Yeast is not a strange ingredient for human beings.
Professor Hu Kuikui told reporters that yeast is a single-celled organism, belonging to facultative anaerobic fungi, and there are many kinds in nature. Usually eat steamed bread, steamed bread, fermented wine, it is inevitable to add some "live" yeast, and then high-temperature treatment will be eliminated.
Some cosmetic brands claim that the bottles of their products are vacuum-packed, that is, the bottles are oxygen-free environment. Facultative anaerobic fungi can grow and reproduce in aerobic or anaerobic environment, but they can ferment in anaerobic environment. Therefore, live yeast packaged in vacuum can ferment metabolites useful for the skin.
Does it seem reasonable?
Director Hu bluntly said: "It is a joke to add live yeast to skin care products. The "Technical Specification for Cosmetic Safety" clearly stipulates that the total number of molds and yeasts in cosmetics shall not be greater than 100 colony forming unit/ml (CFU/ ml) or 100 CFU/ g, and those exceeding the standard are first-class pollutants. "
In other words, yeast in cosmetics is a pollution index. Even if the number of yeast added at the beginning is not over the standard, these live yeasts will continue to multiply in the product, and they will not pass the test, let alone become qualified products and sell them to you through formal channels.
"Moreover, the living environment of live yeast requires high requirements, the survival cycle is short, and vacuum packaging is not foolproof." Hu Kuikui said.
The implication is that the live yeast in cosmetics such as water, lotion and cream has just "lived" and will not live until you use it.
Even if there is live yeast, the effect on skin care is very good.
"The method, dosage and morphology used need further evidence from relevant research," said Hu Kuikui.
A brand claims that there are three kinds of live yeasts in its products, such as beer yeast. Assuming it is true, it is useless for skin care. Is it harmful?
Hu Kuikui pointed out that, first, although the live yeast refers to beer yeast, yeast will mutate in different environments, producing some harmful metabolites, which will lead to skin allergy and even mutate into pathogenic fungi of the skin, thus causing infectious dermatitis; Second, it will cause the natural balance of the skin to be broken, leading to the destruction of the skin barrier, increasing the risk of infection, allergies and so on, and eventually the skin will appear rash, inflammation, peeling and pigmentation.
Big brand yeast extract is another matter.
Students who have studied skin care may know that some big-name essence lotions or muscle bottom lotions are called yeast, but if you look at the ingredients list, yeast essence is actually added.
Live yeast can't protect skin, so can yeast extract?
Hu Kuikui explained that the extract of metabolites produced by yeast fermentation was added to brand-name skin care products. These metabolites contain a variety of vitamins, amino acids and enzymes. Long-term use can moisturize skin, enhance skin metabolism, accelerate cell renewal, and improve skin luster and barrier function.
"So, this kind of nutrient solution is often added to various skin care products, which can be said to be very safe and can stand the test of' healthy makeup'. However, this is only related to yeast and is different from' live yeast'. "
Author: Li Hukuikui (executive director of Anti-aging Branch of China Plastic Surgery Association, deputy director of South China Medical Beauty Committee, director, chief physician and professor of Plastic Surgery Center of Guangdong Maternal and Child Health Hospital)
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