What are anti-oxidants, what do they do and
which ones are best?
Skin ageing is a complex process driven by a combination of genetic and environmental factors. Essentially it is a manifestation of the decline in optimal functioning of the skin. Traditionally we make the distinction between intrinsic and extrinsic ageing. Intrinsic ageing occurs with the passage of time and is thought to be determined by genetic make-up while factors causing extrinsic ageing are generally environmental factors such as exposure to sunlight and air pollution, and, lifestyle choices, such as diet and smoking. Extrinsic factors often accelerate the natural process of intrinsic ageing.
The effects of intrinsic ageing and extrinsic ageing merge and it’s not often possible to tell apart.
What are reactive oxygen species and antioxidants?
Basic cellular metabolic processes in skin cells generate free radicals which are mainly reactive oxygen species (ROS). To add to this ultraviolet light and a growing list of other environmental factors as mentioned above cause direct DNA damage and ‘stress’ the skin also producing ROS. These high energy oxygen molecules cause damage to skin cell membranes, cell proteins and cellular DNA inducing inflammation that further damage skin cells and precipitate skin diseases. Of course nature did not leave us without any help at all…
Antioxidants are molecules that donate or remove electrons from reactive oxygen species (ROS), neutralising them and preventing them from causing damage. The body has its own internal antioxidant systems to ‘scavenge’ harmful free radicals, but these become less effective as we grow older upsetting the balance and creating ‘oxidative stress’. In addition to these our internal DNA repair mechanisms become less efficient. When the skin is subject to excessive DNA damage, these repair mechanisms become overwhelmed leading to skin cancer.
The effects of environmental factors on the skin
There is overwhelming, well documented evidence for the role of ultraviolet light, specifically UVB (290-320 nm) and UVA (320-400nm) in causing skin ageing and skin cancers.
Recently there is growing evidence that visible light (400-700 nm) infrared radiation (above800 nm) and other atmospheric factors such as air pollution (smog, ozone and particulate matter) cause skin cell damage and oxidative stress similar to that caused by UV light and are therefore implicated in premature skin ageing and skin diseases
Visible light and infrared cause similar damage to UVA. Long term exposure induces the breakdown of collagen and elastin in the dermis, while simultaneously preventing the production of new collagen and elastin. The overall effect is thinning of the dermis, loss of elasticity, wrinkling and volume loss.
Visible light and infrared are also responsible for stimulating melanocytes and worsening hyperpigmentation. This effect is especially found in darker skins. Visible light seems to have no effect on melanocytes in light skin.
Visible light is responsible for inflammatory skin conditions like actinic dermatitis, photoallergic skin reactions and porphyria.
Ozone is an environmental toxin that is unable to penetrate the skin. Chronic exposure can however lead to depletion of antioxidants with resultant skin damage and inflammation. Studies have shown that pre-treatment of the skin with antioxidant can prevent the resultant sun damage. We know that conventional sunscreens provide protection from UVA and UVB. The lack of protection against these other environmental aggressors represents a gap in the current sun protection and antiaging strategy. Antioxidants have been proven to fill this gap and together with sunscreens provide a more comprehensive strategy of environmental protection. By boosting our own antioxidant mechanisms topical and oral antioxidants possibly also improve intrinsic ageing.
The benefits of topical antioxidants
Antioxidants are naturally present in the skin as part of our inbuilt skin protection system. Some of these are vitamin E, catalase, superoxide dismutase, glutathione peroxidase and Vitamin C. As mentioned, these antioxidants decline with age and are depleted by UV exposure. Antioxidants can be taken orally to benefit the skin and body, but we are unsure of how much oral antioxidants needs to be taken to actually reach the skin. The skin is in a unique position to absorb topical antioxidants directly to replenish declining reserves.
Regular application of topical antioxidants creates a reservoir in the skin to boost our declining natural antioxidant mechanisms. In this way antioxidants provide us with an ‘active’ protection against skin cancer, photo-ageing, and inflammation.
Antioxidants are multi-functional, in that they prevent sunburn, stimulate collagen production and improve the appearance of fine lines, wrinkles and dark spots, thereby reversing the effects of environmental damage.
Topical antioxidants serums have the added benefits of stabilising melanocytes and assisting in the treatment of hyperpigmentation, and promoting the formation of barrier lipids to improve skin barrier function and hydration.
Antioxidants are also anti-inflammatory, thus assisting with management of acne and resultant post inflammatory hyperpigmentation (post acne marks), while providing younger skin with comfort and hydration.
It’s not too late for those who already have sun damage and a history of skin cancers. While antioxidants cannot treat skin cancers, they can help to prevent further DNA mutations and new skin cancers and improve the appearance of dry, sun damaged skin by boosting barrier lipid production and collagen repair.
What are the best topical antioxidants?
The best studied antioxidants are vitamin C and vitamin E. The potency of an antioxidant is determined by its ORAC (oxygen radical absorbance capacity) value.
Vitamin C also known as L-ascorbic acid is one of the most potent, and frequently used antioxidants. It has been extensively studied and proven to have powerful beneficial effects on the skin. Vitamin C is found in high concentrations in the skin, but this decreases with age and sun damage, hence the benefit of topically applied product. Other than being an antioxidant, Vitamin C is a cofactor in collagen production, improves wound healing and inhibits melanin synthesis, thus improving fine lines and wrinkles, targeting pigmentation and lightening dark spots.
Vitamin C is unstable in light so the correct formulation in essential to preserve efficacy.
The optimal concentration of Vitamin C in a product is 15% which is comparable to the quantity in the skin. Combination preparations with a lower dose of Vitamin C and other antioxidants seem to increase the overall antioxidant potential of the product by improving stability. Some of these combinations include Phloretin, Vitamin E and Ferulic acid.
Vitamin E otherwise known as tocopherol is another well studied skincare ingredient. Besides being a potent antioxidant, it is known for its natural moisturising and anti-inflammatory properties. It also inhibits melanin production and can help with hyperpigmentation. Unlike Vitamin C which can be used alone, Vitamin E is best used in combination formulations.
Resveratrol which is derived from the skin of red grapes is both antioxidant and anti-inflammatory. It is particularly suitable to reduce sun damage in patients with rosacea and sensitive skins
When in combination antioxidants work synergistically multiplying their antioxidant potential.
The major limitation is adding these ingredients to skincare products so that they remain stable and effective throughout the period of use. Not all products that contain antioxidants are equal. For this reason, higher concentration of antioxidants in the formulation does not equate to better. There seems to be a cap on the concentration that should be in a product and anything beyond this lends to instability of the formulation. Certain combinations may be antagonistic rather than synergistic. Antioxidants must be used in conjunction with a good sunscreen, and as part of a comprehensive anti-ageing routine.
Written by Dermatologist, Dr Kesiree Naidoo
- The role of antioxidants in photoprotection: A critical review Lucy Chen, BA,a Judy Y. Hu, MD,b and Steven Q. Wang, MDa New York, New York, and Hermitage, Tennessee
- Atmospheric skin aging—Contributors and inhibitors David McDaniel MD, FAAD1,2,3,4 | Patricia Farris MD, FAAD5,6 | Giuseppe Valacchi PhD7,8
- Topical L-Ascorbic Acid: Percutaneous Absorption Studies Sheldon R. Pinnell, MD,* Huanshu Yang, MD,‡ Mostafa Omar, PhD,† Nancy Monteiro Riviere, PhD,‡ Holly V. DeBuys, MD,* Linda C. Walker,* Yaohui Wang, MD,§ and Mark Levine, MD§ *Duke University Medical Center, Durham, North Carolina, †PhytoCeuticals, Elmwood Park, New Jersey, ‡College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, and §National Institute of Diabetes & Digestive & Kidney Diseases, NIH, Bethesda, Maryland
- A topical antioxidant solution containing vitamins C and E stabilized by ferulic acid provides protection for human skin against damage caused by ultraviolet irradiation John C. Murray, MD, James A. Burch, Robert D. Streilein, Mary Ann Iannacchione, Russell P. Hall, MD, and Sheldon R. Pinnell, MD Durham, North Carolina.