Oct 10 / Star Khechara

Skin Ageing Decoded: Evidence-Based Facts Every Practitioner Should Know

Skin ageing is a multifactorial process influenced by intrinsic biological mechanisms and extrinsic environmental factors. The following student-submitted data highlights key statistics and evidence-based findings on how ageing affects the skin’s structure, function, and appearance.

This compilation draws from published research and reputable scientific sources, offering a concise evidence review for beauty, nutrition, and wellness practitioners who integrate skin health into their work.

1. Hydration and Skin Health

Dry skin and itching are common in later life. About 85% of older people develop "winter itch," because overheated indoor air is dry. The loss of oil glands as we age may also worsen dry skin. Anything that further dries the skin (such as overuse of soaps or hot baths) will make the problem worse. If your skin is very dry and itchy, see a doctor because this condition can affect your sleep, cause irritability, or be a symptom of a disease. Some medicines make the itchiness worse.
Olivia Crooke - WebMD

In Australia, a huge 80% of adults suffer chronic dehydration, drinking only 1.29 ml per day on average. It takes only a 2% loss of total water content for the body to start feeling thirsty — and chronic dehydration accelerates the ageing process.
Michelle Bailey - Waterlogic Australia

A study confirmed that even short exposure of skin to a low‐humidity environment induces changes in the stratum corneum and skin surface pattern, leading to fine wrinkles related to lack of water.
Linda Zafirati - Wiley Online Library

2. Cellular Turnover and Epidermal Dynamics

Keratinocytes, the predominant cell of the epidermis, account for 70–80% of its cell population and desquamate in 28 days — until our late 20s. This timeframe increases by more than 10 days from the age of 30. Reduced turnover slows multiple physiological processes, directly influencing skin ageing.
Langerhans cells make up 2–5% of epidermal cells and account for 25% of barrier defence. One in every ten cells in the basal layer is a melanocyte, each contacting approximately 35 keratinocytes.
Michelle Bailey -  Pastiche Training | PubMed

3. Collagen and Nutrient Dependency

For fibroblasts to synthesise healthy collagen, proper nutrients must be available. Key cofactors include:

  • Vitamin C
  • Vitamin A
  • Amino acids (proline & glycine)
  • Copper peptides
  • Silicon with magnesium and calcium
  • Bioflavonoids
  • Growth factors and hormones
  • Zinc and iron (as cofactors)
  • Essential fatty acids for cell membrane integrity

Lindi Botes - Virtual Beauty NZ

4. Nutrition and Lifestyle Influences

A whole-food, plant-based diet may slow or reverse cellular ageing by increasing telomere length, while control groups on conventional diets showed telomere shortening.
Valeria Dolbel - JCAD Online

High-sugar diets damage collagen and elastin, causing loss of elasticity, wrinkles, and sagging. Diets lower in refined carbohydrates may help maintain youthful skin.
Huda Al-Hakim - U.S. News Health

Studies suggest that consuming 10 tablespoons of tomato puree daily may help reverse skin ageing, likely due to lycopene’s antioxidant effects.
Katrien Weemaes - Ergo Log

5. Environmental and Extrinsic Ageing

You actually need sunscreen with at least SPF 30 every day—regardless of weather or season. Up to 80% of UV rays pass through clouds, and UV exposure accounts for over 90% of visible ageing signs.
Stefanie Clifford - Washington University Physicians

Ultraviolet light, pollution, and cigarette smoke cause DNA alterations, amplifying normal chronological decline.
Kimberly Ann - NCBI

Exposure to UV radiation is the primary factor in extrinsic ageing, accounting for about 80% of facial ageing. Interestingly, UV-exposed epidermis thickens — unlike the thinner epidermis seen in intrinsic ageing.

6. Intrinsic Ageing and Structural Changes

Intrinsic ageing is gradual and marked by epidermal and dermal atrophy, loss of fibroblasts, reduced collagen, and more MMPs. The dermal-epidermal junction flattens with age — its surface area dropping from 2.64 mm² (ages 21–40) to 1.90 mm² (ages 61–80) — reducing nutrient exchange and increasing fragility.

7. Immunosenescence and Barrier Defence

Skin’s immune system weakens with age (“immunosenescence”), reducing the migration and function of antigen-presenting cells like Langerhans cells. This leads to increased infections, malignancies, and reduced vaccine response.
Glenise Gomez - NCBI

8. Fun Skin Facts

  • The average adult has about 21 sq ft of skin, weighing 9 lbs and containing 11 miles of blood vessels.
  • There are 300 million skin cells, with 19 million cells and up to 300 sweat glands per square inch.
  • Humans shed 30,000–40,000 dead cells per minute — about 9 lbs per year.
  • More than half of household dust may be dead skin!

SkinGuru - Derm Specialists

Conclusions

From cellular renewal to diet, hydration, UV exposure, and immune regulation — skin ageing is a complex interplay of internal and external factors. For practitioners, understanding these mechanisms provides the foundation for creating evidence-based treatment plans and holistic skin nutrition strategies that address both intrinsic and extrinsic ageing processes.

References

  • WebMD — [Cosmetic Procedures and Aging Skin](https://www.webmd.com/beauty/cosmetic-procedures-aging-skin)
  •  BBC Science Focus — [10 Remarkable Facts About Skin](https://www.sciencefocus.com/the-human-body/10-remarkable-facts-about-skin/)
  • Waterlogic Australia — [Dehydration in Adults](https://www.waterlogicaustralia.com.au/resources/are-we-drinking-enough-water/#:~:text=Dehydration%20in%20Adults)
  • Pastiche Training — [Epidermal Turnover: The 30-Day Myth](https://pastiche-training.com/epidermal-turnover-the-30-day-myth/)
  • PubMed — [Epidermal Cell Turnover Study](https://pubmed.ncbi.nlm.nih.gov/6827031/)
  • Virtual Beauty NZ — [Collagen Stimulating Supplements](https://www.virtualbeauty.co.nz/collagen-stimulating-supplements/)
  • Wiley Online Library — [Dry Environment and Skin Moisture Study](https://onlinelibrary.wiley.com/doi/abs/10.1034/j.1600-0846.2002.00351.x)
  • Washington University Physicians — [Facing the Facts: Busting the Most Common Anti-Aging Myths](https://physicians.wustl.edu/facing-the-facts-busting-the-most-common-anti-aging-myths/)
  • JCAD Online — [Diet and Dermatology: Plant-Based Nutrition and Skin Health](https://jcadonline.com/diet-and-dermatology-plant-based/)
  • U.S. News Health — [4 Diet Changes That Are Better Than Botox](https://health.usnews.com/health-news/blogs/eat-run/articles/2018-05-03/4-diet-changes-that-are-better-than-botox)
  • Ergo Log — [Tomato Puree and Skin Ageing Study](https://www.ergo-log.com/tomatoskin.html)
  • NCBI — [Environmental Factors and Skin Ageing](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3840548/)
  • International Journal of Cosmetic Science — [A New Wrinkle on Old Skin: The Role of Elastic Fibres in Skin Ageing](https://onlinelibrary.wiley.com/doi/full/10.1111/j.1468-2494.2010.00574.x)
  • NCBI — [Skin Immunosenescence Study](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4292080/)
  • Cell Transplant Journal — [Fighting Against Skin Aging: The Way from Bench to Bedside](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6047276/)
  • Derm Specialists — [Skin Fun Facts](https://derm-specialists.com/skin-fun-facts/)

    • Inspired by our students’ insights? You can learn to decode skin science just like they do. Enrol today and start your journey toward skin nutrition mastery.

    Article by Star Khechara

    Professional agehacker, author, speaker, founder of skin nutrition institute
    About me
    Ex-skincare formulator and beauty author turned skin-nutrition educator: Star distilled her 20+ years of skin-health knowledge into the world’s first international accredited skin-nutrition school to teach skin therapists, facialists, face yoga practitioners and estheticians how to help their clients feed the skin from within for cellular-level rejuvenation and vibrant beauty. 
    Write your awesome label here.

    TAKE THE FREE CLASS

    Sign up foe the free 'Introduction to Skin Nutrition' class & get your Skin Nutrition Practitioner Start Kit.
    Created with