According to research by L'Oreal, it takes between a few weeks and several years for skin to regrow, depending on the severity of the injury. Superficial injuries, such as shallow cuts or first degree burns, take the shortest time to heal, as they only affect the epidermis.
WebMD states that it takes only 27 days for the skin to regenerate itself, under normal conditions, because of the body’s ability to grow new cells. It uses the proteins, vitamins and minerals found in food to complete this process. The necessary elements of the food are absorbed into the bloodstream, through the intestinal wall, and distributed throughout the body, as required.