Learn How to Protect Your Skin
Skin care consists of many practices that benefit the skin, but their objectives are generally to improve the skin’s appearance, maintain its integrity and relieve specific skin conditions. Practices that improve the skin’s appearance include cosmetics, exfoliation and medical procedures such as microdermabrasion, dermal fillers, laser resurfacing, peels and retinol therapy. Maintaining the skin’s integrity involves practices such as skin nutrition, moisturization and avoiding excessive exposure to the sun. Avoidance of the causative agent is often the most effective treatment for skin conditions such as dermatitis, although topical and oral medications may be able to relieve their symptoms.
Skin care often involves some overlap between cosmetics and dermatology, which may be subject to governmental regulation. For example, the Federal Food, Drug, and Cosmetic Act in the United States defines cosmetics as products that clean the body or increase its aesthetic appeal, which includes soaps, moisturizers, shampoo and lipstick. This legislation defines a separate category for medications that treat or prevent disease or affect the body’s structure or function. Skin care products that fall into this category include acne cream and sunscreens. Some products such as anti-dandruff shampoos and moisturizing sunscreens may fall into both categories.
Non-medical professionals such as estheticians normally perform skin care, whereas dermatology is a medical specialty. However, dermatologists may also practice some aspects of skin care, especially in the U.S. The distinction between skin care and dermatology is significantly sharper in other countries such as the U.K.
The following list includes some of the most beneficial ingredients for skin care products:
- Vitamin C
- Vitamin E
Sunscreen is also commonly known by other names such as sunblock, suntan lotion and sun cream, depending on the specific formulation. In addition to providing protection from sunburn, sunscreen can also slow the development of other conditions caused by UV such as moles, wrinkles and sagging skin. These topical products protect the wearer from sun burn by either absorbing some of the sun’s ultraviolet (UV) radiation or reflecting. Products that absorb UV radiation are classified as chemical sunscreens, while those that reflect it are known as physical sunscreens.
The U.S. Food and Drug Administration (FDA) maintains a list of specific chemicals it considers to be acceptable active ingredients in sunscreen. This list currently includes the following 16 compounds:
- Aminobenzoic acid
- Padimate O
- Titanium dioxide
- Trolamine salicylate
- Zinc oxide
The active ingredients in chemical sunscreens are generally aromatic compounds with a carbonyl group. Molecules with this structure are able to absorb high-energy UV radiation and release it at a lower energy level, thus preventing UV rays from reaching the skin. Most chemical sunscreens don’t change significantly during this process, allowing them to continue absorbing UV rays over time. Avobenzone is an exception to this general rule, so sunscreens containing this active ingredient must include a stabilizing agent such as bemotrizinol or octocrylene. Proper storage of sunscreens will help them retain their potency for several years.
Physical sunscreens use inorganic compounds to reflect or scatter UV light. The only active ingredients that the FDA allows for physical sunscreens are titanium dioxide and zinc dioxide.
The current sun protection factor (SPF) rating system was introduced in 1974 to inform consumers about the level of protection the product provides from UV radiation. An SPF of “X” means the product allows 1/X of the UV radiation to reach the skin, assuming a dosage of two milligrams (mg) sunscreen per square centimeter of skin. This rating also assumes the product is reapplied as directed, typically every two hours. For example, an SPF 15 sunscreen exposes the wearer to 1/15 of the UV radiation from the sun. As of 2011, the FDA also requires sunscreen products pass specific tests against UVA and UVB radiation before it may be classified as “broad spectrum.”
The American Cancer Society recommends the use of sunscreen to aid in the prevention of skin cancers such as squamous cell carcinomas and melanomas. This practice is especially important for people with fair complexions whose skin lacks melanin, a natural pigment that protects the skin from UV radiation. A 2013 study in Annals of Internal Medicine showed that using sunscreen every day could slow the development of wrinkles and sagging skin. The study group consisted of 900 white Australians who applied a broad-spectrum sunscreen every day for 4.5 years. The skin of these subjects was noticeably smoother and more resilient after this period than that of the control group.
Skin serves as a physical barrier that protects the body from contamination, pathogens and injury. This function requires the skin to retain its water content, so that doesn’t become rigid and brittle. However, water is continually evaporating from the deeper layers of skin in a process known as transepidermal water loss (TEWL), typically at a rate of four to eight grams of water per square meter of skin per hour (g/m²⋅h).
Healthy skin normally produces sebum, a natural oil that moisturizes, protects and lubricates the skin by reducing TEWL. Emollients, commonly known as moisturizers, are cosmetic products that perform this function when the skin’s sebum production is unable to provide a healthy level of hydration. They’re readily available in a variety of formulations, including lotions, oils and creams.
Thicker products generally contain more lipids, which increases the emollient effect. A layer of petrolatum, commonly known as petroleum jelly, can reduce TEWL by 50 to 75 percent for several hours. Other common emollients in skin moisturizers include the following:
- Castor oil
- Cetyl alcohol
- Cetearyl alcohol
- Cocoa butter
- Isopropyl myristate
- Isopropyl palmitate
- Liquid paraffin
- Polyethylene glycols
- Shea butter
- Silicone oil
- Stearic acid
- Stearyl alcohol
Most moisturizers contain more than one emollient. For example, the emollients in Belli’s All Day Moisture Body Lotion include cetearyl alcohol, cetyl alcohol, isopropyl myristate and stearyl alcohol.
The emollients in the above list are all mineral oils and waxes. Vegetable oils were previously used moisturizers due to their lower cost, but their greater oxidation rate causes them to become rancid more quickly than mineral oils. Moisturizers typically contain many other ingredients besides emollients such as the following:
- Penetration enhancers
Antioxidants prevent the formation of free radicals, which can react readily with skin cells to cause damage. Emulsifiers help stabilizes an emulsion in a moisturizer, while humectants attract moisture from the air. Penetration enhancers are also included in some moisturizers to allow the skin to absorb them more quickly and deeply.
In addition to simple moisturization, emollients are also used to treat skin conditions such as atopic dermatitis, ichthyosis, psoriasis, vulgaris and xerosis. They also serve as a base for topical medications that provide the therapeutic effect. This use of emollients is especially common with keratolytic agents, which treat skin lesions like calluses and warts that are caused by an excess production of epidermis. Common keratolytic agents include benzoic acid, salicylic acid and urea. Emollients are also used in other skin care products that provide health benefits such as skin cleansers and sunscreens.
A 2017 Cochrane Review examined 77 studies on the effects of moisturizers on skin conditions. The authors concluded that most moisturizers provided some benefits, especially for eczema. In particular, they found that adding moisturizers reduced the dosage of topical corticosteroids needed to reduce the severity of an eczema flare-up. The authors of this review failed to find reliable evidence favoring any specific moisturizer over another.
3. Vitamin C
Vitamin C, known chemically as L-ascorbic acid or just ascorbic acid, is an essential nutrient for humans and a few other mammals. It’s found in many fruits and vegetables, especially citrus fruits. Vitamin C is commonly available as a dietary supplement and is also an ingredient in many skin care products.
Vitamin C is best known as the treatment and cure for scurvy, which is a nutritional deficiency of vitamin C. It plays essential roles in tissue repair, immune system function and the biosynthesis of certain neurotransmitters. Vitamin C is also a strong antioxidant, which helps to prevent cellular damage from free radicals. A 2013 Cochrane Review also found evidence that regular vitamin C supplements may shorten the length colds.
Vitamin C is generally well tolerated, as any excess is easily metabolized and excreted in the urine without ill effects. Nevertheless, the United States Institute of Medicine recommends against large doses of vitamin C, as it can cause gastrointestinal pain and flushing of the skin. Normal doses are safe and recommended during pregnancy.
The dietary reference intake of vitamin C is 1,000 mg per day for adults. Nutritional deficiency of vitamin C is rare in the United States due to its prevalence in the typical diet in addition to supplements and other over-the-counter products. In addition to citrus fruits such as oranges, dietary sources of vitamin C include broccoli, spinach and strawberries.
The epidermis and dermis both contain high levels of vitamin C, primarily due to its role in collagen production. This function means that Vitamin C helps heal damaged skin and delay the signs of aging in the skin. Its antioxidant properties are part of the reason why skin care products use vitamin C to treat age spots, dryness, redness and wrinkles. Taking oral supplements of vitamin C can also improve the effectiveness of sunscreen by reducing the damage caused by UV radiation.
A 2013 study in Indian Dermatology Online Journal examined the use of vitamin C in skin care products, especially sunscreens. Vitamin C doesn’t absorb UV light by itself, but it does neutralize the free radicals it produces. Sunscreens without an antioxidant like vitamin C only block 55 percent of the free radicals from UV light. A topical application containing 10 percent vitamin C reduced the erythema caused by UVB by 52 percent and sunburn by 40 to 60 percent.
This study also showed that vitamin C works better when combined with vitamin E, resulting in a four-fold increase in vitamin C activity. A combination of 15 percent vitamin C, one percent vitamin E and 0.5 percent ferulic acid increased vitamin C’s efficacy by a factor of eight. The proposed mechanism of action for the synergistic effect is that water-soluble vitamin C helps to regenerate fat-soluble vitamin E, allowing them to limit cell death from chronic UV exposure.
4. Vitamin E
The term “Vitamin E” refers to a group of eight similar compounds, including four tocopherols and four tocotrienols. The combination of these compounds qualifies them as a vitamin, meaning they’re essential for human nutrition and can’t be biosynthesized. Nut and grain oils are the primary dietary source of vitamin E, with wheat germ oil being the most abundant source by far. Other vegetable oils that are high in vitamin E include the following:
The critical functions that vitamin E performs isn’t well understood, but the most popular theory is that it has something to antioxidant activity in the cell membranes. Other researchers hold that vitamin E controls cell signal transduction and gene expression, especially the R stereoisomer of alpha-tocopherol.
A nutritional deficiency of vitamin E is rare, due both to its abundance in many foods and the small amount that’s required. Such a deficiency is usually the result of an underlying medical problem that prevents the patient from digesting fat, rather than a diet that doesn’t contain enough vitamin E. However, studies still show that worldwide consumption of vitamin E is below recommended standards. A 2016 review of over 100 studies found that the median dietary intake of alpha-tocopherol was only 6.2 mg per day, whereas government recommendations range from seven to 15 mg per day.
Research on high doses of vitamin have had mixed results. Population studies of people who consumed up to 2,000 mg of alpha-tocopherol per day showed they had a lower rate of health conditions such as cancer, cardiovascular disease and dementia. However, controlled clinical trials aren’t always able to replicate these findings. The role of vitamin E in nutrition continues to be actively researched as of 2019.
Vitamin E is found in a variety of commercial sources, including dietary supplements and skin care products. Its primary function in skin care is to protect the skin from UV radiation with its antioxidant activity. This capability allows vitamin E to absorb UV light before it reaches the skin, helping to prevent wrinkles and dark spots. Vitamin E can also help soothe inflamed skin.
The skin normally produces sebum, which contains vitamin E. However, people with dry skin can use products like Belli’s Stretchmark Minimizing Cream to supplement a natural lack of vitamin E in the skin. The specific form of vitamin E in this product is vitamin E acetate, known chemically as tocopheryl acetate. This compound is the ester of vitamin E and acetic acid and is often used in skin care products.
Tocopheryl acetate has two primary advantages over the basic form of vitamin E with respect to skin care. It's less acidic than tocopherol itself, giving it a longer shelf life. Tocopheryl acetate also penetrates the skin more readily to reach living cells, where about five percent hydrolyzes back into tocopherol.