To monitor the effectiveness of salt-reduction initiatives in processed foods and changes in Dutch iodine policy on Na and iodine intakes in Dutch adults between 2006 and 2010.

Two cross-sectional studies among adults, conducted in 2006 and 2010, using identical protocols. Participants collected single 24 h urine samples and completed two short questionnaires on food consumption and urine collection procedures. Daily intakes of salt, iodine, K and Na:K were estimated, based on the analysis of Na, K and iodine excreted in urine.

Doetinchem, the Netherlands.

Men and women aged 19 to 70 years were recruited through random sampling of the Doetinchem population and among participants of the Doetinchem Cohort Study (2006: n 317, mean age 48·9 years, 43 % men; 2010: n 342, mean age 46·2 years, 45 % men).

While median iodine intake was lower in 2010 (179 μg/d) compared with 2006 (257 μg/d; P < 0·0001), no difference in median salt intake was observed (8·7 g/d in 2006 v. 8·5 g/d in 2010, P = 0·70). In 2006, median K intake was 2·6 g/d v. 2·8 g/d in 2010 (P < 0·01). In this 4-year period, median Na:K improved from 2·4 in 2006 to 2·2 in 2010 (P < 0·001).

Despite initiatives to lower salt in processed foods, dietary salt intake in this population remains well above the recommended intake of 6 g/d. Iodine intake is still adequate, although a decline was observed between 2006 and 2010. This reduction is probably due to changes in iodine policy.

All previous studies on monetary diet cost have examined the relationship of monetary cost of self-reported diet to self-reported, rather than biomarker-based, estimates of dietary intake. The present cross-sectional study examined the association between monetary costs of self-reported diet and biomarker-based estimates of nutrient intake.

Monetary diet cost (Japanese yen/1000 kJ) was calculated based on dietary intake information from a self-administered, comprehensive diet history questionnaire using retail food prices. Biomarker-based estimates of nutrient intake (percentage of energy for protein and mg/1000 kJ for K and Na) were estimated based on 24 h urinary excretion and estimated energy expenditure.

A total of fifteen universities and colleges in Japan.

A total of 1046 female Japanese dietetic students aged 18–22 years.

Total monetary diet cost showed a significant positive association with biomarker-based estimates of protein, K and Na. Vegetables and fish were not only the main contributors to total monetary diet cost (16·4 % and 15·5 %, respectively) but also were relatively strongly correlated with total monetary diet cost (Pearson’s correlation coefficient: 0·70 and 0·68, respectively). Monetary cost of vegetables was significantly positively associated with all three nutrients, while that of fish showed a significant and positive association only with protein.

Total monetary cost of self-reported diet was positively associated with biomarker-based estimates of protein, K and Na intake in young Japanese women, and appeared mainly to be explained by the monetary costs of vegetables and fish.