TABLE 1.

Select demographic and lifestyle characteristics according to quintiles of total flavonoid intake in 35,816 postmenopausal women in the Iowa Women's Health Study¹

	Quintile of total flavonoid intake
	1	2	3	4	5	P for trend2
n	7163	7163	7164	7163	7163
Median intake, mg/d	90.4	167.0	238.5	342.5	680.4
Intake range, mg/d	0.63–132.9	132.9–201.4	201.5–281.4	281.4–425.6	425.6–3524
Incident diabetes, cases/person-y	686/88,908	674/92,793	732/93,646	653/94,255	650/94,033
Age, y	61.2 ± 0.05	61.4 ± 0.05	61.6 ± 0.05	61.9 ± 0.05	61.9 ± 0.05	<0.001
>High school education, %	32.7	38.5	40.8	43.6	45.7	<0.001
BMI, kg/m2	26.8 ± 0.06	26.8 ± 0.06	26.9 ± 0.06	26.8 ± 0.06	26.6 ± 0.06	0.001
Waist:hip ratio	0.84 ± 0.001	0.83 ± 0.001	0.83 ± 0.001	0.83 ± 0.001	0.83 ± 0.001	<0.001
Physical activity,3 % high level	17.1	20.9	26.1	29.1	32.2	<0.001
Smoking, % current	22.5	16.7	13.2	10.8	10.6	<0.001
Multivitamin use, %	28.3	30.7	33.3	35.3	37.4	<0.001
Hormone therapy, % ever users	37.8	38.9	39.5	38.2	40.6	0.002
Family history of diabetes,4 %	21.7	23.2	22.3	22.5	22.8	0.26
Self-reported hypertension, %	34.3	35.1	35.5	35.2	33.7	0.20

¹Values for continuous variables are means ± SEM, and for categorical variables, percentages. Person-y represents person time at risk (y).

²Tests for a trend across intake categories were performed by assigning each quintile its median intake value and treating the variable as a linear term.

³Women who participated in vigorous activity ≥2 times/wk and those who reported moderate activity >4 times/wk were categorized as having a “high” level of physical activity.

⁴Family history of type 2 diabetes was assessed during the third follow-up in 1997 and thereafter. Person-y associated with this variable for total flavonoid intake quintiles 1–5 are as follows: Q1 = 21,218; Q2 = 22,819; Q3 = 22,089; Q4 = 22,419; Q5 = 23,221.