The Food
Choice at Work study recruited 802 participants aged 18e64 years, 50 of whom formed the validation
sample. The mean measured 24-h urinary sodium (gold standard) was 138 mmol/day
(8.1 g salt). At the group level, mean differences were small for both dietary methods and for
the arithmetic extrapolations from morning urine samples. The Tanaka, Kawasaki and INTERSALT
methods provided biased estimates of 24-h urinary sodium. R2 values for all methods ranged
from 0.1 to 0.48 and AUC findings from 0.57 to 0.76.