Table II.

Mixed effects regression of dietary vitamin C intake and plasma vitamin C, respectively, on other covariates, EPIC-Norfolk study, n=323.^*

	FFQ, raw		FFQ, cal.-adj.		DR, raw		DR, cal.-adj.		Plasma Vitamin C
Variable	Beta±s.e.	p-Value	Beta±s.e.	p-Value	Beta±s.e.	p-Value	Beta±s.e.	p-Value	Beta±s.e.	p-Value
Constant	−4.8±117.7		−9.6±110.3		−24.5±100.0		−13.7±100.4		127.0±38.3
Age (yrs)	1.10±1.01	0.27	1.02±0.94	0.28	0.02±0.85	0.98	0.15±0.86	0.86	−0.93±0.33	0.005
Male gender (1=yes/0=no)	−15.5±10.0	0.12	−15.0±9.4	0.11	−12.0±8.6	0.16	−9.8±8.6	0.26	−14.1±3.2	<0.001
Height (cm)	0.15±0.51	0.77	0.20±0.48	0.68	0.76±0.44	0.085	0.59±0.44	0.18	0.10±0.17	0.53
BMI (kg/m2)	1.78±0.82	0.032	1.85±0.77	0.017	−0.13±0.70	0.85	0.10±0.70	0.89	−0.73±0.27	0.008
Smoking status
Current	−9.6±13.3	0.47	−15.1±12.4	0.23	−28.7±11.2	0.010	−30.4±11.3	0.007	−21.0±4.4	<0.001
Past	−6.6±6.7	0.33	−9.1±6.3	0.15	−4.0±5.7	0.49	−4.5±5.7	0.43	−0.9±2.2	0.67
Vitamin C supplement use	4.7±8.7	0.59	2.4±8.2	0.77	1.4±7.5	0.85	2.6±7.5	0.73	14.7±2.8	<0.001
Visit (1=visit2/0=visit1)	−4.1±5.3	0.45	−4.1±4.9	0.41	4.3±4.4	0.33	3.3±4.5	0.46	11.3±1.8	<0.001
Correlation between repeated measures†	0.56		0.58		0.61		0.58		0.43

^*Based on PROC MIXED of SAS.

^†Using a compound symmetry correlation structure.