Do moisturizers work?

Sensory neuron activation from topical treatments modulates the sensorial perception of human skin

Neural signaling of skin sensory perception from topical treatments is often reported in subjective terms such as a sensation of skin "tightness" after using a cleanser or "softness" after applying a moisturizer. However, the mechanism whereby cutaneous mechanoreceptors and corresponding sensory neurons are activated giving rise to these perceptions has not been established. Here, we provide a quantitative approach that couples in vitro biomechanical testing and detailed computational neural stimulation modeling along with a comprehensive in vivo self-assessment survey to demonstrate how cutaneous biomechanical changes in response to treatments are involved in the sensorial perception of the human skin. Strong correlations are identified between reported perception up to 12 hours post treatment and changes in the computed neural stimulation from mechanoreceptors residing deep under the skin surface. The study reveals a quantitative framework for understanding the biomechanical neural activation mechanism and the subjective perception by individuals.

Effects of oral intake fruit or fruit extract on skin aging in healthy adults: a systematic review and Meta-analysis of randomized controlled trials

Background

In recent years, oral various fruits or supplements of fruits natural extracts have been reported to have significant anti-aging effects on the skin (1, 2), However, despite many studies on this topic, there is often no clear evidence to support their efficacy and safety. In this paper, we present a comprehensive review and Meta-analysis of the evidence for the safety and efficacy of oral fruits and fruits extracts in improving skin aging.

Methods

Four databases, Pubmed, Embase, Web of Science, and Cochrane Library (CENTRAL), were searched for relevant literature from 2000-01 to 2023-03. Seven randomized controlled trials (RCTs) of fruit intake or fruit extracts associated with anti-skin aging were screened for Meta-analysis.

Results

Compared to placebo, oral intake of fruit or fruit extracts showed significant statistical differences in skin hydration and transepidermal water loss (TEWL), with a significant improvement in skin hydration and a significant decrease in TEWL. No significant statistical difference was observed in minimal erythema dose (MED), overall skin elasticity (R2), or wrinkle depth, and no evidence of significant improvement in skin condition was observed.

Conclusion

Meta-analysis results suggest that consume administration of fruits or fruit extracts significantly enhances skin hydration and reduces transcutaneous water loss, but there is insufficient evidence to support other outcome recommendations, including minimal erythema dose (MED), overall skin elasticity(R2), and wrinkle depth.

Systematic Review Registration

PROSPERO (york.ac.uk), identifier CRD42023410382.

Effectiveness of Dietary Supplement for Skin Moisturizing in Healthy Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

The dietary supplement industry offers many oral cosmetics that purportedly assist in skin moisturization often with unclear evidence supporting efficacy and safety. To update the accessible proofs pertaining to the safety and effectiveness of oral dietary supplements to facilitate skin moisturizing via an all-around review and meta-analysis.

Methods

Three on-line databases [Pubmed, Embase, and Cochrane Library (CENTRAL)] were retrieved from January 2000 to November 2021. An overall 66 randomized controlled trials (RCTs) of skin care were recognized. Meta-analysis was performed for dietary supplements with four or more available research.

Results

Oral collagen or ceramide resulted in a statistically significant increase in skin hydration and a decrease in transepidermal water loss (TEWL) compared to placebo. No benefits regarding the improvement of skin conditions in terms of water content and TEWL were observed for lactic acid bacteria or Lactobacillus fermented foods. A statistically significant and positive effect on skin hydration was observed for both hyaluronan and procyanidin, with an unknown effect on TEWL due to insufficient RCTs. There was a non-significant improvement in the water content of stratum corneum for astaxanthin based on subgroup analyses. Among the dietary supplements trialed in ≤ 3 RCTs, the judgment regarding their effects on skin moisturizing was prevented by inconsistent conclusions as well as insufficient research. All food supplements were safe throughout the research (normally ≤ 24 weeks).

Conclusion

Oral dietary supplements, including collagen, ceramides, hyaluronan, and procyanidin, were proven to be effective for skin moisturization. At present, for skin moisturization, the proofs supporting the recommendation of other dietary supplements, such as lactic acid bacteria and astaxanthin, are insufficient.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/ identifier CRD42021290818.

A consistent skin care regimen leads to objective and subjective improvements in dry human skin: investigator-blinded randomized clinical trial

BACKGROUND

Dry, itchy skin can lower quality of life (QoL) and aggravate skin diseases. Moisturizing skin care products can have beneficial effects on dry skin. However, the role of a daily skin care routine is understudied.

OBJECTIVE

To understand how daily skin care with a mild cleanser and moisturizer impacts skin health and patients' QoL, in dry skin population.

METHODS

A randomized, investigator-blinded study of 52 participants with moderate to severe dry skin. The treatment group (n = 39) used mild cleanser and moisturizer twice daily for two weeks whereas the control group (n = 13) used mild cleanser without moisturizer. Total Clinical Score (TCS; erythema, scale and fissures), Visual Dryness Score (VDS) and subjective itch-related quality of life (ItchyQoL) were collected.

RESULTS

The treatment group showed significantly more improvement in TCS and VDS compared to the control group after two weeks. Among the three components of the ItchyQoL (symptoms, functioning, and emotions), symptom showed significantly greater improvement in the treatment compared to the control group. Over 80% of participants in the treatment group agreed that the regimen led to decrease in dryness/pruritus and improved skin texture.

CONCLUSIONS

A consistent skin care regimen should be an integral component of management of dry skin.

Safety and efficacy of Sclerocarya birrea (A.Rich.) Hochst (Marula) oil: A clinical perspective

ETHNOPHARMACOLOGICAL RELEVANCE

Sclerocarya birrea (A.Rich.) Hochst (Marula) nut oil is a popular ingredient in cosmetics such as skin lotions, lipsticks and foundations. The demand for this African oil increased tremendously such that in 2008 almost US$ 20 million was spent on Marula oil for cosmetic product manufacturing. The ethnobotanical literature states that the Zulu people in South Africa amongst others applied the oil to maintain a healthy skin. Scientific studies to support the traditional use as well as the inclusion of Marula oil in cosmetic products is lacking. This study evaluated the irritancy potential (safety), the moisturising and hydrating effects as well occlusivity properties (efficacy) of Marula oil after topical application. In addition, the Marula oil used in this study was comprehensively characterised using two-dimensional gas chromatography coupled to mass spectrometry.

METHODS AND MATERIALS

Quantification of the fatty acid methyl esters (FAMEs) was done using a LECO Pegasus 4D GC × GC-MS. To determine the safety and efficacy of Marula oil healthy caucasian adult female volunteers (n = 20) who complied with the inclusion and exclusion criteria for the irritancy patch, moisture efficacy, hydrating and occlusivity tests were recruited for each study. A 2 × magnifying lamp (visual observation), Chromameter®, Aquaflux® and Corneometer® instruments were used to evaluate and monitor the irritancy level, skin barrier function, transepidermal water loss, hydrating and occlusive effects of topically applied Marula oil.

RESULTS

The GC × GC-MS analysis identified several saturated as well as unsaturated fatty acids. Oleic acid was the major fatty acid constituting 69.0% of the oil followed by palmitic acid (15.3%), linoleic acid (9.2%), palmitoleic acid (4.1%) and stearic acid (1.5%). The clinical study revealed that Marula oil is non-irritant (p < 0.001), with moisturising and hydrating properties (p < 0.001) when applied to a lipid-dry (xerosis) skin. Additionally the oil exhibited occlusive effects (p < 0.001) when applied to normal skin. These findings may be linked to the absorption of the oil into the skin due to the high percentage of oleic acid and the presence of palmitic acid which are known to disturb the stratum corneum intercellular lipids. These fatty acids present in Marula oil are very similar to those present in the epidermis, and can be considered biomimetic.

CONCLUSIONS

Marula oil rich in fatty acids exhibits moisturising, hydrating and occlusive properties. As the oil is non-irritating and provides a moisturising effect with moderate prevention of transepidermal water loss, average moisture retention properties and noteworthy occlusive effects, its inclusion in cosmetic products based on its traditional use may be justified depending on the application.

Conditioned medium from human bone marrow-derived mesenchymal stem cells promotes skin moisturization and effacement of wrinkles in UVB-irradiated SKH-1 hairless mice

BACKGROUND

Mesenchymal stem cells (MSCs) are promising therapeutic agents for various diseases.

AIMS

To investigate the effects of conditioned medium from human bone marrow-derived mesenchymal stem cells (MSC-CdM) on pro-collagen production and wrinkle formation, we performed in vitro and in vivo experiments.

METHODS

We assessed the effects of MSC-CdM on proliferation and photo-aging in human dermal fibroblasts after UVB exposure using enzyme activity assays for collagen type I secretion and MMP-1. To determine the effect of topically applied MSC-CdM on wrinkle formation, MSC-CdM (1% and 10%) and vehicle (propylene glycol: ethanol, 7 : 3) were applied to the dorsal skin of UVB-irradiated hairless mice for 8 weeks. We examined the effects on wrinkle formation by assessing visual skin grading, replica, tape stripping, transepidermal water loss (TEWL), and skin hydration measurement. We also examined histology of the lesions using hematoxylin-eosin, Masson's trichrome, and immunohistochemical staining.

RESULTS

MSC-CdM markedly reduced UV-induced matrix metalloproteinase-1 expression and increased pro-collagen synthesis in a dose-dependent manner. Our findings suggest that MSC-CdM induces repair of dermal damage and effacement of wrinkles on UVB-irradiated hairless mice through protective effect of hydration.

CONCLUSION

These results support an anti-wrinkle effect of MSC-CdM that involves increased collagen synthesis and suggest that MSC-CdM might be a potential candidate for preventing UV-induced skin damage.

Guidelines for diagnosis, prevention and treatment of hand eczema

The guidelines aim to provide advice on the management of hand eczema (HE), using an evidence- and consensus-based approach. The guidelines consider a systematic Cochrane review on interventions for HE, which is based on a systematic search of the published literature (including hand-searching). In addition to the evidence- and consensus-based recommendation on the treatment of HE, the guidelines cover mainly consensus-based diagnostic aspects and preventive measures (primary and secondary prevention). Treatment recommendations include non-pharmacological interventions, topical, physical and systemic treatments. Topical corticosteroids are recommended as first line treatment in the management of HE, however continuous long-term treatment beyond six weeks only when necessary and under careful me-dical supervision. Alitretinoin is recommended as a second line treatment (relative to topical corticosteroids) for patients with severe chronic HE. Randomized control trials (RCT) are missing for other used systemic treatments and comparison of systemic drugs in “head-to-head” RCTs are needed.The guidelines development group is a working group of the European Society of Contact Dermatitis (ESCD) and has carefully tried to reconcile opposite views, define current optimal practice and provide specific recommendations, and meetings have been chaired by a professional moderator of the AWMF (Arbeitsgemeinschaft der Wis-senschaftlichen Medizinischen Fachgesellschaften; Association of the Scientific Medi-cal Societies in Germany).No financial support was given by any medical company. The guidelines are expected to be valid until December 2017 at the latest.

The Counterbalance of Skin Metabolism on Orbits and Diseases

Human organ functions are regulated by the nervous system. When human cells receive a message, this message is transmitted to the nervous system through a series of signal transmission processes. Skin conditions that occur after applying skin cream are closely related to signal transmission and nervous regulation. We determined the connection between signal regulation and natural rhythmic operations. The diurnal variations resulting from the earth’s rotation and indicate the relative relationships between the sympathetic nervous system and the parasympathetic nerve system. A spectrum was developed to assess neural transmission conditions by using skin signals which from Fourier transformation of the waves and established the association between the spectrum and diseases. The results could explain the relationships between the neurological illnesses and established spectrum. The objective was to promote the use of this spectrum as a new tool for conducting the nervous system tests in the future.

Moisturizing effect of a cosmetic formulation containing pequi oil (Caryocar brasiliense) from the Brazilian cerrado biome

Caryocar brasiliense, popularly known in Brazil as “pequi”, is a species widely distributed in the Brazilian Cerrado. The seeds are surrounded by a woody endocarp coated with a yellow fleshy mesocarp rich in oil and vitamin A, whose oil has a useful role in the treatment of skin aging and protection of human skin against UV-induced damage and skin hydration. The aim of this study was to evaluate the effect of cosmetic formulations containing pequi oil (Caryocar brasiliense) on skin hydration, after a single application. Hydration effect assessment was performed by applying the formulations under study (Control – no formulation, vehicle, and vehicle + pequi oil) onto forearm skin of 30 human volunteers. Skin capacitance and Transepidermal Water Loss (TEWL) measurements were analyzed before, and at 1, 2 and 3 hours after, a single application. Evaluation results of a single application of the vehicle containing pequi oil showed an increase in stratum corneum water content, indicating a skin moisturizing effect. Results of the evaluation of immediate effects of TEWL demonstrated that the vehicle containing pequi oil significantly increased skin moisture during the 3 h evaluation period. The formulations containing pequi oil showed clinical efficacy, increasing stratum corneum water content and enhancing skin barrier function.

The infant skin barrier: can we preserve, protect, and enhance the barrier?

Infant skin is different from adult in structure, function, and composition. Despite these differences, the skin barrier is competent at birth in healthy, full-term neonates. The primary focus of this paper is on the developing skin barrier in healthy, full-term neonates and infants. Additionally, a brief discussion of the properties of the skin barrier in premature neonates and infants with abnormal skin conditions (i.e., atopic dermatitis and eczema) is included. As infant skin continues to mature through the first years of life, it is important that skin care products (e.g., cleansers and emollients) are formulated appropriately. Ideally, products that are used on infants should not interfere with skin surface pH or perturb the skin barrier. For cleansers, this can be achieved by choosing the right type of surfactant, by blending surfactants, or by blending hydrophobically-modified polymers (HMPs) with surfactants to increase product mildness. Similarly, choosing the right type of oil for emollients is important. Unlike some vegetable oils, mineral oil is more stable and is not subject to oxidation and hydrolysis. Although emollients can improve the skin barrier, more studies are needed to determine the potential long-term benefits of using emollients on healthy, full-term neonates and infants.

Effectiveness of skin protection creams in the prevention of occupational dermatitis: results of a randomized, controlled trial

OBJECTIVES

The aim of the trial was to investigate whether the publicized effects of skin protection creams can be replicated in a real occupational setting during activities that expose the skin.

METHODS

A prospective, randomized, four-tailed controlled pilot trial was performed to compare the effect of skin protection and skin care alone or in combination with cleansing against a control group (only cleansing). Two branches were selected for the investigation: the building industry and the timber industry. A total of 1,006 workers from these two branches were recruited, and out of these 485 workers were examined longitudinally for at least three time points over 1 year (lost for follow-up: 430 workers, exclusion: 91 workers). At each time point, as a primary outcome measure, we assessed the condition of the skin at both hands in a blinded manner and the individual was assigned to one of the following categories: no eczema, mild, moderate and severe eczema. As a secondary outcome measure, the worker's transepidermal water loss (TEWL) was measured under standardized conditions at the back of both hands. In addition, the workers were asked to evaluate their skin condition during the study.

RESULTS

With regard to differences in the occurrence of eczemas, we found only in workers in building industry without application of skin protection or skin care creams a statistical significant increase in the incidence between the first and the second visit and a statistical significant decrease in the incidence between the second and third visit. When evaluating the secondary outcome-measurement changes in the TEWL values, an improvement was found for the group skin protection and skin care in combination and by skin care alone. Females in the timber industry started with better TEWL values than males, which may be due to better overall skin care. In this group we found an improvement for the group skin protection and skin care in combination and by skin protection alone. For skin protection alone, we noted a slight, but not significant improvement in all other groups. The subjective improvement of skin condition was reported from the participants who used skin protection and skin care in combination.

CONCLUSIONS

Taking all these secondary-outcome measurements together, the main result of this study was that skin protection creams alone have a small effect on the skin barrier in workers in the building and timber industries compared with skin care alone or in combination with skin protection.

Changes in skin barrier function following long-term treatment with moisturizers, a randomized controlled trial

BACKGROUND

Moisturizers are commonly used by patients with dry skin conditions as well as people with healthy skin. Previous studies on short-term treatment have shown that moisturizers can weaken or strengthen skin barrier function and also influence skin barrier recovery. However, knowledge of the effects on skin barrier function of long-term treatment with moisturizers is still scarce.

OBJECTIVES

To investigate the impact of long-term treatment with moisturizers on the barrier function of normal skin, as measured by transepidermal water loss (TEWL) and susceptibility to an irritant, and to relate those effects to the composition of the designed experimental moisturizers.

METHODS

Volunteers (n = 78) were randomized into five groups. Each group treated one volar forearm for 7 weeks with one of the following preparations: (i) one of three simplified creams, containing only a few ingredients in order to minimize the complexity of the system; (ii) a lipid-free gel; (iii) one ordinary cream, containing 5% urea, which has previously been shown to decrease TEWL. The lipids in the simplified creams were either hydrocarbons or vegetable triglyceride oil, and one of them also contained 5% urea. After 7 weeks, treated and control forearms were exposed for 24 h to sodium lauryl sulfate (SLS) using a patch test. TEWL, blood flow and skin capacitance of both SLS-exposed and undamaged skin were evaluated 24 h after removal of patches. Additionally, a 24-h irritancy patch test of all test preparations was performed on 11 volunteers in order to check their possible acute irritancy potential.

RESULTS

Changes were found in the barrier function of normal skin after 7 weeks of treatment with the test preparations. The simplified creams and the lipid-free gel increased TEWL and skin response to SLS, while the ordinary cream had the opposite effect. One of the simplified creams also decreased skin capacitance. All test preparations were shown to be nonirritant, both by short-term irritancy patch test and by measurement of blood flow after long-term treatment.

CONCLUSIONS

Moisturizers influence the skin barrier function of normal skin, as measured by TEWL and susceptibility to SLS. Moreover, the effect on skin barrier function is determined by the composition of the moisturizer. The ingredients which influence the skin barrier function need to be identified, and the mechanism clarified at the molecular level.