Ecological Iodine Supplementation And Regional Difference

Iodine is one of the essential trace elements for humans.Both iodine deficiency and iodine excess have vital impacts on human health.The Universal Salt Iodization(USI)has made great achievements,but also has many disadvantages.Zhejiang Province was chosen as the study area in this paper and the regional differences in iodine content of crops and milk were studied.A zoning index system was comprehensively established for the ecological iodine supplementation.The Bihu basin in Lishui city,where the iodine is deficient,was chosen as the experiment base to investigate the feasibility to cultivate iodine-rich vegetables and grains under field conditions to substitute for the salt iodization to prevent iodine deficiency and iodine excess.The results were as follows:After analyzing the content of iodine in vegetables and fruits collected from the coastal plains of Yaojiang River and the inland Lishui Bihu Basin,it was found that the iodine content of vegetables and milk in coastal areas was significantly higher than that in inland areas.In general,the iodine contents in crops followed the descending order of leafy,stem,fruit and root vegetables.Ofthese,the iodine contents of spinach and celery ranked the highest in both coastal and inland areas.While the iodine content of milk in different areas of Zhejiang Province was between 0.081 and 0.479 mg/L,and the iodine content of milk from plain areas was higher than that from mountain areas.The index system of ecological iodine supplementation of Zhejiang Province was established after analyzing the background of iodine content from different soil and water,terrain and location,iodine nutritional status of residents and their dietary iodine intake.The method of expert questionnaire was adopted to determine the proportion of each indicator.And the GIS technology was applied to draw the zoning map of iodine supplementation in Zhejiang Province.The results showed that iodine content were abundant in the water and soil environment and food from Zhoushan Islands,Ningbo Peninsula,Xiangshan Peninsula,Taizhou and Wenzhou plains which were natural iodine-supplementing areas.The Hangjiahu Plain and most parts of Ningshao Plain,Taizhou,Wenzhou coastal hilly areas were mild iodine supplement region while Tianmu Mountain,Jinqu Basin,Kuaiji Mountain,west of Tiantai Mountain,South of Yandang Mountain were moderate iodine supplement area.Due to high terrain and located inland,Baiji Mountain,Qianligang Mountain,Xianxia Ling Mountain district and Donggong Mountain Area were the focus of iodine supplement area.Seaweed iodine fertilizer experiment showed that rice,gourd,eggplant,cowpea,soybean,cucumber,watermelon,tomato and other fruit vegetables and fruit crops can indeed be applied to iodine fertilizer to improve their iodine content in edible parts.The daily consumption can meet the 150 ug/d iodine demand of adults recommended by World Health Organization.The effect of low dose of exogenous iodine(0.375 kg/hm~2)on the improvement of the iodine content in edible parts of rice and vegetables was not obvious but the high concentration of exo genous iodine(Greater than or equal to 3.000 kg/hm~2)inhibited the accumulation of iodine in some fruit and vegetables.Eventually 1.500 kg/hm~2 can be used as recommended exogenous iodine concentration to apply to cultivate the iodine-rich field crops.