Unaged567

Skin Health
Contents

Skin Structure
Epidermis: the outer barrier
Dermis: the inner support
Challenges faced by healthy skin
Skin and Nutrition
General nutrition requirements
Oral nutrition vs. topical supplementation
Nutrients in Skin Health
Vitamin A
Vitamin C
Vitamin D
Vitamin E
Minerals
Essential fatty acids
Flavonoids
Peptides
Authors and Reviewers
References
Overview
Nutritional status plays an important role in the maintenance of healthy skin (1-4). Macronutrients (carbohydrates, proteins, and lipids) and micronutrients (vitamins and nutritionally essential minerals) work together to maintain the barrier functions of skin in the face of everyday challenges. Changes in nutritional status that alter skin structure and function can also directly affect skin appearance. Unlike many organs, skin nutrition may be enhanced directly through topical applications. Topical application of micronutrients can complement dietary consumption, leading to a stronger, healthier protective barrier for the body. This article discusses the roles of select micronutrients and other dietary compounds in the maintenance of skin health. Topical use of these compounds is discussed, and the effects of micronutrient deficiencies in the skin are also covered.

Skin Structure
Skin provides a physical and chemical barrier between the outside environment and the inside tissues of the body (5, 6). This ‘barrier function’ is critical to protect underlying tissues from pathogens, chemicals, and environmental exposures (5, 7). Structurally, skin is comprised of two main layers, the epidermis and the dermis (Figure 1) (6, 7). The epidermis, the upper layer, is responsible for many of the barrier functions of skin. The dermis is the structural and nutritive support network underneath the epidermis. Since each layer has its own unique structure and function, the nutritive requirements of each must be considered separately.

Figure 1. Skin Structure. See article text for details on the structure of skin.

Epidermis: the outer barrier
Human epidermis comprises the outermost layers of skin cells, ranging from 0.1 mm to 0.6 mm thick, depending on the location on the body (7). Keratinocytes compose the vast majority (90-95%) of cells within the epidermis. These cells are found in layers of varying size and thickness (6). The bottom or basal layer of the epidermis consists of a layer of round, undifferentiated keratinocytes that is supported by contact to the underlying dermis. Cells in this layer are constantly dividing in order to produce new cells that will make up the remainder of the epidermal layers (6, 7). Thus, it is in this fashion that skin is replenished, with new cells from the basal layer replacing the outer layer of skin cells that is shed over time.

Once a keratinocyte leaves the basal layer, it begins the process of cell differentiation known as keratinization (6). During keratinization, keratinocytes undergo several morphological changes that result in the synthesis of unique structural proteins (especially keratin) and the secretion of a variety of specialized lipids that will comprise key components of the epidermal barrier. These cells also undergo a process known as cornification, in which the synthesized proteins are assembled in an envelope just inside the cell membrane (5-7). At the end of this process, the large protein-laden cells, now known as corneocytes, lose their nuclei and other cellular organelles. Thus, there is little metabolic activity present in the outer layers of the skin (often referred to as ‘dead’ cells).

The outermost layer of skin, the stratum corneum, interacts with the outside environment. Lipids secreted by cells during the keratinization process are now assembled with extracellular proteins into a protective layer. This barrier is often likened to a ‘brick and mortar’ system: large, flattened, metabolically inactive corneocytes (the protein-rich ‘bricks’) are sealed together with a variety of extracellular lipids and proteins (the ‘mortar’) (5, 6). The chemical properties and structural design of this layer slow absorption and limit pe*******on of the skin, as well as limit the loss of vital nutrients and water from the underlying tissue. As new layers of cells are produced, the outer cells of the stratum corneum are enzymatically detached from this layer and shed in a process called desquamation (5).

Further, other cells contribute to the function of the epidermis. Melanocytes are cells that produce melanin, a compound involved in skin pigmentation produced in response to ultraviolet (UV) light exposure (6). Melanin can absorb energy from UV light to shield underlying tissues from damage. Langerhans cells are antigen-presenting cells involved in epidermal immunity. Merkel cells have various neuronal and endocrine roles; these cells function as mechanical sensors and produce growth factors that regulate sweat glands, hair follicles, nail growth, and nerve function in skin (6).

Skin care: 5 tips for healthy skin
Good skin care — including sun protection and gentle cleansing — can keep your skin healthy and glowing.

By Mayo Clinic Staff
Don't have time for intensive skin care? You can still pamper yourself by acing the basics. Good skin care and healthy lifestyle choices can help delay natural aging and prevent various skin problems. Get started with these five no-nonsense tips.

1. Protect yourself from the sun
One of the most important ways to take care of your skin is to protect it from the sun. A lifetime of sun exposure can cause wrinkles, age spots and other skin problems — as well as increase the risk of skin cancer.

For the most complete sun protection:

Use sunscreen. Use a broad-spectrum sunscreen with an SPF of at least 15. Apply sunscreen generously, and reapply every two hours — or more often if you're swimming or perspiring.
Seek shade. Avoid the sun between 10 a.m. and 4 p.m., when the sun's rays are strongest.
Wear protective clothing. Cover your skin with tightly woven long-sleeved shirts, long pants and wide-brimmed hats. Also consider laundry additives, which give clothing an additional layer of ultraviolet protection for a certain number of washings, or special sun-protective clothing — which is specifically designed to block ultraviolet rays.
2. Don't smoke
Smoking makes your skin look older and contributes to wrinkles. Smoking narrows the tiny blood vessels in the outermost layers of skin, which decreases blood flow and makes skin paler. This also depletes the skin of oxygen and nutrients that are important to skin health.

Smoking also damages collagen and elastin — the fibers that give your skin strength and elasticity. In addition, the repetitive facial expressions you make when smoking — such as pursing your lips when inhaling and squinting your eyes to keep out smoke — can contribute to wrinkles.

In addition, smoking increases your risk of squamous cell skin cancer. If you smoke, the best way to protect your skin is to quit. Ask your doctor for tips or treatments to help you stop smoking.

3. Treat your skin gently
Daily cleansing and shaving can take a toll on your skin. To keep it gentle:

Limit bath time. Hot water and long showers or baths remove oils from your skin. Limit your bath or shower time, and use warm — rather than hot — water.
Avoid strong soaps. Strong soaps and detergents can strip oil from your skin. Instead, choose mild cleansers.
Shave carefully. To protect and lubricate your skin, apply shaving cream, lotion or gel before shaving. For the closest shave, use a clean, sharp razor. Shave in the direction the hair grows, not against it.
Pat dry. After washing or bathing, gently pat or blot your skin dry with a towel so that some moisture remains on your skin.
Moisturize dry skin. If your skin is dry, use a moisturizer that fits your skin type. For daily use, consider a moisturizer that contains SPF.
4. Eat a healthy diet
A healthy diet can help you look and feel your best. Eat plenty of fruits, vegetables, whole grains and lean proteins. The association between diet and acne isn't clear — but some research suggests that a diet rich in fish oil or fish oil supplements and low in unhealthy fats and processed or refined carbohydrates might promote younger looking skin. Drinking plenty of water helps keep your skin hydrated.

5. Manage stress
Uncontrolled stress can make your skin more sensitive and trigger acne breakouts and other skin problems. To encourage healthy skin — and a healthy state of mind — take steps to manage your stress. Get enough sleep, set reasonable limits, scale back your to-do list and make time to do the things you enjoy. The results might be more dramatic than you expect.