Survey of iodine nutritional status in 2011, Zhejiang, China

Universal salt iodization (USI) was introduced in China in 1995, but whether the iodine status is optimal is questionable. This study was conducted to assess the iodine nutrition among Zhejiang population in coastal regions in China.

A cross-sectional survey for iodine nutritional status was conducted with general population (n=10,350), including pregnant and lactating women (n=450 each) selected by stratified multistage sampling. Iodine content in drinking water, table salt and urine, were determined using arsenic-cerium catalytic spectrophotometry, the direct titration and the arsenic-cerium catalytic spectrophotometry, respectively, and daily iodine intake was estimated by 3 days of 24-hour recall method.

The median iodine content in drinking water was 2.46 μg/L, Zhejiang belonged to the region of iodine deficiency in outer environment according to China standard. The median iodine content in table salt was 27.9 mg/kg, conforming to the standard requirements; the household coverage rate of qualified iodized salt reached 76.8%, which does not reach the standard requirement of WHO >90%. The dietary iodine intake of a reference individual averaged 379 μg/d, which indicated that the current iodine intake in diet was appropriate. In addition, the median urinary iodine concentration (UIC) was 162 μg/L in general population, and 130 μg/L in pregnant women, which didn't reach the standard requirements.

The current dietary iodine intake in Zhejiang was generally sufficient and safe, but there is a risk of iodine deficiency among pregnant women and the population who do not consume iodized salt.