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Fri Feb 08, 2013 6:05 pm  |
The distribution of vitamin C varies widely in the tissues of the human body. For example, the brain has a concentration of vitamin C about 15 times higher than the blood. The levels in most tissues have been measured many times, and it is well-known that the lenses of the eye, the adrenal glands, and the pituitary gland have the highest concentrations…in the range of 25 – 50 mg per 100 grams of tissue, values that are at least 25 – 50 times higher than found in the blood plasma. It is clear that vitamin C is more important in some tissues than others.
Interestingly, the levels in human skin have only rarely been measured. In my research, I have found two different studies where human skin levels were measured: according to Shindo et al, skin contains about 34 mg/100g, and according to McArdle et al, the value is about 32 mg/100g. If these measurements are correct, then human skin has a higher concentration of vitamin C than almost all other human tissues.
And here’s a fascinating calculation: The skin of an average size person weighs about 2500 grams, so the amount of vitamin C in a normal person’s skin is apparently about 800 mg. The total amount of vitamin C in the whole body is estimated to be about 1500 mg (Kallner et al), so it appears that about half of the vitamin C in a normal person’s body is found in their skin!
Shindo Y, Witt E, Han D, Epstein W, Packer L (1994) Enzymic and non-enzymic antioxidants in epidermis and dermis of human skin. J Invest Dermatol 102: 122-124.
McArdle F, Rhodes LE, Parslew R, Jack CI, Friedmann PS, et al. (2002) UVR-induced oxidative stress in human skin in vivo: effects of oral vitamin C supplementation. Free Radic Biol Med 33: 1355-1362
Kallner A, Hartmann D, Hornig D (1979) Steady-state turnover and body pool of ascorbic acid in man. Am J Clin Nutr 32: 530-539. |
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Sat Feb 09, 2013 9:21 am |
| Vitamin c is important because it helps repair damage due to free radicals such as pollution etc. our cells are made up of bunch of electrons. We need a balanced amount of electrons to be happy. Free radicals will interfere and take out our electrons (causing wrinkles and all that unwanted stuff). So that's why vitamin c is there for a just in case free radicals take away a cells electron, vitamin c has the ability to replace An electron to make a cell balanced and happy. This is why the choice of vit c is important and you want it to be active and not oxidized |
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Late 20's, clarisonic, Vit C serum, hormonal acne, congested pores, combination skin, living in Vancouver Canada |
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Sun Feb 10, 2013 2:06 am |
| BCgirl wrote: |
| ...our cells are made up of bunch of electrons. We need a balanced amount of electrons to be happy. Free radicals will interfere and take out our electrons (causing wrinkles and all that unwanted stuff). So that's why vitamin c is there for a just in case free radicals take away a cells electron, vitamin c has the ability to replace An electron to make a cell balanced and happy. |
I like your way of describing the major function of vitamin C because it is simple and accurate. Being an electron donor is what makes ascorbic acid a "reducing agent," and it becomes "oxidized" when it has given up electrons. Then the cells recycle the oxidized molecules of vitamin C by "reducing" them back into ascorbic acid molecules. Each molecule is used over and over again, in a reduction-oxidation cycle (a "redox" cycle)until it finally is "worn out" and needs to be replaced.
| BCgirl wrote: |
| This is why the choice of vit c is important and you want it to be active and not oxidized |
But "active" vitamin C has nothing to do with whether or not it is "oxidized." Both the reduced form and the oxidized form are "active" forms of vitamin C because both forms are available for the cell to utilize in the redox cycle. The amazing thing about the oxidized form is that it is absorbed by the skin much easier and faster than the reduced form. |
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Sun Feb 10, 2013 7:20 am |
topical or internal?
if internal is 200mg enough? |
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Sun Feb 10, 2013 8:28 am |
| I'm also skeptical about the oxidized form being beneficial. I took an advanced nutrition and metabolism course last year, and oxidized vitamin C was not viewed as the active form, nor is it recommended in supplementation by the Institute of Medicine (IOM). Sure, both reduced and oxidized vitamin C participate in redox reactions, but adding more oxidized vitamin C to the system does not allow more free radical to be quenched. In fact, based on reaction dynamics, you would expect that adding more oxidized vitamin C (the product) to the reaction would shift the reaction in favor of the reactants, thereby allowing more free radicals to remain unquenched--which is not a good thing. If you have evidence to the contrary from the literature, could you post it here? Thanks. |
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34 y.o. FlexEffect and massage. Love experimenting with DIY and botanical skin care products. Appreciate both hard science and natural approaches. Eat green smoothies + lots of raw fruit and veggies. |
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Sun Feb 10, 2013 11:07 am |
| cm5597 wrote: |
| If you have evidence to the contrary from the literature, could you post it here? Thanks. |
I'd suggest this article as a start towards a real understanding of the chemical behavior of ascorbic acid and dehydroascorbic acid in the body: Recycling of Vitamin C by a Bystander Effect.
I would also recommend this excellent review article: Deutsch, JC. Dehydroascorbic acid. Journal of Chromatography A, 881 (2000) 299–307. I haven't posted a link because this article is copyrighted and not available for free on the internet. Many university libraries have subscriptions, so it is likely you can get this article free at such a library. But I can post an excerpt from the article, which is pertinent to your statement
| cm5597 wrote: |
| based on reaction dynamics, you would expect that adding more oxidized vitamin C (the product) to the reaction would shift the reaction in favor of the reactants, thereby allowing more free radicals to remain unquenched |
"Up until the last few decades, DHA was felt to be a product of AA rather than a species with its own important chemical and biological characteristics. Although both DHA and AA are antiscorbutic when taken orally, DHA has several properties that set it apart from AA...
Although AA is the more highly reduced species in the AA:DHA pair, DHA appears to have antioxidant properties of its own, beyond that of AA." |
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Sun Feb 10, 2013 1:21 pm |
| Salome_B wrote: |
topical or internal?
if internal is 200mg enough? |
I'm among those who believe that BOTH dietary and topical vitamin C are important. I'm also among those who believe that a dietary amount of 200 mg daily is not enough. |
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Sun Feb 10, 2013 9:14 pm |
| Salome_B wrote: |
if internal is 200mg enough? |
I never noticed a difference in my skin until I upped my dosage to a full gram of vitamin C a day (1 gram=1000 mgs.) I think any more than that is a total waste, because your body can only absorb so much at a single time. Also, I bet a lot of the C I take just gets "filtered out" into waste anyhow. |
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Mon Feb 11, 2013 9:11 am |
This was talked about on TV during Daybreak, and they picked it apart. As was pointed out they used a synthetic Vit C supplement in this study, and next to no information about the control group is available aside from age and it was thought that the control group used had other influences in relation to the production of kidney stones. So I'm throwing this study to the side.
I think like most things its a scary story when you first hear it, but I felt so much better after hearing Dr Hilary etc talking about it on daybreak for sure! |
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Tue Feb 12, 2013 11:58 pm |
| Salome_B wrote: |
| i take...200mg of ascorbic acid. I am afraid excessive may go to waste |
| Chlorophyll wrote: |
| I never noticed a difference in my skin until I upped my dosage to a full gram of vitamin C a day (1 gram=1000 mgs.) I think any more than that is a total waste...just gets "filtered out" into waste anyhow. |
The problem with people is that they are all mutants. 
That statement is not intended to offend anyone. It refers to the fact that humans have a genetic defect that prevents us from making vitamin C. In normal mammals, the liver manufactures vitamin C that is continuously delivered into the bloodstream, and the liver can greatly increase the amount produced whenever it is needed. Humans must have ingested a large amount of vitamin C within just a few hours if they expect there to be sufficient amount available in their blood during times of large demand. A significant "waste" of vitamin C in humans is necessary to assure that tissues don't get depleted during times of high oxidative stress, unless we can predict exactly when such periods of high oxidative stress will occur. Can you predict when your skin will be exposed to an infectious bacteria or virus? Or to high atmospheric ozone levels? Or even to intense UV radiation from the sun? You should dramatically increase your vitamin C consumption about 2 to 4 hours prior to any of these events. Whether the amount you need at that time is 200 mg or 1000 mg is anybody's guess. But another way of dealing with the problem for the skin is to use topical vitamin C regularly, because it can increase the amount of vitamin C stored in the skin. A very large amount of vitamin C is needed by the skin, which was the original topic of this thread. |
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Wed Feb 13, 2013 8:19 am |
ReCverin,
Thank you for this information.
But what about people like me, who have rosacea?
Vitamin C makes my skin flare up. |
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Wed Feb 13, 2013 5:59 pm |
| Holmes wrote: |
ReCverin,
Thank you for this information.
But what about people like me, who have rosacea?
Vitamin C makes my skin flare up. |
A problem with serums that use l-ascorbic acid (LAA) as the only vitamin C source is that they are generally very strong solutions; 10% or greater is common. LAA absorbs into skin quite slowly, and that is why such high concentrations are used. People with sensitive skin sometimes find these strong serums irritating, and can experience flare-ups like you describe.
The oxidized form of vitamin C (called dehydroascorbic acid, or DHAA) absorbs into the skin 12 times faster than LAA. Each molecule of DHAA is converted into a molecule of LAA once it is absorbed into a living skin cell. Therefore people with sensitive skin can use a lower, much more gentle concentration and still absorb lots of vitamin C.
A previous thread on this forum has more info about DHAA:
http://www.essentialdayspa.com/forum/viewthread.php?p=6401134&highlight=#6401134 |
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cassied
New Member
 
Joined: 15 Feb 2013
Posts: 5
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Fri Feb 15, 2013 1:17 pm |
| It's important because humans don't naturally produce Vitamin C...we need to get it from an external source, whether that's food (citrus fruits etc) or topical creams (c-serums etc). |
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Sun Jan 01, 2017 3:54 pm |
It's pretty well accepted that ultraviolet light can have serious effects on skin aging, but a study from 2012 tested the effects of the visible light portion of the spectrum and found that even this had detrimental effects. Irradiation of Skin with Visible Light Induces Reactive Oxygen Species and Matrix-Degrading Enzymes
Certainly avoiding excess UV radiation, including the use of sunscreens, should be at the top of everyone's list for routine skin care. I believe that topical vitamin C should be the second most important part, because vitamin C provides photoprotection in a different way that is synergistic with sunscreens. As the authors of this study stated:
"Commercially available sunscreens were found to have minimal effects on reducing visible light-induced ROS, suggesting that UVA/UVB sunscreens do not protect the skin from visible light-induced responses. Using clinical models to assess the generation of free radicals from oxidative stress, higher levels of free radical activity were found after visible light exposure. Pretreatment with a photostable UVA/UVB sunscreen containing an antioxidant combination significantly reduced the production of ROS, cytokines, and MMP expression in vitro, and decreased oxidative stress in human subjects after visible light irradiation."
P.S. Happy New Year! |
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