(Sources for the above statements: International Journal
of Toxicology, Volume 24, Supplement 2, 2005, pages 51-111;
Experimental Dermatology, September 2005, pages 684-691
and June 2003, pages 237-244; Dermatologic Surgery, July
2005, pages 814-817; Nutrition Reviews, March 2005, pages
81-90; Skin Pharmacology and Physiology, November-December
2004, pages 298-303; BMC Dermatology, September 2004,
page 13; International Journal of Dermatology, August
2004, pages 604-607; and Archives of Facial Plastic Surgery,
Volume 5, Issue 2m March-April 2003, pages 145-149.)
An article in Plastic and Reconstructive Surgery (January
2000, pages 464–465) nicely summed up the positive effects
of vitamin C stating that it "...is a valuable antioxidant
and protectant against photodamage that is created by
sunlight in both the UVB and UVA bands... . Although oral
supplementation may also be useful, topical preparations
are able to deliver a higher dosage to the needed area.
Topical vitamin C…augments the skin's ability to neutralize
reactive oxygen singlets [free-radical damage] that are
created by the ultraviolet radiation, thereby preventing
photodamage to the skin…Used appropriately, topical vitamin
C is an important adjunct to the use of sunscreens, an
adjunctive treatment to lessen erythema [redness] in skin
resurfacing, a helpful adjunct or an alternative to Retin-A
in the treatment of fine wrinkles, and a stimulant to
wound healing."
As with most vitamins, there are many forms of vitamin
C but the ones primarily found in skin-care products are
ascorbic acid, L-ascorbic acid, tetrahexyldecyl ascorbate,
ascorbyl palmitate, ascorbyl phosphate, ascorbyl glucoside,
retinyl ascorbate, ascorbyl stearate, sodium ascorbyl
phosphate, and magnesium ascorbyl phosphate (Source: International
Cosmetic and Ingredient Dictionary and Handbook, 10th
Edition, 2004). So is there a best form of vitamin C for
your skin? The simple answer is no, though many seem to
be reliable and beneficial for skin.
L-ascorbic acid is a good option in terms of its potential
bioavailability on skin, but Pinnell's own research about
his prized form of vitamin C shows it is highly sensitive
to formulary concerns, including concentration and the
pH needed for it to remain stable (Source: Dermatologic
Surgery, February 2001, pages 137–142). Current research
has demonstrated that adding magnesium sulfate with L-ascorbic
acid can make this form of vitamin C stable much longer
without acidic pH concerns (Source: Journal of Cosmetic
Science, January-February 2004, pages 1-12).
Ascorbyl palmitate is considered stable and there is
research showing it to be effective as an antioxidant
(Sources: Photochemistry and Photobiology, June 1998,
pages 669–675; and Journal of Pharmaceutical and Biomedical
Analysis, March 1997, pages 795–801).
In terms of stability, magnesium ascorbyl phosphate is
reliable for skin as well (Source: Journal of Pharmaceutical
and Biomedical Analysis, Volume 15, Issue 6, March 1997,
pages 795-801). A single study demonstrated that it can
also be effective for skin lightening when used at a 10%
concentration (Source: Journal of the American Academy
of Dermatology, January 1996, pages 29–33). That’s good
to know, but, to the best of my knowledge, there are no
products with that amount of magnesium ascorbyl phosphate
available and no other research has duplicated those results
(or compared it to other effective antioxidants).
Ascorbic acid (Sources: Skin Pharmacology and Physiology,
July-August 2004, pages 200-206 and Experimental Dermatology,
June 2003, pages 237-244) and retinyl ascorbate (Source:
Free Radical Research, May 2005, pages 491-498) have also
been shown to be potent and effective forms of vitamin
C (with ascorbic acid being the entire vitamin C molecule).
Rounding out the list is sodium ascorbyl phosphate. Research
has shown it to be a stable form of vitamin C (Source:
International Journal of Pharmaceutics, April 30, 2003,
pages 65-73).
IMPORTANT NOTE: All forms of antioxidants
are extremely vulnerable to the presence of light and
oxygen. When antioxidants are exposed to sunlight or air
they quickly break down and deteriorate, losing their
benefit for skin. This means the type of packaging used
for formulations containing antioxidants (as well as other
types of ingredients) is critical. As a general rule it
is best to completely avoid products packaged in jar containers
or any other container that exposes the product to air
or light.
REMINDER: Despite the benefits topical
vitamin C provides, it is important not to get hung up
on any one antioxidant, regardless of its history. Aging
is more complicated than just the loss or need for vitamin
C—or any other vitamin, enzyme, protein, peptide, fatty
acid, amino acid, or lipid in the skin. Although vitamin
C is clearly an effective ingredient for skin, there are
many antioxidants that are as good, including beta-glucan,
vitamin E, vitamin A, green tea, grape extract, selenium,
curcumin, lycopene, superoxide dismutase, and on and on.
Furthermore, many researchers studying antioxidants and
their effects on the human body feel the best plan of
attack is to use multiple antioxidants rather than narrowing
your choices to a few well-publicized options or the mistaken
belief that there is a single "best" antioxidant
to apply and consume (Sources: Archives of Dermatologic
Research, April 2005, pages 473-481; Plastic and Reconstructive
Surgery, February 2005, pages 515-528; Photochemistry
and Photobiology, January-February 2005, pages 38-45;
and Mutation Research, April 2005, pages 153-173).