Onion(Allium cepa) Prebiotic

Ref American Society For Microbiology

(mSystems.) 2024 Dec 23;10(1):e01189-24. doi: 10.1128/msystems.01189-24

The prebiotic potential of dietary onion extracts: shaping gut microbial structures and promoting beneficial metabolites

Yebeen Yoo 1,#, Seongok Kim 1,2,#, WonJune Lee 2, Jinwoo Kim 1,2, Bokyung Son 3, Kwang Jun Lee 4,✉, Hakdong Shin 

 Introduction 

Allium cepa, commonly known as onion, is a bulbous plant that is extensively cultivated worldwide. Compounds from onion have been reported to offer a range of health benefits, including anti-carcinogenic, anti-platelet activity, anti-thrombotic activity, anti-asthmatic, and antibiotic effects (1). These compounds are phytomolecules, including various carbohydrates, polyphenols, dietary fibers, flavonoids, and sulfur compounds 

(2–5). Among them, carborhydrates such as oligosaccharides have gained significant attention for their prebiotic application, as its supplementation has been shown to improve human health disorders, including Chron’s disease, allergen reaction, atopic dermatitis, and intestinal diseases (6–11).

Prebiotics have recently been defined by the International Scientific Association for Probiotics and Prebiotics as “a substrate that is selectively utilized by host microorganisms conferring a health benefit (12).

” Substrates considered prebiotics include non-digestible oligosaccharides, such as fructooligosaccharide (FOS) and galactooligosaccharide, dietary fiber like inulin and pectin, plant-derived polyphenols, and polysaturated fatty acids (12, 13). 

These compounds naturally exist in different dietary food products, including asparagus, sugar beet, garlic, chicory, onion, and other vegetables (14).

 Prebiotics are metabolized by gut microbiota, resulting in the production of beneficial products through microbial cross-feeding, such as short-chain fatty acid and tryptophan-derived metabolites (indolelactate [ILA] and indolepropionate [IPA]). These metabolites have been shown to impact host biological functions, including the maintenance of epithelial barrier integrity, immune modulation, the control of intestinal inflammation, and metabolic disorders (15–23).

The gut microbiota, consisting of 10–100 trillion microorganisms, is considered as an important factor due to its contribution to human health (24). 

The structure of gut microbiota varies significantly among individuals and is influenced by host factors such as age, nationality, gender, and body mass index (BMI) (25). 

These variations have posed challenges in studying the relationships between the human microbiome and health. To address this, recent studies have introduced enterotyping, which categorizes complex human gut microbial communities into three distinct enterotypes based on the predominance of specific genera: Bacteroides (enterotype 1), Prevotella (enterotype 2), and Ruminococcus (enterotype 3), although the classification of enterotype 3 remains controversial (25, 26).

 These enterotypes represent densely populated areas of community composition within a multi-dimensional space, simplifying the complex gut microbial community by minimizing individual variation (25).

 This approach has facilitated deeper exploration of the connections between the human microbiome and various diseases or diets, which has contributed to advances in cancer diagnostics, implications for weight loss, and the development of personalized nutrition plans for obesity management (27–30).

In this study, we demonstrate the potential of dietary onion extract as a prebiotic, 

Allium cepa, commonly known as onion, is a bulbous plant that is extensively cultivated worldwide. Compounds from onion have been reported to offer a range of health benefits, including anti-carcinogenic, anti-platelet activity, anti-thrombotic activity, anti-asthmatic, and antibiotic effects (1). These compounds are phytomolecules, including various carbohydrates, polyphenols, dietary fibers, flavonoids, and sulfur compounds (2–5). Among them, carborhydrates such as oligosaccharides have gained significant attention for their prebiotic application, as its supplementation has been shown to improve human health disorders, including Chron’s disease, allergen reaction, atopic dermatitis, and intestinal diseases (6–11).

Prebiotics have recently been defined by the International Scientific Association for Probiotics and Prebiotics as “a substrate that is selectively utilized by host microorganisms conferring a health benefit (12).” Substrates considered prebiotics include non-digestible oligosaccharides, such as fructooligosaccharide (FOS) and galactooligosaccharide, dietary fiber like inulin and pectin, plant-derived polyphenols, and polysaturated fatty acids (12, 13). These compounds naturally exist in different dietary food products, including asparagus, sugar beet, garlic, chicory, onion, and other vegetables (14). Prebiotics are metabolized by gut microbiota, resulting in the production of beneficial products through microbial cross-feeding, such as short-chain fatty acid and tryptophan-derived metabolites (indolelactate [ILA] and indolepropionate [IPA]). These metabolites have been shown to impact host biological functions, including the maintenance of epithelial barrier integrity, immune modulation, the control of intestinal inflammation, and metabolic disorders (15–23).

The gut microbiota, consisting of 10–100 trillion microorganisms, is considered as an important factor due to its contribution to human health (24). The structure of gut microbiota varies significantly among individuals and is influenced by host factors such as age, nationality, gender, and body mass index (BMI) (25). These variations have posed challenges in studying the relationships between the human microbiome and health. To address this, recent studies have introduced enterotyping, which categorizes complex human gut microbial communities into three distinct enterotypes based on the predominance of specific genera: Bacteroides (enterotype 1), Prevotella (enterotype 2), and Ruminococcus (enterotype 3), although the classification of enterotype 3 remains controversial (25, 26). These enterotypes represent densely populated areas of community composition within a multi-dimensional space, simplifying the complex gut microbial community by minimizing individual variation (25). This approach has facilitated deeper exploration of the connections between the human microbiome and various diseases or diets, which has contributed to advances in cancer diagnostics, implications for weight loss, and the development of personalized nutrition plans for obesity management (27–30).

In this study, we demonstrate the potential of dietary onion extract as a prebiotic, highlighting its significant impact on gut microbial composition and its ability to enhance the production of beneficial metabolites such as butyrate and IPA/ILA.

MATERIALS AND  its significant impact on gut microbial composition and its ability to enhance the production of beneficial metabolites such as butyrate and IPA/ILA