Explain why, people are advised to use iodised salt in cooking food.

People are advised to use iodized salt in cooking because iodine is an essential micronutrient that the human body cannot produce on its own and must obtain through diet. Iodine is a critical component of thyroid hormones—thyroxine (T4) and triiodothyronine (T3)—which the thyroid gland produces to regulate metabolism, growth, development, and numerous bodily functions. Without adequate iodine intake, the thyroid cannot synthesize these hormones properly, leading to a cascade of health problems. In many regions worldwide, soil and water naturally lack sufficient iodine, meaning locally-grown foods don't provide enough of this essential nutrient.

Iodine deficiency causes several serious health conditions. The most visible is goitre—an abnormal enlargement of the thyroid gland as it attempts to compensate for low iodine by growing larger to capture more of the limited iodine available. Beyond goitre, iodine deficiency leads to hypothyroidism with symptoms including fatigue, weight gain, depression, cold sensitivity, and poor concentration. In pregnant women, severe iodine deficiency is particularly devastating, potentially causing miscarriage, stillbirth, and congenital abnormalities. Infants born to iodine-deficient mothers may suffer from cretinism—a condition characterized by severe mental retardation, stunted growth, and developmental disabilities. Even mild iodine deficiency during childhood can impair cognitive development and reduce IQ scores, affecting learning ability and academic performance.

Salt iodization is one of the most cost-effective public health interventions ever developed. Adding iodine to salt (typically as potassium iodate or potassium iodide) costs only a few cents per person annually but prevents the devastating consequences of iodine deficiency. Salt was chosen as the delivery vehicle because it's universally consumed in relatively consistent amounts across all socioeconomic groups, is centrally processed making fortification feasible, and the small amount of iodine needed doesn't affect salt's taste or appearance. The recommended daily iodine intake is approximately 150 micrograms for adults, which is easily achieved through regular use of iodized salt. Since implementing iodized salt programs globally, many countries have virtually eliminated iodine deficiency disorders. However, using sea salt, Himalayan pink salt, or other specialty salts that aren't iodized may not provide adequate iodine, which is why public health authorities specifically recommend iodized salt. For people following low-sodium diets who restrict salt intake, alternative iodine sources like seafood, dairy products, and iodine-rich vegetables become more important, or supplements may be necessary under medical guidance.