Table 1.

Characteristics of the China Health and Nutrition Survey participants with plasma metabolomic data, median (interquartile range) or %

	Urbana	Rurala	P-valueb
N	240	260
Age	54.6 (46.4–60.3)	51.8 (44.3–60.1)	0.193
Women	57.9	60.4	0.575
Completed high school education	46.7	15.8	<0.0001
Per capita household income (¥1000)	20.3 (12.4–34.0)	12.8 (5.1–21.5)	<0.0001
Physical activity (METS/wk)c	63.8 (18.9–111.8)	130.5 (57.8–253.3)	<0.0001
Total energy intake (kcal)d	1872.8 (1435.3–2293.7)	1744.3 (1400.7–2188.79)	0.112
Animal-source foods (%kcal)d	24.0 (16.7–32.7)	24.0 (14.8–33.9)	0.862
Diet diversitye	12.0 (10.0–14.0)	10.0 (8.0–12.0)	<0.0001

^aWe used a 12-component index with a continuous scale of 0–120 points to assess multiple aspects of urbanization, including population density, economic activity, transportation infrastructure, and sanitation. We dichotomized this urbanization index by median (=73.1) to define urban (76.1–99.6) and rural areas (39.2–73.1).

^bUrban-rural differences in categorical variables were assessed with χ2 and continuous variables were assessed with Wilcoxon rank sum test.

^cPhysical activity in metabolic equivalent of tasks (METs) per week was measured by 7-day recalls of all domestic, occupational, transportation, and leisure activities.

^dNutrients intake was estimated using 3 consecutive 24-h recalls and household food inventories by trained interviewers, with total energy intake validated by doubly labeled water.

^eA count of number of food groups consumed, including staple grains, fruits, vegetables, nuts, eggs, meat, seafood, and dairy products.