Hydrochloric acid is necessary for easy digestion of: 

1. Fats
2. Enzymes
3. Food
4. Proteins

Hydrochloric acid is necessary for easy digestion of proteins. Stomach HCl (pH 1.5-3.5) denatures proteins by breaking disulfide bonds, enabling pepsin enzyme activation. It also kills pathogens. Produced by parietal cells, 1.5L is secreted daily. Low HCl causes indigestion, while excess leads to ulcers. Fats are digested by lipase in the small intestine.