Health effects of sunlight exposure

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Sunbaker, by Max Dupain Sunbaker maxdupain nga76.54.jpg
Sunbaker , by Max Dupain

Exposure of skin to ultraviolet radiation from sunlight presents both positive and negative health effects. On the positive side, UV exposure enables the synthesis of vitamin D3, which is essential for bone health [1] and potentially plays a role in inhibiting certain cancers. [2] [3] While vitamin D can also be obtained through dietary supplements, [4] UV exposure offers benefits such as enhanced subdermal nitric oxide production and improved endorphin levels, which are not achievable through supplementation alone. [5] [6] [7] [8] [9] Additionally, exposure to visible light supports melatonin synthesis, maintains circadian rhythms, and reduces the risk of seasonal affective disorder. [10]

Contents

However, UV radiation is also a mutagen and carcinogen for the skin, posing significant risks. [11] [12] Acute exposure can lead to painful sunburns and increase the likelihood of developing serious skin conditions later in life. [13] Prolonged exposure is associated with the development of skin cancers, photoaging or premature skin aging, immune suppression, and eye diseases like cataracts. [14] [15]

Given these dual effects, public health organizations emphasize the importance of striking a balance between the benefits and risks of UV exposure. They recommend avoiding sunburn at all costs and advocate for moderation in sun exposure to minimize the risks associated with UV radiation while still reaping its health benefits. [16]

Vitamin D3 production

Radiograph of a child with rickets, usually caused by insufficient vitamin D XrayRicketsLegssmall.jpg
Radiograph of a child with rickets, usually caused by insufficient vitamin D

UVB radiation with a wavelength of 290–315 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3. [17] [18] [19] UVB radiation does not penetrate glass, so exposure to sunshine indoors through a window does not produce vitamin D. [20] Time of day, time of year, geographic latitude, ground altitude, cloud cover, smog, skin melanin content, and sunscreen are among the factors that greatly affect UV intensity and vitamin D synthesis, [19] making it difficult to provide general guidelines. It has been suggested by some researchers, for example, that adequate amounts of vitamin D can be produced with moderate sun exposure to the face, arms and legs, averaging 5–30 minutes twice per week without sunscreen. (The darker the complexion, or the weaker the sunlight, the more minutes of exposure are needed, approximating 25% of the time for minimal sunburn. Vitamin D overdose is impossible from UV exposure; the skin reaches an equilibrium where the vitamin degrades as fast as it is created.) [19] [21] [22] Individuals with limited sun exposure need to include good sources of vitamin D in their diet or take a supplement.

The only way to quantify adequate levels of vitamin D is with a serum 25(OH)D3 (calcifediol) test. [23] In the United States, serum 25(OH)D3 was below the recommended level for more than a third of white men in a 2005 study, with serum levels even lower in women and in most minorities. This indicates that vitamin D deficiency may be a common problem in the US. [24] Australia and New Zealand have had similar findings, which indicate insufficient protection against rickets for children and osteoporosis for adults. [25]

Over the past several years, levels of ultraviolet radiation have been tracked at over 30 sites across North America as part of the United States Department of Agriculture's UVB Monitoring and Research Program at Colorado State University. The first map at right shows levels of UVB radiation in June 2008, expressed in Vitamin D Equivalents. [26]

UV map (Vitamin D Equivalents) All20080601-1206872731 con.png
UV map (Vitamin D Equivalents)

Using satellite data, measurements from the European Space Agency produce similar maps expressed in units of the widely followed UV Index, for locations around the world. [27] Effects of UV-radiation at high latitudes, where snow stays on the ground into early summer and the sun then remains at a low position even at its zenith, have been reviewed by Meyer-Rochow. [15]

UV map (UV Index) GOME.uviecclimyear lr.gif
UV map (UV Index)

Exposure to ultraviolet radiation from the sun is a source of vitamin D. One minimal erythemal dose of sunlight UV radiation provides the equivalent of about 20,000 IU of vitamin D2, taken as an oral supplement.[ citation needed ] If an adult's arms and legs are exposed to a half minimal erythemal UV radiation, it is the same as taking 3,000 IU of vitamin D3 through an oral supplement. This exposure of 10–15 minutes, on a frequency of two to three times per week, will cause the adult's skin to produce enough vitamin D. It is not necessary to expose the face to the UV, as facial skin provides little vitamin D3. Individuals whose metabolism makes taking oral vitamin D ineffective are able, through exposure to an ultraviolet lamp that emits UV-B radiation, to achieve a 25 (OH) D blood level. [28]

Three benefits of UV exposure are production of vitamin D, improvement in mood, and increased energy. [29]

UVB induces production of vitamin D in the skin at rates of up to 1,000 IUs per minute. This vitamin helps to regulate calcium metabolism (vital for the nervous system and bone health), immunity, cell proliferation, insulin secretion, and blood pressure. [30] In low and middle income countries, foods fortified with vitamin D are "practically nonexistent." Most people in the world depend on the sun to get vitamin D, [31] and elderly populations in low UVB countries experience higher rates of cancer. [32]

There are not many foods that naturally have vitamin D. [33] Examples are cod liver oil and oily fish. If people cannot get sunlight, then they will need 1,000 IU of vitamin D per day to stay healthy. [34] A person would have to eat oily fish three or four times per week in order to get enough vitamin D from that food source alone.

People with higher levels of vitamin D tend to have lower rates of diabetes, heart disease, and stroke and tend to have lower blood pressure. However, it has been found that vitamin D supplementation does not improve cardiovascular health or metabolism, so the link with vitamin D must be in part indirect.[ citation needed ] People who get more sun are generally healthier, and also have higher vitamin D levels. It has been found that ultraviolet radiation (even UVA) produces nitric oxide (NO) in the skin, and nitric oxide can lower blood pressure. High blood pressure increases the risk of stroke and heart disease. Although long-term exposure to ultraviolet contributes to non-melanoma skin cancers that are rarely fatal, it has been found in a Danish study that those who get these cancers were less likely to die during the study, and were much less likely to have a heart attack, than those who did not have these cancers. [35]

People in certain situations, such as people with intellectual disabilities and neurodevelopmental disorders who stay inside most of the time have low vitamin D levels. Getting enough vitamin D can help stave off "autoimmune diseases, cardiovascular disease, many types of cancer, dementia, types 1 and 2 diabetes mellitus, and respiratory tract infections." [36]

Fetuses and children who do not get enough vitamin D can result in "growth retardation and skeletal deformities." [33]

Multiple sclerosis risk

Multiple sclerosis (MS) is least prevalent in the sunniest regions. [37] [38] [39] Exposure to the ultraviolet-B radiation of sunlight appears to be most important and this may operate via vitamin D synthesis. [40]

Effects on skin

Melanoma on human skin Melanoma.jpg
Melanoma on human skin
Sunburn peeling Sun burn.JPG
Sunburn peeling

Ultraviolet (UV) irradiation present in sunlight is an environmental human carcinogen. The toxic effects of UV from natural sunlight and therapeutic artificial lamps are a major concern for human health. Skin surface lipids, including unsaturated lipids such as squalene, sebaleic acid, linoleic acid, and cholesterol can be a subject of oxidation by singlet oxygen and ozone as well as free radicals. Ultraviolet radiation activates lipoxygenase and cyclooxygenase, inducing specific enzymatic oxidation of lipids. Free radical mediated lipid peroxidation gives multiple oxidation products which may induce various skin diseases [41]

The major acute effects of UV irradiation on normal human skin comprise sunburn inflammation erythema, tanning, and local or systemic immunosuppression. [42] The most deadly form, malignant melanoma, is mostly caused by indirect DNA damage from UVA radiation.[ dubious – discuss ] This can be seen from the absence of a direct UV signature mutation in 92% of all melanoma. [43] [ failed verification ] UVC is the highest-energy, most-dangerous type of ultraviolet radiation, and causes adverse effects that can variously be mutagenic or carcinogenic. [44]

Despite the importance of the sun to vitamin D synthesis, it is prudent to limit the exposure of skin to UV radiation from sunlight [45] and from tanning beds. [46] According to the National Toxicology Program Report on Carcinogens from the US Department of Health and Human Services, broad-spectrum UV radiation is a carcinogen whose DNA damage is thought to contribute to most of the estimated 1.5 million skin cancers and the 8,000 deaths due to metastatic melanoma that occur annually in the United States. [45] [47] The use of sunbeds is reported by the World Health Organization to be responsible for over 450,000 cases of non-melanoma skin cancer and over 10,000 cases of melanoma every year in the U.S., Europe, as well as Australia. [48] Lifetime cumulative UV exposure to skin is also responsible for significant age-associated dryness, wrinkling, elastin and collagen damage, freckling, IGH, age spots and other cosmetic changes. The American Academy of Dermatology advises that photoprotective measures be taken, including the use of sunscreen, whenever one is exposed to the sun. [49] Short-term over-exposure causes the pain and itching of sunburn, which in extreme cases can produce more-severe effects like blistering.

Several countries (such as Australia) provide public forecasts of UV irradiation in the form of the UV Index. The index can be used as a guide to the public of dangers from over-exposure to sunlight, especially around noon, when direct sunlight is at its most intense.

Effects on eyes

Prolonged optical exposure to sunlight, especially intense ultraviolet light, may be linked to cortical cataracts, [50] [15] and high levels of visible light is maybe linked to macular degeneration.

However, significant daily exposure to bright light may be necessary for children to avoid myopia (nearsightedness). [51]

Short-term over-exposure can cause snow blindness, which is analogous to sunburn of the cornea, or can cause solar retinopathy, which is long-lasting retinal damage and vision impairment from sungazing. [52] [53]

Frequent exposure to the sun can cause yellow non-cancerous bumps on the middle part of the sclera of the eye, called pingueculae. It is most common in younger people, mainly those who spend a lot of their time outdoors and do not protect their eyes from UV rays. To decrease the risk of developing pingueculae, it may be wise to wear sunglasses when outdoors, even on overcast days. [54]

Circadian rhythm

Light to the eyes, primarily blue-wavelength light, is important for the entrainment and maintenance of robust circadian rhythms. Exposure to sunlight in the morning is particularly effective; it leads to earlier melatonin onset in the evening and makes it easier to fall asleep. Natural daylight exposure, particularly at high intensities, has been shown to have numerous beneficial effects on sleep patterns. It can advance sleep timing (leading to earlier bedtimes), affect sleep duration, and improve overall sleep quality. [55] Bright morning light has been shown to be effective against insomnia, premenstrual syndrome and seasonal affective disorder (SAD). [56]

Folate degradation

Blood levels of folate, a nutrient vital for fetal development, can be degraded by UV radiation, [57] raising concerns about sun exposure for pregnant women. [58] Lifespan and fertility can be adversely affected for individuals born during peaks of the 11-year solar cycle, possibly because of UV-related folate deficiency during gestation. [59]

Blood pressure

A seasonal variation in blood pressure has been noted for decades. Research indicates that skin exposure to sunlight results in a modest reduction in systolic blood pressure. The effect is independent of vitamin D status, instead being mediated by nitric oxide release from skin upon exposure to UV light. The effect is greater in fair-skinned individuals. [60]

Cognitive Functioning and Mood

UV exposure plays a role in motor learning and object recognition memory. Moderate UV exposure enhances cognitive functioning through a specialized glutamate (GLU) biosynthetic pathway in the brain. [61] The process begins when UV exposure triggers an increase in blood levels of urocanic acid (UCA), which possesses the unique ability to cross the blood-brain barrier. Upon entering the brain, UCA initiates a cascade of biochemical reactions that promote glutamate biosynthesis, particularly in critical regions such as the motor cortex and hippocampus. This increased glutamate production leads to notable cognitive enhancements, including improved motor learning capabilities, enhanced object recognition memory, and strengthened synaptic plasticity. [62]

Ultraviolet (UV) light has been shown to influence various neurological functions, including mood, addiction, cognition, and memory. [63] This impact likely occurs through UV-induced changes in brain chemistry, potentially altering neurotransmitter systems and neuroplasticity. UV exposure might, for example, affect serotonin levels, which play a significant role in mood regulation and cognitive functions. This hormonal effect can helps stabilize circadian rhythms. This stabilizing effect is particularly important for individuals with mental disorders, who often experience circadian desynchronization and sleep problems. As a result, light therapy has emerged as an increasingly popular treatment option for various mood and psychiatric disorders. [64]

Safe level of sun exposure

According to a 2007 study submitted by the University of Ottawa to the US Department of Health and Human Services, there is not enough information to determine a safe level of sun exposure that imposes minimal risk of skin cancer. [65] In addition, there is not yet conclusive evidence on which components of ultraviolet radiation (UVA, UVB, UVC) are actually carcinogenic. [12] UVC is almost completely absorbed by the atmosphere and does not reach the surface in any appreciable quantity. [66] As a result, only the broad-spectrum combination (UVA, UVB, UVC) known as "ultraviolet radiation" is listed as a carcinogen; the components are only "likely to become" known carcinogens. Solar radiation (sunlight) and sunlamps are listed as carcinogens because they contain ultraviolet radiation. [12]

Lifetime sun exposure

Map of human skin color distribution for native populations, by R. Biassutti in the Von Luschan's chromatic scale for classifying skin color. It was reported that for areas with no data Biasutti simply filled in the map by extrapolation from findings obtained in other areas. Imprecise-Biasutti-map.jpg
Map of human skin color distribution for native populations, by R. Biassutti in the Von Luschan's chromatic scale for classifying skin color. It was reported that for areas with no data Biasutti simply filled in the map by extrapolation from findings obtained in other areas.

There are currently no recommendations on a safe level of total lifetime sun exposure. [65] According to epidemiologist Robyn Lucas at Australian National University, analysis of lifespan versus disease shows that far more lives worldwide could be lost to diseases caused by lack of sunlight than to those caused by too much, [68] and it is inappropriate to recommend total avoidance of sunlight. [69]

Over thousands of years, in many climate zones, genetic selection has helped indigenous human populations adapt toward skin pigmentation levels that provide a healthy level of UV exposure. This largely explains the tendency toward darker-skinned populations in the sunniest tropical environments, and lighter skin tones in less-sunny regions and for those who most need vitamin D for rapid bone growth, specifically children and reproductive-age women. The map to the right illustrates the geographic distribution of skin color for native populations prior to 1940, based on von Luschan's chromatic scale. These long-term adaptations for optimal health can be confounded by patterns of food, clothing and shelter, especially at a time when large populations have migrated far from the climates for which their skin was genetically adapted. [70] [71]

See also

Related Research Articles

<span class="mw-page-title-main">Rickets</span> Childhood bone disorder

Rickets, scientific nomenclature: rachitis, is a condition that results in weak or soft bones in children and is caused by either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications may include bone deformities, bone pseudofractures and fractures, muscle spasms, or an abnormally curved spine. The analogous condition in adults is osteomalacia.

<span class="mw-page-title-main">Sunlight</span> Light emitted by the Sun

Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere as daylight when the Sun is above the horizon. When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat (atmospheric). When blocked by clouds or reflected off other objects, sunlight is diffused. Sources estimate a global average of between 164 watts to 340 watts per square meter over a 24-hour day; this figure is estimated by NASA to be about a quarter of Earth's average total solar irradiance.

<span class="mw-page-title-main">Ultraviolet</span> Energetic, invisible radiant energy range

Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs, Cherenkov radiation, and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.

<span class="mw-page-title-main">Electromagnetic radiation and health</span> Aspect of public health

Electromagnetic radiation can be classified into two types: ionizing radiation and non-ionizing radiation, based on the capability of a single photon with more than 10 eV energy to ionize atoms or break chemical bonds. Extreme ultraviolet and higher frequencies, such as X-rays or gamma rays are ionizing, and these pose their own special hazards: see radiation poisoning. The field strength of electromagnetic radiation is measured in volts per meter (V/m).

<span class="mw-page-title-main">7-Dehydrocholesterol</span> Chemical compound

7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically converted to vitamin D3 in the skin, therefore functioning as provitamin-D3. The presence of this compound in human skin enables humans to manufacture vitamin D3 (cholecalciferol). Upon exposure to ultraviolet UV-B rays in the sun light, 7-DHC is converted into vitamin D3 via previtamin D3 as an intermediate isomer. It is also found in the milk of several mammalian species. Lanolin, a waxy substance that is naturally secreted by wool-bearing mammals, contains 7-DHC which is converted into vitamin D by sunlight and then ingested during grooming as a nutrient. In insects 7-dehydrocholesterol is a precursor for the hormone ecdysone, required for reaching adulthood. 7-DHC was discovered by Nobel-laureate organic chemist Adolf Windaus.

<span class="mw-page-title-main">Skin cancer</span> Medical condition involving uncontrolled growth of skin cells

Skin cancers are cancers that arise from the skin. They are due to the development of abnormal cells that have the ability to invade or spread to other parts of the body. It occurs when skin cells grow uncontrollably, forming malignant tumors. The primary cause of skin cancer is prolonged exposure to ultraviolet (UV) radiation from the sun or tanning devices. Skin cancer is the most commonly diagnosed form of cancer in humans. There are three main types of skin cancers: basal-cell skin cancer (BCC), squamous-cell skin cancer (SCC) and melanoma. The first two, along with a number of less common skin cancers, are known as nonmelanoma skin cancer (NMSC). Basal-cell cancer grows slowly and can damage the tissue around it but is unlikely to spread to distant areas or result in death. It often appears as a painless raised area of skin that may be shiny with small blood vessels running over it or may present as a raised area with an ulcer. Squamous-cell skin cancer is more likely to spread. It usually presents as a hard lump with a scaly top but may also form an ulcer. Melanomas are the most aggressive. Signs include a mole that has changed in size, shape, color, has irregular edges, has more than one color, is itchy or bleeds.

<span class="mw-page-title-main">Sunscreen</span> Skin product helping to prevent sunburn

Sunscreen, also known as sunblock, sun lotion or sun cream, is a photoprotective topical product for the skin that helps protect against sunburn and prevent skin cancer. Sunscreens come as lotions, sprays, gels, foams, sticks, powders and other topical products. Sunscreens are common supplements to clothing, particularly sunglasses, sunhats and special sun protective clothing, and other forms of photoprotection.

<span class="mw-page-title-main">Cholecalciferol</span> Vitamin D3, a chemical compound

Cholecalciferol, also known as vitamin D3 or colecalciferol, is a type of vitamin D that is produced by the skin when exposed to UVB light; it is found in certain foods and can be taken as a dietary supplement.

<span class="mw-page-title-main">Sun tanning</span> Darkening of skin in response to ultraviolet light

Sun tanning or tanning is the process whereby skin color is darkened or tanned. It is most often a result of exposure to ultraviolet (UV) radiation from sunlight or from artificial sources, such as a tanning lamp found in indoor tanning beds. People who deliberately tan their skin by exposure to the sun engage in a passive recreational activity of sun bathing. Some people use chemical products that can produce a tanning effect without exposure to ultraviolet radiation, known as sunless tanning.

<span class="mw-page-title-main">Indoor tanning</span> Tanning using an artificial source of ultraviolet light

Indoor tanning involves using a device that emits ultraviolet radiation to produce a cosmetic tan. Typically found in tanning salons, gyms, spas, hotels, and sporting facilities, and less often in private residences, the most common device is a horizontal tanning bed, also known as a sunbed or solarium. Vertical devices are known as tanning booths or stand-up sunbeds.

<span class="mw-page-title-main">Ultraviolet index</span> Measurement of strength of sunburn-producing ultraviolet (UV) radiation

The ultraviolet index, or UV index, is an international standard measurement of the strength of the sunburn-producing ultraviolet (UV) radiation at a particular place and time. It is primarily used in daily and hourly forecasts aimed at the general public. The UV index is designed as an open-ended linear scale, directly proportional to the intensity of UV radiation, and adjusting for wavelength based on what causes human skin to sunburn. The purpose of the UV index is to help people effectively protect themselves from UV radiation, which has health benefits in moderation but in excess causes sunburn, skin aging, DNA damage, skin cancer, immunosuppression, and eye damage, such as cataracts.

UVB-induced apoptosis is the programmed cell death of cells that become damaged by ultraviolet rays. This is notable in skin cells, to prevent melanoma. Some studies have shown that exercise accelerates this process.

UV-B lamps are lamps that emit a spectrum of ultraviolet light with wavelengths ranging from 290–320 nanometers. This spectrum is also commonly called the biological spectrum due to the human body's sensitivity to light of such a wavelength. UV-B light does not tan the skin very much, compared to the UV-A lamps that are used in tanning beds.

<span class="mw-page-title-main">Sunburn</span> Burning of the skin by the suns radiation

Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun. Common symptoms in humans and other animals include red or reddish skin that is hot to the touch or painful, general fatigue, and mild dizziness. Other symptoms include blistering, peeling skin, swelling, itching, and nausea. Excessive UV radiation is the leading cause of (primarily) non-malignant skin tumors, which in extreme cases can be life-threatening. Sunburn is an inflammatory response in the tissue triggered by direct DNA damage by UV radiation. When the cells' DNA is overly damaged by UV radiation, type I cell-death is triggered and the tissue is replaced.

<span class="mw-page-title-main">Vitamin D deficiency</span> Human disorder

Vitamin D deficiency or hypovitaminosis D is a vitamin D level that is below normal. It most commonly occurs in people when they have inadequate exposure to sunlight, particularly sunlight with adequate ultraviolet B rays (UVB). Vitamin D deficiency can also be caused by inadequate nutritional intake of vitamin D; disorders that limit vitamin D absorption; and disorders that impair the conversion of vitamin D to active metabolites, including certain liver, kidney, and hereditary disorders. Deficiency impairs bone mineralization, leading to bone-softening diseases, such as rickets in children. It can also worsen osteomalacia and osteoporosis in adults, increasing the risk of bone fractures. Muscle weakness is also a common symptom of vitamin D deficiency, further increasing the risk of falls and bone fractures in adults. Vitamin D deficiency is associated with the development of schizophrenia.

<span class="mw-page-title-main">Vitamin D</span> Group of fat-soluble secosteroids

Vitamin D is a group of structurally related, fat-soluble compounds responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, along with numerous other biological functions. In humans, the most important compounds within this group are vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol).

Animal-type melanoma is a rare subtype of melanoma that is characterized by heavily pigmented dermal epithelioid and spindled melanocytes. Animal-type melanoma is also known to be called equine-type melanoma, pigment synthesizing melanoma, and pigmented epithelioid melanocytoma (PEM). While melanoma is known as the most aggressive skin cancer, the mortality for PEM is lower than in other melanoma types. Animal-type melanoma earned its name due to the resemblance of melanocytic tumors in grey horses.

<span class="mw-page-title-main">Dark skin</span> Human skin color

Dark skin is a type of human skin color that is rich in melanin pigments. People with dark skin are often referred to as black people, although this usage can be ambiguous in some countries where it is also used to specifically refer to different ethnic groups or populations.

<span class="mw-page-title-main">Skin cancer in Australia</span>

Skin cancer in Australia kills over 2,000 each year, with more than 750,000 diagnosed and treated. Tanning became embedded in Australian culture and proved to be a controversial issue because of its popularity among teens and solarium users, despite correlations between tanning and an increased risk of developing melanoma. Australia experienced relative success through skin cancer prevention campaigns started in the 1980s and continued to invest and promote awareness through government-funded mass media strategies. Although Australia has one of the highest national rates of skin cancer, mortality trends in melanoma stabilized.

Vitamin D deficiency in Australia has been estimated as aflicting nearly one-quarter of all adults.

References

  1. ↑ Cranney A, Horsley T, O'Donnell S, Weiler H, Puil L, Ooi D, et al. (August 2007). "Effectiveness and safety of vitamin D in relation to bone health". Evidence Report/Technology Assessment (158): 1–235. PMC   4781354 . PMID   18088161.
  2. ↑ John EM, Schwartz GG, Koo J, Van Den Berg D, Ingles SA (June 2005). "Sun exposure, vitamin D receptor gene polymorphisms, and risk of advanced prostate cancer". Cancer Research. 65 (12): 5470–5479. doi:10.1158/0008-5472.can-04-3134. PMID   15958597.
  3. ↑ Egan KM, Sosman JA, Blot WJ (February 2005). "Sunlight and reduced risk of cancer: is the real story vitamin D?". Journal of the National Cancer Institute. 97 (3): 161–163. doi:10.1093/jnci/dji047. PMID   15687354.
  4. ↑ "Dietary Supplement Fact Sheet: Vitamin D". Office of Dietary Supplements, National Institutes of Health. Archived from the original on July 16, 2007. Retrieved January 4, 2010.
  5. ↑ Hoel DG, Berwick M, de Gruijl FR, Holick MF (January 2016). "The risks and benefits of sun exposure 2016". Dermato-Endocrinology. 8 (1): e1248325. doi:10.1080/19381980.2016.1248325. PMC   5129901 . PMID   27942349.
  6. ↑ Lindqvist PG, Epstein E, Nielsen K, Landin-Olsson M, Ingvar C, Olsson H (October 2016). "Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort". Journal of Internal Medicine. 280 (4): 375–387. doi: 10.1111/joim.12496 . PMID   26992108. S2CID   23771787.
  7. ↑ Alfredsson L, Armstrong BK, Butterfield DA, Chowdhury R, de Gruijl FR, Feelisch M, et al. (July 2020). "Insufficient Sun Exposure Has Become a Real Public Health Problem". International Journal of Environmental Research and Public Health. 17 (14): 5014. doi: 10.3390/ijerph17145014 . PMC   7400257 . PMID   32668607.
  8. ↑ Šimoliūnas E, Rinkūnaitė I, Bukelskienė Ž, Bukelskienė V (June 2019). "Bioavailability of Different Vitamin D Oral Supplements in Laboratory Animal Model". Medicina. 55 (6): 265. doi: 10.3390/medicina55060265 . PMC   6631968 . PMID   31185696.
  9. ↑ Holliman G, Lowe D, Cohen H, Felton S, Raj K (September 2017). "Ultraviolet Radiation-Induced Production of Nitric Oxide:A multi-cell and multi-donor analysis". Scientific Reports. 7 (1): 11105. Bibcode:2017NatSR...711105H. doi:10.1038/s41598-017-11567-5. PMC   5593895 . PMID   28894213.
  10. ↑ Mead MN (April 2008). "Benefits of sunlight: a bright spot for human health". Environmental Health Perspectives. 116 (4): A160 –A167. doi:10.1289/ehp.116-a160. PMC   2290997 . PMID   18414615.
  11. ↑ Osborne JE, Hutchinson PE (August 2002). "Vitamin D and systemic cancer: is this relevant to malignant melanoma?". The British Journal of Dermatology. 147 (2): 197–213. doi:10.1046/j.1365-2133.2002.04960.x. PMID   12174089. S2CID   34388656.
  12. 1 2 3 "13th Report on Carcinogens: Ultraviolet-Radiation-Related Exposures" (PDF). National Toxicology Program. October 2014. Archived (PDF) from the original on December 22, 2014. Retrieved December 22, 2014.
  13. ↑ "Sunburn". www.nhsinform.scot. Archived from the original on March 29, 2023. Retrieved March 22, 2023.
  14. ↑ Lucas RM, Repacholi MH, McMichael AJ (June 2006). "Is the current public health message on UV exposure correct?". Bulletin of the World Health Organization. 84 (6): 485–491. doi:10.2471/BLT.05.026559 (inactive December 5, 2024). PMC   2627377 . PMID   16799733.{{cite journal}}: CS1 maint: DOI inactive as of December 2024 (link)
  15. 1 2 3 Meyer-Rochow VB (January 2000). "Risks, especially for the eye, emanating from the rise of solar UV-radiation in the Arctic and Antarctic regions". International Journal of Circumpolar Health. 59 (1): 38–51. PMID   10850006.
  16. ↑ "Risks and Benefits of Sun Exposure" (PDF). Cancer Council Australia. May 3, 2007. Archived (PDF) from the original on March 21, 2015. Retrieved March 25, 2015.
  17. ↑ Hayes CE, Nashold FE, Spach KM, Pedersen LB (March 2003). "The immunological functions of the vitamin D endocrine system". Cellular and Molecular Biology. 49 (2): 277–300. PMID   12887108.
  18. ↑ Holick MF (October 1994). "McCollum Award Lecture, 1994: vitamin D--new horizons for the 21st century". The American Journal of Clinical Nutrition. 60 (4): 619–630. doi:10.1093/ajcn/60.4.619. PMID   8092101. Archived from the original on March 15, 2020. Retrieved January 13, 2010.
  19. 1 2 3 Holick MF (February 2002). "Vitamin D: the underappreciated D-lightful hormone that is important for skeletal and cellular health". Current Opinion in Endocrinology, Diabetes and Obesity. 9 (1): 87–98. doi:10.1097/00060793-200202000-00011. S2CID   87725403.
  20. ↑ Holick MF (2005). "Photobiology of vitamin D". In Feldman, David Henry; Glorieux, Francis H. (eds.). Vitamin D. Amsterdam: Elsevier Academic Press. ISBN   978-0-12-252687-9.
  21. ↑ Holick MF (September 2002). "Sunlight and vitamin D: both good for cardiovascular health". Journal of General Internal Medicine. 17 (9): 733–735. doi:10.1046/j.1525-1497.2002.20731.x. PMC   1495109 . PMID   12220371.
  22. ↑ Holick MF (July 2007). "Vitamin D deficiency". The New England Journal of Medicine. 357 (3): 266–281. doi:10.1056/NEJMra070553. PMID   17634462. S2CID   18566028.
  23. ↑ Topiwala S (July 19, 2012). "25-hydroxy vitamin D test". MedlinePlus. US National Institutes of Health. Archived from the original on July 5, 2016. Retrieved March 25, 2015.
  24. ↑ Zadshir A, Tareen N, Pan D, Norris K, Martins D (2005). "The prevalence of hypovitaminosis D among US adults: data from the NHANES III". Ethnicity & Disease. 15 (4 Suppl 5): S5–97–S5–101. PMID   16315387.
  25. ↑ Nowson CA, Margerison C (August 2002). "Vitamin D intake and vitamin D status of Australians". The Medical Journal of Australia. 177 (3): 149–152. doi:10.5694/j.1326-5377.2002.tb04702.x. PMID   12149085. S2CID   20278782. Archived from the original on March 1, 2012. Retrieved December 23, 2014.
  26. ↑ "UV-B Monitoring and Research Program". Colorado State University. Archived from the original on January 29, 2019. Retrieved May 13, 2010.
  27. ↑ "UV index & UV dose based on GOME". KNMI/TEMIS. Archived from the original on April 2, 2015. Retrieved March 17, 2015.
  28. ↑ Hossein-nezhad A, Holick MF (July 2013). "Vitamin D for health: a global perspective". Mayo Clinic Proceedings. 88 (7): 720–755. doi:10.1016/j.mayocp.2013.05.011. PMC   3761874 . PMID   23790560.
  29. ↑ Sivamani RK, Crane LA, Dellavalle RP (April 2009). "The benefits and risks of ultraviolet tanning and its alternatives: the role of prudent sun exposure". Dermatologic Clinics. 27 (2): 149–54, vi. doi:10.1016/j.det.2008.11.008. PMC   2692214 . PMID   19254658.
  30. ↑ "Vitamin D". Oregon State University. Archived from the original on October 26, 2011. Retrieved November 8, 2011.
  31. ↑ Shah D, Gupta P (2015). "Vitamin D Deficiency: Is The Pandemic for Real?". Indian Journal of Community Medicine. 40 (4): 215–217. doi: 10.4103/0970-0218.164378 . PMC   4581139 . PMID   26435592.
  32. ↑ Purushothaman VL, Cuomo RE, Garland CF, Mackey TK (July 2021). "Could age increase the strength of inverse association between ultraviolet B exposure and colorectal cancer?". BMC Public Health. 21 (1): 1238. doi: 10.1186/s12889-021-11089-w . PMC   8256562 . PMID   34218809.
  33. 1 2 Holick MF (July 2007). "Vitamin D deficiency". The New England Journal of Medicine. 357 (3): 266–281. doi:10.1056/NEJMra070553. PMID   17634462. S2CID   18566028.
  34. ↑ Holick MF (March 2004). "Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis". The American Journal of Clinical Nutrition. 79 (3): 362–371. doi: 10.1093/ajcn/79.3.362 . PMID   14985208.
  35. ↑ Richard Weller (June 10, 2015). "Shunning the sun may be killing you in more ways than you think". New Scientist . Archived from the original on June 9, 2017.
  36. ↑ Grant WB, Wimalawansa SJ, Holick MF, Cannell JJ, Pludowski P, Lappe JM, et al. (February 2015). "Emphasizing the health benefits of vitamin D for those with neurodevelopmental disorders and intellectual disabilities". Nutrients. 7 (3): 1538–1564. doi: 10.3390/nu7031538 . PMC   4377865 . PMID   25734565.
  37. ↑ Ascherio A, Munger KL (June 2007). "Environmental risk factors for multiple sclerosis. Part II: Noninfectious factors". Annals of Neurology. 61 (6): 504–513. doi: 10.1002/ana.21141 . PMID   17492755. S2CID   36999504.
  38. ↑ Milo R, Kahana E (March 2010). "Multiple sclerosis: geoepidemiology, genetics and the environment". Autoimmunity Reviews. 9 (5): A387 –A394. doi:10.1016/j.autrev.2009.11.010. PMID   19932200.
  39. ↑ Ascherio A, Munger KL, Simon KC (June 2010). "Vitamin D and multiple sclerosis". The Lancet. Neurology. 9 (6): 599–612. doi:10.1016/S1474-4422(10)70086-7. PMID   20494325. S2CID   12802790.
  40. ↑ Koch MW, Metz LM, Agrawal SM, Yong VW (January 2013). "Environmental factors and their regulation of immunity in multiple sclerosis". Journal of the Neurological Sciences. 324 (1–2): 10–16. doi:10.1016/j.jns.2012.10.021. PMC   7127277 . PMID   23154080.
  41. ↑ Niki E (August 2014). "Lipid oxidation in the skin". Free Radical Research. 49 (7): 827–834. doi:10.3109/10715762.2014.976213. PMID   25312699. S2CID   19975554.
  42. ↑ Matsumura Y, Ananthaswamy HN (March 2004). "Toxic effects of ultraviolet radiation on the skin". Toxicology and Applied Pharmacology. 195 (3): 298–308. Bibcode:2004ToxAP.195..298M. doi:10.1016/j.taap.2003.08.019. PMID   15020192.
  43. ↑ Davies H, Bignell GR, Cox C, Stephens P, Edkins S, Clegg S, et al. (June 2002). "Mutations of the BRAF gene in human cancer" (PDF). Nature. 417 (6892): 949–954. Bibcode:2002Natur.417..949D. doi:10.1038/nature00766. PMID   12068308. S2CID   3071547. Archived (PDF) from the original on August 5, 2020. Retrieved September 28, 2019.
  44. ↑ Hogan CM (2011). "Sunlight". In Saundry P, Cleveland C (eds.). Encyclopedia of Earth. Archived from the original on October 19, 2013.
  45. 1 2 Wolpowitz D, Gilchrest BA (February 2006). "The vitamin D questions: how much do you need and how should you get it?". Journal of the American Academy of Dermatology. 54 (2): 301–317. doi:10.1016/j.jaad.2005.11.1057. PMID   16443061.
  46. ↑ "The association of use of sunbeds with cutaneous malignant melanoma and other skin cancers: A systematic review". International Journal of Cancer. 120 (5): 1116–1122. March 2007. doi: 10.1002/ijc.22453 . PMID   17131335.
  47. ↑ "Ultraviolet (UV) Radiation, Broad Spectrum and UVA, UVB, and UVC". National Toxicology Program. January 5, 2009. Archived from the original on May 28, 2010. Retrieved May 13, 2010.
  48. ↑ "More can be done to restrict sunbeds to prevent increasing rates of skin cancer". World Health Organization. Archived from the original on April 30, 2018. Retrieved May 5, 2018.
  49. ↑ "Position statement on vitamin D." (PDF). American Academy of Dermatology. November 1, 2008. Archived from the original (PDF) on January 14, 2018.
  50. ↑ West SK, Duncan DD, Muñoz B, Rubin GS, Fried LP, Bandeen-Roche K, Schein OD (August 1998). "Sunlight exposure and risk of lens opacities in a population-based study: the Salisbury Eye Evaluation project". JAMA. 280 (8): 714–718. doi:10.1001/jama.280.8.714. PMID   9728643. S2CID   24926534.
  51. ↑ Dolgin E (March 2015). "The myopia boom". Nature. 519 (7543): 276–278. Bibcode:2015Natur.519..276D. doi: 10.1038/519276a . PMID   25788077.
  52. ↑ Chen JC, Lee LR (November 2004). "Solar retinopathy and associated optical coherence tomography findings". Clinical & Experimental Optometry. 87 (6): 390–393. doi: 10.1111/j.1444-0938.2004.tb03100.x . PMID   15575813.
  53. ↑ Källmark FP, Ygge J (October 2005). "Photo-induced foveal injury after viewing a solar eclipse". Acta Ophthalmologica Scandinavica. 83 (5): 586–589. doi: 10.1111/j.1600-0420.2005.00511.x . PMID   16187997.
  54. ↑ Lusby F, Zieve D, Ogilvie I. "Pinguecula". MedicinePlus. U.S. National Library of Medicine. Retrieved October 28, 2016.
  55. ↑ Blume, Christine; Garbazza, Corrado; Spitschan, Manuel (August 20, 2019). "Effects of light on human circadian rhythms, sleep and mood". Somnologie. 23 (3): 147–156. doi:10.1007/s11818-019-00215-x. PMC   6751071 . PMID   31534436.
  56. ↑ Mead, M Nathaniel (May 2008). "Benefits of Sunlight: A Bright Spot for Human Health". Environmental Health Perspectives. 116 (4): A160 –A167. doi:10.1289/ehp.116-a160. PMC   2290997 . PMID   18414615.
  57. ↑ Borradale D, Isenring E, Hacker E, Kimlin MG (February 2014). "Exposure to solar ultraviolet radiation is associated with a decreased folate status in women of childbearing age" (PDF). Journal of Photochemistry and Photobiology. B, Biology. 131: 90–95. Bibcode:2014JPPB..131...90B. doi:10.1016/j.jphotobiol.2014.01.002. hdl:10072/432100. PMID   24509071. Archived (PDF) from the original on November 3, 2018. Retrieved September 19, 2019.
  58. ↑ "Pregnancy and Tanning". American Pregnancy Association. January 2014. Archived from the original on July 3, 2014. Retrieved January 11, 2015.
  59. ↑ Skjærvø GR, Fossøy F, Røskaft E (February 2015). "Solar activity at birth predicted infant survival and women's fertility in historical Norway". Proceedings. Biological Sciences. 282 (1801): 20142032. doi:10.1098/rspb.2014.2032. PMC   4308994 . PMID   25567646.
  60. ↑ Weller RB, Wang Y, He J, Maddux FW, Usvyat L, Zhang H, et al. (March 2020). "Does Incident Solar Ultraviolet Radiation Lower Blood Pressure?". Journal of the American Heart Association. 9 (5): e013837. doi:10.1161/JAHA.119.013837. PMC   7335547 . PMID   32106744.
  61. ↑ Zhu, Hongying (June 14, 2018). "Moderate UV Exposure Enhances Learning and Memory by Promoting a Novel Glutamate Biosynthetic Pathway in the Brain". Cell. 173 (7): 1716–1727.e17. doi:10.1016/j.cell.2018.04.014. PMID   29779945.
  62. ↑ cao, Jianping (December 26, 2018). "The glutamate biosynthetic pathway in brain: a novel mechanism of moderate UV-induced neurobehavioral changes". Acta Biochimica et Biophysica Sinica. 51 (2): 227–228. doi: 10.1093/abbs/gmy166 . PMID   30590380.
  63. ↑ Slominski, Andrzej (May 2018). "How UV Light Touches the Brain and Endocrine System Through Skin, and Why". Endocrinology. 159 (5): 1992–2007. doi:10.1210/en.2017-03230. PMC   5905393 . PMID   29546369.
  64. ↑ Blume, Christine; Garbazza, Corrado; Spitschan, Manuel (August 20, 2019). "Effects of light on human circadian rhythms, sleep and mood". Somnologie. 23 (3): 147–156. doi:10.1007/s11818-019-00215-x. PMC   6751071 . PMID   31534436.
  65. 1 2 Cranney A, Horsley T, O'Donnell S, Weiler H, Puil L, Ooi D, et al. (August 2007). "Effectiveness and safety of vitamin D in relation to bone health". Evidence Report/Technology Assessment (158): 1–235. PMC   4781354 . PMID   18088161.
  66. ↑ Brannon H (January 1, 2014). "UVC Radiation". About.com. Archived from the original on March 5, 2016. Retrieved March 25, 2015.
  67. ↑ Jablonski NG (October 2004). "The Evolution of Human Skin Color" (PDF). Annual Review of Anthropology. 33 (1): 585-623 (600). doi:10.1146/annurev.anthro.33.070203.143955. Archived (PDF) from the original on August 24, 2018.
  68. ↑ Lucas RM, McMichael AJ, Armstrong BK, Smith WT (June 2008). "Estimating the global disease burden due to ultraviolet radiation exposure". International Journal of Epidemiology. 37 (3): 654–667. doi:10.1093/ije/dyn017. PMID   18276627.
  69. ↑ Lucas RM, Ponsonby AL (December 2002). "Ultraviolet radiation and health: friend and foe". The Medical Journal of Australia. 177 (11–12): 594–598. doi:10.5694/j.1326-5377.2002.tb04979.x. PMID   12463975. S2CID   22389294. Archived from the original on April 2, 2015. Retrieved March 24, 2015.
  70. ↑ Webb AR (September 2006). "Who, what, where and when-influences on cutaneous vitamin D synthesis". Progress in Biophysics and Molecular Biology. 92 (1): 17–25. doi:10.1016/j.pbiomolbio.2006.02.004. PMID   16766240.
  71. ↑ Jablonski, Nina (2012). Living Color. University of California Press. ISBN   978-0-520-25153-3.
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