Zinc's an essential trace element that helps growth alongside our immune, endocrine and nervous systems. It keeps us happy and focused, improves vision and helps our sense of taste and smell. It plays a vital role in blood-clotting, thyroid function and insulin metabolism. That said, our bodies only stock around 2 to 3 grams, 65% of which is stored in our muscles and 20% in our bones. Nowadays, a lot of us are slightly deficient. Women, teenagers, kids and older people often lack zinc in their diet.