Iodine Status of Taiwanese Population in 2013: 10 Years After Changing From Mandatory to Voluntary Salt Iodization.

BACKGROUND: In 2003, Taiwan's iodine policy changed from mandatory to voluntary. The Nutrition and Health Survey in Taiwan (NAHSIT) 2001-2002 for schoolchildren showed adequate iodine nutrition, while NAHSIT 2005-2008 for adults showed the iodine status was at borderline adequacy. OBJECTIVE: To investigate the iodine status of the Taiwanese population from schoolchildren to adulthood 10 years after the change of the salt iodization policy. METHOD: Urinary iodine was measured in samples from subjects in NAHSIT 2013. RESULTS: The median urinary iodine concentration (UIC) of the Taiwanese population aged 6 years and above in 2013 was 96 µg/L, indicating mild iodine deficiency. The median UIC of 6- to 12-year-old schoolchildren was 124 µg/L (interquartile range [IQR]: 92-213 µg/L), and 115 µg/L (IQR: 80-166 µg/L), 125 µg/L (IQR: 74-161 µg/L), 73 µg/L (IQR: 52-131 µg/L), and 78 µg/L (IQR: 52-132 µg/L) in populations aged 13 to 18 years, 19 to 44 years, 45 to 64 years, and ≥65 years, respectively. Declining iodine nutrition in age groups ≥45 years old was noted that the median UIC of populations aged 45 to 64 years and ≥65 years was 99 and 88 µg/L, respectively, in NAHSIT 2005-2008. The median UIC of schoolchildren was not lower than that during the mandatory salt fortification period, but the distribution of urinary iodine levels signified a dietary pattern change. CONCLUSION: Wide-ranging variation in iodine nutrition levels was observed in different age groups. Universal salt iodization, as suggested by the World Health Organization, should be the best strategy to achieve adequate iodine nutrition.

Trends in hyperuricemia and gout prevalence: Nutrition and Health Survey in Taiwan from 1993-1996 to 2005-2008.

Hyperuricemia is a recognized risk factor for cardiovascular disease. This study investigated trends in uric acid levels, hyperuricemia and gout among adults in Taiwan from 1993-1996 to 2005-2008, using data collection from, Nutrition and health surveys in Taiwan (NAHSIT) conducted in 1993-1996 and 2005-2008. Information on food frequency, medical history, physical measures and fasting blood parameters were analyzed. Mean uric acid levels decreased between 1993-1996 and 2005-2008 in both genders (6.77 vs 6.59 mg/dL in men and 5.33 vs 4.97 mg/dL in women) and the prevalence of hyperuricemia declined from 25.3% to 22.0% in men (p<0.0001) and from 16.7% to 9.7% in women (p<0.0001). However, the prevalence of gout (self-reported) increased (4.74% vs 8.21% in men and 2.19% vs 2.33% in women, p<0.0001). Reduced rank regression was used to identify dietary patterns that explained significant amounts of variance in uric acid. Frequency of consumption of lean meat, soy products and soymilk, milk, eggs, vegetables, carrots, mushrooms, fruit and coffee were negatively associated with hyperuricemia, whereas consumption of organ meats, bamboo shoots, and soft drinks were positively associated with hyperuricemia. The dietary factor score (DFS) composed of the frequency of above food items decreased from -5.40 to -6.00 between the two surveys (p<0.0001). In conclusion, uric acid levels and prevalence of hyperuricemia both declined, whilst self-reported gout increased between 1993-1996 and 2005-2008. Changes in dietary patterns may in part explain the decrease in uric acid levels between the two national surveys.