Why do Indians cook food in iron and earthen vessels?

Reason

1. Iron is one of the most important elements that is essential to human blood. An iron deficiency zaps our energy, making us feel tired and sluggish so it needs to be included in our daily diet. Meats have the highest iron content. Indian vegetarians avoid killing animals for food. There came in the idea to cook food in iron vessels oxidise slowly and mixes with food in small quantities everytime food is cooked.
2. Just like iron, other minerals are needed in small quanities for man to survive. Earthen vessels made from clay release biologically important quantities of minerals like calcium and sodium into the food while cooking.