Hydrochloric acid secretion in the stomach assists protein digestion by activating pepsinogen to pepsin, renders the stomach sterile against ingested pathogens, inhibits undesirable overgrowth in the small intestine, and encourages the flow of bile and pancreatic enzymes. Hydrochloric acid also facilitates the absorption of a number of nutrients, including folate, vitamin B12, ascorbic acid, beta-carotene, iron, and some forms of calcium, magnesium, and zinc. Numerous studies show hydrochloric acid secretion in the stomach declines with advancing age. Overuse of antacids can also lead to low levels of hydrochloric acid in the stomach, which can result in poor protein digestion. Thorne Research offers hydrochloric acid and pure pepsin from a porcine source. Unlike many supplement companies, the pepsin utilized in Thorne Research’s product is pure, undiluted, and lactose-free.