Intake of nutrients and food groups was assessed from unannounced 24-hour dietary recalls conducted by telephone interviewers. 15 Two recalls (one obtained on a weekday and the other
on a weekend day) were obtained at baseline and 6 months by the Diet Assessment Center of Pennsylvania State University.Nutrient and food group intakes were then calculated using the
Nutrition Data System Version NDS-R 1998 (University of Minnesota). Biomarkers of dietary intake were 24-hour urinary excretion of sodium, potassium (reflecting fruit and vegetable intake), phosphorus (reflecting dairy intake), and urea nitrogen (reflecting protein intake). Alcohol intake was obtained from questionnaire.