ZRT Laboratory Published Review of Japanese Iodine Intake Based on Seaweed Consumption in Japan

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Portland, Oregon 11/1/2011 - A thorough literature-based analysis conducted by ZRT Laboratory clears up much of the confusion surrounding the iodine content of the Japanese diet.  Previous estimations for the amount of iodine the Japanese consume daily from seaweeds have been as high as 13.5 to 45 mg/day by sources that used ambiguous data to approximate intake.  This is 4.5 to 15 times greater than the safe upper limit of 3 mg/day set by the Ministry of Health, Labor and Welfare in Japan. 

For the assessment, published in the October 2011 issue of Thyroid Research, a collection of Japanese diet studies measuring the amount of iodine in 24-hour diet samples were analyzed along with studies reporting urine iodine levels. Approximately 97% of dietary iodine is excreted in the urine and levels can increase in a single day and return to normal within a couple of days, depending on seaweed intake.  It was concluded that the daily iodine intake of the Japanese, based on both 24-hour diet samples and urine collections, typically does not exceed 3 mg.

Co-author Theodore Zava states, “After extensively searching through iodine related publications and websites, it became evident that Japanese iodine intake was improperly estimated and cited throughout blogs, forums and publications. I researched numerous publications measuring iodine content in urine and food in Japan and was able to make a reliable estimate of Japanese iodine intake. Japan’s high iodine intake has been linked to lower cancer rates and a longer life expectancy, reasons for supplementation with higher levels of iodine. My goal was to provide an accurate estimate of Japanese iodine intake to be used as a reference for those wishing to consume foods high in iodine or supplement with amounts exceeding the safe upper limit of daily iodine intake provided by the World Health Organization.” 

ZRT Laboratory, based in Beaverton, Oregon, is an industry leader in hormone and wellness testing, through the use of cutting edge technologies. ZRT Laboratory provides saliva, blood spot and dried urine testing through a network of thousands of domestic and international medical providers specializing in health and hormone wellness.

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