What is the role of stomach acid in digestion?

Stomach acid, primarily hydrochloric acid, plays a crucial role in breaking down food and absorbing nutrients in the body.

Stomach acid, also known as gastric acid, is a digestive fluid formed in the stomach. It is composed of hydrochloric acid (HCl), potassium chloride (KCl), and sodium chloride (NaCl). The primary role of stomach acid is to sterilise the food you eat and to prevent harmful bacteria from entering the GI tract.

Hydrochloric acid, the main component of stomach acid, creates an acidic environment in the stomach, typically with a pH of 1.5 to 3.5. This acidic environment is essential for the activation of pepsinogen into pepsin, an enzyme that breaks down proteins into smaller, more easily absorbed substances. Without sufficient stomach acid, proper protein digestion would not occur.

Stomach acid also aids in the absorption of certain nutrients. For instance, it helps absorb vitamin B12 by separating it from the protein to which it is attached. This allows the vitamin to be absorbed into the body. Similarly, stomach acid aids in the absorption of calcium, iron, and zinc.

Moreover, stomach acid plays a defensive role by killing off harmful bacteria and parasites that may be present in the food we consume. The highly acidic environment in the stomach helps destroy these potentially harmful microorganisms, thus preventing them from causing infections or diseases.

In summary, stomach acid is vital for digestion as it breaks down food, absorbs nutrients, activates enzymes, and protects against harmful bacteria. Without it, our bodies would struggle to extract the necessary nutrients from the food we eat.