Sodium alginate is a naturally occurring substance found in a particular type of seaweed. In the presence of stomach acid, the Sodium
alginate reacts to form a gel.

Sodium bicarbonate also reacts with the acid in the stomach to form bubbles of carbon dioxide. These bubbles are trapped by the gel, allowing it to float like a raft on top of the stomach contents. The raft stops gastric acid (stomach acid) from flowing back up into the oesophagus (food pipe), which relieves reflux symptoms like heartburn.

Calcium carbonate increases raft strength, due to its ability to cross-link alginic acid polymers, allowing the gel to form an ‘eggbox’ structure.

The calcium carbonate and sodium bicarbonate also have an antacid effect – hence the double action of Gelusil Plus. They bind to and neutralise excess acid in the stomach, which relieves the pain and discomfort of indigestion and heartburn.