Prevention and treatment of skin ageing

This section highlights most of the current treatments available for preventing and reducing skin ageing. Not all the interventions mentioned are available for commercial use as some are still in the early phases of research. Figure 1 provides a summary of where skin anti-ageing interventions act on the skin layers.

Sunscreens

Sunscreens are divided into organic filters and inorganic filters such as titanium dioxide and zinc oxide67. Organic filters give adequate UVA and UVB protection. However, to have the utmost protection, a combination with inorganic filters should be used because they also protect against visible light67, 68. A sunscreen sun protection factor (SPF) number is a poor guide to skin photodamage because it only shows the minimal erythema produced by UVB. To protect against photodamage, sunscreens should be broad-spectrum and at least SPF 1569. In vivo studies have shown that sunscreens diminish UV-induced epidermal and dermal changes70–72. Although randomised, controlled trials are lacking, regular application of a broad-spectrum sunscreen potentially slows skin ageing73.

Antioxidants

The most common antioxidants investigated in the treatment of skin ageing include vitamins such as C, E and B3, CoQ10, alpha lipoic acid (ALA), carotenoids and polyphenols. Most of these have been shown to protect against UV-induced erythema, while also acting on the dermis to prevent skin ageing. Photo-protection and anti-ageing can be achieved both topically and systemically but, to date, long-term studies on their effects are not yet available.

Vitamins

As well as its antioxidant activities, vitamin C, or L-ascorbic acid in the skin is an important cofactor for lysyl hydroxylase and prolyl hydroxylase enzymes required for collagen synthesis74. It also inhibits tyrosinase and can be used cosmetically for depigmentation75. A double-blind, randomised trial using 5% topical vitamin C cream concluded that after 6 months of treatment cutaneous improvements were observed clinically, topographically and ultrastructurally76. Topical application of vitamin C of 5–15% has an anti-ageing effect77. L-ascorbic acid derivatives are mostly used because they are less unstable and penetrate more easily78. However, many products based on vitamin C derivatives do not necessarily convert to active L-ascorbic acid79. On the contrary, another study showed that a stable ascorbic acid derivative 2-O-α-glucopyranosyl-l-ascorbic acid (AA-2G), when compared with L-ascorbic acid, is longer lasting. AA-2G can protect dermal fibroblasts from oxidative stress and senescence80.

Tocopherol, or vitamin E, is a group made out of eight compounds81. It is mainly found in vegetables, vegetable oil, sunflower oil, corn, soy and seeds81. Oral intake from these sources helps to prevent cross-linking of collagen and lipid peroxidation. α-tocopherol decreases IL-8 production and suppresses AP-1 DNA binding, therefore down-regulating MMP-1 production81. In aged fibroblasts, it does this without altering the natural TIMPs82. High oral intake of vitamin E may have an effect on the human response to UVB radiation83. Topically-applied vitamin E has also been found to reduce the chronic effects of UVB radiation, erythema and oedema78, 84. Vitamin E and C often work synergistically and their combination increases the photoprotective effects when compared with monotherapies85. Therefore, future studies should focus on their combination for preventing skin ageing. When combined with 15% vitamin C and 1% vitamin E, 0.5% ferulic acid — a potent plant antioxidant — acts as both a sunscreen and an antioxidant agent, doubling its photo-protection efficacy86.

Application of 5% vitamin B3 or niacinamide is known to improve skin elasticity and reduce red blotchiness, skin sallowness, hyperpigmentatation and wrinkles87–89. An 8-week study showed that the combination of 5% niacinamide and 1% N-undecylenoyl phenylalanine was more effective in reducing hyperpigmentation then the vehicle and 5% niacinamide alone90.

Coenzyme Q10

CoQ10 is frequently contained in anti-ageing products91. A 10-fold higher concentration is found in the epidermis than the dermis92. In a 6-month pilot study, topical CoQ10 use led to significant decrease in wrinkle measurements when assessed with optical profilometry93. CoQ10 is effective against UVA radiation by preventing oxidative stress in keratinocytes and suppressing collagenase activity in dermal fibroblasts93. Owing to its lipid solubility, CoQ10 depends on topical dermal delivery for optimal antioxidant activity. A nanostructure, or possibly an ultra-small nanostructure, lipid carrier seems to be far better for topical dermal penetration and antioxidant activity than the CoQ10 emulsion91, 94.

Alpha lipoic acid

ALA is both an antioxidant and an anti-inflammatory agent that decreases the production of NF-κB and effects the gene expression of inflammatory cytokines95. A randomised, placebo-controlled, double-blind study on 33 women, with a median age of 54.4 years, to assess the clinical efficacy of 5% ALA cream showed that there is a significant improvement in facial skin roughness on the treated side when compared with the placebo side96.