To assess agreement between established methods of estimating salt intake from spot urine collections and 24 h urinary Na (24hUNa) and then to develop a valid formula that can be used in the Iranian population to estimate salt intake from spot urine samples.

A validation study. Three spot urine samples were collected (fasting second-void morning; afternoon; evening) on the same day as a 24 h urine collection. We estimated 24hUNa from spot specimens using the Kawasaki, Tanaka and INTERSALT equations. Two new formulas were developed, the Iran formula 1 (Iran 1) and Iran formula 2 (Iran 2), based on our population characteristics.

Iranian adults recruited in 2014–2015.

Healthy volunteer adults aged ≥18 years.

With all three spot urine specimens, predicted population 24hUNa was underestimated based on the INTERSALT equation (−469 to −708 mg/d; all P < 0·05) and conversely overestimation occurred with the Kawasaki equation (926 to 1080 mg/d; all P < 0·01). The Tanaka equation produced comparable estimates to measured 24hUNa (–151 to 86 mg/d; all P > 0·49). The newly derived formulas, Iran 1 and Iran 2, showed less mean bias than the established equations (Iran 1: 43 to 80 mg/d, all P > 0·55; Iran 2: 22 to 90 mg/d, all P > 0·50).

In this Iranian sample, the Tanaka equation and newly derived formulas produced group-level estimates comparable to measured 24hUNa. The newly developed formulas showed less mean bias than established equations; however, they need to be tested for generalization in a larger sample.

To investigate average sodium excretion in 24 h urine as a marker for salt intake in the Slovene population.

Salt intake was determined by measuring sodium excretion in 24 h urine collected from a representative sample of geographically diverse Slovene adults.

Slovenia.

A random sample of 600 adults aged 25–65 years was generated from census data. The effective sample yield was 143 people, 42·7 % men and 57·3 % women.

Urinary sodium excretion was significantly higher in men (220·9 (sd 86·0) mmol Na/d) than in women (169·8 (sd 73·8) mmol Na/d); t test = 14·5, P < 0·001. Average salt intake was 11·3 (sd 4·9) g/d, higher in men than in women (13·0 (sd 5·1) v. 9·9 (sd 4·3) g/d, respectively). Average intakes of salt among regions were not significantly different. Salt intake increases slightly with increasing age, but there was no significant correlation between age and salt intake. Salt intake was increased with BMI (r = 0·384, P < 0·001).

Salt intake in Slovene adults, especially in men, exceeds the WHO recommended population nutrient intake goal of 5 g by more than twofold. A national programme for reducing salt intake in Slovenia needs to be implemented through systematic efforts including public education and involving the health-care sector and the food industry.