UV-Radiation and Protection from the Damaging Effects of Sunlight
By Jason E. Barker, ND
Ultraviolet (UV) light is an invisible component of sunlight that damages our eyes, skin and immune system.1-2 There are 3 types of UV light (A, B and C) that are classified based on their wavelength. UVA penetrates the skin more deeply than UVB and damages keratinocytes (skin cells) in the basal layer of the epidermis, where most skin cancers occur. UVA contributes to and may even initiate the development of skin cancers. UVB, the major cause of skin reddening, sunburn and wrinkling, damages the skin’s more superficial epidermal layers and is also involved in skin cancer development.3 UVA and UVB work together to cause synergistic damage.
In excess, UV light damages the body’s genetic blueprint material, deoxyribonucleic acid (DNA).4-5 Damaged DNA results in premature skin aging, skin cancer and wrinkling.6-7 The skin tries to protect itself from UV light by producing the pigment melanin—better known as having a “tan.” However, the eyes have no way to protect themselves from UV light. UV exposure in the eye contributes to macular degeneration and cataracts.8
UV radiation is most intense from 10:00 a.m. to 3:00 p.m., at high altitudes and in the summer. Additionally, man-made chemicals released into the atmosphere have increased the amount of UV light that we are exposed to; chlorofluorocarbons (CFCs) destroy ozone that filters UV light. Air particulates (smog) filter UV light but it can pass through thin clouds, fog and about 12 inches of clear water.
UV light is not all bad—it helps the body produce vitamin D. Wearing sunscreen, which is necessary to prevent damaging sunburns, dramatically lowers vitamin D production. This is problematic in that higher levels of vitamin D3 are associated with both thinner tumors and better survival from melanoma.9 As reported in past articles in this newsletter, vitamin D3 is linked to almost every aspect of health.
At the same time that we need sufficient levels of vitamin D3, protecting the skin and eyes from UV light is imperative, as UV light is considered a “complete carcinogen,” meaning that it alone, without any other additional processes, can cause skin and eye cancer.10 While avoidance of excessive UV light and wearing sunglasses and sunscreen should comprise the basis of protection, the severity of UV damage requires that additional measures be incorporated.
Protecting the Skin
Antioxidants are an effective tool for mitigating UV radiation damage to the skin.11 Beta carotene, vitamins E and C, rosemary, turmeric, green tea and grape seed (all found in Extension Antioxidant) are good skin-protective choices.
In an analysis of the medical literature, researchers concluded that 10 weeks’ supplementation with beta carotene protects against sunburn and that the protective effect was increased with each additional month of supplementation.12 Similarly, vitamins E and C have UV-radiation protective effects. Supplementation with vitamins C and E was shown to significantly reduce the levels of free radicals inside of cells that had previously been exposed to UVB light radiation.13 Skin cells (melanocytes) exposed to both UVA and UVB radiation had lowered intracellular amounts of reduced glutathione (a potent antioxidant), increased transcription factor NF-KappaB and apoptotic (programmed) cell death. Cells treated with alpha-tocopherol (vitamin E) before UVA and UVB exposure did not show loss of glutathione nor NF-KappaB activation and went through less apoptosis suggesting that vitamin E has a useful role in protecting melanocytes from UV damage.14
Certain botanicals can also protect the skin both indirectly and directly from UV-related damage. Rosemary (Rosmarinus officinalis L) protects the skin through its anti-inflammatory and antioxidative compounds. Rosemary protects DNA from the deleterious effects of UV light and significantly reduces the growth of two types of melanoma cells and stimulates apoptosis (cell death) of melanoma cells.15
Turmeric is another botanical with skin-protective effects from its antioxidative compounds. An extract of turmeric (Tumerin) protects against free radical-induced DNA damage and mutagenicity.16 These are the same mechanisms through which UV light damages skin. Turmeric may attenuate sun damage in the skin and eyes.
Green tea also has many positive effects throughout the body and a prominent area where green tea shows strong protective effects is in the skin.
Green tea polyphenols protect cells by blocking UVB-induced free radicals and UVB-induced damage to the cellular mitochondria and other organelles.17-18 Of the green tea polyphenols, epigallocatechin-3-gallate (EGCG) provides the highest level of photoprotectivity. EGCG prevents UVB-induced skin damage by inducing cytokines that regulate immunity, DNA repair, inhibition of UV-induced immunosuppression, stimulation of cytotoxic T cells and by inhibiting angiogenic factors.19 Green tea and its constituents are perhaps the most potent of all skin protective botanicals due to the multifaceted protective effects.
Grape seed (Vitis vinifera) is another botanical that protects against UV light damage. In animal studies, supplementation with grape seed proanthocyanidins (GSPs) decreased UVB-induced damage.20 Researchers attribute this effect to the ability of GSPs to attenuate UV-caused oxidative stress, immunosuppression, and activation of cell-signaling pathways suggesting that GSPs are a useful element for protecting against sun-induced skin damage.
As mentioned above, vitamin D3 supplementation is essential since sunscreen dramatically reduces the production of vitamin D in the body.
Hyaluronic acid (HA) is another useful tool in protecting and rejuvenating sun-damaged skin. Hyaluronic acid is a natural compound found within the body in connective tissues and fluids. Clinical applications of hyaluronic acid range from injection into the knee joints for lubrication to topical application for skin rejuvenation. As skin ages (predominately from exposure to UV radiation) it loses its elastic qualities and becomes wrinkled.21-22 Additionally, aging skin produces less hyaluronic acid (which helps the skin to retain moisture) and is thinner, drier and less able to rejuvenate itself. Using hyaluronic acid to treat UV-light-induced wrinkles can reduce their appearance and production.
In addition to skin health, hyaluronic acid can also benefit the eyes from a UV light and aging perspective. Decreased amounts of hyaluronic acid in the eye is thought to contribute to the appearance of retinal disorders.23 A newer study showed that when human corneal cells were exposed to hyaluronic acid before exposure to UVB light, the hyaluronic acid protected the cells against UVB radiation-induced inflammation and protected cells against apoptosis, a sign of significant cellular damage.24
Applying hyaluronic acid topically to the skin by using Pure Hyaluronic Acid Serum or Facelift Serum and consuming oral HA Lozenges can help promote skin health in individuals exposed to the sun.
Protecting the Eyes
UV light is a major contributor toward cataract formation.25 In addition to wearing sunglasses, internal support to provide a foundation of health for the eyes is important. A combination of taurine, quercetin, bilberry, L-carnosine and carotenoids (as found in Extension Vision) can strengthen ocular health. A number of studies show the beneficial role of the amino acid taurine on eye health.26-28 Likewise, the amino acid N-acetyl cysteine, a glutathione precursor, is also protective against eye damage.29-31
Quercetin inhibits UV light-induced degradation of type 1 collagen in human lens cells in vitro.32 Quercetin also protects human lens cells from damage resulting from toxic chemicals.33 Researchers speculate that quercetin may have a role in protecting lens cells against UV-induced damage. Bilberry’s (Vaccinium myrtillus) flavonoid components act as potent antioxidants. A recent animal study showed that when supplemented with bilberry, this prevented the formation of cataracts in the animals while 70 percent of untreated control animals developed cataracts.34
L-carnosine is a naturally occurring dipeptide molecule that can reverse lens opacity by denaturing irregular protein deposits.35 Additionally, the carotenoids lutein, zeaxanthin and astaxanthin all play a role in ocular health.36-37
Sunlight is necessary in order for the skin to produce vitamin D. However, sun exposure is a double-edged sword, with excessive amounts leading to UV damage. Natural compounds that provide significant protection of the skin and eyes should be considered in anyone continually exposed to UV light.
Nutritional supplements can alleviate sun damage and wrinkles and relieve numerous skin conditions natural substances can play an important role in protecting and healing damaged skin. In clinical trials, numerous natural alternatives have prevented or al
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