Prebiotics are food components that demonstrate beneficial effects on human health and support the balance of the gut microbiota. These compounds resist digestion in the gastrointestinal tract and reach the colon intact, where they selectively stimulate the growth and activity of beneficial bacteria residing in the gut. Through this mechanism, prebiotics contribute to the optimal utilization of metabolism by gut microorganisms. Carbohydrates that are indigestible in the upper gastrointestinal system such as resistant starch and certain polyols exhibit prebiotic properties.
The fermentation of prebiotics in the colon helps regulate stool consistency, prevents conditions such as constipation and diarrhea, and aids in balancing glucose and cholesterol levels. Simultaneously, they promote the proliferation of bifidobacteria and lactobacilli, enhancing the production and absorption of B vitamins and supporting immune system regulation. Prebiotics also assist in reducing the risk of obesity, colorectal cancer, and osteoporosis. Endogenous prebiotics produced by the human body and human milk oligosaccharides serve as natural prebiotic sources that support the development of the infant gut microbiota.
Oligosaccharide-Based Prebiotics
- Oligosaccharides are short-chain carbohydrates typically composed of 3–10 monosaccharide units that exhibit prebiotic properties. They can be naturally isolated from plants or produced through enzymatic and hydrothermal processes.
- Fructooligosaccharides are found in many plants such as banana, garlic, onion, tomato, wheat, asparagus, artichoke, leek, honey, and rye. They are broken down by the host microbiota in the proximal intestine into short-chain fatty acids and promote the growth of bifidobacteria. They also enhance calcium and magnesium absorption.
- Galactooligosaccharides are derived from milk and legumes and support the development of bifidobacteria in the gut. Daily intake levels may vary depending on individual health status, and dosage adjustments are important for individuals with diabetes or high cholesterol.
- Xylooligosaccharides are obtained through enzymatic hydrolysis of xylan and selectively modulate the gut flora by inhibiting the growth of pathogenic bacteria. Isomaltooligosaccharides are produced via enzymatic reactions from starch and exhibit bifidogenic effects. Soyoligosaccharides are extracted from soybeans and support gut microbiota balance while inhibiting pathogenic microorganisms.
- Lactosucrose is a prebiotic produced by the enzymatic synthesis of lactose and sucrose. It increases the abundance of bifidobacterial species in the fecal microbiota and exhibits a strong laxative effect. Oligosaccharides derived from lactulose are lactulose-based and possess high prebiotic activity. Raffinose oligosaccharides contain raffinose, stachyose, and verbascose compounds, exert bifidogenic effects in the gut, and possess anticancer and antioxidant properties.
- Pectic oligosaccharides are obtained from agricultural waste rich in pectin and exhibit competitive antimicrobial activity. Arabinoxylan oligosaccharides are derived from side products of arabinoxylan in cereal cell walls and provide bifidogenic effects. Mannooligosaccharides are linear chains of mannose sugars obtained from yeast cell walls or coconut waste, which inhibit pathogenic microorganisms and support immune function.
- Neoagaro-oligosaccharides are produced by enzymatic hydrolysis of agarose, are resistant to gastrointestinal enzymes, and support the growth of lactobacilli and bifidobacteria. Chitosan-oligosaccharides are obtained through enzymatic hydrolysis of chitosan, inhibit the proliferation of enteropathogenic bacteria, and enhance the activity of beneficial bacteria. Phosphorylated oligosaccharides are derived from potato starch, increase calcium absorption, and exhibit prebiotic effects similar to other oligosaccharides. Prebiotic components sourced from yak milk possess antihypertensive and immunomodulatory properties.
Production and Analysis of Prebiotics
Prebiotics can be produced through isolation from plants, microbial or enzymatic synthesis, and enzymatic hydrolysis of polysaccharides. Structural analysis of oligosaccharides involves determining monosaccharide sequence, linkage types, branching patterns, and anomeric configuration. Major analytical techniques include thin-layer chromatography, high-performance liquid chromatography, mass spectrometry, NMR, and MALDI-TOF-MS.
Health Effects of Prebiotics
Prebiotics promote the growth of beneficial microorganisms by balancing the gut microbiota, regulate intestinal transit, enhance mineral absorption, and support immune function. They also reduce the risk of obesity and colorectal cancer, balance lipid and glucose metabolism, and increase the production and absorption of B vitamins. From the perspective of the functional food industry, prebiotics hold a significant position as health-promoting and metabolism-balancing food components.
