Only a small number of topical antioxidants have been shown in clinical trials to reduce signs of skin aging and wrinkles.
Retinoic acid (tretinoin)
The most significant and well-researched topical anti-wrinkle agent. It is currently available only on prescription for treating established damage. Retinoic acid can also stimulate new collagen formation in the skin. The cosmetic effect of retinoic acid on skin is to reduce fine wrinkles, smooth rough skin and lighten brown spots. Retinoic acid also thins the top layer of your skin the stratum corneum, which leads to its ‘smoothing effects but it may result in increased water loss (dehydration). Tretinoin may also have a tendency to make skin light sensitive and should only be applied at night. It is essential that you use sunscreen and monitor skin dryness. Tretinoin should only be used under supervision.
Retinol and retinal (vitamin A)
These compounds are widely used in OTC skin creams. To become active they must be converted into retinoic acid. This is a very inefficient process and so the activity of products containing retinol is far less than retinoic acid. For best results, select a product with a high-concentration of retinol or ones that have been specifically stabilized to prevent degradation with light and time.
Vitamin C is an antioxidant that also stimulates collagen production in the skin. When used topically Vitamin C provides a degree of photo-protection from ultraviolet rays. For best effect, look for products that have vitamin C content greater than 10%. In order to get enough to the deeper layers of the skin. Stabilized forms, such as magnesium ascorbyl phosphate or ascorbyl palmitate, are preferred as they degrade more slowly. However, even in these forms, vitamin C must be kept away from direct sunlight and used quickly once opened.
Polypodium leucotomos fern extract (P. leucotomos)
This has been shown to help protect skin against UV rays. The extract has a number of beneficial actions: it inhibits free-radical generation and helps prevent DNA damage and UV-induced skin-cell death. The extract may also form a useful ingredient in a sunscreen.
Coenzyme Q10 (or Ubiquinione)
This is a potent antioxidant as well as working to maintain cellular energy production. Reduced CoQ10 levels in aging skin increase its vulnerability to solar damage as well as reduce its (energy dependent) ability to repair and regenerate. When applied topically, a regular application of Coq10 can improve wrinkle and elasticity. For best results, use a product with a concentration of at least 0.5 %.
These antioxidants are extracted from plants such as pine bark, grapes and apples. When used topically these can reduce inflammation associated with sun damage, and therefore improve healing and long term appearance. Regular application can also lead to increases in skin hydration. Look for products with a one per cent concentration of proanthcyanidins: these may be listed as grape-seed or flavonoids or Pycnogenol ® – extracted from pine bark.
These are potent antioxidants of plant origin: the best known include the catechins present in green tea; genistein, an isoflavone found in soybean; curcumin, found in the curry spice turmeric; and apigenin, present in many fruits and vegetables. When topically applied, these extracts can reduce the effects of aging in the skin. However, the concentration required for these to have their optimal effects remain to be determined.