Invited Review Manipulating effects of fruits and vegetables on gut microbiota – a critical review Jing Luo, 1 Xian Lin, 1,2 Matteo Bordiga, 3 Charles Brennan 4 & Baojun Xu 1 * 1 Food Science and Technology Program, BNU–HKBU United International College, Zhuhai, China 2 Guangdong Academy of Agricultural Sciences/Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs/Guangdong Key Laboratory of Agricultural Products Processing, Sericultural & Agri-Food Research Institute, Guangdong, China 3 Dipartimento di Scienze del Farmaco, Universit a degli Studi del Piemonte Orientale ‘A. Avogadro’, Novara, Italy 4 Faculty of Agriculture and Life Sciences, Lincoln University, Christchurch, New Zealand (Received 12 September 2020; Accepted in revised form 9 December 2020) Abstract The objective of the current review was to systematically investigate health-promoting manipulating effects of fruits and vegetables (F&V) on the gut microbiota. The function of gut microbes was found to pro- mote health effects in the host by scavenging free radicals, modulating immune system, alleviating obesity and diabetes. Masters that manipulate the gut microbiota are the phytochemicals within specific types of F&V, where polyphenols account for the largest proportion, along with alkaloids, terpenes, nitrogen-con- taining compounds, polysaccharides and natural pigments present in plants. These bioactive compounds exhibit the regulative influences on gut microorganisms characterised by rescuing dysbiosis of gut micro- biota, increasing/decreasing microbial abundance, restructuring microbial composition, and rebalancing gut microbial homeostasis. This review indicated that F&V extracts targeting at gut microbiota could be a new scope of ingredient selection in the field of functional food especially for amelioration of dysfunc- tion of intestinal ecosystem. Keywords Fruits and vegetables, gut microbiota, intestinal ecosystem, phytochemicals. Introduction The gut is a host for a wide range of microorganisms, including fungi, bacteria, archaea, protozoa and even viruses, and these microorganisms are called gut microbiota or gut microbiome (Hugon et al., 2016). Microbiota in human gut comprises of more than 1000 species and 7000 subspecies. The predominant microbes colonise in the intestines belong to phyla Fir- micutes, Bacteroidetes, Actinobacteria, Proteobacteria and Fusobacteria (Cho & Blaser, 2012; Human Micro- biome Project Consortium, 2012). Specifically, the most abundant gut microbe genera are Bacteroidetes, Bifidobacterium, Faecalibacterium and Roseburia (Human Microbiome Project Consortium, 2012). Gut microbiota has received growing attention in recent years, and studies have revealed its correlation with health and diseases. Dysbiosis of gut microbiota is linked with certain diseased conditions, including gas- trointestinal diseases (such as constipation, irritable bowel syndrome) (Zuo & Ng, 2018; Khan et al., 2019), inflammatory diseases (such as inflammatory bowel disease) (Pickard et al., 2017; Van den Elsen et al., 2017), metabolic disorders (such as type 2 diabetes, obesity) (Boulang e et al., 2016; Agus et al., 2018; Ganesan et al., 2018) and neurological disorders (such as depression, Parkinson’s disease and Alzheimer’s dis- ease) (Jiang et al., 2017; Parashar & Udayabanu, 2017; Sherwin et al., 2017). Composition of gut microbiome is susceptible to dietary intake of food, especially fruits and vegetables (F&V). F&V-rich diets provide abundant source of fibres that promote the growth of gut microbiota by serving as prebiotics. Dietary fibres in F&V are a ser- ies of complex polysaccharides, such as pectin, inulin, cellulose, hemicellulose and resistant starch (Davison & Temple, 2018). Fibres are indigestible by human intestines but can be broken down by gut bacterial fer- mentation (Flint, 2012). Metabolites produced from the fermentation, such as short-chain fatty acids, lac- tate and pyruvate (Flint et al., 2012), can be absorbed to the host and used as nutrients. Apart from dietary fibres, F&V also comprises a wide range of bioactive compounds, such as polyphenols, alkaloids, terpenoids *Correspondent: E-mail: baojunxu@uic.edu.cn International Journal of Food Science and Technology 2021, 56, 2055–2067 doi:10.1111/ijfs.14927 © 2020 Institute of Food Science and Technology 2055