UVA vs UVB: Harmful vs Healthful
Sunlight consists of two types of ultraviolet rays: UVA and UVB. Of these two, UVA rays are the most harmful, penetrating deep into the dermis layer of the skin. UVA rays can pass through window glass, meaning that exposure can happen even while you are indoors or in your car. UVA damages collagen fibers in the skin, and destroys vitamin A and D, causing signs of premature aging such as wrinkling and age spots. UVA is thought to be primarily responsible for melanoma skin cancer.
UVB rays do not penetrate as deeply into the skin as UVA rays and are easily blocked. UVB rays are actually an important source of vitamin D, which is generated in the skin at a rate of up to 1,000 IUs per minute during sunlight exposure. Avoiding sun exposure and using sunscreens can lead to a vitamin D deficiency. Low levels of vitamin D are a major risk factor for melanoma as well as other health issues. Healthy sun exposure can even improve some of the symptoms of multiple sclerosis, psoriasis, and depression. On the other hand, too much UVB exposure can lead to sunburn, premature aging, and skin cancer.
Our skin is divided into three main layers: the subcutaneous layer, which is deepest layer, the dermis, which is the middle collagen-filled layer, and the epidermis, which is the topmost visible layer. Above the epidermis is a very thin layer of skin called the stratum corneum, which is the skin’s main barrier, preventing chemicals that come in contact with the skin from absorbing into the body, and keeping water in the body from leaching out. The stratum corneum contains very high levels of ceramides, which are important to skin health, integrity, and immune function.
Every time that our skin is exposed to sunlight, the UV radiation causes microscopic photo-damage. This damage has a cumulative effect on the skin, adding up as we get older and contributing greatly to the aging process. Wrinkles and other signs of skin damage and aging are a result of collagen damage, causing upper layers of skin tissue to collapse.
Tanning is the skin’s own built in defense against UV over exposure. When the skin detects UV radiation, it prompts the release of the brown pigment melanin, which absorbs the radiation and dissipates the energy as heat, preventing the DNA damage that is responsible for the formation of malignant melanoma and other skin cancers. Full sunscreen coverage can actually block certain wavelengths of light that trigger this natural body defense. Therefore, appropriate sun exposure can actually help prevent skin cancer.
Sun Protection Options
Always avoid intense or prolonged solar exposure whenever possible. Use additional protection such as hat, clothing, shade, and sunblock for times when you can’t avoid this. Overexposure to the sun causes erythema (redness), which is an indicator that damage has exceeded the body’s ability to repair.
When using sunscreen, it is important to choose that provides protection from both UVB and UVA radiation. Avoid sunscreens with harsh chemical ingredients which can be absorbed through the skin into the bloodstream. There are actually several natural substances that provide UV protective properties when used regularly before sun exposure. Sage extract, green tea extract, and melatonin, for example, are all powerful natural antioxidants that protect the skin from damage associated with UV overexposure (sunburn, DNA damage, hydroxyl formation, ROS formation, and ceramide bundle destruction), while enhancing the skin’s production of natural vitamin D3 and melanin (tanning pigment), and activating the skin’s own repair mechanisms.
Natural UV Protection
Sage extract enhances the skin’s natural defense system through its antifungal, antiviral, and antibacterial properties. In addition, sage extract stimulates ceramide and collagen production in the skin, improving skin resilience and giving skin a firmer texture. In one scientific study, compounds found in high levels in the leaves of sage displayed antioxidant and anti-inflammatory effects in vitro, significantly reducing ultraviolet-induced erythema (redness) to a similar extent as hydrocortisone.
Green tea extract antioxidants have substantial free radical scavenging activity and have been shown to protect healthy cells from UV-induced oxidative damage such as erythema, premature aging, and skin cancer. Also significant is green tea extract’s ability to inhibit telomerase activity, which reduces the proliferative potential of cancer cells. In studies, green tea polyphenols have antioxidant and anti-inflammatory properties, and they have been shown to have a protective role against a variety of cancers, including skin cancer. Green tea polyphenols have protective effects against the UV-induced sunburn response, UV-induced immunosuppression, and photoaging of skin and have been shown to reduce the number of sunburn cells, inhibit tumor angiogenesis, decrease oxidative stress, increase DNA-repair ability, and increase apoptosis of photo-damaged cells.
Melatonin is a potent inhibitor of hydroxyl radicals, the most harmful of the free radicals. Sunlight exposure generates these hydroxyl radicals, which degrade lipids in the skin, resulting in cell membrane damage. When applied topically, melatonin accumulates in the stratum corneum, the skin’s outermost layer, providing extended release protection.
• Essense of Life UV and Anti-Aging Health Topic
• Melatonin As a Major Skin Protectant
• Melatonin’s Protective Effect Against UV Radiation
• Suncream May Interfere with Skin’s Natural Defense to UV Light
• Green Tea Prevents Skin Cancer by Two Mechanisms
• Sun Can Actually Help Protect You from Skin Cancer
• Sage Extract Rich in Phenolic Diterpenes Inhibits UV-Induced Erythema
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