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Letters to the Editor
Iodization of salt is a safe and successful strategy which has been tested and proven Sir, We wish to comment on an article entitled “Iodized Salt, a boon or bane?”: A retrospective Study” published in October — December 2013 issue of Journal of Dr. NTR University of Medical Sciences.[1] The research communication is extremely informative keeping in view of >50 years of universal salt iodization in the country. However, it does not convey the scientific facts correctly. The upper safe limit of iodine intake is 1100 μg/day by an adult as per the recommendations by National Institutes of Health, United States. [2] The authors should have estimated the total iodine intake rather than the consumption of the total amount of iodized salt and should have reported association of iodine if existed. After estimating the total iodine intake, the authors should have divided them into two groups; high iodine intake and low iodine intake and should have found an association of iodine. The authors have made a wrong conclusion by making statement that iodized salt was associated with hypothyroidism, hypertension, and diabetes. However, it might be the total quantity of salt consumed by the subjects, which was associated with high prevalence of hypothyroidism, hypertension, and diabetes. Iodized salt is a successful strategy which has been tested and proven to be extremely safe. At present, this strategy is being implemented in >160 countries in the world. A sound research methodology is essential to make scientifically valid conclusion. In the introduction, the investigator used the word “ONLY” 263 districts out of 324 are endemic to iodine deficiency in India as per Iodine Deficiency Disorder and Nutrition Cell, National Rural Health Mission, 2006. Such framing of the sentence misleads the readers. These 263 districts accounts for 81% of surveyed district, which is a huge Journal of Dr. NTR University of Health Sciences 2014;3(4) 291-292
proportion. No reference was made available for the provided data. The author has also mentioned that “as per the recent national family survey adequate usage of iodized salt has increased by 20% in rural households of India as against survey results in 2005-2006.” National Family Health Survey-4 (2014-2015) is still under process, then which national family survey is mentioned in the text. No reference was made available. The study design is not clear. Is this a case — control study? The author neither has mentioned about the calculation of sample size nor was the response rate documented. The author nowhere has documented the case definition of hypothyroidism utilized in the study. The calculation of the amount of salt ingested per day by a subject is a cumbersome process. It’s an important variable in this study, but the methodology was not mentioned anywhere in the research paper. The data on family history of hypothyroidism was collected, but it was nowhere utilized in results. Similarly, author documented in methodology that “Serum levels of thyrotropin, free triiodothyronine (FT3), free thyroxine (FT4), thyroid peroxidase (TPO) antibody, and thyroglobulin (Tg) antibody were measured in all subjects.” However, no descriptive or analytical statistics utilizing these variables were presented in results. In results, the subjects in two groups are significantly different in terms of gender (P < 0.001) and age (P = 0.001). The author should have either matched these parameters or should have adjusted with appropriate statistical methods of analysis. The Chi-square value and P value are wrongly calculated while comparing hypothyroidism with diabetes. As per the best of our understanding we think it would have been more informative if a correlation 291
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Letters to the Editor
between serum levels of thyrotropin, FT3, FT4, TPO antibody, and Tg antibody could have been presented with iodine intake and urinary iodine excretion levels.
Ajeet Singh Bhadoria, Umesh Kapil1 Department of Epidemiology, Institute of Liver and Biliary Sciences, 1Department of Human Nutrition, AIIMS, New Delhi, India Address for correspondence Dr. Ajeet Singh Bhadoria, Department of Epidemiology, Institute of Liver and Biliary Sciences, D-1, Vasant Kunj, New Delhi - 110 070, India. E-mail:
[email protected]
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REFERENCES 1.
2.
Ganti E, Kurada SV, Pakalapati S, Dana SR, Pothukuchi M. Iodized salt, a boon or bane?: A retrospective study. J NTR Univ Health Sci 2013;2:239-44. Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press; 2001. Access this article online Quick Response Code: Website: www.jdrntruhs.org DOI: 10.4103/2277-8632.146665
Journal of Dr. NTR University of Health Sciences 2014;3(4)
