There is a history of those with thyroid issues being encouraged to take iodine supplementation. Indeed, at the level of iodised salt, this is often national policy. (Though not in the UK.)
However, some sources encourage consumption of iodine in quantities far greater than the highest levels found in diet. Japan is often quoted as having the highest population intake of iodine of any of the larger countries of the world – typically around 3 milligrams a day is quoted.
This paper claims to identify an association between higher iodine intake levels and bone mass density, osteopenia and osteoporosis.
Relationships between iodine nutrition status, and bone mineral density and bone metabolism: a cross-sectional study of 1207 thyroid disease-free adults in China
Published online by Cambridge University Press: 10 April 2025
Zheng Zhou, Jinjin Liu, Baoxiang Li, Yun Chen, Yanhong He, Bingxuan Ren, Qiuyang Wei, Meihui Jin, Yao Chen, Haiyan Gao, Siyuan Wan, Lixiang Liu and Hongmei Shen
Abstract
Little is known about the association between iodine nutrition status and bone health. The present study aimed to explore the connection between iodine nutrition status, bone metabolism parameters, and bone disease (osteopenia and osteoporosis). A cross-sectional survey was conducted involving 391, 395, and 421 adults from iodine fortification areas (IFA), iodine adequate areas (IAA), and iodine excess areas (IEA) of China. Iodine nutrition status, bone metabolism parameters and BMD were measured. Our results showed that, in IEA, the urine iodine concentrations (UIC) and serum iodine concentrations (SIC) were significantly higher than in IAA. BMD and Ca2+ levels were significantly different under different iodine nutrition levels and the BMD were negatively correlated with UIC and SIC. Univariate linear regression showed that gender, age, BMI, menopausal status, smoking status, alcohol consumption, UIC, SIC, free thyroxine, TSH, and alkaline phosphatase were associated with BMD. The prevalence of osteopenia was significantly increased in IEA, UIC ≥ 300µg/L and SIC > 90µg/L groups. UIC ≥ 300µg/L and SIC > 90µg/L were risk factors for BMD T value < -1.0 SD. In conclusion, excess iodine can not only lead to changes in bone metabolism parameters and BMD, but is also a risk factor for osteopenia and osteoporosis.
Keywords
Water iodine concentrations, BMD, Iodine nutrition, Bone metabolism
Abstract and full paper (as PDF) open access:
DOI: 10.1017/S0007114525000790