Aging is a natural process that we all go through, which affects the appearance of our skin. Many cosmetic companies market products targeted at reducing the signs of aging: in fact, in 2018 the worldwide anti-aging product market size was valued at over $38 billion and it is predicted to increase to over $60 billion by 2026 [1]. So, what are the ingredients in these widely sought-after products, and do they work?
The skin is made up of three layers. The outermost layer is called the epidermis, next is the dermis, and the bottom layer is called the subcutaneous tissue or the hypodermis [2]. The outermost layer of the epidermis is called the stratum corneum and it is a major barrier to the penetration of many compounds into the skin [3]. The primary target of anti-aging skin care is the epidermis-dermis junction and the dermis tissues [4]. How deep a skin care ingredient can penetrate into the skin depends on its molecular weight and its polarity. Non-polar, low molecular weight ingredients can penetrate further [4].
So now that you know about the structure of skin, here’s some information about the skin aging process, which is categorised as intrinsic and extrinsic aging. Intrinsic aging occurs when cell renewal takes place more slowly and there are changes in the synthesis of hormones that affect the appearance of the skin [5]. Extrinsic aging, on the other hand, occurs as a result of lifestyle and environmental factors [6]. It is estimated that UV radiation contributes up to 80% of extrinsic aging [7] and other external factors include smoking, poor diet and excess alcohol intake, as well as some diseases such as diabetes [5].
Exposure to environmental factors can increase premature skin aging through the formation of free radicals, which have been shown to increase activity of enzymes called matrix metalloproteases (MMPs) that can degrade collagen and elastin [8]. Decreased amounts of collagen in skin, due to an increase in its breakdown and reduced synthesis of new collagen, is a key feature of skin aging [9].
As collagen is a necessary component of youthful skin some anti-aging skin care treatments offer formulae containing collagen. However, collagen is a triple-helix protein that is too large to be applied topically and will not penetrate the surface of the skin [10]. Alternatively, drinks containing collagen have been marketed as anti-aging treatments but as collagen is a protein it will be digested in the stomach and broken down into amino acids. It is possible that some of these amino acids may be used to make collagen as it is such an abundant protein, but that is not necessarily the case [11].
A much better approach is to use products containing antioxidants which prevent free radicals causing breakdown of collagen and ingredients which stimulate collagen production. Some of these ingredients include:
- Vitamin C (ascorbic acid). Vitamin C is a potent antioxidant, and it has been proven to have a skin anti-aging effect by increasing collagen production and inducing inhibitors of MMPs and collagenases, which break down collagen [12].
- Niacinamide (vitamin B-3). Niacinamide is a potent antioxidant, which reduces trans-epidermal water loss and it may also improve skin elasticity [13].
- Coenzyme Q10. CoQ10 is an antioxidant, which has been shown to improve mitochondrial function in human skin samples and may therefore prevent the appearance of aging that starts at the cellular level [14].
- Polyphenols. These are naturally found in fruits, vegetables and nuts and have powerful antioxidant and photoprotective effects, reducing signs of skin aging [15].
- Alpha and Beta Hydroxy acids(AHAs and BHAs). These weak acids chemically exfoliate the skin as well as reducing fine lines and wrinkles, and they have also been shown to induce collagen synthesis [16].
- Peptides. Some peptides, such as palmitoyl pentapeptide-3, have been shown to stimulate collagen production, and in doing so they improve skin texture and reduce wrinkles [17].
- Retinoids (Vitamin A compounds, such as retinol and retinoic acid). Vitamin A and its derivatives are some of the most effective substances to slow down the aging process. Retinoids reduce signs of aging by reducing trans-epidermal water loss and increasing the protective function of the epidermis, as well as increasing collagen in the skin by inhibiting MMP activity and reducing collagen degradation [18].
So there seems to be an assortment of ingredients to reduce signs of aging, but are they the secret to a youthful appearance?
Unfortunately, there isn’t rigorous testing on the effectiveness of cosmetics, like there is for pharmaceuticals, and so there is no guarantee that any over the counter (OTC) treatment will reduce signs of wrinkles and aging [13]. If cosmetics companies can prove that a product does heal damaged skin, it could be classified as a medicine, but this would require years of expensive tests before getting a licence [19].
This is true for vitamin A, which is the first vitamin approved by the American Food and Drug Administration as an anti-wrinkle agent: Tazarotene is a vitamin A prescription medication that can be applied topically to improve sun-damaged skin and decrease signs of wrinkles [18,20]. Prescription retinoids are more potent than OTC products and therefore although there may be strong evidence that retinoids reduce signs of aging, there is less evidence that OTC retinols will make a difference.
Additionally, the research that has been done on the anti-aging effects of an ingredient may be carried out at different concentrations to those offered in OTC products, or they may be based on in vitro tests, which are likely to give different results to topical application [21]. For example, peptides, and some ingredients shown to have antioxidant properties in vitro aren’t very well absorbed by the skin and cannot penetrate into the dermis, or they only have short-term effects [17,22,23].
So while some OTC anti-aging products may be able to reduce the appearance of wrinkles it is important to remember that UV radiation is the primary cause of extrinsic skin aging, so the best way to keep wrinkles at bay is to wear sun cream daily to protect your skin. Preventative treatment is always the best approach, and so wearing sun cream is the best anti-aging treatment, as well as one of the cheapest.
Ella White
Bibliography:
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