Simple questions in salt intake behavior assessment: comparison with urinary sodium excretion in Japanese adults

To clarify whether six conventional 'high-risk' behaviors toward excess salt intake captured by simple questions such as frequency of salty food consumption are related to actual salt intake. Also, to examine the relationship of nutrition knowledge, food label use, and food preparation with actual salt intake.

Study participants were 742 subjects (370 men and 372 women) aged 20-69 years from 20 areas of Japan. Salt intake and dietary knowledge/behavior were evaluated with two 24-hour urine collections and a questionnaire, respectively. Multivariable linear regression analyses by sex included sodium excretion as a dependent variable, each knowledge/behavior item as an independent variable, and with age, body mass index, education, and smoking as covariates.

Four 'high-risk' behaviors (frequency of miso soup and salty foods consumption, proportion of consumed noodle soup, and amount of seasoning/condiment use) were associated with higher sodium excretion in men (p for trend <=0.04) and were marginally associated in women (p for trend <=0.06). Combination of these behaviors elevated the odds ratios for excess salt intake (sodium excretion: >136 mmol/day). Most of the other nine dietary factors were not associated with sodium excretion. Interestingly, women who decided to purchase foods after referring to the salt/sodium content information on food label, had significant lower sodium excretion than other women (p for trend=0.03).

High-risk behaviors toward excess salt intake captured by simple questions were actually related to excess salt intake. Specific and practical advice based on answers to these questions might contribute to salt reduction in Japanese population.