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 Table of Contents  
Year : 2019  |  Volume : 9  |  Issue : 1  |  Page : 42-45

Evaluation of the accessible level of iodine in marketed iodised salt in Iran: A comparison with standard recommended values

1 Research Center of Gastroenterology and Hepatology, Qom University of Medical Sciences, Qom, Iran
2 Department of Environmental Health Engineering, Research Center for Environmental Pollutants, Qom University of Medical Sciences, Qom, Iran

Date of Web Publication4-Jan-2019

Correspondence Address:
Mahdi Asadi-Ghalhari
Department of Environmental Health Engineering, Research Center for Environmental Pollutants, Qom University of Medical Sciences, Qom
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/AIHB.AIHB_30_18

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Background: Iodine is one of the essential micronutrients for synthesise and secrete adequate amounts of thyroid gland hormones. Its deficiency is the most important threatening causes for human health. The aim of this study was to evaluate iodine concentration in marketed edible salt samples in Qom city and to compare with existing standards and offering solutions necessary to fix the probably problems. Materials and Methods: A cross-sectional, descriptive study was carried out on 60 samples of 20 brands of marketed edible salt in Qom during 2017. Iodine concentration was evaluated by the British Pharmacopoeia titration method. Results: According to the national standard of Iran during this study, iodine concentration in 51.67% of salt samples was in acceptable limits and 48.33% of samples were out of acceptable ranges. None of the tested samples had iodine content more than the standard limit. Conclusions: To improve salt fortification status and removing iodine deficiency in society, the following actions should be considered: enforcing producers to follow national and international standards, continuous monitoring the producers, necessary legal actions against offending manufacturers and appropriate measures by health ministry and relevant authorities.

Keywords: Edible salts, iodine, Iran, Qom

How to cite this article:
Mohammadbeigi A, Salehi A, Heidari H, Asadi-Ghalhari M. Evaluation of the accessible level of iodine in marketed iodised salt in Iran: A comparison with standard recommended values. Adv Hum Biol 2019;9:42-5

How to cite this URL:
Mohammadbeigi A, Salehi A, Heidari H, Asadi-Ghalhari M. Evaluation of the accessible level of iodine in marketed iodised salt in Iran: A comparison with standard recommended values. Adv Hum Biol [serial online] 2019 [cited 2020 Jul 2];9:42-5. Available from: http://www.aihbonline.com/text.asp?2019/9/1/42/249517

  Introduction Top

Iodine is a trace element naturally existed in seafood and plants grown on iodine-rich soil[1] and is an essential component of the hormones produced by the thyroid gland. It is one of the most important and essential micronutrients for mammalian life,[2] but these amounts generally vary at low concentrations.[1] Iodine deficiency (ID) is one of the globally known nutritional disorders and is characterised as the most common preventable cause of mental and physical retardations.[3] Only 49 countries have achieved to the adequacy of salt iodisation.[4],[5] In 1994, the Joint Committee of the World Health Organization (WHO) (UNHCR) and the United Nations Children's Fund (UNICEF) defined the salt iodisation program as a safe and effective strategy to provide the required value of daily iodine intake.[6]

The ID is still remained as a public health problem in 47 countries, and about 2 billion people are at risk and minimum 750 million people are exposed to ID disorders (IDDs), worldwide.[7] It is estimated that 20 million people in Iran suffered from ID before iodised salt marketing at 1989.[8],[9] IDDs are endemic in many provinces of Iran, and based on the recent studies, Iran is located along the ID belt.[10] A nationwide survey of goitre in 1989 presented that goitre prevalence in schoolchildren in most provinces was 30%–80%.[9],[11] Iran's iodine supplementation programs for eliminating IDD began in 1989.[9] The present law enacted by Iran's national health committee requires factory salt products to maintain 40-ppm iodine in the form of potassium iodate. Recently, it has been reported that approximately 93% of rural people and 97% of urban people of Iran use iodised salt.[12]

Iodine is present mostly insufficient quantities in the environment around the world.[1] Due to atmospheric changes such as floods and long rains, iodine is washed out in the soil. As a result, crops grown in these soils have low in iodine concentration and man/animals that consuming these foods grown become affecting to iodine deficiency.[13] To prevent ID complications, different methods of iodination of foods can be used such as iodisation of salt, bread and milk.

In the USA and Europe, bread contains significant amounts of iodine due to iodised salt being used in the baking process, and in some countries, iodisation process is used in the dairy industry.[1] The best strategy for controlling the ID in most countries is salt iodisation since it is cheaper and accessible to general public and also supported economic and social development.[2] However, the salt iodisation program has several problems including technical problems in factories, poor quality of packaging, the production and distribution of iodised salts in non-standard or counterfeit, the possibility of iodine loss due to transportation and physical activity and long storage time in stores and warehouses. According to the importance of iodine concentration monitoring in salt, this study aimed to evaluate the iodine concentration in marketed edible salt samples in Qom city, Iran, and to compare with existing standards and offering necessary solutions to fix the probably problems.

  Materials and Methods Top


This cross-sectional survey was conducted on 60 samples in all 20 different brands (three samples of each brand) of marketed edible salt in Qom, Iran. Samples of edible salt were collected randomly from grocery stores according to the geographic maps. All samples were transferred to food control laboratory, and iodine concentration was evaluated triplicate.

Laboratory measurement of iodine in salt

All samples were tested by the British Pharmacopoeia titration method. According to the recommended procedure, 10 g of salt was dissolved in distilled water in a 50-mL volumetric flask and mix thoroughly. Then, the resulting solution was transferred to a 250-ml Erlenmeyer flask and was stirred repeatedly to obtain a uniform solution. About 1-ml sulphuric acid (2N) and 5 ml of 10% potassium iodide were added. The subsequent reaction released the iodine of the salt and solution turned to yellow. The cup of Erlenmeyer flask was kept out in dark area for 10 min to let the reaction run its course. Then, a few drops of indicator starch (1%) were added to it and titrated with sodium thiosulphate (0.005 N) until the colour dissipates.[14]

To calculate the iodine concentration of the sample, the following formula was used and the results were expressed as microgram per gram or ppm.

Iodine concentration (ppm) = the volume of consumed titre × 10.58 × 1000/weight of used salt.

Statistical analysis

The obtained data were analysed using Chi-square test and one sample t-test using IBM SPSS software V.21 (SPSS Inc., Chicago, Illinois, USA). Statistical significance was identified at 95% confidence level (P < 0.05).

  Results Top

Iodine content of salt samples is presented in [Figure 1] and [Table 1]. Over the course of study during the December 2017 and January 2018, a total of 60 samples of 20 different brands of edible salt were sampled.
Figure 1: Iodine concentration of iodised salts in Qom city in 2017–2018. The unit expressed in mg iodine per kg of salt.

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Table 1: Limit of iodine concentration of edible salts in Qom city

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According to the recommendations of the Iodine Standards National Committee of Iran, the samples were classified into three groups based on their iodine content: under standard limit (<30 ppm), allowable standard limit (30–50 ppm) and over standard limit (>50 ppm) [Table 1]. Iodine concentration in 51.67% (31 samples) of salt samples was in acceptable limits and in 48.33% (29 samples) of samples was less than the standard limits. The one sample t-test showed that the mean of iodine content in the samples was not higher than the standard limit (P > 0.05).

Among the 20 brand of salts, samples with G and Q brands have significantly (P < 0.05) higher mean of iodine content than other samples (47.26 and 46.55 ppm, respectively). The lowest iodine content was significantly (P < 0.05) found in the sample with N brand (12.7 ppm) [Figure 1].

  Discussion Top

The WHO recommends that the dietary allowed level of iodine is 50 μg/day from 0 to 6 months, 90 μg/day from 6 months to 6 years and 150 μg/day for adolescence and it should be increased to 200–300 μg/day at pregnancy and lactation.[7] The WHO, UNICEF and the International Council for Control for IDD (ICCIDD) have defined three degrees for ID severity including mild (iodine intake of 50–99 μg/day), moderate (20–49 μg/day) and severe (<20 μg/day).[15] Insufficient daily intake of iodine is related to occurrence a series of functional and developmental abnormalities including mental and physical retardations. The consequences of these abnormalities are endemic goitre, hypothyroidism, endemic cretinism and cognitive impairment, decreased fertility rate and increased infant mortality.[16] Moreover, ID leads to dysfunction of central nervous system and impairments of motor and psychomotor function.[17]

Based on the results of the present study, it was expected that more salt brands would be a higher percentage of iodine in the standard limit, but only 51.67% of the samples had good iodine. The D, E, I, L, M, N, O, P, R and S salt samples with unacceptable concentration of iodine were under 30 ppm. Although national salt iodisation in has taken several decades, there is also a large percentage of Qom people suffering from marginal or mild ID. Therefore, we should concern about the irreparable consequences of ID. Hence, in the present experiment, iodine concentration of edible salt samples has been evaluated in Qom city.

According to the tests used in data analysis, there was a significant difference between the average iodine contents of different brands. On average, in 50% of tested salt brands, iodine content was lower than the standard limit. The highest concentration of iodine was 47.26% in sample with G brand. It seems that producers of edible salts overlooked the importance of iodised salt quality that will ultimately lead to higher risks of goitre among the population. Despite the compulsion of the Iranian Ministry of Health to use iodised salt, there is still observed that the many households are reluctant to use iodised salt. One of the main causes of failure in ID elimination programs is the use of marine salts and families' belief to traditional medicine in Qom city. Several studies in the decades ago showed that goitre prevalence was >60% in the majority of the provinces in Iran.[18]

Several studies in different provinces of Iran to assess the iodine concentration of edible salts. In a study in the Lorestan Province of Iran, 240 samples of 20 brands of marketed edible salt were sampled. Results presented that iodine concentration in 64.59% of salt samples was in acceptable limits according to the national standard of Iran.[4] Mohammadi et al. study reported that from a total of 54 samples, 55% of iodine content was at an acceptable level, and in 45% of the samples, iodine content was less than the standard limits that this is in accordance with the present study.[19] Dehghani et al. study showed that of 13 brands iodised salts, 8 brands (61.53%) had acceptable ranges (30–50 ppm) and 5 brands (38.46%) were out of acceptable ranges, and they were not any salts with more than iodine acceptable maximum ranges.[20]

Pasdar et al. study reported that the mean content of iodine in salt samples supplied in Kermanshah was 28.3 ± 14.8 ppm, which was 50% less than the recommended level in Iran.[21] Reducing of iodine content in salt (<30 ppm) will lead to a failure to meet the goals of national program to eliminate of ID problems.

Nowadays, availability to iodised salt in the world has increased significantly so that in many parts of the world accessing to iodised salt is considered as a main priority. Therefore, continuous monitoring and more serious control on iodised salt factories are necessary. Salt iodisation program has also began in other countries such as Tunisia, Haiti, Mexico, Columbia, Guatemala, Argentina, Republic Dominican and Thailand, but due to the lack of regular monitoring and interrupting regular monitoring and control, IDD increased gradually.[22],[23],[24]

Wang et al. studied on IDD after a decade of universal salt iodisation (USI) in a severe ID region in China. According to the findings of their study, after 10 years of USI, iodine nutrition of people improved and the total goitre rates decreased through 10 years of USI.[25]

Obtained results of our study had accordance with mentioned studies and showed that intense supervision is necessary on salt iodisation programs. In other words, the main key of continuity of the salt iodisation program is precise monitoring of the program.

  Conclusions Top

The results of this study showed that the iodine in 48.33% of salt samples in Qom was less than the acceptable standard limits. Regarding the adverse effects of ID on the human body, this considerable amount alarms researchers and authorities to take action in dealing with it. Accurate and continuous monitoring the amount of iodine in iodised salts, warning the offenders and punishing them are among the actions that the relevant authorities should take to improve the overall health and well-being of the community. Due to the effect of moisture and light on the amount of salt iodine, it is recommended to use appropriate packaging and store the salt away from the light and moisture in order to avoid its reduction as much as possible.


The authors are very grateful from Qom University of Medical Sciences staffs and all subjects who participate in the study.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Andersson M, Aeberli I, Wüst N, Piacenza AM, Bucher T, Henschen I, et al. The Swiss iodized salt program provides adequate iodine for school children and pregnant women, but weaning infants not receiving iodine-containing complementary foods as well as their mothers are iodine deficient. J Clin Endocrinol Metab 2010;95:5217-24.  Back to cited text no. 22
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