Hydrochloric acid (whose chemical formula is HCl) is a strong, aggressive acid. Technically-speaking it is very corrosive. But it can also take part in many types of chemical reactions in your stomach: - HCl breaks down the proteins you eat for use in the synthesis of muscle and body tissue - It prevents bacterial pathogens descending in your gastro-intestinal tract; these would cause infections that can lead to disease and stomach cancer - It activates vital substances like hormones and enzymes that help digest food - It helps absorb crucial nutrients that are in food: vitamins A, C, E, B6 and B12, calcium, magnesium, zinc, iron etc.

Can you digest your own stomach then?

If this acid is so aggressive that it can help digest a steak, why doesn’t it digest your stomach, too? Well, the inner layer of your stomach is protected by so-called epithelial cells. They produce and secrete a bicarbonate solution that coats this stomach layer. Bicarbonate is alkaline, a base; it neutralises the acid secreted and this process produces water. The continuous supply of bicarbonate protects your stomach from self-digesting. By the way, many of the tablets people take when they feel too much gastric acid in their throat contain the same bicarbonate.