Second-largest salt producer state ranks last in usage of iodised salt; children lose up to 15 IQ points due to iodine deficiency

Tamil Nadu, India's second-largest salt-producing state, has the lowest share of households using adequately iodised salt, with only 62% meeting the standard against a national average of 76%, according to the 2018-19 India iodine survey cited by state health officials.

Health minister K G Arunraj raised the concern on Monday at an event marking Iodine Deficiency Disorders Prevention Day at Justice Basheer Ahmed Sayeed College for Women. He urged residents to reduce their daily salt intake while ensuring the salt they consume contains adequate iodine.

“We cannot accept iodine deficiency in the land that produces the salt,” Arunraj said.


The state government's concerns extend beyond household consumption. District-level testing has found variations in iodine levels in cooking salt, while health department screenings have detected goitre among schoolchildren in several districts.

Why household salt choices matter

Arunraj said many families buy loose, unbranded rock salt and store it in open containers exposed to sunlight and moisture. Adding salt early in cooking and boiling food for long periods can also cause iodine losses, he said.

These practices matter because iodine is an essential trace mineral that the human body cannot produce on its own. The thyroid gland uses it to make hormones that regulate growth and metabolism and support brain development.

Director of public health Dr A Somasundaram said iodine is particularly important during pregnancy, when a developing fetus depends entirely on its mother's iodine supply.

Severe deficiency can cause goitre, miscarriage, stillbirth and lasting intellectual impairment in children. Even milder deficiency has been linked to lower verbal scores and weaker reading skills.

Arunraj cited the World Health Organisation's position that iodine deficiency is the leading preventable cause of brain damage. He also referred to studies linking iodine deficiency in communities with average IQ scores 10 to 15 points lower among children.

Rural residents consume around 13g of salt daily

A recent study by a Chennai-based medical institution found that rural residents consume around 13g of salt a day, while a third of households use salt with insufficient iodine.

The findings highlight two separate public health concerns: excessive salt consumption and inadequate iodine intake.

High salt consumption increases the risk of hypertension, heart disease, stroke and kidney damage. Inadequate iodine intake, meanwhile, can affect thyroid function and development.

The state is running a campaign to encourage people to reduce salt consumption. Arunraj said the recommended limit is less than 5g a day, while stressing that people should continue to use iodised salt.

“ It means we must use less than 5g a day, but only iodised salt,” he said.

The advice is not to eliminate iodine from the diet while reducing salt consumption. Instead, households should use smaller quantities of salt that meets the required iodine standards.

Goitre detected in schoolchildren across districts

The Tamil Nadu public health department screens schoolchildren for goitre in every district. Data released in parts by the department on Monday showed that 9% of schoolchildren screened in Ramanathapuram had goitre in 2024-25.

Villupuram reported a similar share of around 9% in 2018-19. Madurai recorded 6% in 2022-23, while Pudukottai reported 5% in 2024-25.

Officials classified all four districts as high-risk areas for goitre.

The figures come from different reporting years and should be read as district-specific screening results rather than a single statewide estimate. They nevertheless illustrate why health authorities continue to monitor iodine deficiency among children.

Salt samples show differences in iodine levels

Food safety rules specify iodine levels for salt intended for human consumption. Salt must contain at least 30mg of iodine per kg at the production stage and 15mg per kg at the household level.

Village health nurses test cooking salt in households to assess whether it meets the required standard.

Between April 2025 and March 2026, district-level sample analysis found that the proportion of adequately iodised salt varied from 70% to 88% in Thanjavur, Tirunelveli, Virudhunagar, Kallakurichi, Thoothukudi and Tiruvarur.

At least 2% of salt samples tested in Thoothukudi contained no iodine, despite the district's association with salt production.

The health minister said the food safety department takes action against manufacturers who violate the prescribed standards. He added that enforcement would continue with greater intensity.

What households should do

Consumers should check packaging and buy properly labelled iodised salt rather than relying on loose, unbranded products of uncertain iodine content. Salt should also be stored in a covered container, away from excessive heat, sunlight and moisture.

Households should avoid adding salt too early when cooking food for long periods, as prolonged heating can reduce its iodine content.

Inputs from agencies