TABLE 2.
Characteristics and outcomes from studies that reported the effect of dietary supplements on TMAO concentrations1
| Reference and country | Participant characteristics | Study design | Intervention compared with control2 | Duration and follow-up | Baseline TMAO concentration (μM)3 | Outcome4 | Dietary status5 |
|---|---|---|---|---|---|---|---|
| Tripolt et al. (38) Austria | n = 13:156 Female: 4% Age: 51 ± 112 y BMI: 35 ± 5 Subjects with metabolic syndrome | Open-label, randomized controlled, parallel study | LcS milk probiotic (3 bottles/d, 65 mL of 108/mL LcS) Compared with no milk | 12 wk | Plasma I: 4.7 ± 2.7 C: 4.6 ± 2.8 | NC* | Uncontrolled7 |
| Boutagy et al. (30) United States | n = 9:106 Female: 0% Age: 22.4 ± 1.1 y BMI: 24.5 ± 1.1 Healthy subjects on hypercaloric HFD | Randomized, placebo-controlled, double-blind, parallel study | VSL#3 probiotic (2 packets, 900 billion live bacteria) Compared with placebo (2 packets, cornstarch) | 4 wk | Plasma NR | NC* | Controlled |
| Fukami et al. (41) Japan | n = 31:476 Female: 56% Age: 55.9 ± 5.2 y 64.6 ± 10.8 y BMI: 21.2 ± 1.9 Healthy subjects compared to subjects on HD | Open label, nonrandomized, interventional study | Oral l-carnitine supplementation (900 mg OD) to both groups | 6 mo | Plasma I: 222.5 ± 111.7 C: 174.3 ± 99.7 | ↑*** | Uncontrolled |
| Poesen et al. (37) Belgium | n = 40 Female: 30% Age: 70 ± 6.0 y BMI: 28.7 ± 5.0 Subjects with CKD | Randomized, placebo-controlled, double-blind, crossover study | AXOS prebiotic (10 g bid) Compared with placebo (maltodextrin 6.7 g bid) | 12 wk | Serum I: 8.9 IQR: (7.1–12.3)8 | ↓** | Uncontrolled |
| Obeid et al. (36) Germany | n = 25:276 Female: 16% Age: 68 ± 9.2 y BMI: 26.4 ± 3.1 Healthy subjects | Randomized, single-blind, non-placebo-controlled, parallel study | B vitamins (0.5 mg folic acid + 50 mg B-6 + 0.5 mg B-12) + cholecalciferol (1200 IU OD) + calcium carbonate (800 mg OD) Compared with cholecalciferol (1200 IU OD) + calcium carbonate (800 mg OD) | 12 mo | Plasma I: 4.2 (5.2) C: 4.3 (2.3) | ↓** | Uncontrolled |
| Borges et al. (42) Brazil | n = 11:106 Female: 72% Age = 54.0 ± 22 y BMI: 24.6 ± 7 Subjects with CKD on HD | Randomized, double-blind, parallel study | Strain-specific probiotic formulation, 3 capsules (9 × 1013 CFU/d) Compared with placebo | 3 mo | Plasma I: 6.2 (2.6–14.9) C: 7.5 (3.1–17.7) | NC* | Uncontrolled |
n = 6. AXOS, arabinoxylan oligosaccharide; bid, twice daily; C, control; CKD, chronic kidney disease; HD, hemodialysis; HFD, high-fat diet; I, intervention; IU, international unit; LcS, Lactobacillus casei Shirota; NC, no change; NR, not reported; OD, once daily; TMAO, trimethylamine N-oxide.
Values are means ± SDs unless otherwise indicated.
Baseline TMAO concentration in micromolar (μM) = μmol/L unless otherwise indicated.
Outcome denotes effect of intervention on TMAO levels (increase or decrease).
Dietary intake of trimethylamine dietary precursors including seafood, fish, choline, l-carnitine, and betaine.
n = intervention: control groups.
“Controlled” indicates dietary intake of TMAO precursors was controlled; “uncontrolled” indicates dietary intake of TMAO precursors was not controlled.
Median (interquartile range).
P > 0.05.
P < 0.05.
P < 0.001.