional and Total Fiber
, Functional fiber: Isolated or extracted fibers added to foods for health benefits (e.g.,
inulin, psyllium husk).
Total fiber: Sum of naturally occurring dietary fiber and functional fiber.
PHYSIOLOGICAL FUNCTIONS OF DIETARY FIBERS
Gastrointestinal Health
Fibers improve bowel function by increasing stool bulk, softening stools, and
stimulating peristalsis. Insoluble fibers prevent constipation, while soluble fibers
help regulate water content and stool consistency. Fermentable fibers in the colon
produce short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate,
which nourish colonocytes, maintain gut integrity, and reduce inflammation.
Dietary fibers are a diverse group of indigestible plant components, primarily
carbohydrates (polysaccharides) and lignin, that resist digestion by human
gastrointestinal enzymes. Unlike starch and other digestible carbohydrates, fibers
are not broken down in the small intestine. Instead, they pass largely intact into the
large intestine, where some fibers undergo partial fermentation by gut microbiota.
Fibers are classified into soluble and insoluble types, each contributing differently
to digestion, metabolism, and overall health. Because humans cannot synthesize
fibers, dietary intake is essential to maintain gastrointestinal, metabolic, and
cardiovascular health.
CLASSIFICATION OF DIETARY FIBERS
Soluble Fibers
Soluble fibers dissolve in water to form viscous gels. Examples include pectins,
gums, mucilages, β-glucans, and some hemicelluloses.
Physiological Effects:
Slow gastric emptying
Reduce postprandial blood glucose spikes
Bind bile acids to lower serum cholesterol
Insoluble Fibers
Insoluble fibers do not dissolve in water and add bulk to the stool. Examples
include cellulose, lignin, and certain hemicelluloses.
Physiological Effects:
Accelerate intestinal transit
Prevent constipation and hemorrhoids
Maintain gut motility and prevent diverticulosis
Functional and Total Fiber
, Functional fiber: Isolated or extracted fibers added to foods for health benefits (e.g.,
inulin, psyllium husk).
Total fiber: Sum of naturally occurring dietary fiber and functional fiber.
PHYSIOLOGICAL FUNCTIONS OF DIETARY FIBERS
Gastrointestinal Health
Fibers improve bowel function by increasing stool bulk, softening stools, and
stimulating peristalsis. Insoluble fibers prevent constipation, while soluble fibers
help regulate water content and stool consistency. Fermentable fibers in the colon
produce short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate,
which nourish colonocytes, maintain gut integrity, and reduce inflammation.
