Origin: Calcium salt of propionic acid, a natural acid present in small quantities in many foods, sometimes in high concentrations produced by bacteria in fermented foods, such as types of Swiss cheese. It is also produced on a large scale by the bacteria in the large intestine. Function & characteristics: Propionic acid and propionates are used as preservatives, mainly against fungi. Products: bakery products Daily intake: no limit Side effects : No side effects. Propionate is a normal small chain fatty acid and is used in many metabolic pathways in the body. Dietary restrictions : None, propionic acid and propionates can be consumed by all religious groups, vegans and vegetarians.