TABLE 4.

Recent studies using microbial profiling techniques highlighting the beneficial role of carotenoids and their potential impact on relevant health outcomes

Study [reference] and main findings	Model	Technique	Design (approach)	Carotenoid	Dosage (duration)	Tissue	Disease state
In vivo animal studies
Gut microbiota regulation and anti-inflammatory effect of β-carotene in dextran sulfate sodium-stimulated ulcerative colitis in rats [212]	Specific pathogen-free male SD rats	16S rRNA	4 groups (n=6/group) -1st group: Normal diet (control group) -2nd group: β-carotene supplementation -3rd group: Dextran sulfate sodium (DSS), ulcerative colitis model -4th group: DSS and β-carotene (Untargeted)	β-Carotene	50 mg/kg bw (1 wk)	Gut microbiota	Ulcerative colitis, inflammation
Findings	β-Carotene: ↑ abundance of Faecalibacterium, Firmicutes and Actinobacteria; ↓ Bacteroidetes and Proteobacteria
Alteration of fecal microbiota by fucoxanthin results in prevention of colorectal cancer in AOM/DSS mice [211]	ICR mice (males, 5-wk-old)	16S rRNA	4 groups (n=5/group). -Groups 1 & 2 (azoxymethane [AOM]/DSS-treated mice): single intraperitoneal injection of AOM (10 mg/kg BW) + 3.0 w/v% DSS in drinking water for 1 wk -Groups 3 & 4: saline injection + water for 1 wk -Groups 1 & 3: oral administration of Fucoxanthin-oil, 3× per week during 14 wk -Groups 2 & 4: oral administration of oil, 3× per week during 14 wk (Untargeted)	Fucoxanthin	30 mg/kg bw, 3× per week (14 wk)	Gut microbiota	Inflammation-associated colorectal cancer
Findings	Fucoxanthin: ↓ Bacteroidlales and Rikenellaceae vs. AOM/DSS control mice, ↑ Number of apoptosis-like cleaved caspase-3 cells in both colonic adenocarcinoma and mucosal crypts in group 1 vs. group 2, ↑ Lachnospiraceae vs. AOM/DSS control mice
Astaxanthin-shifted gut microbiota is associated with inflammation and metabolic homeostasis in mice [210]	C57BL/6J mice (n=80)	16S rRNA	C57BL/6J mice of each sex grouped into 4 treatments (8 treatment groups in total considering both sexes (n=10 mice/group) -KO-CONT (BCO2 KO mice fed control) ×2 -KO-ASTX (BCO2 KO fed astaxanthin) ×2 -WT-CONT (WT fed control) ×2 -WT-ASTX (WT fed astaxanthin) ×2 (Untargeted)	Astaxanthin	0.04% (wt/wt) in diet (8 wk)	Gut microbiota	Inflammation, oxidative stress, and metabolic homeostasis
Findings	BCO2 KO mice fed astaxanthin had 10-fold more astaxanthin than WT mice fed astaxanthin in liver, resulting in: ↑ 385% of gut Akkermansia muciniphila in male KO mice than the WT mice
Astaxanthin prevents alcoholic fatty liver disease by modulating mouse gut microbiota [209]	C57BL/6J mice (n=60)	16S rRNA	Five groups (n=12 mice/group): -1st group: normal standard growth diet for 16 wk. -2nd group: high-fat liquid diets (HFT, 35% fat, 18% protein, 47% carbohydrates) for 16 wk. -3rd group: HFT for 2 wk acclimation, then HFT combined with the astaxanthin (AST group, 50 mg/kg bw) treatments for 12 wk. -4th group: HFT for 2 wk acclimation, then HFT combined with ethanol-containing (Et group, 5% ethanol v/v, for 36% of the total caloric intake) treatments for 12 wk. -5th group: HFT for 2 wk acclimation, then HFT combined with ethanol plus astaxanthin (EtAST group) treatments for 12 wk (Untargeted)	Astaxanthin	50 mg/kg bw (12 wk)	Liver	Alcoholic fatty liver disease
Findings	Astaxanthin: ↓ Bacteroidetes, Proteobacteria, Butyricimonas, Bilophila, and Parabacteroides compared to ethanol group, ↑ Verrucomicrobia and Akkermansia compared to ethanol group
In vivo human studies
A multi-omic analysis for low bone mineral density in postmenopausal women suggests a relationship between diet, metabolites, and microbiota [213]	Postmenopausal women (n=92) (≥45 y, postmenopausal status [12 consecutive months without menstruation])	16S rRNA	Postmenopausal women classified into: -Normal bone mineral density (normal-BMD, n=34) -Low-BMD (n=58) (Untargeted)	Lycopene	Data and samples collected from [252]	Gut microbiota	Bone mineral density
Findings	Lycopene consumption positively correlated with Oscillospira and negatively correlated with Pantoea genus abundance The low-BMD group had lower consumption of lycopene, and higher abundance of γ-Proteobacteria, compared with the normal-BMD group. Intestinal microbiota of women with vitamin D deficiency was related to Erysipelotrichaceae and Veillonellaceae abundance compared to the vitamin D nondeficient group.
Dietary and plasma carotenoids are positively associated with alpha diversity in the fecal microbiota of pregnant women [253]	Pregnant women (n=27)	16S rRNA	2-arm, randomized, controlled gestational study with pregnant women at 3 different time points: -1st group: 32-wk gestation, preintervention -2nd group: 36-wk gestation, mid-intervention -3rd group: 6 wk after child is born, post-intervention (Untargeted)	Diet containing α- and β-carotene, lutein and zeaxanthin, β-cryptoxanthin, and trans-lycopene	Variable (from 32-wk gestation to 6-wk postpartum).	Fecal microbiota	Microbiota diversity
Findings	α-Carotene: ↓ Akkermansia and ↑ Phascolarctobacterium. β-Carotene: ↑ Ruminococcaceae UCG002 Trans-lycopene: ↓ Akkermansia, ↓ Escherichia Shigella, ↓ Phascolarctobacterium, ↓ Ruminococcaceae UCG002, ↓ Prevotella 9 and ↑ Ruminococcus 2 β-Cryptoxanthin: ↑ Phascolarctobacterium and ↓ Prevotella 9 Lutein and zeaxanthin: ↑ Akkermansia, ↑ Phascolarctobacterium and ↓ Prevotella 9
Prebiotic effect of lycopene and dark chocolate on gut microbiome with systemic changes in liver metabolism, skeletal muscles and skin in moderately obese persons [21]	30 volunteers (15 women and 15 men), mean age of 55 ± 5.7 y and with moderate obesity, 30 < BMI < 35 kg/m2	16S rRNA	Volunteers randomized into five equal interventional groups: -1st: 10 dark chocolate (DC) containing 7 mg of lycopene -2nd: 7 mg lycopene formulated with medium saturated fatty acids (GAL-MSFA) -3rd: 30 mg GAL-MSFA -4th: 30 mg lycopene formulated with polyunsaturated fatty acids (GAL-PUFA) -5th: 10 g DC (Untargeted)	Lycopene	7–30 mg (1 mo)	Fecal microbiota	Obesity
Findings	Lycopene groups: ↑ Bifidobacterium adolescentis and Bifidobacterium longum

Abbreviations: AOM, azoxymethane; BCO2, β-carotene oxygenase 2; BMD, bone mineral density; bw, body weight; DC, dark chocolate; DSS, dextran sulfate sodium; GAL, GA-lycopene, a proprietory product; HFT, high-fat liquid diet; SD, Sprague-Dawley.