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Alopecia (hair loss) can be caused by factors such as reduced physiological function, scalp tension-induced blood flow disorders, genetic predisposition and poor scalp nutrition. While microbiome-focused research into alopecia is limited, biomolecules of fermented fruits and fermenting microbes show promise as a potential solution. What We Know: Studies investigating the scalp microbiome determined that Cutibacterium spp. and Staphylococcus spp. make up approximately 90% of a healthy scalp microbiome, with the remaining 10% consisting of Corynebacterium spp., Streptococcus spp., Acinetobacter spp. and Prevotella spp (Jo et al., 2022). The scalp microbiome may impact scalp health and alopecia. Research indicates no variance in species diversity or abundance between alopecia-affected and healthy scalps. However, a study found a >10% difference in Proteobacteria and Actinobacteria distributions. Healthy scalps showed higher Proteobacteria abundance, while alopecia-affected scalps had higher Actinobacteria levels (Jo et al., 2022). Fermented aloe vera and kimchi were successfully used to treat burn wounds and improve the skin microbiota pattern, maintaining probiotic (saprophytic) bacteria, including Lactobacillus, and reducing pathogenic bacteria (such as Prevotella and Cutibacterium acnes) (Yoon et al., 2022; Park et al., 2020). Industry Impact and Potential: Hair care products containing fermented papaya and mangosteen improved hair shaft conditions and reduced hair loss compared to control groups, showing potential for alopecia (Mayer et al., 2023). These experimental products improved the scalp microbiota, correcting the alopecia-associated altered microbiota pattern by decreasing pathogen content whilst maintaining probiotic (saprophyte) levels (Mayer et al., 2023). Fermented papaya's probiotic activity may involve selectively inhibiting catalase in microbial pathogens, which they rely on for enzymatic antioxidant defence against the host's immune response (Mayer et al., 2023). Further studies are needed to explore the preclinical and clinical effects of using food-grade fermented products in cosmetics, aiming to better understand their mechanisms and potential benefits for hair health. Integrating phytochemical and biological experiments could help identify specific plant- and microbe-derived substances with hair loss prevention and hair quality enhancement properties (Mayer et al., 2023). Our Solution: With a vast database of over 20,000 microbiome samples and 4,000 ingredients, coupled with a global network of over 10,000 testing participants, Sequential offers comprehensive services to evaluate product impacts and formulations. Our customisable microbiome studies provide real-life context testing, while formulation support ensures products maintain biome integrity. Therefore, we are your ideal candidate to utilise our solutions for your product development and efficacy. References: Jo, H., Kim, S.Y., Kang, B.H., Baek, C., Kwon, J.E., Jeang, J.W., Heo, Y.M., Kim, H.-B., Heo, C.Y., Kang, S.M., Shin, B.H., Nam, D.Y., Lee, Y.-G., Kang, S.C. & Lee, D.-G. (2022) Staphylococcus epidermidis Cicaria, a Novel Strain Derived from the Human Microbiome, and Its Efficacy as a Treatment for Hair Loss. Molecules. 27 (16). doi:10.3390/molecules27165136. Mayer, W., Weibel, M., De Luca, C., Ibragimova, G., Trakhtman, I., Kharaeva, Z., Chandler, D.L. & Korkina, L. (2023) Biomolecules of Fermented Tropical Fruits and Fermenting Microbes as Regulators of Human Hair Loss, Hair Quality, and Scalp Microbiota. Biomolecules. 13 (4), 699. doi:10.3390/biom13040699. Park, D.-W., Lee, H.S., Shim, M.-S., Yum, K.J. & Seo, J.T. (2020) Do Kimchi and Cheonggukjang Probiotics as a Functional Food Improve Androgenetic Alopecia? A Clinical Pilot Study. The World Journal of Men’s Health. 38 (1), 95–102. doi:10.5534/wjmh.180119. Yoon, Y.C., Ahn, B.H., Min, J.W., Lee, K.R., Park, S.H. & Kang, H.C. (2022) Stimulatory Effects of Extracellular Vesicles Derived from Leuconostoc holzapfelii That Exists in Human Scalp on Hair Growth in Human Follicle Dermal Papilla Cells. Current Issues in Molecular Biology. 44 (2), 845–866. doi:10.3390/cimb44020058.

Sudden skin reactions to skincare products can result from various factors, such as the introduction of new allergens, shifts in skin sensitivity, and the cumulative impact of product usage. Understanding these responses involves examining the allergens in cosmetics, the mechanisms behind skin reactions, and the influence of individual skin conditions. Types of allergens in skincare products Fragrance and preservatives: Common allergens like fragrances such as hydroxyisohexyl-3-cyclohexene carboxaldehyde, and preservatives like formaldehyde, parabens are frequently associated with allergic contact dermatitis (White & Groot, 2011). These ingredients can sensitize the skin over time, making it more reactive with continued exposure. Hair dyes: Ingredients such as p-phenylenediamine, often found in hair dyes, can cause allergic reactions, including redness, swelling, and itching around the scalp and face (White & Groot, 2011). Plant and Animal Derivatives: Natural components derived from plants and animals can provoke skin reactions, especially in sensitive individuals. Examples include lanolin, often derived from sheep's wool, and botanical extracts (Verhulst & Goossens, 2016). Alcohols and Acids:   Alcohols and exfoliating agents like glycolic acid or salicylic acid are popular in skincare for their renewing properties. However, they can irritate sensitive or damaged skin, causing redness and burning sensations (Verhulst & Goossens, 2016). Mechanisms of skin reactions Immediate Contact Reactions:  Some people experience Contact Urticaria Syndrome (CUS), where symptoms such as wheals or redness appear within minutes of exposure to a certain substance (Giménez-Arnau et al., 2010). Cumulative Sensitization: Repeated exposure to certain allergens can lead to cumulative sensitization, where skin that initially tolerated a product begins to react adversely over time (Wolf et al ., 2001). Skin Barrier Dysfunction:  A compromised skin barrier, due to over-exfoliation, dehydration, or pre-existing conditions becomes more permeable to irritants and allergens, increasing the risk of reactions (Engebretsen & Thyssen, 2016). Individual Factors Influencing Reactions Skin type:  People with sensitive skin, eczema, or rosacea are more prone to adverse reactions to skincare products. These conditions make the skin barrier more fragile and reactive. Age and Hormonal Changes: Aging skin or hormonal fluctuations, such as those occurring during pregnancy or menopause, can alter the skin's physiology, making it more sensitive and less resilient. Environmental Stressors: External factors like climate changes, UV exposure, pollution, or high stress can exacerbate skin sensitivity, increasing the likelihood of adverse reactions. Conclusion Most cosmetic products are considered safe for use, and proper diagnostic tools, such as patch testing, play a crucial role in identifying specific allergens and distinguishing between allergic and irritant reactions, enabling effective management and prevention strategies (Lazzarini, Duarte & Ferreira, 2013). Understanding the intricate mechanisms behind these reactions is essential for maintaining skin health. References Engebretsen KA, Thyssen JP. Skin Barrier Function and Allergens. Curr Probl Dermatol.  2016;49:90-102. doi: 10.1159/000441548. Epub 2016 Feb 4. PMID: 26844901. Lazzarini R, Duarte I, Ferreira AL. Patch tests. An Bras Dermatol. 2013  Nov-Dec;88(6):879-88. doi: 10.1590/abd1806-4841.20132323. PMID: 24474094; PMCID: PMC3900336. Wolf, R., Wolf, D., Tuzun, B., & Tuzun, Y. (2001). Cosmetics and contact dermatitis.  Dermatologic Therapy, 14(3), 181–187. doi:10.1046/j.1529-8019.2001.01025.x  White, Jonathan & De Groot, Anton - Ton & White, Ian. (2011). Cosmetics and Skin Care  Products. 10.1007/978-3-642-03827-3_32.  Verhulst L, Goossens A. Cosmetic components causing contact urticaria: a review and  update. Contact Dermatitis. 2016 Dec;75(6):333-344. doi: 10.1111/cod.12679. Epub 2016 Sep 4. PMID: 27593503.

Testing skincare products requires a structured approach to assess the products effectiveness and safety. This involves various methods, including in vitro testing, and clinical trials. As a consumer, testing skincare requires the products compatibility with personal needs. These testing include methods such as in-store testing, and patch testing. Testing methodologies  In vitro testing In vitro testing plays a critical role in assessing the safety and efficacy of skincare products. Under the European legislation, the evaluation of individual cosmetic ingredients is essential, with a strict prohibition on animal testing for cosmetic ingredients and products since 2004 and 2009, respectively. Additionally, the sale of products containing ingredients tested on animals has been banned since 2009 (Almeida, Sarmento & Rodrigues, 2017).  To meet these regulatory requirements, the European Centre for the Validation of Alternative Methods (ECVAM) has developed and validated various in vitro models such as skin irritation potential on cultured human or mammalian cell lines, skin cytotoxicity, skin and eye corrosion and irritation, phototoxicity…etc, to predict the safety and toxicity of cosmetic ingredients. These cell-based systems are valuable tools that provide reliable alternatives to animal testing, enabling researchers to evaluate factors such as absorption, permeability, and potential toxicity  (Almeida, Sarmento & Rodrigues, 2017).  Clinical trials Clinical trials are crucial for evaluating the performance of skincare products on human subjects. They consist of different phases and each phase typically involves a significant number of participants and incorporate both subjective feedback and objective assessments.  For example, a 4-week clinical study with 176 participants tested five targeted skincare formulations addressing irritated skin, dry skin, aging skin, oily skin, and dark circles. Results from the clinical study showed significant improvements in all conditions, with the products proving effective and safe, and no adverse effects (Duschek et al ., 2022). Consumer evaluation methods In store testing This allows consumers to directly observe the immediate effects of a skincare product on their skin. By evaluating factors such as texture, absorption, and any visible improvements, such as reduced redness or smoother skin, consumers can gain insight into the product's performance. This first hand observation is important, as it provides a sense of how the product may work for their individual skin needs. Patch testing Before using a new skincare product, it's advised to do a patch test. This involves applying a small amount of the product to a small area of your skin, like behind your ear or on your wrist, and leaving it for a certain period of time (usually 24-48 hours). This allows you to check for any signs of irritation, redness, or allergic reaction before applying the product to larger areas of your skin. It's a simple way to test if the product is safe to use. Conclusion In conclusion, testing skincare products is a crucial step in ensuring the products safety, effectiveness, and suitability for individual skin needs. There are a variety of testing methods that help provide a comprehensive understanding of how products perform. While in vitro models offer an ethical alternative to animal testing and clinical trials provide valuable insights into product performance, consumer methods are crucial to allow individuals to assess the product's compatibility with their own skin.  References Almeida, A., Sarmento, B., & Rodrigues, F. (2017). Insights on in vitro models for safety and  toxicity assessment of cosmetic ingredients. International Journal of Pharmaceutics, 519(1-2), 178–185. doi:10.1016/j.ijpharm.2017.01.024  Duschek N, Cajkovsky M, Prinz V, Müller D, Hundsamer A, Baierl A, Möllhoff N, Sulovsky M,  Frank K. An open-label, 4-week, prospective clinical study evaluating the efficacy and safety of a novel targeted skin care line addressing five common skin conditions. J Cosmet Dermatol. 2022 Nov;21(11):5760-5768. doi: 10.1111/jocd.15223. Epub 2022 Jul 28. PMID: 35810352.

The reason that skin appears healthier without the use of skincare products stems from various factors, such as, over-cleansing, and certain products could contain ingredients that may irritate skin. Therefore, simplifying skincare routines could enhance the skin’s natural balance and appearance.  Over-cleansing and skin health Over-cleansing is a key factor in improved skin appearance when skincare is avoided, as excessive washing strips the skin of its natural oils, causing dryness and irritation. A study done by Sverdrup showed that dry skin which is common in fibromyalgia patients' skin worsened by cosmetic use and aggressive cleansing routines (Sverdrup, 2004). The skin's natural oils are essential for hydration and maintaining the barrier function and their excess removal can trigger increased oil production, creating a cycle of dryness and oiliness that impacts the skin's overall appearance (Güell & Schneider, 2023). Irritation from ingredients Many skincare products contain chemicals and fragrances that can irritate the skin, causing redness, breakouts, or other adverse reactions. The growing popularity of "free from" claims in cosmetics reflects concerns about allergens and irritants, with avoiding such products potentially reducing irritation and promoting clearer skin (Nobile, 2016).  Regular use of products with harsh ingredients can also increase skin sensitivity, making it more reactive to environmental factors, while minimizing product use may help restore the skin’s natural resilience. Moreover, the skin has an ability to maintain its health and appearance when allowed to function naturally. The epidermis, the skin's outermost layer, acts as a protective barrier against environmental stressors. Discontinuing the use of potentially irritating products enables the skin to restore its natural balance and operate more efficiently (Lim, 2021). A study involving different age groups and lifestyles found that ceasing the use of potentially irritating products allowed the skin to restore its natural hydration and protective barrier, resulting in noticeable improvements. Younger individuals and new mothers, who often have less time for self-care, reported significant boosts in skin appearance and self-esteem when following simple skincare routines, highlighting how excessive or misused products can sometimes overwhelm the skin (Zhang et al ., 2020). The skin's microbiome plays a vital role in maintaining skin health as well. Overuse of cleansers and other products can disrupt the delicate balance of beneficial bacteria on the skin, leading to conditions such as acne or eczema (Hwang et al ., 2021). Hence it is important to incorporate products that support the skin microbiome rather than hindering it. Conclusion While a simplified approach to skincare may improve skin appearance for some individuals by reducing irritation and allowing the skin’s natural functions to flourish, it is important to balance this approach with targeted and purposeful skincare. Over-cleansing and the use of harsh or unsuitable products can disrupt the skin barrier, leading to cycles of dryness, oiliness, and sensitivity. However, well-formulated skincare routines that incorporate gentle cleansers, moisturizers, and sun protection can enhance the skin's resilience and prevent long-term damage from environmental stressors. Ultimately, the key to healthy skin lies in understanding individual skin needs and using products that support the balance of the skin. References Güell M, Schneider MR. In preprints: progress in sebaceous gland homeostasis,  regeneration and immunomodulatory functions. Development. 2023 Aug 1;150(15):dev202177. doi: 10.1242/dev.202177. Epub 2023 Jul 31. PMID: 37522362. Hwang BK, Lee S, Myoung J, Hwang SJ, Lim JM, Jeong ET, Park SG, Youn SH. Effect of  the skincare product on facial skin microbial structure and biophysical parameters: A pilot study. Microbiologyopen. 2021 Oct;10(5):e1236. doi: 10.1002/mbo3.1236. PMID: 34713611; PMCID: PMC8494714. Lim KM. Skin Epidermis and Barrier Function. Int J Mol Sci. 2021 Mar 16;22(6):3035. doi:  10.3390/ijms22063035. PMID: 33809733; PMCID: PMC8002265. Nobile, Vincenzo. “Misleading Marketing of Cosmetics. Do the Free from Parabens and Free  from Allergenic Substances Claims Really Make Sense.” (2016). Sverdrup B. Use less cosmetics--suffer less from fibromyalgia? J Womens Health (Larchmt).  2004 Mar;13(2):187-94. doi: 10.1089/154099904322966173. PMID: 15072733. Zhang, L., Adique, A., Sarkar, P., Shenai, V., Sampath, M., Lai, R., … & Farage, M. A.  (2020). The impact of routine skin care on the quality of life. Cosmetics, 7(3), 59. https://doi.org/10.3390/cosmetics7030059

Calculating skincare ingredients requires a structured approach that considers the components, proportions, and interactions involved in creating effective formulations. This process is crucial to ensure the final product achieves the desired efficacy and adheres to safety standards. Water as a Base   Water typically constitutes 55% to 80% of most skincare formulations. It serves as a solvent and carrier, enabling other ingredients to be absorbed effectively into the skin (Moldovan et al ., 2017).   Active Ingredients  Active ingredients deliver targeted benefits such as hydration, anti-aging effects, or sun protection. For example, formulations might include 3–5% herbal extracts or 15–20% sun-blocking agents like avobenzone (National Academies of Sciences, Engineering, and Medicine 2022). Emollients and Oils  Emollients and oils are used to moisturize and soften the skin. Their proportions can vary significantly, with some formulations containing up to 20% oil-based agents (Tomokazu & Hidehiro, 2014). Formulations are often expressed in mass percentages for simplicity. For instance, in a 100-gram product, a 5% concentration of an active ingredient would equate to 5 grams (Tomokazu & Hidehiro, 2014). Ingredient Interaction and Stability   Compatibility Testing   Evaluating how different ingredients interact is vital. For example, some herbal extracts may enhance or diminish the efficacy of other active ingredients, requiring careful adjustment of their ratios (Panico et al ., 2019). Preservatives and Stabilizers  These ingredients play a critical role in extending the shelf life of skincare products. Preservative ratios typically range from 0.5% to 1.5%, depending on the water content of the formulation and its susceptibility to microbial growth (Varvaresou et al ., 2009).   The formulation process often involves various adjustments based on results from stability testing and consumer feedback. This ensures the final product meets both efficacy and sensory expectations. Conclusion In conclusion, calculating ingredient ratios for skincare formulations requires a precise and methodical approach, and by understanding the roles of key ingredients, conducting compatibility tests, formulators can create effective, and safe skincare products. References Moldovan M, Lahmar A, Bogdan C, Părăuan S, Tomuţă I, Crişan M. Formulation and  evaluation of a water-in-oil cream containing herbal active ingredients and ferulic acid. Clujul Med. 2017;90(2):212-219. doi: 10.15386/cjmed-668. Epub 2017 Apr 25. PMID: 28559707; PMCID: PMC5433575. National Academies of Sciences, Engineering, and Medicine 2022. Review of Fate, Exposure, and Effects of Sunscreens in Aquatic Environments and Implications for Sunscreen Usage and Human Health . Washington, DC: The National Academies Press. https://doi.org/10.17226/26381 . Panico A, Serio F, Bagordo F, Grassi T, Idolo A, DE Giorgi M, Guido M, Congedo M, DE Donno  A. Skin safety and health prevention: an overview of chemicals in cosmetic products. J Prev Med Hyg. 2019 Mar 29;60(1):E50-E57. doi: 10.15167/2421-4248/jpmh2019.60.1.1080. PMID: 31041411; PMCID: PMC6477564. Tomokazu, Yoshida., Hidehiro, Nagasawa. (2014). Skin cosmetic composition Varvaresou, Athanasia & Papageorgiou, Spyridon & Tsirivas, E & Protopapa, Evangelia &  Kintziou, H & Kefala, Vasiliki & Demetzos, Costas. (2009). Self-preserving cosmetics. International journal of cosmetic science. 31. 163-75. 10.1111/j.1468-2494.2009.00492.x.

What is the microbiome? The human microbiome is defined as the full array of microorganisms, and their genomes, that live in and on humans. These microorganisms inhabit a particular site of the human body and form distinct microbial communities (microbiota) such as those found on the skin or the scalp microbiome. The composition of an individual's microbiome can be influenced by several factors such as age, environment and method of birth.   Without testing, there are a few signs that can indicate whether your microbiome is potentially off-balance. An imbalance in the microbiome, also known as dysbiosis, can manifest as a condition in different body areas such as acne vulgaris or dandruff. In this post, we explore potential signs of imbalance in the skin, scalp, oral and vaginal microbiomes.    Signs of a skin microbiome imbalance Skin-resident microbes inherently help to maintain a healthy skin barrier, however, if disrupted, changes in the skin microbiome can lead to inflammation, dryness, irritation and itchy skin (Skowron et al ., 2021). Several studies have also shown that dysbiosis is implicated in the manifestation of inflammatory skin conditions such as acne and atopic dermatitis.    Acne One of the major factors involved in acne pathogenesis is thought to be an imbalance of the bacteria Cutibacterium acnes . Although C.acnes  is also present on healthy skin, studies show that a loss of microbial diversity and loss of balance between C. acnes  phylotypes appears to play a role in the triggering of acne (Dréno et al. , 2020).   Atopic Dermatitis (Eczema)  Studies have shown that individuals with atopic dermatitis have a disturbed skin microbiome and are more often colonised with Staphylococcus aureus  compared to healthy individuals. The presence of S. aureus  contributes to the inflamed, dry and itchy skin commonly experienced by individuals with atopic dermatitis.   Signs of a scalp microbiome imbalance Studies have revealed that the scalp microbiome is characterized by a relatively low bacterial diversity, as compared to the other body sites and is dominated by Cutibacterium acnes , Staphylococcus epidermidis  and Malassezia  spp (Saxena et al., 2021) . Dysbiosis of the scalp microbiome has been linked to conditions such as seborrheic dermatitis and dandruff.   Seborrheic Dermatitis Seborrheic dermatitis is a common chronic, inflammatory skin disease that can affect the scalp and other sebum-gland-rich areas of the body. Scalp seborrheic dermatitis (SD) is a chronic type of inflammatory dermatosis associated with the proliferation of Malassezia  species (Wang et al., 2021). The common signs of seborrheic dermatitis are flaking, scaling and inflammation.   Dandruff Dandruff is a light disease state of seborrheic dermatitis, also associated with the proliferation of Malassezia species. Thus, scalp microbiome dysbiosis may present itself as dandruff, characterised by mild inflammatory reactions that present as abnormal flaking of the scalp and sometimes with mild erythema (redness).   Signs of an oral microbiome imbalance The oral microbiome comprises a complex and diverse community of microorganisms living within the oral cavity and is the third most diverse after the gut and skin microbiome. Changes in the oral cavity can lead to dysbiosis which has been associated with the development of diseases such as periodontitis and gingivitis.   Periodontitis (Gum Disease) Periodontitis, otherwise known as gum disease, is an irreversible inflammatory condition that affects over half of the world’s population and is a major cause of tooth loss. Although the cause of periodontitis is multifactorial, the presence of plaque is thought to be the primary factor. Plaque is formed when salivary glycoproteins adhere to the tooth surface, creating an environment for both Gram-positive and Gram-negative bacteria to colonise. It is the uncontrolled growth of the Gram-negative component of subgingival biofilm that leads to periodontitis (Aruni et al.,  2015). Common signs of periodontitis include persistent bad breath, swollen gums and loose teeth.   Gingivitis Gingivitis and periodontitis are a continuum of the same inflammatory disease, whereby gingivitis may lead to periodontitis if left untreated. Dysbiosis in the oral microbiome may manifest as gingivitis which is characterised by red, swollen and bleeding gums.   Signs of a vaginal microbiome imbalance  Vaginal microbiota constitutes about 9% of the total human microbiota. These microbes live in a mutualistic relationship with the host vagina protecting it from potentially pathogenic microbes like those causing bacterial vaginosis (Saraf et al., 2021).   Bacterial Vaginosis Changes in the vaginal microbiota including a loss of Lactobacillus species and an increase in facultative and anaerobic organism populations result in bacterial vaginosis (Saraf et al. , 2021). This imbalance in the vaginal microbiome often leads to unusual discharge.   In summary Whilst these signs can indicate a potential imbalance in your microbiome, they can also be caused by other factors. Microbiome testing would be ideal to provide certainty of an imbalance, however not many personal care brands offer this method of diagnosis to consumers. One example of a skincare brand that does offer this service is Gallinée, enabling personalised skin routine recommendations via an in-depth skin health report.   Advice for brands We recommend differentiating your brand by harnessing the power of microbiome testing. The results of our market research on over 3,500 participants found that 80% demand a customised microbiome-based skincare product that factors ethnicity, age, location and skin concerns. By conducting in vivo  testing on your products you can ensure they maintain the microbiome. Additionally, we can partner with your brand to offer our at-home skin microbiome testing kit, allowing you to provide skin health reports and personalised product recommendations to your customers based on their individual microbiome profiles.   References   Aruni, A. W., Dou, Y., Mishra, A., & Fletcher, H. M. (2015). The biofilm community: Rebels with a cause.  Current Oral Health Reports, 2 (1), 48-56. doi:10.1007/s40496-014-0044-5   Dréno, B., Dagnelie, M. A., Khammari, A., & Corvec, S. (2020). The skin microbiome: A new actor in inflammatory acne.  American Journal of Clinical Dermatology, 21 (Suppl 1), 18-24. doi:10.1007/s40257-020-00531-1   Saraf, V. S., Sheikh, S. A., Ahmad, A., Gillevet, P. M., Bokhari, H., & Javed, S. (2021). Vaginal microbiome: Normalcy vs dysbiosis.  Archives of Microbiology, 203 (7), 3793-3802. doi:10.1007/s00203-021-02414-3   Saxena, R., Mittal, P., Clavaud, C., Dhakan, D. B., Roy, N., Breton, L., . . . Sharma, V. K. (2021). Longitudinal study of the scalp microbiome suggests coconut oil to enrich healthy scalp commensals.  Scientific Reports, 11 (1), 7220. doi:10.1038/s41598-021-86454-1   Skowron, K., Bauza-Kaszewska, J., Kraszewska, Z., Wiktorczyk-Kapischke, N., Grudlewska-Buda, K., Kwiecińska-Piróg, J., . . . Gospodarek-Komkowska, E. (2021). Human skin microbiome: Impact of intrinsic and extrinsic factors on skin microbiota.  Microorganisms (Basel), 9 (3), 543. doi:10.3390/microorganisms9030543   Wang, H., Wang, C., Hsieh, S., Hung, Y., & Chen, H. (2022). Evaluation of a new‐formula shampoo containing 6% glycyrrhetinic acid complex for scalp seborrheic dermatitis: A pilot study.  Journal of Cosmetic Dermatology, 21 (8), 3423-3430. doi:10.1111/jocd.14623

The microbiome refers to the collection of trillions of microorganisms, such as bacteria, fungi, and viruses, that live in and on your body, particularly in your gut. (Lloyd-Price, Abu-Ali & Huttenhower, 2016) These microbes are vital components in maintaining our health by aiding digestion, regulating the immune system, and even influencing mood and overall brain function. Given the growing interest in the microbiome's impact on overall well-being, testing the microbiome has broadened its appeal among people. Here's an overview of the process, why it's important, and what the results could reveal. Types of Microbiome Tests Skin tests:   Skin microbiome samples are typically collected using non-invasive methods, such as swabs, tape strips, or skin scrapings. A swab is gently rubbed over the surface of the skin to capture microbial communities from different body areas, depending on the research or diagnostic needs. These samples are then sent to a lab for DNA sequencing to identify and quantify the microbial species present (Grice & Segre, 2011). This approach allows for a deeper understanding of how the skin's microbial balance impacts health conditions like acne, eczema, and skin infections. Saliva tests:  Saliva microbiome testing is a non-invasive approach to assess the bacterial communities in the mouth, offering insights into oral and overall health. Through next-generation sequencing, saliva samples can reveal significant shifts in microbial composition, serving as early biomarkers for health conditions.For example, Aas et al. (2005) demonstrated that saliva microbiome testing could reveal distinct bacterial profiles associated with oral diseases, suggesting its importance in both oral and systemic health management. Stool tests : Stool microbiome testing evaluates the gut’s microbial composition by analysing bacteria, viruses, and fungi in stool samples. This non-invasive test helps identify microbial imbalances (dysbiosis) linked to conditions like irritable bowel syndrome, inflammatory bowel disease, and metabolic disorders. By using next-generation sequencing, it reveals the diversity and abundance of gut microbes, which can inform insights into digestive, immune, and even mental health. Zhernakova et al. (2016) highlighted its potential in detecting gut-related health issues and promoting personalised healthcare strategies. Comprehensive clinical tests:   In some cases, healthcare providers may recommend a more comprehensive testing that goes beyond the standard saliva and stool samples which include blood tests or even tissue biopsies; particularly when chronic conditions are present. These approaches can hold valuable information regarding systemic infections or localised imbalances in microbiota, which can significantly aid in the management of diseases such as inflammatory bowel disease and even cancer. (Schulfer & Blaser, 2015) Conclusion By testing our microbiome, we dive into important insights of our overall health by identifying imbalances in microbial communities, known as dysbiosis, which are interlinked to various health conditions. Understanding our microbiome composition allows for customised dietary and lifestyle adjustments to restore balance, as specific gut bacteria are essential for digestion, immune function, and mood regulation. (Zhernakova et al., 2016; Young, 2017) Advancements in microbiome research show that testing can aid in managing chronic diseases by guiding personalised treatment and dietary plans based on an individual's microbial profile, improving clinical outcomes and overall well-being (Lloyd-Price et al., 2016; Hu et al., 2021). Regular testing can optimise health, particularly concerning the gut-brain axis and metabolic health. References Aas, J. A., Paster, B. J., Stokes, L. N., Olsen, I., & Dewhirst, F. E. (2005). Defining the normal bacterial flora of the oral cavity. Journal of Clinical Microbiology, 43(11), 5721-5732. https://doi.org/10.1128/JCM.43.11.5721-5732.2005 Lloyd-Price, J., Abu-Ali, G., & Huttenhower, C. (2016). The healthy human microbiome. Genome Medicine, 8(51), 1-11. https://doi.org/10.1186/s13073-016-0307-y Schulfer , A., & Blaser, M. J. (2015). Risks of antibiotic exposures early in life on the developing microbiome. PLoS Pathogens, 11(7), e1004903. https://doi.org/10.1371/journal.ppat.1004903 Zhernakova, A., et al. (2016). Population-based metagenomics analysis reveals markers for gut microbiome composition and diversity. Science, 352(6285), 565-569. https://doi.org/10.1126/science.aad3369

As interest in the human microbiome grows, various microbiome tests have emerged, each offering unique insights into our health. Understanding which tests are best suited for individual needs can help inform decisions regarding health management and lifestyle changes. Skin Microbiome Testing Skin microbiome testing involves collecting samples from the skin's surface using methods like swabs, tape strips, or skin scrapings to analyse the diversity and composition of microorganisms residing on the skin. The samples are then processed through DNA sequencing techniques to identify microbial species and their relative abundance. This testing provides insights into how the skin's microbial ecosystem impacts health conditions such as acne and eczema. Skin microbiome research is increasingly being used to develop personalised skincare products and therapeutic approaches (Byrd et al., 2018). Stool Microbiome Testing Stool testing remains one of the most common and accessible methods for analysing the gut microbiome. These tests evaluate the diversity and abundance of microbial species, helping to identify imbalances linked to conditions such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and obesity. A study by Zhernakova et al. (2016) emphasises the utility of stool microbiome tests in detecting dysbiosis and understanding its relationship to health outcomes. Saliva Microbiome Testing Saliva microbiome testing is another non-invasive method, focusing on the oral microbiota. This test can provide insights into oral health, periodontal disease, and even systemic health conditions linked to the oral microbiome. A study by Aas et al. (2005) illustrates that the oral microbiome reflects changes in health status, making saliva testing an essential tool for early disease detection. Blood Microbiome Testing While less common, blood microbiome testing is gaining traction, especially for identifying systemic infections or chronic conditions. This testing method analyses microbial DNA present in the bloodstream, which can reveal insights into conditions like sepsis and cardiovascular diseases.  A paper by Cheng et al. (2023) reviews the emerging concept of the blood microbiome, highlighting its potential role in human health and disease, while addressing existing controversies and the need for further research to understand its clinical implications. Tissue Biopsy Microbiome Testing Tissue biopsies are increasingly utilised for studying the microbiome within specific organs, particularly the gastrointestinal tract. This method allows for direct analysis of microbial communities in tissue samples, providing insights into diseases such as colorectal cancer and IBD. Recent advancements in next-generation sequencing have enhanced the ability to identify and characterise microbial populations in biopsies, as noted by Schulfer and Blaser (2015). Conclusion Choosing the right microbiome test depends on individual health concerns and goals. Stool and saliva tests are excellent for general gut and oral health insights, while blood and tissue tests offer deeper analysis for chronic diseases. As research continues to evolve, these tests will likely become even more integral to personalised healthcare and preventative strategies. References Aas, J. A., Paster, B. J., Stokes, L. N., Olsen, I., & Dewhirst, F. E. (2005). Defining the normal bacterial flora of the oral cavity. Journal of Clinical Microbiology, 43(11), 5721-5732. https://doi.org/10.1128/JCM.43.11.5721-5732.2005 Byrd , A. L., Belkaid, Y., & Segre, J. A. (2018). The human skin microbiome. Nature Reviews Microbiology, 16(3), 143-155. https://doi.org/10.1038/nrmicro.2017.157 Cheng , H. S., Tan, S. P., Wong, D. M. K., Koo, W. L. Y., Wong, S. H., & Tan, N. S. (2023). The blood microbiome and health: Current evidence, controversies, and challenges. International Journal of Molecular Sciences, 24(6), 5633. https://doi.org/10.3390/ijms24065633 Schulfer, A., & Blaser, M. J. (2015). Risks of antibiotic exposures early in life on the developing microbiome. PLoS Pathogens, 11(7), e1004903. https://doi.org/10.1371/journal.ppat.1004903 Zhernakova, A., Kurilshikov, A., Bonder, M. J., Tigchelaar, E. F., Schirmer, M., Vatanen, T., ... & Wijmenga, C. (2016). Population-based metagenomics analysis reveals markers for gut microbiome composition and diversity. Science, 352(6285), 565-569. https://doi.org/10.1126/science.aad3369

Advancements in next-generation sequencing (NGS) have made it easier for consumers to analyse their microbiome at home, providing insights into digestion, immune function and risks for chronic conditions like obesity and inflammatory bowel disease (Kashyap et al., 2013; Mills et al., 2019). What was once confined to research labs is now accessible to individuals through at-home testing kits. Testing your microbiome at home involves using specialised kits that analyse stool, saliva, or skin samples to provide insights into the composition of your microbiota. At-Home Microbiome Testing Walkthrough Choose a Testing Kit:  Several companies offer microbiome testing kits that can be purchased online. The most common ones focus on gut bacteria via stool samples, while others may analyse saliva or skin samples. Sample Collection:  The kit will come with tools to collect your sample, usually a test tube for stool, saliva, or skin swabs. Each kit typically contains instructions, a sterile collection tool, a labelled container for the sample, and a prepaid shipping label to send the sample back to the lab for analysis. Return Your Sample:  After collecting the sample, you place it in the provided container, label it, and use the prepaid shipping label to return it to the lab. DNA Analysis:  Once the sample reaches the lab, it undergoes DNA sequencing, usually through next-generation sequencing (NGS) techniques. This process identifies the types and quantities of bacteria and other microbes in the sample. (Franzosa et al., 2018) Results:  After the analysis, the company provides a detailed report of your microbiome, including the diversity and relative abundance of microbes. Some tests may offer personalised health or dietary recommendations based on your microbiome profile. (Mills et al., 2019) Actionable Insights:  Based on your results, you may be able to adjust your diet or lifestyle to improve your microbiome balance and overall health. Conclusion At-home microbiome testing relies on the use of NGS, which sequences the DNA of the microorganisms in your sample. This technology has been validated in numerous scientific studies and is widely used in microbiome research. (Turnbaugh et al., 2007) Companies typically compare your microbiome profile against large databases of microbial genomes to provide insights into how your microbiome compares to others in terms of diversity and health markers. (Human Microbiome Project Consortium, 2012) While at-home microbiome tests are an exciting development in personalised health and have become a beacon in providing valuable information, it’s important to note that the science is still evolving. The relationships between specific microbes and health conditions are not fully understood yet and more research is needed to translate these findings into actionable clinical advice (Zhernakova et al., 2016). As research into the human microbiome continues, these tests will likely become even more accurate and influential in shaping personalised health strategies. References Franzosa, E. A., McIver, L. J., Rahnavard, G., Thompson, L. R., Schirmer, M., Weingart, G., … & Huttenhower, C. (2018). Species-level functional profiling of metagenomes and metatranscriptomes. Nature Methods, 15(11), 962-968. https://doi.org/10.1038/s41592-018-0176-y Human Microbiome Project Consortium. (2012). Structure, function and diversity of the healthy human microbiome. Nature, 486(7402), 207-214. https://doi.org/10.1038/nature11234 Kashyap, P. C., Marcobal, A., Ursell, L. K., Smits, S. A., Sonnenburg, E. D., Costello, E. K., ... & Sonnenburg, J. L. (2013). Genetically dictated change in host mucus carbohydrate landscape exerts a diet-dependent effect on the gut microbiota. Proceedings of the National Academy of Sciences, 110(42), 17059-17064. https://doi.org/10.1073/pnas.1306070110 Lloyd-Price, J., Abu-Ali, G., & Huttenhower, C. (2016). The healthy human microbiome. Genome Medicine, 8(1), 51. https://doi.org/10.1186/s13073-016-0307-y Mills, S., Stanton, C., Lane, J. A., Smith, G. J., & Ross, R. P. (2019). Precision nutrition and the microbiome, part I: Current state of the science. Nutrients, 11(4), 923. https://doi.org/10.3390/nu11040923 Rothschild, D., Weissbrod, O., Barkan, E., Kurilshikov, A., Korem, T., Zeevi, D., … & Segal, E. (2018). Environment dominates over host genetics in shaping human gut microbiota. Nature, 555(7695), 210-215. https://doi.org/10.1038/nature25973 Zhernakova, A., Kurilshikov, A., Bonder, M. J., Tigchelaar, E. F., Schirmer, M., Vatanen, T., … & Wijmenga, C. (2016). Population-based metagenomics analysis reveals markers for gut microbiome composition and diversity. Science, 352(6285), 565-569. https://doi.org/10.1126/science.aad3369

Formulating skincare products is a process that combines different ingredients to provide targeted skin benefits. The type of product being used, the particular skin concern and the formulation's stability and effectiveness are some of the variables that can affect the formulation process.  Key Components of Skincare formulation: Choosing the right ingredients when formulating skincare products is important, as it determines the products effectiveness. Moreover, the chemical composition of the ingredients and their concentrations in a formulation is as important as it establishes its overall effect on our health. Most skincare products typically include 15 to 20 ingredients in their formulation (Goyal & Jerold, 2023). Water  Ultra-pure distilled water serves as the foundation for nearly every cosmetic formulation, including creams, lotions, makeup, deodorants, shampoos, and conditioners. It functions primarily as a solvent, helping to emulsify ingredients and ensure a smooth and consistent texture in the final product (Goyal & Jerold, 2023). Emulsifiers Promotes the formation of a homogenous and consistent texture in the formulation by encouraging the suspension of water and oil (Goyal & Jerold, 2023). Humectants Humectants are crucial for the skin's hydration balance, moisture retention, and desiccation prevention. Multiple hydroxyl, carboxyl, or other polar groups found in humectants have the ability to create hydrogen bonds with water molecules, which allows them to absorb and hold onto moisture (Du et al ., 2024). Thickeners Long carbon chains and polar groups like hydroxyl, carboxyl, and amide groups make up most of the thickeners. Within solutions, these long-chain structures increase the viscosity of the solution by increasing its resistance to flow (Du et al ., 2024). Preservatives Preservatives are added to prevent the growth of pathogenic and non-pathogenic microorganisms that could degrade the product or negatively impact the consumer's health De et al ., 2017). Active Ingredients Ingredients that offer therapeutic advantages and improve the efficacy of skincare products, such as hyaluronic acid, are used as active components in formulations (Morganti et al ., 2023). Therefore, selecting the appropriate active ingredient is crucial to creating a high-quality skin care product (Calixto & Maia, 2017).  Stability testing and sensory analysis The formulations afterwards need to be tested for its stability at different temperatures and sensory evaluation such as spreadability, cohesiveness, consistency, firmness and viscosity (Calixto & Maia, 2017).  Targeting microbiome with Skincare products Our skin is home to millions of microbial species called the Skin microbiome. A balance of all these microbes is crucial to obtain a healthy skin. Imbalances cause several skin problems such as acne, rosacea…etc. So when formulating skincare products it is important to investigate each ingredient's impact on the skin microbiome.  Conclusion It is of great importance to carefully consider the ingredients that are put into skincare formulations whilst considering the skin microbiome. Developing safe and efficient products is frequently the main goal, there is also a growing tendency towards customisation based on the demands of each individual's skin. This trend towards customised skincare highlights the value of customised solutions in the beauty industry and represents a deeper awareness of the various needs of various skin types and conditions. References Calixto LS, Maia Campos PMBG. Physical-Mechanical characterization of cosmetic  formulations and correlation between instrumental measurements and sensorial properties. Int J Cosmet Sci. 2017 Oct;39(5):527-534. doi: 10.1111/ics.12406. Epub 2017 Jul 24. PMID: 28555924. De Groot, A. C., & White, I. R. (2001). Cosmetics and Skin Care Products. Textbook of  Contact Dermatitis, 661–685. doi:10.1007/978-3-662-10302-9_32  Du XN, He Y, Chen YW, Liu Q, Sun L, Sun HM, Wu XF, Lu Y. Decoding Cosmetic  Complexities: A Comprehensive Guide to Matrix Composition and Pretreatment Technology. Molecules. 2024 Jan 15;29(2):411. doi: 10.3390/molecules29020411. PMID: 38257324; PMCID: PMC10818968. Goyal N, Jerold F. Biocosmetics: technological advances and future outlook. Environ Sci  Pollut Res Int. 2023 Feb;30(10):25148-25169. doi: 10.1007/s11356-021-17567-3. Epub 2021 Nov 25. PMID: 34825334; PMCID: PMC8616574. Morganti, P.; Lohani, A.; Gagliardini, A.; Morganti, G.; Coltelli, M.-B. Active Ingredients and  Carriers in Nutritional Eco-Cosmetics. Compounds  2023, 3 , 122-141. https://doi.org/10.3390/compounds3010011

Less is More approach Statistically, Women typically apply around 16 beauty products each day, exposing their skin to about 515 synthetic chemicals daily. (“The Average Woman Uses 16 Beauty Products Every Day. Here Are the Ones Worth the Investment,” 2018) This extensive exposure has led to a rise in skin sensitivity, which now affects 60-70% of women and 50-60% of men worldwide (Sensitive skins wear their own skin microbiota, 2024) - a number that continues to climb. To mitigate these effects, experts advise using fewer, essential ingredients and prioritising simple, balanced formulations over emphasising single "hero" ingredients. This holistic approach fosters skin compatibility, supporting healthier skin with reduced risk of irritation. Traditional vs Microbiome approach The traditional skin care approach highlights a single, "hero" ingredient or a blend of active ingredients to deliver specific benefits, with the spotlight on these components as the main drivers of product efficacy. However, a microbiome-focused approach takes a broader, more holistic perspective. It considers how each ingredient, including non-active additives (functional ingredients), interacts with the skin and its microbiome. This method aims to create formulations that support the skin's natural microbial balance, ensuring that every component contributes positively to overall skin health. Anhydrous Products Anhydrous products, with no water, do not require preservatives since bacteria need moisture to grow. However, they face challenges: incorporating water-soluble actives is difficult, and they are more prone to oxidation and rancidity. Their thick, oil-based consistency may also not suit all skin types, especially oily or sensitive skin. Despite these drawbacks, anhydrous formulations appeal to consumers interested in preservative-free, minimal skincare. Water-based Products Water in skincare products often makes up 80%, requiring emulsifiers to mix with oils and preservatives to prevent bacterial and fungal growth. To avoid contamination, effective preservation is essential. Instead of skipping preservation, reducing water activity can enhance product stability by limiting moisture, which is crucial for safer, less chemically intensive formulations. pH Maintaining a skincare formulation with a slightly acidic pH, ideally below 5, supports the skin's microbiome and barrier function. Alkaline cleansers with pH levels above 7 can disrupt the acid mantle, weakening the barrier and encouraging harmful bacteria. Hülpüsch et al. (2022) found that a higher skin pH (5.7–6.2) in atopic dermatitis patients is linked to increased Staphylococcus aureus colonisation, worsening inflammation and barrier issues. Acidic formulations may help control bacterial overgrowth, reducing flare-ups and promoting skin health in at-risk groups like those with AD. Ingredients Formulations that are high in lipids can strengthen the skin barrier, enhancing hydration and resilience against irritants. Combining gentle surfactants with super fatty agents further reduces potential for irritation and maintains moisture, which is particularly beneficial for sensitive skin types. These principles help prevent disruption of the microbiome, ensuring the skin remains balanced and resilient over time (Van Belkum et al., 2023). The selection of mildly acidic, pH-balanced ingredients close to the skin’s natural acidity (4.7 < pH < 5.7) is crucial, as it helps preserve the skin’s barrier and microbiome. Preservatives To protect the skin microbiome and reduce bacterial growth, it’s essential to minimise preservatives, especially in oil-based products. Anhydrous formulations, which don’t require preservatives, are ideal when possible. For water-based products, alternatives such as antimicrobial peptides (AMPs), and natural humectants like glycerin, sodium lactate, and NMF components (ceramide, urea), can improve microbial stability and skin barrier function (Halla et al., 2018). Airless packaging and sterilisation methods like UHT technology can further enhance product safety by minimising contamination, reducing the need for traditional preservatives. Surfactants Water-in-oil System: Choose emulsifiers with a low hydrophilic-lipophilic balance ratio and natural ingredients like plant oils or sugars. Limit emulsifier concentration to maintain skin barrier integrity. Avoid Polysorbate 80, which can promote pathogen growth, and use alternatives like Polyglyceryl 4 Oleate, which self-emulsify when mixed with water. Oil-in-water System: Use microbiome-friendly emulsifiers derived from natural sources like plant oils and sugars. Examples include Olivem 1000, made from olive oil (Cetearyl Olivate and Sorbitan Olivate), and Emulium Mellifera MB, which combines beeswax and jojoba wax (Polyglyceryl-6 Distearate and Jojoba Esters). These emulsifiers help maintain skin health while supporting the microbiome. It's also important to limit the concentration of emulsifiers to avoid disrupting the skin barrier. Fragrances/Essential Oils Fragrances should generally be avoided in skincare formulations, especially for sensitive skin, as many fragrances can cause irritation. However, certain essential oils may serve as antimicrobial agents in products for non-sensitive skin, offering a natural alternative to synthetic preservatives. For instance, bergamot and lavender oils demonstrate antibacterial and antifungal effects, particularly against Staphylococcus aureus, though they do not affect S. epidermidis  (Kim et al., 2022). Additionally, rosemary oil and phenylethyl alcohol show strong antifungal properties, adding preservative benefits without traditional preservatives. Reference Byrd, A. L., Belkaid, Y., & Segre, J. A. (2018). The human skin microbiome. Nature Reviews Microbiology, 16(3), 143-155.Halla, N., Fernandes, I. P., Heleno, S. A., Costa, P., Boucherit-Otmani, Z., Boucherit, K., Rodrigues, A. E., Ferreira, I. C. F. R., & Barreiro, M. F. (2018). Cosmetics Preservation: A Review on Present Strategies. Molecules, 23(7), 1571. https://doi.org/10.3390/molecules23071571 The average woman uses 16 beauty products every day. Here are the ones worth the investment. (2018, December 6). The Telegraph. https://www.telegraph.co.uk/beauty/face/essential-skincare-makeup-products-use-everyday/ Sensitive skins wear their own skin microbiota - BEAUTY HORIZONS 1 2021 WW. (2024, March 27). https://digital.teknoscienze.com/beauty_horizons_1_2021_ww/sensitive_skins_wear_their_own_skin_microbiota Hülpüsch, C., Tremmel, K., Hammel, G., Bhattacharyya, M., De Tomassi, A., Nussbaumer, T., Neumann, A. U., Reiger, M., & Traidl‐Hoffmann, C. (2020). Skin pH–dependent Staphylococcus aureus abundance as predictor for increasing atopic dermatitis severity. Allergy, 75(11), 2888–2898. https://doi.org/10.1111/all.14461 Van Belkum, A., Lisotto, P., Pirovano, W., Mongiat, S., Zorgani, A., Gempeler, M., Bongoni, R., & Klaassens, E. (2023). Being friendly to the skin microbiome: Experimental assessment. Frontiers in Microbiomes, 1. https://doi.org/10.3389/frmbi.2022.1077151 Nielsen, H. L., et al. (2016). Influence of emulsifiers on microbial stability in cosmetic formulations. International Journal of Cosmetic Science, 38(4), 357-366. https://doi.org/10.1111/ics.12301 Kim, J., et al. (2022). Antimicrobial effects of essential oils on skin microbiota. 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The skin microbiome is an intricate ecosystem of bacteria, fungi, and viruses that protect and maintain skin health (Smythe & Wilkinson, 2023). It acts as a defence against harmful pathogens, regulates inflammation, and supports the skin’s overall barrier function. However, disruptions to this microbiome can eventually lead to skin issues like acne, eczema, and various skin infections (Wallen-Russell, 2019). Understanding these disruptions is key to making informed choices about skincare, diet, and lifestyle to promote healthy skin. 1. Harsh Skincare Products Personal care products like soaps and lotions can disrupt the skin microbiome by removing natural oils and beneficial microbes. Many contain harsh chemicals, such as preservatives and fragrances, which reduce microbial diversity and promote the growth of harmful bacteria like Staphylococcus aureus. A study by Wallen-Russel (2018) found that synthetic ingredients generally lower the positive effects on skin biodiversity. Using essential, pH-balanced skincare products is recommended to maintain a healthy skin microbiome. 2. Antibiotics and Medications The use of antibiotics is a major disruptor of the skin microbiome. While antibiotics are essential for treating bacterial infections, their overuse or misuse can eliminate beneficial bacteria alongside harmful pathogens. This disruption can lead to a decrease in microbial diversity and the dominance of antibiotic-resistant bacteria, which may contribute to skin conditions like eczema and psoriasis. Studies have shown that prolonged antibiotic use can have lasting effects on the skin's microbial communities, making it more prone to dysbiosis and related diseases (Byrd et al., 2018). 3. Environmental Factors Environmental exposures are a major cause of skin microbiome disruption. Pollution, particularly airborne particulate matter and toxins, weakens the skin barrier and alters microbial diversity by causing oxidative stress and inflammation. This imbalance favours harmful microbes while reducing beneficial ones. Araviiskaia et al. (2019) found that chronic inflammatory skin conditions like eczema and psoriasis tend to worsen in individuals, including children, when exposed to high pollution levels. While moderate sun exposure is beneficial, excessive UV exposure can cause acute and chronic skin damage, including inflammation, premature ageing, and increased cancer risk. Patra, Sérézal & Wolf (2020) highlights how UV radiation disrupts the skin microbiome, potentially leading to dysbiosis and compromised skin health.  4. Diet and Lifestyle Diet and lifestyle choices can also direct the overall health of the skin microbiome. Ghosh, McMahon & Lappin (2021) revealed that a plant-based diet can positively influence the skin microbiome, reducing inflammation and oxidative stress, thereby supporting overall skin health. Conversely, diets high in processed foods and saturated fats can negatively impact the microbiome and lead to health issues, including skin conditions. 5. Stress and Hormonal Changes Stress can significantly impact the skin microbiome, primarily through hormonal and behavioural changes. Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, leading to increased production of cortisol and other stress hormones. This hormonal response can cause inflammation and immune dysregulation, which may exacerbate various skin conditions like psoriasis, eczema, and acne. Additionally, stress can lead to changes in behaviour, such as neglecting skincare routines or engaging in unhealthy habits (e.g., smoking, poor diet) that further disrupt the skin microbiome. (Holmes et al., 2015) Reference Araviiskaia, E., Berardesca, E., Bieber, T., Gontijo, G., Sanchez Viera, M., Marrot, L., Chuberre, B., & Dreno, B. (2019). The impact of airborne pollution on skin. Journal of the European Academy of Dermatology and Venereology : JEADV, 33(8), 1496–1505. https://doi.org/10.1111/jdv.15583 Byrd, A. L., Belkaid, Y., & Segre, J. A. (2018). The human skin microbiome. Nature Reviews Microbiology, 16(3), 143-155. https://doi.org/10.1038/nrmicro.2017.157 Ghosh , S., McMahon, A., & Lappin, D. F. (2021). The relationship between diet, gut microbiota, and skin health. Nutrients, 13 (5), 1568.  Holmes, C. J., Plichta, J. K., Gamelli, R. L., & Radek, K. A. (2015). Dynamic Role of Host Stress Responses in Modulating the Cutaneous Microbiome: Implications for Wound Healing and Infection. Advances in wound care, 4(1), 24–37. https://doi.org/10.1089/wound.2014.0546 Patra, V., Sérézal, I. G., & Wolf, P. (2020). Potential of Skin Microbiome, Pro- and/or Pre-Biotics to Affect Local Cutaneous Responses to UV Exposure. Nutrients, 12(6), 1795. https://doi.org/10.3390/nu12061795 Smythe, P., & Wilkinson, H. N. (2023). The skin microbiome: Current landscape and future opportunities. International Journal of Molecular Sciences, 24(4), 3950. https://doi.org/10.3390/ijms24043950 Wallen-Russell, C. (2018). The role of Every-Day Cosmetics in Altering the skin Microbiome: A study using biodiversity. Cosmetics, 6(1), 2. https://doi.org/10.3390/cosmetics6010002 Wallen-Russell, C. (2019). The impact of skin care products on skin chemistry and microbiome dynamics. BMC Biology, 17(1), 47. https://doi.org/10.1186/s12915-019-0660-6