The Science Behind Every Step of Your Skincare Routine


The Science Behind Your Skincare Routine

When it comes to skincare, it can be easy to get overwhelmed. Your skin does a lot of different jobs for your body, and its needs can vary depending on where on your body it is located. Add to this the wide variety of products and treatments available on the market today, and the amount of information on how skincare works will quickly become mentally paralyzing.

To create a truly effective skincare routine, learning more about the science behind how your skin works and what it needs to look and feel its best can be very helpful. In this guide, we're taking a deep dive into the intricate science behind skincare, exploring how your skin, skincare ingredients, and the aging process each influence each other. We'll also debunk harmful skincare myths and take a look at the chemistry of skincare and how products affect your skin, giving you the power to make informed decisions about the health of your skin.

Skin Anatomy

To begin, let's look at the structure and biology of the skin itself. More than just an external covering for your body, the skin is actually a complex organ that carries out various functions every day to keep your body healthy. Skincare science begins with a closer look at your skin's anatomy.


The epidermis is the outermost layer of your skin. This is your body's first line of defense against outside threats, acting as a protective barrier. The epidermis itself is also split into several sub-layers:

Stratum Corneum

As the outermost layer of the epidermis, the stratum corneum is where dead skin cells shed away from the body and are replaced by younger cells underneath.

Stratum Corneum

As the outermost layer of the epidermis, the stratum corneum is where dead skin cells shed away from the body and are replaced by younger cells underneath.

Stratum Lucidum

Only present in the palms of the hands and the soles of the feet, the stratum lucidum provides friction-reducing padding between the corneum and granulosum.

Stratum Granulosum

The stratum granulosum is responsible for producing fatty oils that help to waterproof the skin.

Stratum Spinosum

This is where the skin cells gain more structural integrity through a process called keratinization. Cells called keratinocytes produce keratin, a tough and fibrous protein that gives the skin more strength and protection. The keratinocytes in the stratum spinosum also play a crucial role in the body's immune system defenses and healing from injuries. In response to an infection or broken skin, keratinocytes and other cells will also release defensins. This peptide protein helps combat the spread of microbes and contributes to wound healing in the skin by stimulating LGR6+ stem cells in the stratum basale.

Stratum Basale

The stratum basale, or basal cell layer, is the deepest part of the epidermis, where new skin cells are born through cellular division. Epidermal stem cells, continuously dividing and creating a wide range of differentiating daughter cells, will first create basal cells. Basal cells are the beginning stage of cell differentiation, where skin cells gradually change and evolve into their specialized roles within the skin. These new cells will gradually move upward through the layers before being sloughed off as dead skin cells in the stratum corneum.


Beneath the epidermis lies the dermis. This is the home of some crucial components, such as collagen, which provides a strong structure; elastin, which ensures skin elasticity; and blood vessels, which nourish the skin with nutrients. The dermis also anchors the epidermis in place with finger-like protrusions known as dermal papillae.


Finally, we reach the hypodermis or subcutaneous tissue. This is a fatty layer of tissue that provides the body with temperature insolation and a good amount of shock absorption. The hypodermis also contains many blood vessels and nerves.

Now that we have an in-depth view of anatomy and skin science, let's look at some common conditions and what causes them.

What Causes Skin Conditions?

Skin conditions like acne, rosacea, and hyperpigmentation can be influenced by various factors.


Acne appears on the skin when hair follicles or sebaceous glands become blocked with skin oils or dead skin cells. These clogs irritate the skin, which can lead to infection and inflammation.

Some of the major factors that contribute to acne developing on the skin include:

  • Excess sebum: Sebum is a fatty substance produced by your skin's sebaceous glands. In healthy amounts, sebum is vital for keeping your skin moist, assists in immune functions, and even acts as a natural sunscreen to block some UV radiation. However, when produced in excess amounts, sebum can clog the hair follicles in your skin.
  • Bacteria: Bacteria such as Propionibacterium acnes (P. acnes) live on the skin naturally. However, inside a clogged hair follicle, P. acnes can thrive, overgrowing within the follicle and causing inflammation and infection.
  • Inflammation: As the body recognizes the presence of bacteria, an immune response kicks in to address the problem, causing swelling, redness, and pus to develop.
  • Hormones: Fluctuations in the body's hormone production can cause the skin to produce more sebum and lead to a breakout. Puberty, menstruation, pregnancy, and hormonal birth control can all change your skin's sebum production and create an environment prone to acne.
  • Genetics: Acne also has a strong genetic component. Though most people experience some acne throughout their life, its severity often runs in families. Depending on your family's history with acne, your genes can make you more or less prone to breaking out.
  • Diet and Lifestyle: Though they aren't the main causes of acne, poor diet and lifestyle can make acne worse for some people. Diets high in dairy, sugar, and overly processed food can contribute to acne, and so can other factors like stress and sleep deprivation.


A chronic skin condition that mostly affects the face, rosacea often manifests in a spotty redness in the skin, with blood vessels below the surface being visible. People with rosacea will also sometimes develop acne-like bumps in the affected areas but without the typical blackheads or whiteheads of acne.

While rosacea is often more visible on fairer skin, it also occurs on darker skin, often being misdiagnosed for a couple of reasons. For one, the melanin in the skin can mask the redness, making the patches of skin affected look violet, purple, or a darker shade of brown than the person's natural skin tone. Second, rosacea often presents on people with darker skin in the form of bumps or pimples, which can cause a misdiagnosis.

While scientists are still studying rosacea and its causes, there are a handful of factors that are believed to be big contributors, such as:

  • Abnormal blood vessels: The blood vessels of the face may have expanded slightly in people with rosacea, which causes patches of redness or discoloration as well as making the veins visible through the skin.
  • Immune system response: An abnormal immune response to an environmental factor can be associated with the onset of rosacea.
  • Demodex mites: Demodex mites are microscopic organisms that naturally live on human skin. It's possible that those with rosacea have more mites than typical on their skin.
  • Triggers: While not the root cause of rosacea, there are many triggers like sunlight, heat, alcohol, stress, spicy foods, and even some skincare products that can temporarily worsen rosacea symptoms.


Hyperpigmentation is a fairly common condition that causes spots or patches of the skin to produce more melanin than the surrounding areas, resulting in some parts of the skin being darker than the skin around them. Freckles are a type of hyperpigmentation, but it can also manifest in larger patches or disruptions to the natural skin tone. For the most part, hyperpigmentation tends to be harmless, and people who experience it usually don't experience other harmful symptoms. However, some individuals are unhappy with their hyperpigmentation from a cosmetic standpoint.

Some causes and contributing factors of hyperpigmentation include:

  • Sun exposure: UV radiation causes the skin to create more melanin as a protective measure. This is the same mechanism that causes skin to tan. However, it can sometimes affect the skin unevenly, resulting in hyperpigmentation.
  • Hormone changes: As hormones fluctuate due to pregnancies, menopause, or as a result of birth control, some people may develop melasma, which is hyperpigmentation that manifests as brown or grayish-brown patches, often on the face.
  • Inflammation: Other conditions that cause inflammation, such as acne, might result in increased melanin in the affected areas, known as post-inflammatory hyperpigmentation.
  • Genetics: Freckles and other hyperpigmentation can be more common in those who are genetically more prone to developing them.
  • Medications: Some medications, including antimalarial drugs and certain types of antibiotics, can make the skin more sensitive to sunlight, which in turn makes the skin more susceptible to hyperpigmentation.

What Causes Changes in Aging Skin?

Aging is a natural process that everybody goes through. After maturing to adulthood, most human bodies will gradually slow down in function, and the functions of the skin are no different. Aging is an unavoidable part of life, and everyone who ages will experience changes in their skin's overall health and structure on some level. However, some factors can cause aging to take more of a toll on your skin, affecting both its health and cosmetics more than necessary.

  • Sun damage: UV exposure is a major contributor to how your skin ages. When your skin cells are exposed to the sun's radiation, it can cause damage to some of the genetic information contained in those cells, making it more difficult for them to divide and create new cells properly and fine lines and wrinkles can occur prematurely. Additionally, the sun can trigger excess melanin production, resulting in hyperpigmentations, like age spots.
  • Genetics: As with many things, genes can determine a lot about how your skin ages, and its overall health in various stages of life. If possible, take a look at how your older family has aged or are currently aging. Though it might not be a one-to-one prediction of your own health, it might tell you a little about the unique skincare challenges your family experiences, and what to be prepared for.
  • Collagen and elastin loss: As people age, the collagen and elastin that their skin produces will naturally decrease. Since these are responsible for the skin's structure and elasticity, having less of these within the skin can cause the skin itself to sag.
  • Smoking: Smoking and other substance abuse problems can accelerate skin aging. This is due to various aspects of smoking and the effects it has on the skin. For one, smoking reduces the production of collagen and elastin, and constricts blood flow, resulting in sagging skin that isn't replenished with enough oxygen or nutrients. Additionally, long-term exposure to the toxic chemicals of tobacco smoke can damage the skin itself.
  • Poor diet: If your body isn't receiving enough of the nutrients it needs, the skin's elasticity and health can suffer. Similarly, eating unhealthy and harmful foods can damage the skin over time.
  • Environmental toxins: Pollutants and toxins in the air and surrounding environment can be harmful to the skin and other parts of the body, and exposure to those pollutants can contribute to premature aging.

Now that we've taken a look at some of the science behind skincare issues, let's explore a little further into the various skincare ingredients that are commonly used and see how you can use them effectively to battle your own skincare issues.

How Skincare Ingredients Combat These Issues

The ingredients you use to address your skin concerns are one of the most important aspects of skincare science. Before using a skincare product, it's important to have a basic understanding of how its ingredients will interact with your skin and what each ingredient is for.

Penetrating the Skin Barrier

The skin has a layer of lipids (fats) and skin cells that keep contaminants like bacteria and pollution out while keeping the skin's moisture in. While this is mostly beneficial, that means that some skincare ingredients will just sit on top of the skin, affecting only the outermost layers. However, if you get certain ingredients involved, such as retinoids, then the skincare ingredients can penetrate deeper into the skin, providing benefits to the cells that lie beneath instead of just the top layers.


Cleansers are a basic tool in skincare routines that no one should be without. By removing dirt, excess oil, and pollutants from your skin, you can prevent a lot of irritation, blockage, or other damage from occurring in the first place and give yourself a clean canvas for the rest of your skincare regimen. It's important that you choose the right cleanser for your skin type. Depending on how dry or oily your skin is, you'll need a cleanser that is formulated especially for cleaning skin like yours.

Also, depending on how oily your skin is and how much makeup and sunscreen you tend to use, it can also be smart to double-cleanse your skin. This entails a two-step process, first using an oil-based cleanser or micellar water to dissolve makeup, sunscreen, and excess oils, loosening them from the skin. Next, a water-based cleanser can remove any impurities and clean the skin deeply. Double cleansing is a popular method of ensuring clean skin, especially if you tend to wear more makeup and sunscreen.

DefenAge's luxurious, hydrating 1-Step Multi Cleanser is not only perfect on its own, but great as part of a double cleanse routine.


A toner is meant to balance the pH level of the skin and allow it to better accept other skincare products. Toners are essentially nutrient-rich liquids that allow your skin to better absorb other products.


A good moisturizer will not only hydrate the skin but will also seal in the moisture, helping the functions of your skin's natural barrier along the way. Moisturizers should also be tailored to your skin type, as different people will have varying moisture needs for their skin.

Check out the 24/7 Barrier Balance Anti-Aging Cream from DefenAge's skincare line. This intense hydrating cream is infused with Age-Repair Defensins®, multi-action barrier balancing ingredients and skin brightening skincare actives that work together to regenerate and rejuvenate the appearance of skin.


Sunscreen is a vital part of skincare. With UV radiation being one of the most common and potentially harmful forces that your skin comes up against, it's important to be prepared for it whenever possible. Sunscreen can work in one of two ways:

  • Chemical Filters: Ingredients like avobenzone, octisalate, or oxybenzone allow sunscreen to absorb most of the UV radiation and chemically convert it into low levels of heat, turning the possible damage of UV radiation into a harmless heat energy.
  • Physical Filters: Ingredients like zinc oxide and titanium dioxide work by providing a physical barrier against UV radiation. By scattering and reflecting the UV rays away from the skin, they prevent most of the radiation from reaching the skin in the first place.

Defensins Science

DefenAge is committed to science-based skincare. Our goal is to deliver real results without making unreasonable or sensational claims.

One of our unique approaches involves using a promising and science-based skincare solution that harnesses defensins. Defensins are naturally occurring molecules that help to promote skin rejuvenation. Here's a closer look at how defensins can be used for skincare.

Science Before Marketing

First, let's take a closer look at what defensins are and how they work. Defensins are small natural molecules found both in white blood cells and within the skin and mucous membranes of the body. They are a crucial part of the body's immune system and are at the front line of the body's defenses. The body holds a backup copy of the younger skin within LGR6+ cells, which can be triggered by defensin molecules to regenerate cells and repair the skin, allowing a smooth, youthful appearance.

The human body has two main types of defensins:

  • Alpha-defensins: Usually found in white blood cells, alpha-defensins are released in response to infections, and more importantly, they trigger a wound-healing regenerative response.
  • Beta-defensins: Beta-defensins are more commonly found in the skin and mucous membranes. Various different types of cells produce beta-defensins, including certain skin cells. Beta-defensins have antimicrobial properties and play a vital role in regulating skin barrier function and its integrity.

Defensins do not cause inflammation or sun-sensitivity.

Defensins are proven to reduce global signs of aging and spark a wound-healing response in the skin, which makes them one of the most powerful anti-aging technologies available and perhaps the greatest breakthrough in skincare since retinol.

Research has shown that both alpha- and beta-defensins play crucial roles in the skin's overall health and aiding in its regeneration.

Multiple scientific and clinical studies have shown that Defensins can trigger a regenerative response in the skin, similar to the natural healing process our bodies undergo as wounds heal. You may have noticed before that as scratches or wounds on your skin heal, the skin that regenerates in that area appears newer and younger than the skin around it. That’s because the body has mobilized dormant cells in order to regenerate brand-new skin to repair the wound. Topical application of defensins allows that same mechanism to activate, helping your body to produce new and younger-looking skin without a wound.

The DefenAge line of products uses defensins to rejuvenate the look of the skin and address many of the telltale signs of aging.

The Ingredients of Skincare

The effectiveness of your skincare routine is greatly dependent on the ingredients you choose to use. Let's look at the chemistry of skincare, what ingredients you need, what you should stay away from, and the best ways to pick safe ingredients.


Some skincare ingredients are crucial in addressing the most common skin conditions. Here are some of the most useful skincare ingredients to add to your arsenal and some clever ways to use them in your skincare routine.

  • Hyaluronic acid (HA): Hyaluronic acid is a great way to help your skin retain moisture, allowing it to have a fuller, more youthful appearance.
    • If your skin is particularly dry, try combining HA with other hydrating ingredients, including glycerin and ceramides, to maximize your skin's moisture.
  • Retinoids (vitamin A derivatives): Retinoids penetrate deeply into the skin to stimulate skin cell turnover to help shed dead skin cells from the surface and promote collagen production. This allows you to fight a variety of skin conditions, from acne and uneven skin tone to fine lines and wrinkles.
    • During the day, try pairing retinoids with sunscreen and adding a moisturizer at night to combat dryness.
  • Vitamin C: By helping slough off patches of dead skin, vitamin C helps to brighten your complexion while also boosting collagen production and absorbing free radicals.
    • Using vitamin E alongside vitamin C, you can add to the antioxidant benefits.
  • Niacinamide (vitamin B3): Niacinamide plays various roles in a skincare routine, from addressing enlarged pores and fine lines to smoothing out uneven skin tones.
    • Try incorporating niacinamide into your routine in tandem with peptides like defensins to enhance the anti-aging benefits.
  • Sunscreen: Sunscreen keeps your skin safe from harmful UV radiation, which can cause a variety of problems, from premature aging to skin cancer. It's recommended to use a broad-spectrum sunscreen with at least SPF 30 whenever you go out during the daytime, even when the sky is overcast.

What to Avoid

Equally important to what you do use is what you stay away from. Here are some healthcare products and ingredients to think twice about.

  • Harsh physical scrubs: Products that include large, abrasive particles or harsh physical exfoliants may be risky to use. Going past merely removing dead skin, these products can damage the protective barrier of the skin.
  • Scented products: Skincare products with added fragrances may use ingredients that can trigger allergies or irritate the skin. If your skin is particularly sensitive, try unscented options instead.
  • Alcohol-based products: Alcohol in high amounts can dry out and irritate the skin. Especially when looking for products like toners or moisturizers, keep an eye out for alcohol-free alternatives.
  • Parabens and phthalates: Studies have suggested that parabens and phthalates can disrupt the balance of your body's hormones. Try skincare products labeled "paraben-free" and "phthalate-free".

Choosing Safe Ingredients

To pick skincare ingredients that are the best for your skin, it's important to be certain of your own particular needs and aware of what you're putting on your body.

  • Consult a dermatologist: If you have any concerns related to your skin and the best ways to treat them, it's always a good idea to speak with your dermatologist. Their experience and expertise can go a long way to addressing important health concerns and giving your skin the best care you can give it.
  • Know your skin type: Is your skin oily, dry, combination, or sensitive? Many skincare products are designed specifically with these distinctions in mind, and using a product that isn't formulated for your skin type can be irritating to the skin.
  • Patch testing: Before diving in and incorporating a new product directly into your skincare routine, try testing it on a small patch of skin first. This can give you a better idea of whether your skin will react negatively, helping determine if it's safe for you to use.
  • Read labels: If you know that you're allergic or sensitive to certain products, pay attention to the ingredient lists and compare them to any new products you try to incorporate.
  • Start gradually: Above all, it's important not to change everything at once. Start small and gradually introduce new products into your routine, giving your skin a chance to adapt to new ingredients and minimize the risk of widespread irritation that you might see if you used a lot of a certain product before realizing your skin couldn't handle it.

Creating a Skincare Routine for Your Full Body

As an important indicator of your overall health and well-being, your skin is an important and complex organ that needs to be taken care of. As you begin your personal skincare journey, remember that skincare isn't merely vanity; it's an important part of your health, in addition to a useful bit of self-care and emotional well-being. Your skincare routine can be a form of self-care that contributes to both your immediate beauty and long-term health.


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