Apple Cider Vinegar. A food source that is high in hydrochloric acid is apple cider vinegar. The website Aim for Health estimates that one to 10 teaspoons of apple cider vinegar combined with a glass of water can increase hydrochloric acid production in the body.hoto Credit Maria Toutoudaki/Photodisc/Getty Images. Hydrochloric acid is needed to break down food in the stomach and absorb the nutrients, according to the website Food Scout. This type of acid can also help the body fight off parasites, fungi, and bacteria.