Мало информации на русских сайтах, даже в вики.
Выкладываю на англ. Переведу позже =)
| <jbramirez> |
Hi Dr Pickart,
Been doing alot of research and reading on HA, and I can't seem to find any commentary from you regarding very low molecular weight HA, as hydrolyzed hyaluronic acid. The reason I ask is because your strong opinions on medium/high molecular weight HA is tied to skin wetting and the fact that it sits on top of the skin, but the hydrolyzed HA seems to have a much higher permeation of the skin? I have my own reservations about the safety of hydrolyzed HA, but I would really like to hear your comments. To be specific, I pasted the hydrolyzed HA datasheet below since they seem to have conducted some basic studies on it. The part that has me curious is the fact that they cite that hydrolyzed HA affected expression of more than 40 genes within the skin. But that's neither here or there, considering that everything put on the skin (or for that matter consumed) respectively affects gene expression. I wasn't able to find any patent literature on it, but according to the manufacturer (per their datasheet) the production process is fermentation via Bacillus Subtilis (a beneficial microbe to which we already have a symbiotic relation with), and an aqueous recovery process. http://www.finecon.sk/admin/pdf/DS_HyaCare_50_e.pdf In any case, would really like to hear your thoughts on the safety or stated benefits of this stuff. This message has been edited. Last edited by: <jbramirez>, |
 [показать]Location: Skin Biology
Registered: 15 September 2004
Posts: 6967
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Hyaluronic acid (scientifically named "hyaluronan") is a sugar-like molecule that can bind huge amounts of water (1000-fold of its own weight).
When applied to the surface of human skin, it feels smooth and sensuous but will slowly wets the skin's outer protective proteins and damages the skin barrier. This can temprarily improve the looks of skin but does not help skin health. The outer layer of skin (what we actually see) is composed of keratinocytes. The signal that causes the skin to send new keratinocytes to the skin's surface is a dryness in the outer layers of the skin. Hydrating (wetting) the outer skin proteins slows or even stops the normal flow of keratinocytes to the skin surface. If the skin is kept wet, such as by using hyaluronan, the skin renewal is slowed and skin ends up looking older. Skin Damaging Cosmetic Moisturizers are designed to push water into the skin and wet the outer skin proteins. Various detergents (but they may not be called detergents) and water-holding molecules such as hyaluronic acid often used to loosen the outer skin proteins so water can interact with them. But this weakens the skin barrier and lets in viruses, bacteria, and allergens. In about 1997, there were studies from Denmark that found that oil/water skin moisturizers broke down the skin barrier. The concern was that this could increase infection in hospital patients. Since then, it has been found that This means to skin is more slowly replaced and damage remains longer. Cosmetic moisturizers are designed to wet the outer skin proteins and push water into the skin to puff it up. Various detergents (but they may not be called detergents) are used to loosen the outer proteins so water can interact with them. The best example is the "cold creams" that women applied every night in the 1930s and 1940s. You may have seen these in old movies. Their skin was kept moist but the women ended with horrible wrinkles. Various polymers of hyaluronan are used as skin injectable skin fillers. Injectable form of hyaluronic acid are sold as "not-from-animals" but they are from pathogenic bacteria. The FDA warns that the material contain small amounts of bacterial protein and this can produce allergic responses in time.
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http://healthyskin.infopop.cc/eve/forums/a/tpc/f/8...088146?r=1211098146#1211098146
Японцы курят по 60 лет, работают под солнцем, живут по 100 лет, и имеют при этом идеальную кожу.
Все благодарят ГК, которую они естественно получают из их "диеты"
Dr. Pickhart, in the link I posted above, claims that "it feels smooth and sensuous but will slowly wets the skin's outer protective proteins and damages the skin barrier. It does not help skin health." And, "The problem with wetting the skin is that bacteria and viruses enter the wet skin barrier".
However, at this point, I'm definitely giving it the benefit of the doubt and will continue to use it.
http://www.essentialdayspa.com/forum/viewthread.ph...postorder=asc&&start=0
Hyaluronic acid is a polymer and the size of its molecules (chains) may vary in a wide range. Depending on the size, HA chains may produce different physiological effects. In particular, relatively large HA chains (molecular weight 500,000 Da or more) appear to reduce inflammatory response. There is some evidence that topically applied HA can reduce skin irritation from various causes (such as retinoids, laser treatments, chemical peels and others). Unfortunately, as of the time of this writing, very few studies investigated HA as a topical anti-irritant. Further research is required to determine optimal HA concentrations and usage patterns for specific conditions. (The concentrations studied so far ranged from 0.1% to 2.5%.)
http://www.smartskincare.com/treatments/topical/hyaluronic-acid.html
Causing dryness
Surprisingly though, some people find that a hyaluronic acid serum cause their skin more dryness and question if concentrated hyaluronic acid formulas should be used as a moisturizer in dry climate. Apparently, when air humidity is very low, hyaluronic acid may preferentially pull water from the skin rather than from the air, thus producing the opposite effect. This is confirmed by skin guru Dr Leslie Baumann MD who cautioned against using a moisturizer with hyaluronic acid.
http://www.vivawoman.net/2012/08/hyaluronic-acid/
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http://www.essentialdayspa.com/forum/viewthread.ph...postorder=asc&&start=0
Exercise prudence
So if you’re applying a hyaluronic acid serum and finding that your skin feels a bit dry or taut, the hyaluronic acid is probably pulling moisture out of your skin instead of pulling moisture from the air and into your skin. In this case, it is best applied onto damp skin and then “sealed” in with a good moisturizer on top. Additionally, do exercise prudence when using this ingredient if you’ve got dry skin and are living in a country with dry, low humidity climate or are constantly enclosed in an air-conditioned environment.
http://www.vivawoman.net/2012/08/hyaluronic-acid/
Еще ссылки
http://szulczyk.blogspot.ru/2014/03/everything-you-wanted-to-know-about.html