Assessment of Japanese iodine intake based on seaweed consumption in Japan: A literature-based analysis

Abstract

Japanese iodine intake from edible seaweeds is amongst the highest in the world. Predicting the type and amount of seaweed the Japanese consume is difficult due to day-to-day meal variation and dietary differences between generations and regions. In addition, iodine content varies considerably between seaweed species, with cooking and/or processing having an influence on iodine content. Due to all these factors, researchers frequently overestimate, or underestimate, Japanese iodine intake from seaweeds, which results in misleading and potentially dangerous diet and supplementation recommendations for people aiming to achieve the same health benefits seen by the Japanese. By combining information from dietary records, food surveys, urine iodine analysis (both spot and 24-hour samples) and seaweed iodine content, we estimate that the Japanese iodine intake--largely from seaweeds--averages 1,000-3,000 μg/day (1-3 mg/day).

Iodine intake by adult residents of a farming area in Iwate Prefecture, Japan, and the accuracy of estimated iodine intake calculated using the Standard Tables of Food Composition in Japan

“…According to the 2014 National Health and Nutrition Survey [12], Japanese consumed 75.6 g/day of fish and shellfish, and 10.5 g/day of algae [12,13]. These foods contain much iodine [4], thus, the high Japanese intake of iodine is derived from seafood, particularly algae.…”

“…Japan is surrounded by the sea and the Japanese population consumes seafood in large quantities, especially AM arithmetic mean, ASD arithmetic standard deviation, BMI body mass index, N number of subjects AM arithmetic mean, ASD arithmetic standard deviation, N number of subjects MAX maximum, MED median, MIN minimum, GM geometric mean, GAS geometric standard deviation seaweeds [13]. As seaweeds have high iodine content [4], Japanese people can be expected to take in more iodine than people in other countries [14][15][16][17][18].…”

“…Comprehensive information in the FCT on iodine content by food group varied from a high of 51.4 % for Group 5 (nuts and seeds), to a low of 16.0 % for both Group 11 (fish and shellfish) and Group 12 (meats). Even for Group 9 (algae), the expected leading source of dietary iodine in Japan [14], the iodine content value was available for only 18 items out of a total of 47 types of algae (38.3 %) [4,13,14].…”

Iodine Contents in Baby Food Consumed in Japan

“…Kombu is a traditional Japanese foodstuff and many Japanese eat it routinenly. As a result, the Japanese average iodine intake is over the tolerable upper intake level of iodine for the US and European people (Zava and Zava, 2011). In a general Japanese, there is almost no report of the health disturbance by excess iodine intake.…”

A Review of Spectrophotometric and Chromatographic Methods and Sample Preparation Procedures for Determination of Iodine in Miscellaneous Matrices

“…Japanese iodine intake from edible seaweeds is relatively high compared to the rest of the world. Having taken into consideration many factors, such as information from dietary records, food surveys, urinalysis and seaweed iodine content, Zava and Zava estimated that the daily iodine intake in Japan averages approximately 1,000 to 3,000 μg/day (Zava & Zava, 2011). In certain diets, seafood is a large source of iodine, containing 2 to 10 times more iodine than meat (Hemken, 1979).…”