Table 1.

Basic sources of six phytochemicals, their roles in different metabolic tissues and their effects on SCFAs

Compound Name	Dietary Source	Role in different metabolic organizations	Effects on SCFAs
Polysaccharides	Seeds	Gut: Altering the concentration of the gut microbiota [110–117]. Downregulation of the expression of TNF-α, and upregulation of the expression of MUC-2 and GPRs [112]. Upregulation of the expression of GLP-1 and PYY [116]. Downregulation of the expression of IL-1β, IL-6, and TNF-α [117].	Upregulation of the concentration of D. vulgaris, llobaculum, Lactococcus, Muribaculaceae_unclassified, Bifidobacterium, Alistipes, Rikenellaceae_RC9_gut_group, Bacteroides Ruminococcus_bromii, Anaerotruncus_colihominis, Clostridium_methylpentosum, Alistipes and Odoribacter. Downregulation of the concentration of Proteobacteria, Lactobacillus, Firmicutes_unclassified, Dubosiella Bilophila, and Streptococcus.
	Stem and leaf tissues
	Herbal plants
	Animal body fluids
	Cell walls
Anthocyanins	Vegetative vesicle	Gut: Altering the concentration of the gut microbiota [123–126, 128]. Upregulation of the expression of FFAR2, FFAR3, and TJ [123]. Upregulation of the expression of TJs and NF-κB pathway protein [127].	Upregulation of the concentration of Ruminococcaceae, Akkermansia, Bacteroide, Odoribacter, Roseburia, Faecalibaculum, Parabacteroides, Ruminococcus, Intestinimonas, and Clostridium_XVIII. Reduction of the Firmicutes/Bacteroide ratio.
Quercetin	Tea, buckwheat	Gut: Altering the concentration of the gut microbiota [133, 134]. Downregulation of the expression of TRPV1, AQP3, and iNOS. Upregulation of the expression of GDNF and c-Kit [133].	Upregulation of the concentration of Coprococcus, Ruminiclostridium and Roseburia. Downregulation of the concentration of Enterococcus and Enterobacter.
	Cranberries, apples
	Lettuce, radish leaves, cilantro and onions
Resveratrol	Grapes and wine	Gut: Altering the concentration of the gut microbiota [142–145]. Downregulation of the expression of IL-6 and IL-1β [143]. Liver: Upregulation of the expression of Nrf2, SOD, and CAT [142].	Upregulation of the concentration of S24-7, Adlercreutzia, Faecalibaculum, and Lactobacillus. Downregulation of the concentration of Allobaculum, Blautia, Lactobacillaceae, and Prevotella.
	Peanuts, soybeans and berries
Carotenoids	Vegetables and fruits	Gut: Altering the concentration of the gut microbiota [154]. Liver: Downregulation of the expression of NLRP3, Pro-Caspase-1, Caspase-1, and NF-κB [154].	Upregulation of the concentration of Allobaculum. Downregulation of the concentration of Lachnospiraceae_NK4A136_group, Desulfovibrio, and Alistipes.
Betaine	Beta vulgaris	Gut: Altering the concentration of the gut microbiota [159, 160]. Liver: Upregulation of the hepatic lipid oxidation genes PPARα and CPT1α and the hepatic lipid transporter gene FATP2 expression [160]. Adipose: Downregulation of the expression of the adipogenic genes Fas and ACC [160].	Upregulation of the concentration of A. muciniphila, Ruminococcus, Oscillospira, Lactobacillus, and Lactobacillus paracasei. Downregulation of the concentration of Aspergillus, Desulfovibrio, and Ruminococcus.
	Bran, Wheat Germ, Spinach