Dietary phosphorus intake estimated by 4-day dietary records and two 24-hour urine collections and their associated factors in Japanese adults.

Abstract

Both self-reported dietary information and urinary excretion have limitations in the assessment of phosphorus intake. We conducted a cross-sectional study to estimate dietary phosphorus intake by dietary records (DR) and 24-h urine collections (UC) and examined associated factors. A total of 161 men and 161 women aged 20-69 years completed a 4-day DR and two 24-h UC. Phosphorus intake by UC was estimated using the mean phosphorus absorption rate of 14 papers. Associations between phosphorus intake and urinary excretion and age, body mass index (BMI), physical activity, education, and smoking status were examined using multiple linear regression. Phosphorus intake estimated by UC was higher than that estimated by DR (mean: 1393 vs. 1176 mg/day, P < 0.0001 in men; 1082 vs. 1021 mg/day, P = 0.008 in women). Values were significantly correlated (r = 0.29, P = 0.0002 in men; r = 0.30, P = 0.0001 in women). Phosphorus intake estimated by DR was positively associated with age in women. Male current smokers consumed less phosphorus than never smokers. Higher urinary phosphorus excretion was associated with higher BMI in both sexes and higher physical activity in women. This study showed dietary phosphorus intakes estimated by 4-day DR and by 2-day UC in adults. Although dietary phosphorus intake estimated by DR showed moderate correlation with that by UC, they differed in their association with age, BMI, physical activity, and smoking status.