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Unbiased evidence-based studies on skin and creams

For skin, the studies clearly show that your complexion radically changes in different climates. For skincare, the results reveal that in order to maximize ingredients efficacy, the formulation must take the user’s climate into account.

  • Changes in filaggrin degradation products and corneocyte surface texture by season (Study on how weather changes skin texture)

https://doi.org/10.1111/bjd.16150 

Authors: K.A. Engebretsen, S. Kezic, C. Riethmüller, J. Franz, I. Jakasa, A. Hedengran, A. Linneberg, J.D. Johansen, J.P. Thyssen​

Published: British Journal of Dermatology; March 2018

Summary: This study shows clearly that the skin barrier is affected by climatic and seasonal changes. 

  • Variation in skin biology to climate in Shanghai, China

https://www.ncbi.nlm.nih.gov/pubmed/

Authors: Liu X, Gao Y, Zhang Y, Wang X​— Department of Mycology, Shanghai Sin Disease Hospital, Shanghai, China ​

Published: Journal of Cutaneous and Ocular Toxicology (November 2016) & US National Library of Medicine (January 2017)​

Summary: This study was done by the Department of Skin & Cosmetics Research at the Shanghai Skin Disease Hospital, recruiting over 2,000 volunteers between the age of 13-69 for it. They found that skin biological parameters are associated with climatic factors. Different sites have different sensitivity to climate factors.​

  • The effect of environmental humidity and temperature on skin barrier function and dermatitis.

https://doi.org/10.1111/jdv.13301 ​

Authors: Engebretsen KA, Johansen JD, Kezic S, Linneberg A, Thyssen JP​

Published: European Academy of Dermatology (October 2015) & US National Library of Medicine (February 2016)​

Summary: The study concludes that low humidity and low temperatures lead to a general decrease in skin barrier function. In particular, people living in the Northern parts of Europe and North America are exposed to harsh weather conditions and will experience dry skin because of it. ​

  • Effects of temperature and humidity on the skin permeation of hydrophilic and hydrophobic drugs (Study on how temperature and humidity effect topical delivery of ingredients)

https://link.springer.com/article/10.1208/s12249-019-1481-1​

Authors: Iikura H, Uchida K, Ogawa-Fuse C, Bito K, Naitou S, Hosokawa M, Uchida T

Published: AAPS PharmSciTech, October 2019​— AAPS PharmSciTech is an official journal of the American Association of Pharmaceutical Scientists and publishes papers that focus on the research, development, and evaluation of pharmaceutical dosage forms and delivery systems.

Summary: Study found that high absolute humidity (AH) significantly contributed to the high skin penetration of the hydrophilic penetrants that solve in water but not the hydrophobic penetrant such as oils. Increasing the amount of water and hydrophilic vehicles such as glycerin in the stratum corneum may enhance the penetration of hydrophilic penetrants.  ​

  • Oxidation events and skin aging​

https://pubmed.ncbi.nlm.nih.gov/

Authors: Kammeyer A, Luiten RM— ​Department of Dermatology, Academic Medical Center (AMC), University of Amsterdam, The Netherlands

Published: Aging Research Reviews, Volume 21, May 2015​

Summary: This review describes in detail the new understanding of skin aging. The highlight are as follow: 1. Skin aging is more influenced by extrinsic than intrinsic processes; 2. Due to extrinsic factors, skin aging differs from aging of other tissue; 3. Oxidative degeneration in the skin overrules anti-aging adaptive responses; 4. Oxidative degeneration is the prime cause of skin aging, rather than senescence (process of deterioration with age); and 5. The rate of skin aging depends on individual genetic makeup and lifestyle.​

  • Seasonal variability in the biophysical properties of forehead skin in women in Guangzhou City, China.

https://www.ncbi.nlm.nih.gov/pubmed/25557023

Authors:  Wan MJ, Su XJ, Zheng Y, Gang ZJ, Yi JL, Zhao Y, Guan XM, Lai W​

Published: The International Society of Dermatology, December 2014

Summary: A cross-sectional study was conducted in 178 healthy, adult Chinese women in whom forehead skin was examined in all four seasons between March 2007 and February 2008. Commercially available, non-invasive devices were used to measure skin hydration, sebum content, pH, and transepidermal water loss (TEWL). There were significant seasonal changes in TEWL and pH (autumn and winter > spring and summer), skin hydration (spring and summer > autumn and winter), and sebum content (spring and summer > autumn and winter). Skin hydration was correlated with average temperature and humidity. Skin TEWL and skin pH were correlated with average temperature, humidity, and ultraviolet (UV) radiation levels. Skin sebum content was correlated with average humidity.

  • Friction, adhesion and durability and influence of humidity on adhesion and surface charging of skin and various skin creams using atomic force microscopy​

https://onlinelibrary.wiley.com/

Authors:  Tang W, Bhushan B, Ge S​— Nanoprobe Laboratory for Nanotechnology and Biomimetics, The Ohio State University​

Published: Journal of Microscope, July 2010

Summary:  Because the environmental dependence of skin and skin cream is of importance, the influence of humidity on adhesive force, film thickness and Young’s modulus mapping were measured using force distance technique. The health and feel of skin are significantly affected by its surface charging, the surface potential of skin and various cream-treated skins was measured using the Kelvin probe method.​

  • Environmental stressors on skin aging. Mechanistic insights​

https://www.frontiersin.org/articles

Authors: Parrado C, Mercado-Saenz S, Perez-Davo A, Gilaberte Y, Gonzalez S, Juarranz A

Published: Journal of Frontiers in Pharmacology, July 2019​

Summary: Skin that is aged only by intrinsic factors virtually doesn’t exist. In general, individuals wear a skin that reflects several stages of extrinsic aging, superimposed on the level of intrinsic aging​.

  • Effect of the regional environment on the skin properties and the early wrinkles in young Chinese women

https://onlinelibrary.wiley.com/

Authors: Kim EJ, Han JY, He QQ, Cho JC, Wei L, Wang X, Li L, Wei L, Liang H, Gao X, Kim BJ​

Published: Journal of Skin Research & Technology, November 2014

Summary: In the Chinese women aged 20–35 years (including twins), the skin was influenced by the climates, so they had regionally a different skin. There were regional differences in the skin characteristics and the wrinkles. Beijing women had dry skin and more wrinkles, but Guangzhou women had high sebum contents, low pH, and less wrinkles. Shanghai women’s TEWL and Wuhan’s women’s skin elasticity were higher compared with that of women from other regions. The wrinkles’ form (area, depth, and length) was different from region to region. Beijing women’s wrinkles were deep and large, but Guangzhou women’s wrinkles were shallow and small. The skin physical parameters that influenced the wrinkles were low sebum content and hydration, high TEWL, and pH. ​

  • A study on seasonal variation of skin parameters in Korean males​

​https://www.ncbi.nlm.nih.gov/pubmed/

Authors: Song EJ, Lee JA, Park JJ, Kin HJ, Kim NS, Byun KS, Choi GS, Moon TK​

Published: International Journal of Cosmetic Science, December 2014​

Summary: The study shows that the skin surface pH, TEWL, sebum content, hydration, elasticity, wrinkles, skin pore and skin sensitivity vary with the seasons.​

  • The effects of regional climate and aging on seasonal variations in Chinese Women’s skin characteristics

https://m.scirp.org/

Authors: Eunjoo K, Hyeokgon P, Beomjoon K, Liu W, Haekwang L, Minah K, Jaeho Y, Lai W

Published: Journal of Cosmetics, Dermatological Science and Applications, June 2017)

Summary: The study concludes that skin hydration and barrier function decreased more during a cold, dry winter than summer. The barrier dysfunctions such as an increase in TEWL and pH occurred more commonly in old age groups when exposed to the climate. The greater the differences between summer and winter climates, the greater damage to skin barrier and skin hydration. The sebum secretion was more affected by hot, humid summers. ​