Although collagen is beneficial to skin, most of the cosmetics and skincare products marketed in Taiwan contain collagen from cows, pigs and chickens. These animals may contain pathogens that are harmful to both man and beast, such as mad cow disease, foot-and-mouth disease and bird flu. If there has been an outbreak of disease among a species of animal, there will always be suspicions that the animal's products have been tainted.
膠原蛋白對肌膚有益，但市售的國產和自國外進口的膠原蛋白美容保養品，多萃取自牛、豬、雞，這些動物可能帶有人畜共通病毒，如狂牛症、口蹄疫、禽流感等，一旦爆發動物性傳染病，不免有病毒汙染的疑慮。