Predicted 25-hydroxyvitamin D in relation to incidence of breast cancer in a large cohort of African American women

Table 1 Predictors of plasma 25-hydroxyvitamin D (25(OH)D) in 2856 participants from the Black Women’s Health Study

Predictors	Beta-coefficient for difference in 25(OH)D (ng/mL)	P	Squared semi-partial correlation coefficient (%)^a
Intercept	11.94
Supplementary vitamin D	9.66	<0.0001	10.41
Multivitamin use	4.60	<0.0001	2.75
Dietary vitamin D (kcal-mcg/day)	0.33	0.01	0.23
Body mass index
25.0–29.9	-2.21	0.001	0.22
30.0–34.9	-2.96	<0.0001	0.36
≥ 35.0	-4.71	<0.0001	0.84
Postmenopausal hormone use
Past use ≥5 years	2.70	0.001	0.30
Current use <5 years	2.39	0.02	0.18
Current use ≥5 years	2.31	0.03	0.16
Vigorous physical activity, ≥1 hour/week	1.59	0.001	0.34
Alcohol consumption
1–6 drinks per week	-2.28	0.02	0.20
≥7 drinks per week	-2.97	0.006	0.26
Cigarette smoking	-1.58	0.13	0.08
Recent use of oral contraceptives	2.58	0.003	0.28
Use of oral contraceptives ≥10 years	1.60	0.02	0.19
Variables controlled in the regression models
Season of blood draw
Summer	1.66	0.01	0.14
Winter	-1.88	0.003	0.28
UVB flux 160+	-1.93	0.01	0.09
Age (years)	0.24	<0.0001	1.40

^aAttributable proportion of variation in 25(OH)D explained by parameter, after adjustment for the other predictors in the model
Adjusted R-squared = 0.252

ISSN: 1465-542X