Table 2. Metabolic changes in smoking habits including heated tobacco product use.

	4-group comparison	HTP vs NS	HTP vs PS	HTP vs CS	CS vs NS	CS vs PS	PS vs NS
Age- and sex-adjusted	P-value	fold change (95% confidence interval)
Glutamate	0.014	1.43 (1.05–1.95)	1.45 (1.06–1.98)	1.10 (0.80–1.53)	1.30 (1.01–1.66)	1.31 (1.03–1.68)	0.99 (0.78–1.24)
Arginine	0.726	1.19 (0.87–1.64)	1.18 (0.86–1.63)	1.03 (0.74–1.44)	1.15 (0.89–1.49)	1.14 (0.89–1.47)	1.01 (0.79–1.28)
Ornithine	0.083	1.25 (0.91–1.71)	1.14 (0.84–1.56)	0.88 (0.64–1.22)	1.41 (1.10–1.81)	1.30 (1.01–1.66)	1.09 (0.87–1.38)
Citrulline	0.572	0.97 (0.71–1.33)	0.90 (0.66–1.23)	0.83 (0.60–1.15)	1.17 (0.91–1.51)	1.08 (0.85–1.39)	1.08 (0.86–1.37)
Trigonelline	0.0004	1.65 (1.27–2.14)	1.29 (1.00–1.68)	1.04 (0.79–1.36)	1.59 (1.28–1.98)	1.25 (1.01–1.55)	1.27 (1.04–1.56)
Fully-adjusted*
Glutamate	0.00003	1.40 (1.08–1.82)	1.42 (1.09–1.84)	1.02 (0.78–1.33)	1.38 (1.13–1.69)	1.40 (1.14–1.71)	0.99 (0.82–1.20)
Arginine	0.616	1.23 (0.89–1.70)	1.20 (0.87–1.65)	1.03 (0.74–1.44)	1.19 (0.93–1.53)	1.16 (0.91–1.49)	1.03 (0.81–1.30)
Ornithine	0.081	1.32 (0.96–1.82)	1.17 (0.85–1.61)	0.92 (0.66–1.29)	1.43 (1.11–1.83)	1.27 (0.99–1.62)	1.13 (0.89–1.42)
Citrulline	0.529	0.93 (0.67–1.29)	0.85 (0.61–1.18)	0.80 (0.57–1.12)	1.17 (0.91–1.51)	1.07 (0.83–1.37)	1.10 (0.86–1.39)
Trigonelline	0.005	1.60 (1.22–2.10)	1.27 (0.97–1.66)	1.02 (0.77–1.35)	1.57 (1.25–1.97)	1.25 (1.00–1.55)	1.26 (1.02–1.55)

CS, current cigarette smokers; HTP, heated tobacco product users; NS, never smokers; PS, past smokers.

^*We included age, sex, drinking status, body mass index, systolic blood pressure, HbA1c, and non-high-density-lipoprotein cholesterol as covariates in the fully-adjusted model.