(edited from the skintherapyletter.com article: The Role of Cosmeceuticals in Antiaging Therapy)
As baby boomers get older, they have shown an increasing interest in maintaining youthful looking skin and preventing the visible signs of aging. As a result, there has been a corresponding rise in the number of topical antiaging formulations found in the marketplace today.
Commonly referred to as cosmeceuticals, these products come with a seemingly limitless number of key active ingredients and the promise of younger, more beautiful skin. The term cosmeceutical was introduced by Albert Kligman in 1984 to refer to substances that exerted both cosmetic and therapeutic benefits.2 Many contain biologically active ingredients, and in general, cosmeceuticals undergo tests to determine safety, but claims of proven results are often largely unsupported.3
Efforts have only recently been made to address the issues surrounding quality control and to establish industry standards and regulations. Demonstrating the skin effect of a cosmeceutical can be difficult; there are no placebos because anything that is applied to the skin will have an effect. This article will look at some common cosmeceutical ingredients that have been studied and their benefits to the skin.
Antioxidants
Antioxidants are naturally occurring substances that may provide protection against the effects of damaging free radicals on the cells in your body, including your skin. Antioxidants also reduce inflammation, which can lead to collagen depletion, and some offer protection against sun damage and skin cancer. Common antioxidants include alpha-lipoic acid (ALA), L-ascorbic acid (vitamin C), niacinamide (vitamin B3), N-acetyl-glucosamine (NAG), á-tocopherol, and ubiquinone (CoQ10).
Alpha-lipoic Acid (ALA)
Alpha-lipoic acid has anti-inflammatory properties and acts as an exfoliant. In a recent study, a topical preparation of Alpha-lipoic Acid applied for 12 weeks reduced skin roughness, lentigines and fine wrinkles.7 However, it does not protect against UV-induced erythema (skin redness) or reduce the number of sunburn cells.
L-Ascorbic Acid (Vitamin C)
There is positive clinical data that supports the use of topical vitamin C to improve fine lines and reduce both pigmentation and inflammation,8 and many cosmeceutical formulations contain this antioxidant. However, many of these formulations are not effective on the skin because:
- The concentration of L-ascorbic acid is too low.
- Exposure of the product to air and light compromises the stability of the product.
- The L-ascorbic acid molecule cannot be absorbed or metabolized effectively by the skin.
In high enough concentrations of the isomer, this antioxidant does inhibit UV damage.9 As more research is conducted, newer formulations of stabilized ascorbic acid derivatives may prove to be more effective.
Niacinamide (Vitamin B3)
Niacinamide is a potent antioxidant that is generally well tolerated. It improves the skin’s natural barrier function, thus reducing skin dryness, and helps prevent hyperpigmentation. Studies have revealed significant reduction in fine lines and wrinkles, hyperpigmented spots, red blotchiness, and skin sallowness, as well as improved skin elasticity.10,11
N-Acetyl-Glucosamine (NAG)
N-Acetyl-Glucosamine is a more stable form of glucosamine, and may prevent new signs of sun damage from occurring, and fade existing imperfections by interrupting the chemical signals that promote melanin production. In a study that utilized a treatment consisting of N-Acetyl-Glucosamine combined with niacinamide on hyperpigmented spots showed a superior reduction in pigmentation.12
á -Tocopherol (Vitamin E)
Vitamin E is one of nature’s super-ingredients with multiple benefits for overall health as well as specific benefits for skin. It has been shown to reduce sunburn cells after UV exposure, neutralize free radicals, and act as a humectant.13In high concentrations, vitamin E has been shown to prevent the acute UV damage of erythema (skin redness),sunburn, and tanning, as well as chronic UV photoaging and skin cancer.9 The combination of Vitamin C and E in cosmeceutical formulations produces an enhanced effect, particularly with regard to UV protection.9
Ubiquinone (CoQ10)
Ubiquinone is an effective antioxidant with anti-aging properties.14 It is a naturally occurring, fat-soluble antioxidant with good evidence that it can help reduce collagen breakdown in the skin.14 It has been shown to be effective against oxidative stress caused by UVA rays. Another study showed that ubiquinone can prevent oxidative stress in the skin caused by UVB rays as well.16
Botanicals
Botanicals comprise the largest category of cosmeceutical additives found in the marketplace today. Their use is unregulated and often unsupported by science and their purported therapeutic properties remain largely unexplored. Listed below are some botanicals that may benefit the skin.
Green Tea Extract
Green Tea has become one of the new age food heroes – a helpful ally in preventing everything from heart disease and cancer, to skin aging and weight gain. The full range of heath benefits may take decades to define, but research on its impact on human skin is reasonably well developed. When applied to the skin, green tea can reduce sun damage by reducing inflammation and tackling free radicals. (It doesn’t block UV rays). Therefore, green tea may compliment sunscreen’s effects when used together. It’s also being studied as a treatment ingredient for rosacea, psoriasis andwarts.
Ferulic Acid
This compound, which is derived from plants, is considered to be a potent antioxidant, and has been shown to provide photoprotection to skin.17,18 Furthermore, when ferulic acid is combined with vitamins C and E, the product has been shown to provide substantial UV protection for human skin.19,20 Moreover, Murray et al. report that because its mechanism of action is different from sunscreens, ferulic acid could be expected to supplement the sun protection provided by sunscreens.20
Grape Seed Extract
Grapeseed oil is light in texture, nearly odorless and easily absorbed by the skin without leaving an oily residue. It has great moisturizing properties, making it an ideal natural skincare ingredient. This botanical has also been established as a potent antioxidant and has been shown to speed up wound healing.21 Topical application of grape seed extract has also been shown to enhance the sun protection factor (SPF) in humans.22
Skin Lighteners
Skin-lightening agents added to product formulations have become increasingly popular. Below are some depigmenting agents that are commonly used.
Hydroquinone
Hydroquinone has been the agent of choice for skin lightening. However, there are concerns over exogenous ochronosis (bluish-black pigmentation of the skin) and permanent depigmentation, as well as possible carcinogenicity.23It has been banned as an over-the-counter depigmenting agent in Europe, Australia and Japan,24 however, the US FDA has proposed concentrations between 1.5% and 2% in skin lighteners.25 A recent report suggested that this concern has been based mainly on studies with animals that were subjected to long-term exposure at high dosages. Routine topical application may pose no greater risk than that from levels present in common foods.26
Licorice Extract (Glabridin)
The root extract of licorice is best known for its distinct flavor. About 20 years ago, scientists isolated three specific compounds in licorice that are useful for skin care products, one of which is Glabridin – a skin whitening ingredient. Glabridin works by inhibiting the production of melanin (the pigment that causes skin discoloration). After repeated application, the outer layer of the darker skin is replaced by lighter skin. Several studies on melasma have shown good results with the lightening of pigmentened areas. These studies also reported mild irritation that disappeared after the treatments were stopped.25
Kojic acid
Kojic acid is a mushroom extract that is used as a lightening agent to fade liver spots, melasma, freckles, acne scarsand other skin discolorations. It’s considered to be a natural alternative to the chemical compound called hydroquinone. Although it has quickly gained popularity as a lightening treatment, there is little research to support its effectiveness as a skin lightener.27
Retinoids
Retinoids are among the most common ingredients found in cosmeceuticals. In fact, they are the most studied and have the most data behind them. They consist of natural and synthetic derivatives of vitamin A that reduce hyperpigmentation and prevent enzymes from breaking down collagen. Many of their cosmeceutical claims are based on data derived from studies on tretinoin and other classes of retinoid drugs. Some key retinoids include retinoic acid (tretinoin), retinol, retinaldehyde.
Retinoic Acid (Tretinoin)
There is extensive literature on the use of tretinoin, which is considered to be one of the most potent compounds for treating the signs of aging and/or photodamaged skin, including fine lines, hyperpigmented spots, and wrinkles.32-34Tretinoin was the first retinoid developed for topical use. However, The one big problem with formulas that contain retinoic acid is that dryness, redness, scaling, itching, and burning can occur. Doctors often recommend introducing it in stages of frequency and concentration in order to build up tolerance.
Retinol (Vitamin A)
Retinol has a long history in skin care products, as a moisturizer. Retinol tends to increase skin oil and has only very modest anti-wrinkle characteristics. However, some formulas in skin care products that are advertised to contain retinol may only have a trace amount that is biologically ineffective. Two randomized, controlled trials reported significant improvement in fine wrinkles after 12 and 24 weeks of treatment, respectively.35,36
Retinaldehyde
Retinaldehyde is a relatively new form of the vitamin A series of retinols that work on wrinkles and aging skin. Early reviews claim that it is “stronger” than most over the counter retinols as well as being “gentler” since most retinols can be quite irritating on sensitive skin. Studies have reported that this retinoid can produce significant clinical improvement in the appearance of fine and deep wrinkles.32,37
Early research shows that skin is able to convert retinaldehyde more quickly and efficiently into vitiamin A than other forms of retinol, which in turn reduces the side effects. Much research remains to be done (to determine optimal concentrations and relative effectiveness), but in the meantime, people with sensitive skin may want to give topical retinaldehyde a try.
In addition to skin rejuvenation, retinaldehyde also has some promise as an effective acne treatment, especially in combination with other anti-acne agents.
Alpha Hydroxy Acids (AHAs)
Also referred to as fruit acids, they are a common ingredient found in cosmeceutical products. Examples include:
- Citric acid
- Glycolic acid
- Lactic acid
- Malic acid
- Pyruvic acid
- Tartaric acid
Alpha Hydroxy Acids improve skin texture and reduce the signs of aging by promoting cell shedding in the outer layers of the skin and by restoring hydration.
Topical Peptides
There are several different types of peptides being developed or already in use for a wide range of dermatologic applications. For example, signal peptides, which are thought to initiate wound healing and increased collagen production, are currently used in several over-the-counter anti-aging and anti-wrinkle skin care products.
Carrier peptides literally “carry” trace elements like copper throughout the body, and are essential for wound healing of the skin. One carrier peptide, called glycyl-l-histidyl- l-lysine (GHK), has several important cellular actions and is thought to improve fine lines, hyperpigmentation and skin texture, in addition to aiding in wound healing.
Neurotransmitter-inhibiting peptides are used in topical cosmeceutical formulations because they have a similar effect to BOTOX. The most popular cosmeceutical neurotransmitter-inhibiting peptide is acetyl hexapeptide-3, marketed as Argireline®.
One variation of Peptides, the palmitoyl pentapeptide known as Pal-KKTKS (Matrixyl™, Sederma) was tested in a study of 93 women between 35 and 55 years of age. The women were treated twice daily for 12 weeks after which significant improvements in wrinkle appearance and length were observed.31
Sunscreens
Sunscreens are the single most important cosmeceutical, because they protect skin against solar radiation, which is the most important damaging environmental agent. As a result, they help to prevent the signs of aging. To be effective, sunscreens should provide broad spectrum coverage that includes both UVA and UVB blocking agents to inhibit photoaging and be part of a daily skin care regimen. Sunscreens contain active ingredients that act as ultraviolet filters.
Although some product claims for the active ingredients used in cosmeceutical formulations are evidence-based, consumers often place their confidence in the claims made by the manufacturer. Without testing to assess the effectiveness of key active ingredients in relation to overall product content, it is possible that at inadequate concentrations, any beneficial effect will become inapparent. Ensuring consistency of formulations is also an area that has been neglected and necessitates regulation.
There is limited research being done on cosmeceuticals in academic dermatology, and there have been no NIH grants available for cosmeceutical research to date. As a result, the best research comes from industry sponsored studies.