Why is it advised to take iodised salt?

Hint: Iodine is a necessary mineral required for the normal rate and synthesis of the thyroid hormone. Thyroid hormone is produced by the thyroid gland. It is the only gland storing its own hormone.

Complete answer:
First of all let’s see what thyroid gland is.
The thyroid gland is basically composed of follicles and stromal cells.
The follicular cells are responsible for the production of thyroxine $(T_4)$ and triiodothyronine $(T_3)$ hormones.





Now, iodine is responsible for the synthesis of these thyroid hormones and also for the normal rate of production of thyroid hormone.

So, deficiency of iodine in our diet results in hypothyroidism which leads to increase in the size of the thyroid gland. This enlargement of the thyroid gland is commonly called as goitre.
It(goitre) can be caused due to the following:-
- Decreased intake in our diet.
- Increased demand during puberty, pregnancy and lactation.
- Intake of goitrogens i.e. cabbage.

It is important to know that hypothyroidism in pregnant women can cause defective development and maturation of the growing baby and in adult women, it may cause menstrual cycle to become irregular.

Hence to prevent these conditions, iodine has been added to our salts and that is why iodised salt is advised.
The recommended daily intake of iodine is: $150\mu \text{g/day}$

Note: Thyroid gland is the largest gland of the body. Thyroid hormones are necessary as they control the basal metabolic rate of cell respiration. Iodine is needed by the thyroid gland for the production of thyroxine hormone.