The Effectiveness of Retinoids in the Treatment of Acne
9 November 2024 / 8 minutes read /
Men and women have always been influenced by gender differences from birth: the blue T-shirt for the boy, the pink one for the girl. These differences remain throughout life and are found even in products as basic as soaps and shavers.
We can't deny it, of course, men and women are different in many ways, and one of them is the skin, but understanding that each human body itself is diverse, are products intended only for men and only for women the real solution? Let's find out from science.
The skin is the largest organ of the body, with a surface area of at least 1.7 m2. Its primary function is to protect the body's internal environment from external aggressions, such as temperature, pressure, exposure to chemicals, radiation, and infections. The thickness, pigmentation, and appendages distribution vary depending upon the function and needs of each area.¹
First, let's talk about the skin structure. In general, it comprises three primary layers, from the most superficial to the deepest: epidermis, dermis, and hypodermis or subcutaneous layer.
It is the most superficial layer and is rich in cells, so rich that it also contains 5 layers of different cell types. About 95% of these are keratinocytes, a cell responsible for producing keratin, the protein that makes the skin firm and elastic.
The second most found cells are melanocytes. These pigment-producing cells transfer melanin to the keratinocytes to protect them from UV light and colour the skin.
Melanocytes are evenly distributed to form a UV-absorption blanket on the surface, reducing radiation penetrating the skin. Both melanocytes and the rest of the cells (Langerhans and Merkel) account for the remaining 5%.¹ ²
Of the five layers of the epidermis, the stratum corneum plays a key role because of its changes. The cells move from the innermost to the outermost, with the stratum corneum being the outer. As this migration takes place, there are changes in their shape and size so that when they reach the stratum corneum, they are flat, larger and full of keratin.
As these cells reach the surface, they overlap and become flatter and more tightly bound together like a network, and at the same time, they fall off like microscopic scales.
This cell migration process is known as the skin's turnover cycle.
This transit is necessary for the exchange of old and dead cells for new ones. It is like a natural exfoliation, and it takes the skin around 52 days to go through this entire process, but it varies from person to person being as short as 10 days in those with psoriasis.
Beneath the epidermis is the tough fibrous layer of the skin: the dermis. It consists of collagen fibres, elastic fibres, ground substance, fibroblasts, and cells with immune function, blood vessels, nerves and lymphatics. Quite full, isn't it?
Type I and III collagen fibres provide mechanical support, while elastic fibres contribute to the elastic recoil of the skin. Damage to the elastic fibres by sunlight (UV rays) is responsible for wrinkles in photo-ageing.
The ground substance supports collagen and elastic tissue, has a remarkable water-binding capacity, and aids in the nutrients passage, hormones and fluid molecules through the dermis. This zone is a gel-like material, transparent and colourless, that fills the spaces between fibres and cells.
This is the skin innermost layer composed of fat cells (lipocytes). These are organised into fat lobules separated from each other by fat bundles. In turn, the dermis fibres extend this far to join the two compartments.
The fat in this layer has an endocrine function, as it produces the hormone leptin to appetite regulation and energy metabolism control.
The skin is not only the layer that covers us; it also involves accessory structures with essential functions, such as the nails, hair follicles, and glands. Glands and hair follicles are the ones that matter most to us for now.
The adult human has two types of hair: terminal and vellus. The vellus are thin, short, and slightly pigmented, while the terminal hairs are thick, pigmented, and longer than the vellus, e.g., the scalp's hair, eyebrows, eyelashes, axillae, and pubis. Some of these are stimulated by androgens, such as the hair of the axillae, pubis, beard, and moustache in men, and its primary functions are protective and sensory.
The sebaceous and apocrine gland ducts open into the hair follicle shaft. Sebaceous glands are wherever there is hair, and together with the hair, form the pilosebaceous unit.
They are extended on the face, scalp, chest and back. Its leading role is to release sebum, a grease of lipids and triglycerides, to protect and lubricate the skin. This release depends on androgen hormones. That is why there are more oily faces and acne during puberty, and men tend to have greasy facial skin.
Then there are the apocrine glands, which open in the hair follicle below the sebaceous glands. These glands are found in some regions of the body; the axillae, anogenital, periareolar, and periumbilical areas. As the sebaceous ones, they are androgen-dependent glands responsible for sweating and skin moisture.
The skin appears to be different just in colour and age at first glance. However, there are differences between the two genders based mainly on hormones, so it could be said that the physiological skin change between women and men begins with puberty.
Let's start with hormones. Skin is a steroidogenic tissue: it metabolises sex hormones and responds to them. Female skin converts testosterone to oestradiol, where too much testosterone can lead to androgen-dependent alopecia or hirsutism. In men, beard growth and male pattern hair loss are suppressed when testosterone is removed.³
Eyebrows and eyelashes do not respond to sex hormones, whereas pubic, axillary and facial hair does. There is also a change in non-sex hormones. Men have higher cortisol levels than women, so they are under greater stress and may explain the delayed healing and more significant UV-induced immune damage.³
Due to hormonal influences, men have more facial hair than women. In fact, men have terminal hair forming the beard, while women have vellus hair. This explains why eunuchs (castrated men) have no beards but a lot of hair. Women with testosterone imbalances often develop masculinising syndromes such as hirsutism.
As mentioned above, the sebaceous (sebum-producing) glands are reactive to androgens. In the presence of high levels of androgens, such as testosterone, they increase in size and sebum production. Excess sebum also leads pores to open up, so men tend to have larger pore sizes with more sebum than women.
For example, a study found that sebum was twice higher in men than women, with 81.27% vs 47.83% respectively between 20-29 years.⁴ Moreover, sebum production remains stable in men throughout life, while it decreases in women over the years as they near menopause.
Male skin is, on average, 20% thicker than female skin due to its larger amount of collagen in the dermis. However, both men and women lose collagen linearly with age, first men starting in their 20s, and then women from 50 onwards.⁵ Again, this varies from person to person, and the difference may not be significant in some cases.⁶
Although the onset age is not well defined for both, the fact is that hormonal changes during women's reproductive life cause skin thickness to decrease near menopause.
Skin colour is given by melanin, blood and other pigments. The former is produced by melanocytes. Melanocytes remain the same in both genders, but men have a darker and less reflective complexion because they have more melanin and more blood vessels in the dermis than women.
Men experience more intense pigmentation after sun exposure and retain it longer than women, while women's skin lightens more quickly than men's.
One thing that can be highlighted is the effect of hormones on melanocytes. These have oestrogen receptors on their surface, so they respond to them.⁷
A common hyperpigmentation condition called melasma is more seen in women than in men, and one of the related factors is hormonal changes such as those induced by pregnancy, menopause or oral contraceptives. In contrast, little is known about melasma in men.⁸
No apparent differences in skin pH between men and women have been described. Some evidence shows that the female pH is lower (hence more acidic) than the male pH.⁹ Others show that these pH changes vary according to body area.¹⁰
Both men and women age at about the same time. Still, differences in hormones, facial thickness, lifestyle, and genetics are vital in determining who sees wrinkles first.
From everything discussed in this article, it would seem that men age last. But the evidence shows a balance between the two genders, even a tendency for men.
For example, a study in the Chinese population found that forehead wrinkles and crow's feet appear earlier and more pronounced in men.¹¹ In addition, men were perceived to be more than 10 years older than their actual age.
In contrast, marionette lines are more pronounced in both Chinese and Caucasian women.¹² Men do not share this pattern and tend to develop them older (50-54 years).
The truth is that comparing who ages first and who does not is ruled to many things. Besides that, ageing itself is influenced by many factors, especially stressful ones, where men have the upper hand.
It is bold to make a precise and accurate comparison between men and women, especially since we do not really know each other's lifestyle, diet, genetics and skincare habits. While men have thicker, more collagen-rich skin, it may be that constant shaving and exfoliative stress decreases its immune capacity and, in turn, collagen and elastin.
On the other hand, women tend to take more care of themselves, apply more products, and use more sunscreen. This may also influence why they do not see wrinkles first.
It's not that men need different products. It's just that the needs of both female and male skin differ significantly, even within themselves.
Understanding the skin diversity in terms of tone, sebum, hair, pH, immune function, and thickness, saying that a men's product will improve the male skin at some point, just because it is a men's product, is not valid.
Every skin is different and dermatological treatments should be focused on their needs and physiological differences. In theory, physiological changes linked to gender exist, but they vary broadly regarding the environment, genetics, and lifestyle. As the famous phrase says, ''correlation is not always causation''.
There may be women with very oily skin, even more so than some men, in which case a ''women's'' treatment would not work for them. Labelling products by gender is a commercial fallacy. Cosmetics have no gender but unique formulations depending on skin types, dermatological conditions and needs.
If men aged first and women later, what difference would a product intended only for women and for men make on this? The treatment should improve the signs of ageing, texture, blemishes and imperfections. That is the real goal.
In the end, what really matters are the active ingredients and their quality, not the packaging or the advertising behind them.
9 November 2024 / 8 minutes read /
9 November 2024 / 8 minutes read /
9 November 2024 / 8 minutes read /
9 November 2024 / 8 minutes read /
9 November 2024 / 8 minutes read /