Vitamin C, having anti-oxidizing properties, stabilizes the collagen messengers and increases protection against free radicals.
"Collagen is a protein which is very important to the skin," according to Andre Rougier, Ph.D., international scientific director at Laroche-Posay Pharmaceutical Laboratories in Asnieres, France, and one of the study's authors.
"When collagen is not well synthesized, which is the case in the elderly, the skin is then thinner and wrinkles appear."
Dr. Rougier notes that sufficient vitamin C must be consumed in the diet to ensure correct functioning of connective tissue cells producing collagen. Most species naturally synthesize collagen, but humans, monkeys and guinea pigs are unable to do so on their own, he tells Dermatology Times.
Regardless of diet, however, ascorbic acid concentration drops with age. That drop cannot be compensated through diet.
Study details The study looked at 10 postmenopausal women aged 55 to 60. They applied an emulsion containing 5 percent vitamin C on the inner part of the forearm on one side and the same preparation without ascorbic acid (placebo) on the other side for six months daily.
Punch biopsies of 5 mm were collected on either side, frozen in liquid nitrogen and processed for extraction of RNA and purification by cesium chloride gradient centrifugation. The 28S ribosomal RNA was used to equalize the amount of RNA in all the samples. Aliquot of the dilutions were used to measure the steady-state level of the messenger RNAs of vimentin (VIM), keratin 10 (K10), procollagen I, procollagen III, procollagen NI peptidase (N-PCP), procollagen C peptidase (C-PCP), lysyloxidase, collagenase 1 (MMP1) and gelatinase A (MMP2) and B (MMP9). Particular messenger RNAs were applied by reverse transcription-polymerase chain reaction (RT-PCR) at the time with an analogous synthetic RNA of a somewhat different size to monitor the reaction and permit quantification.
Researchers witnessed a rising steady-state level of messenger RNA for two major collagen molecules, those being I and III; three post-translational processing enzymes, those being N and C procollagen peptidase and lysyloxidase; and markers of dermal and epidermal cells activity. The steady-state matrix metalloproteinases were not significantly altered through topical administration of vitamin C. Three patients in the sample were not responsive at all.
"The product permitted the native collagen to be effective and to synthesize," Dr. Rougier says, noting that the Laroche-Posay product is marketed as Active C. "There were also no adverse events that the subjects reported."
Previous studies Dr. Rougier published a previous study in Experimental Dermatology, which demonstrated that topical application of 5 percent vitamin C cream produced significant improvement in experimental subjects over controls. For one, there was a decrease in deepfurrows of the skin. In that study, healthy femalesubjects used self-assessment to gauge improvement, and a dermatologist conducted a clinical examination of subjects at the beginning, after three months and after six months of treatment. The cream was applied in a double-blind, randomized fashion on the neck and arms.
Another study that Dr. Rougier authored, which appeared in Gerontology in 2003, found an inverse correlation between concentrations of ascorbic acid in the skin and increasing age. It also showed concentrations of ascorbic acid and iron differed depending on the body site.
"It is also important that people avoid activities that promote oxidation, such as smoking and sunbathing, which results in exposure to ultraviolet rays," says Dr. Rougier, who holds a Ph.D. in biochemistry. "These activities would moderate the effect of using topically applied vitamin C to tighten skin and prevent the depletion of moisture."