I read the informative and useful article by Marwaha, et al.(1), in
the April 2010 issue of Indian Pediatrics. In their research
communication, authors have made an unwarranted and potentially damaging
extrapolation of their data. Authors have concluded that "this study shows
evidence of excess iodine nutrition in USES school children. The source of
this iodine could be salt or non salt iodine. The increased urinary iodine
is associated with thyroid dysfunction though not with goiter". Their
conclusions are based on the findings of 997 USES school children studied
which had median UIE level of 352 µg/L (97% of the urine samples had UIE
level 300 and more µg/L). To have excretion of iodine of 300 µg/L, a child
has to consume at least 20 g of salt per day, the possibility of all
children consuming this high amount is very remote. The earlier
multicentric study conducted in 1988 by Indian Council of Medical Research
documented that in neighboring state of Haryana, the per capita per day
consumption of salt was 10.2g in winter, 9.2 g in summer and 9.2 g in
rainy seasons. Similarly in Uttar Pradesh state, per capita per day
consumption of salt, was 12.4 g (winter), 12.9 g (summer) and 14.9 g
(rainy) seasons(2). Also, the NFHS-III survey data of Delhi, conducted in
2005-2006 in which iodine content of salt was estimated, also documented
that nearly 14% of the household in the highest income group were
consuming salt with less than 15 ppm of iodine. These facts substantiate
that the iodine intake of children could not come from iodized salt. In an
earlier study, conducted in school age children in Delhi in 1999(3), we
found that median UIE was 170 mcg /L and 42% of the households were
consuming salt with less than 15 ppm of iodine. Another study conducted in
Delhi in 2010, has reported that the median urinary iodine excretion was
found to be 198.4 mg/L and 11.7% of
household were consuming iodized salt less than 15 ppm(4).
Salt manufacturers in general try to save money by
adding less iodine in the salt as the cost of iodine is about 10% of the
total cost of the salt at the production level. There are no foods which
are rich in iodine and most common source of dietary iodine intake in
India is iodized salt. The investigators have used a new methodology for
estimation of UIE which could be possibly responsible for reported higher
value of UIE levels. The findings of the study indicate the excessive
intake of iodine by the child-ren, which is a cause of great concern as it
might lead increase in thyroid disorders and can have adverse impact on
the universal salt iodization program in the country. Hence, the results
of present study should be urgently communicated to managers of National
Iodine Deficiency Disorders Control Program in the Ministry of Health and
Family Welfare, New Delhi, so that corrective measures can be initiated.
References
1. Marwaha RK, Tandon N, Desai A, Kanwar R, Maini K.
Iodine nutrition in upper socioeconomic school children of Delhi. India
Pediatr 2010; 47: 35-37.
2. Pattern of Salt Consumption in Different Regions of
India- A Multi Centric study. Indian Council of Medical Research, New
Delhi: ICMR Offset Printing Press; 1990.
3. Kapil U, Saxena N, Nayar D, Ramachandran S.
Assessment of status of salt iodization in Delhi. Indian J Pediatr 1999;
66: 185-187.
4. Agarwal J, Pandav CS, Karmarkar MG, Nair S.
Community monitoring of the National Iodine Deficiency Disorders Control
Programme in the National Capital Region of Delhi. Public Health Nutr
2010; 1: 1-4.