Table 2.

Forty metabolites with significant differences ($p<0.05$ prior to adjustment for multiple comparisons) before, during, after the 2008 Beijing Olympics in 26 nonsmoking adults.

Super class, class, and metabolite	Level of metabolitesa			Overall comparison		During vs. before the Olympics			After vs. during the Olympics			Missing (%)b
	Before	During	After	p-Value	Q-Value	Ratio	p-Value	Q-Value	Ratio	p-Value	Q-Value
Amino acid super class
Glutamate metabolism class
N-Acetylglutamate	1.04	1.08	1.06	0.03*	1.00	1.04*	0.03	0.99	0.98	0.9	0.99	0
Phenylalanine and tyrosine metabolism class
p-Toluic acid	0.95	1.07	0.87	0.08	1.00	1.13*	0.02	0.99	0.81	0.14	0.99	0
Carbohydrate super class
Fructose, mannose, and galactose metabolism class
Sorbitol	1.20	1.07	2.02	0.10	1.00	0.89*	0.05	0.99	1.90	0.82	0.99	0
Pentose metabolism class
Ribitol	1.07	1.02	1.32	0.05	1.00	0.96	0.67	0.99	1.29	0.06	0.99	0
Cofactors and vitamins super class
Ascorbate and aldarate metabolism class
Oxalate (ethanedioate)	0.94	1.02	1.17	0.02*	1.00	1.09	0.44	0.99	1.14*	0.05	0.99	0
Ascorbate (vitamin C)	0.83	1.13	1.55	0.03*	1.00	1.35	0.44	0.99	1.38	0.07	0.99	9.75
Nicotinate and nicotinamide metabolism class
Nicotinamide	1.04	0.91	1.09	0.22	1.00	0.87*	0.04	0.99	1.20	0.5	0.99	8.75
Lipid super class
Endocannabinoid subclass
N-Stearoyltaurine	1.79	0.98	1.52	0.05	1.00	0.55*	0.02	0.99	1.55*	0.03	0.99	5.50
Fatty acid metabolism (acyl carnitine) class
Hydroxybutyrylcarnitinec	1.75	1.12	1.59	0.09	1.00	0.64*	0.04	0.99	1.42	0.07	0.99	0
Fatty acid, dicarboxylate class
2-Hydroxyglutarate	1.10	0.92	1.14	0.02*	1.00	0.83*	0.02	0.99	1.24*	0.01	0.92	0
Sebacate (decanedioate)	1.23	1.09	1.34	0.10	1.00	0.88	0.58	0.99	1.23*	0.03	0.99	33.50
Fatty acid, monohydroxy class
3-Hydroxydecanoate	1.15	1.01	1.31	0.03*	1.00	0.88*	0.04	0.99	1.29*	0.01	0.92	0
3-Hydroxyoctanoate	1.24	1.10	1.52	0.06	1.00	0.89	0.29	0.99	1.38*	0.02	0.95	0
Glycerolipid metabolism class
Glycerol 3-phosphate (G3P)	1.03	1.41	1.02	0.06	1.00	1.37	0.21	0.99	0.72*	0.03	0.99	0
Long-chain fatty acid class
Eicosenoate (20:1n9 or 11)	1.18	1.12	1.46	0.02*	1.00	0.95	0.69	0.99	1.30*	0.01	0.92	0
Pentadecanoate (15:0)	1.03	0.89	1.09	0.03*	1.00	0.86*	0.02	0.99	1.22*	0.04	0.99	0
10-Nonadecenoate (19:1n9)	1.12	0.95	1.18	0.03*	1.00	0.85	0.05	0.99	1.24*	0.01	0.92	9.50
Myristoleate (14:1n5)	1.17	1.10	1.43	0.09	1.00	0.94	0.28	0.99	1.30*	0.02	0.92	0
Palmitoleate (16:1n7)	1.08	1.00	1.25	0.10	1.00	0.92	0.30	0.99	1.25*	0.02	0.95	0
10-Heptadecenoate (17:1n7)	1.04	0.93	1.13	0.12	1.00	0.90	0.12	0.99	1.22*	0.04	0.99	0
Oleate (18:1n9)	1.03	0.96	1.11	0.13	1.00	0.93	0.43	0.99	1.17*	0.03	0.99	0
Lysolipid class
1-Palmitoylglycerophosphoglycerolc	1.55	1.22	1.31	0.14	1.00	0.78*	0.04	0.99	1.08	0.42	0.99	0
Medium-chain fatty acid class
Caprylate (8:0)	1.12	1.01	1.34	$<0.01$*	1.00	0.90	0.91	0.99	1.33*	0.01	0.92	8.75
Caprate (10:0)	1.05	0.98	1.28	0.03*	1.00	0.93	0.36	0.99	1.30*	0.01	0.92	0
Caproate (6:0)	1.07	0.93	1.20	0.05	1.00	0.87	0.15	0.99	1.30*	0.02	0.92	0
5-Dodecenoate (12:1n7)	1.36	1.14	1.64	0.07	1.00	0.83	0.20	0.99	1.44*	0.02	0.92	0
Polyunsaturated fatty acid (n3 and n6) class
Docosatrienoate (22:3n3)	1.14	0.97	1.19	0.04*	1.00	0.85	0.14	0.99	1.23*	0.01	0.92	0
Dihomo-linoleate (20:2n6)	1.10	0.94	1.12	0.07	1.00	0.85	0.09	0.99	1.19*	0.02	0.95	0
Docosadienoate (22:2n6)	1.08	0.98	1.19	0.07	1.00	0.91	0.36	0.99	1.22*	0.03	0.99	5.50
Arachidonate (20:4n6)	1.08	0.99	1.04	0.15	1.00	0.91	0.57	0.99	1.06*	0.04	0.99	20.50
Mead acid (20:3n9)	1.17	1.00	1.07	0.18	1.00	0.85	0.26	0.99	1.07*	0.04	0.99	20.25
Steroid Class
Pregnanediol-3-glucuronide	2.37	2.55	3.87	0.02*	1.00	1.07	0.39	0.99	1.52*	0.03	0.99	0
Pregn steroid monosulfatec	1.18	1.23	1.17	0.04*	1.00	1.04	0.06	0.99	0.96	0.66	0.99	0
Cortisone	1.02	1.00	0.96	0.09	1.00	0.98*	0.04	0.99	0.96	0.78	0.99	0
Sterol class
Campesterol	0.89	0.81	1.04	0.10	1.00	0.92	0.99	1.00	1.27*	0.03	0.99	1.75
Peptide super class
Dipeptide class
Phenylalanyltryptophan	0.97	1.03	1.14	0.14	1.00	1.06	0.22	0.99	1.11*	0.04	0.99	0
Threonylphenylalanine	1.26	0.97	1.69	0.15	1.00	0.77	0.67	0.99	1.74*	0.04	0.99	0
γ-Glutamyl amino acid class
γ-Glutamylthreoninec	1.10	1.10	1.04	0.02*	1.00	1.00	0.67	0.99	0.95*	0.02	0.92	29.75
Xenobiotics super class
Chemical class
Glycerol 2-phosphate	1.06	1.37	1.03	0.08	1.00	1.30	0.54	0.99	0.75*	0.05	0.99	0
Food component/plant class
Dihydroferulic acid	1.33	1.11	1.05	0.17	1.00	0.83	0.27	0.99	0.95*	0.04	0.99	0

Note: Statistical comparisons were adjusted for time-invariant variables (age, sex, BMI) and time-varying variables including diet and transportation mode. p-Value was calculated from ANOVA for overall comparison and from post hoc tests for during vs. before and after vs. during contrasts. Q-value was calculated as false discovery rate–adjusted p-value using Storey method. $\text{Ratio}>1$ indicates increased, whereas $<1$ indicates decreased levels of metabolites. *, $p<0.05$.

^aSet median as 1 and scaled according to a per biochemical basis.

^bAveraged proportion of missing value from the three time points.

^cIndicates compounds with Level 3 identity confidence (lacked authenticated standards but had characteristics correlated with known metabolites).