The Exposome || Intrinsic vs Extrinsic Ageing

"Nature gives you the face you have at twenty. Life shapes the face you have at thirty. But at fifty you get the face you deserve.", Coco Chanel

Skin is often seen as the hallmark of perceived age. When we speak of Skin Ageing at Le Formulaire, it may seem that we’re speaking of the chronological age of our skin alone, as it relates to our age. However, skin ageing actually refers to two processes that are occurring in tandem at the level of our skin. These processes are generally known as intrinsic and extrinsic ageing. While factors such as our age, genetics and ethnicity contribute to our skin’s intrinsic age, external factors, or the “exposome” of our skin, can lead to premature or accelerated ageing of our lovely visage. The term "exposome" describes all of the exposures we encounter throughout our lives and the net effect of these can contribute to ageing significantly. 

Looking to maintain the youth of our skin is not simply a cosmetic concern, but relates to the integrity of one of our most important organs as we age. Intrinsic ageing progression is mostly governed by genetic design, physiological alterations to the neuroendocrine system and development of diseases – either systemic or cutaneous. The intrinsic side of ageing has a degree of inevitably related to it that is largely responsible for, as Coco put it, “the face you have at twenty”. 

Interestingly, we do have control over the face we have at thirty and beyond, and that’s where the exciting side of regenerative medicine and lifestyle alterations become relevant. Accumulation of external factors increase the rate and degree of ageing as perceived aesthetically and at a physiological level.(1) Exogenous causes of ageing may take the form of a chemical, biological or physical insult. Factors such as sleep and stress have been identified as skin ageing agents. The most significant environmental elements unveiled include ultraviolet radiation (UVR), cigarette smoke and exposure to particulate matter from pollution among others which we will discuss in this series. 

Let’s look at the two types of skin ageing and how we can preserve our glowing skin.

Intrinsic Ageing

Endogenous processes lead to a natural, progressive decline as time progresses. Intrinsic ageing refers to the natural ageing process of our skin as we age. Intrinsic ageing factors include free radical damage to the skin due to declining levels of antioxidants, the slowing down of collagen production, our genetics, and hormonal changes.

Free radicals are unstable molecules that can cause issues for the DNA and collagen in our skin, affecting the skin’s structure. Free radical damage occurs in our skin throughout our lives, and is caused by internal and external processes, however our skin’s ability to fight free radicals declines as we age, leading to dryer skin and wrinkles forming.

 Our genetic makeup can influence how our skin responds to age. Melanin in the skin protects against UV damage. For example, Darker skin types can have up to 500 times the protection against UV radiation compared to Caucasian skin,(2) minimising the impact of photoageing and incidence of skin cancer in those with darker skin. Similarly, Asian skin has been shown to show signs of wrinkles later and with less severity than European skin.(3)

Hormonal changes affect the elasticity and strength of our skin. Oestrogen, among its other roles, helps with the production of collagen and hyaluronic acid in the skin, and so as we go through menopause, our oestrogen production reduces, we can see changes in our skin as a result.

Extrinsic Ageing

 Although there are varied factors of intrinsic ageing, internal influences are believed to account for only 10% of our skin’s ageing process! Leaving a staggering 90% of skin ageing attributable to extrinsic factors. These external factors are known as the exposome of skin.(5) It’s empowering to know that we can manage the ageing and health of our skin to a great degree by understanding extrinsic ageing factors.

If you’ve read any Le Formulaire article before, we’re certain you already know the biggest culprit of extrinsic skin ageing or exposome of skin – UV damage. Ironically, ​​Chanel herself has been implicated in making tanning fashionable in the 1920s, and the effects of sun exposure have been demonstrated in sun protected skin as young as 30 years old. The significant solar radiation that reaches the earth’s surface, consists of wavelengths made up of UVR (UVA, UVB, UVC), visible light and infrared radiation (IR). The largest body of research in photoaging relates to UVA and UVB with emerging focus on the role IR and visible light. Exposure is influenced by geographic location, diurnal timing of exposure, atmospheric absorption and the ability of the solar wavelength to penetrate the skin. UVC is readily absorbed by an intact ozone layer, as is UVB, whilst UVA is not. Additionally artificial sources of UVR and IR have a direct effect on skin that is exposed. Regarding skin penetration, UVB is mostly absorbed in the epidermis (upper layer), UVA reaches the dermis and IR, particularly the predominant IRA bandwidth, is believed to penetrate to the dermis and the subcutaneous layer.

Multiple processes occur at a molecular level when skin is exposed including, DNA damage, free-radical formation and receptor signaling. The negative effects are numerous, but the collagen and elastin degradation, pigmentary disorders, and the DNA mutations predisposing to skin cancers are the most significant. 

This damage leads to changes in our skin’s colour making it appear dull, it changes the skin texture making our skin dryer and rougher, and forms deep wrinkles in the skin. Caucasian Australians, due to the fact that they are regularly exposed to sun from an early age and tend to have a Fitzpatrick skin type of 1-3, have been shown to appear older much earlier than their counterparts in the UK and USA.(5)

At Le Formulaire we believe in empowering our community with knowledge so that you are armed to make the best choices for your health. Sun avoidance, sunscreen and antioxidant use can all help to mitigate one of the biggest exposome culprits effects. That’s a good news story to end on!

Next in this series we will describe some other lesser known contributors to ageing and what we can do about them.

References

(1)   Naylor EC, Watson RE, Sherratt MJ. Molecular aspects of skin ageing. Maturitas. 2011;69(3):249-56.

(2)Farage, M.A., Miller, K.W., Elsner, P., Maibach, H.I. Intrinsic and extrinsic factors in skin ageing: a review. International Journal of Cosmetic Science. 13 March 2008. doi:  https://doi.org/10.1111/j.1468-2494.2007.00415.x

(3)   Sudel, K.M., Venzke, K., Mielke, H. et al. Novel aspects of intrinsic and extrinsic aging of human skin: beneficial effects of soy extract. Photochem. Photobiol. 81, 581–587 (2005).

(4) Krutmann J, Bouloc A, Sore G, Bernard BA, Passeron T. The skin aging exposome. J Dermatol Sci. 2017 Mar;85(3):152-161. doi: 10.1016/j.jdermsci.2016.09.015. Epub 2016 Sep 28. PMID: 27720464.

(5) Goodman, G.J., Predictors of ageing: An analysis of two cross sectional studies illustrating the effects of alcohol and smoking and how Australian women age when compared to counterparts in three other countries. Australasian Society of Cosmetic Dermatologists. May 2023