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. Author manuscript; available in PMC: 2017 Dec 11.
Published in final edited form as: J Nutr. 2015 Feb 4;145(4):766–774. doi: 10.3945/jn.114.205476

Figure 1.

Figure 1

Relationship of caffeine metabolism in humans to correlations observed between spot urine caffeine and caffeine metabolite concentrations and excretion rates with 24-h caffeine intake from foods and dietary supplements in U.S. persons aged ≥6 y, NHANES 2009–2010. “Group 1” consists of compounds for which Spearman correlations of 0.55 ≤ |r| ≤ 0.68 with intake were observed; “Group 2” consists of compounds for which Spearman correlations of 0.15 ≤ |r| ≤ 0.33 with intake were observed (Table 4, Supplemental Table 7). 137U, 1,3,7-trimethyluric acid; 13U, 1,3-dimethyluric acid; 17U, 1,7-dimethyluric acid; 1U, 1-methyluric acid; 1X, 1-methylxanthine; 37U, 3,7-dimethyluric acid; 3U, 3-methyluric acid; 3X, 3-methylxanthine; 7U, 7-methyluric acid; 7X, 7-methylxanthine; AAMU, 5-acetylamino-6-amino-3-methyluracil.