(NaturalNews) A study by researchers at the Institute for Cancer Research in Oslo, Norway has given further credence to the claim that the benefits of modest sun exposure outweigh the risk of skin cancer for most people. Johan Moan, the researcher who led the study said, "Modest sun exposure gives enormous vitamin D benefits."
He estimated that doubling the amount of sun exposure for residents of Norway would double the number of deaths due to skin cancer to 300. However, the great benefit to this would be a decrease of 3,000 people who die from other cancers [1].
The human skin synthesizes vitamin D when exposed to the ultraviolet type B (UVB) radiation in sunlight. Solar radiation is the main source of vitamin D for most people. Modest sun exposure causes a significant amount of vitamin D to accumulate in the body and protect from some internal cancers and other illnesses such as diabetes and rickets. Vitamin D promotes bone mineralization and calcium absorption thus protecting against osteomalacia and osteoporosis. The vitamin also helps the body's immune system function properly [2]. When deficient, the human body is at great risk of acquiring these conditions and deficiency is linked to heart attacks and mental depression. Most people could experience the benefits by increasing their sun exposure, but not too much as to cause any burning.
Vitamin D deficiency has been measured to be as high as 21 to 58 percent in adolescents and adults in the United States [3].
Several factors reduce individuals' exposure to sunlight and UVB light rays: the amount of time spent in the sun is the most obvious. Also, more polar latitudes, the time of day such as dusk compared to noon, high cloud cover, smog, and sunscreen use lower the amount of UVB radiation that reaches people.
Geographic latitude plays a significant role. Generally, the farther an individual is from the equator, the more difficult it is to synthesize enough vitamin D. For example, in Boston, MA, from November through February, the average amount of sunlight is inadequate for an individual to synthesize enough vitamin D [4]. Additionally, the researchers at the Institute for Cancer Research in Oslo determined that, given the same amount of sunlight, inhabitants of Australia just below the equator produced 3.4 more times the vitamin D than people in Britain and 4.8 times that of Scandinavians [1].
It's essential to learn the optimal amount of sun exposure that is healthy for you without causing sunburn. Moan recommended that a person's daily sun exposure should be about half the time that it would take to burn. Lighter skinned people are more sensitive to sunburn and skin damage, but they are more proficient at creating vitamin D with less sun exposure than a darker skinned person (Please see [5] below for a related, generally accepted theory for skin color variance). Light skinned peoples in Southern United States can synthesize enough vitamin D by exposing their face and arms to the sun without sunscreen for about 15 minutes a few times a week. Dark skinned people need about 5 to 10 times more exposure [2].
A consensus has not been made for how much vitamin D is a healthy level for most people, but it's generally agreed that for people up to the age of 50, 200 IUs (international unit) is the Adequate Intake (AI). For 51 to 70 year olds, 400 IUs is the AI and for individuals over 70, 600 IUs is recommended. The ability to synthesize vitamin D decreases with age. However, recent studies have shown amounts of vitamin D of 2,000 IUs and higher to be more effective and still safe [6]. If a person works outside under the summer sun for hours in a tank-top and shorts, his skin will have made thousands of IUs. Of course, a baseline tan to prevent burning would be a good idea. Normal body levels of vitamin D can't reach the level that a large vitamin D pill would produce. The body self-regulates; reducing vitamin D synthesis when levels are getting high from sun exposure.
Is there a difference between taking say, 1,000 IUs in pill form and synthesizing it via UVB radiation? Is putting a 1,000 IU pill in your body versus forming it all over your skin comparable to drinking 8 glass of water at once versus spreading it throughout the day? This, I am unsure of.
Within UVB light are a range of wavelengths. Some are more optimal for vitamin D synthesis than others. A person at sea level will receive these wavelengths when the sun is 45 degrees above the horizon or the UV index for the day is above 3. When the sun is at or above this elevation in the sky, sufficient amounts of vitamin D can be made by the skin in about 15 minutes a few times a week. The area of the planet within the tropics provides this solar elevation daily, but it occurs daily only in the spring and summer seasons of temperate regions, and nearly never in the arctic circles [7]. Seasonal supplementation seems to be appropriate.
Sunscreen with a sun protection factor (SPF) of 8 prevents more than 95% of vitamin D production [11]. So when you lather up with this sunscreen, it will take 20 times longer than usual to make enough vitamin D. This effect was observed during a campaign in Australia to increase sunscreen use to prevent skin cancer. The result was an increase in Australians with vitamin D deficiency [8].
If the minimum level of sun exposure can not be obtained, people should look to their diet for vitamin D. Since few foods contain enough vitamin D, some foods are fortified with vitamin D and supplements can be taken to attain an adequate level.
To complicate matters further, there are 5 forms of vitamin D. The two major forms are vitamin D2 (ergocalciferol) and D3 (cholecalciferol). Both forms are present in human nutritional supplements. When our skin comes into contact with UVB radiation, it synthesizes only vitamin D3. Both of these forms are prohormones, precursors to the vitamin D hormone that goes on to perform all of the beneficial processes that have been mentioned. However, the vitamin D3 form is about 3 times more effective at creating the vitamin D hormone and its duration of action is longer that the D2 form. Supplementing with vitamin D3 would be the wiser choice [9].
UVA and UVB radiation exposure is a double edged sword. Excessive exposure will cause damage to the skin and more importantly, to the DNA inside the cells. With more DNA damage comes a greater chance of developing skin cancer. However, only a small percentage of skin cancers are the type that will metastasize (to spread throughout the body from the origin of formation). The wavelengths of UVA light are longer and penetrate farther into the skin. UVA radiation is a more potent cause of skin cancer than the shorter UVB light.
Skin cancers are among the fastest growing types of cancer in the United States and make up about 1 out of 3 new cancers.
With the rise in popularity of sun bathing, something must be said about tanning beds. Although the time spent in a tanning bed is typically much less than say, an afternoon at the beach, the radiation levels are more intense than from sunlight and the UVA to UVB radiation ratio is much higher than from the sun. The amount of UVA radiation in the light of tanning beds is typically between 3 to 8 times greater than in sunlight [10]. Recall that UVA radiation, and UVB less so, put individuals at risk for DNA damage and skin cancer, but only exposure to UVB radiation will produce vitamin D, which protects against many illnesses. Therefore, it is this author's humble opinion that, while tanning beds may be more convenient, it is safer to get your healthy glow from the sun and good nutrition.
References:
[1]"Addressing the health benefits and risks, involving vitamin D or skin cancer, of increased sun exposure"(
http://www.pnas.org/cgi/content/abstract/105/2/668?maxtoshow=&HITS=10&hit...)
[2](
http://www.medicinenet.com/script/main/art.asp?articlekey=78684)
[3]"Vitamin D Deficiency-The Once and Present Epidemic" (
http://www.aafp.org/afp/20050115/editorials.html)
[4](
http://healthlink.mcw.edu/article/982088787.html)
[5]"Skin Color Adaptation" (
http://anthro.palomar.edu/adapt/adapt_4.htm)
[6](
http://www.vitamindcouncil.com/treatment.shtml)
[7](
http://upload.wikimedia.org/wikipedia/commons/a/ab/WorldMapLongLat-eq-cir...)
[8]Nowson C, Margerison C (2002). "Vitamin D intake and vitamin D status of Australians". Med J Aust 177 (3): 149-52. PMID 12149085.
[9]"Vitamin D2 Is Much Less Effective than Vitamin D3 in Humans" (
http://jcem.endojournals.org/cgi/content/full/89/11/5387)
[10]Woollons, A., Clingen, P.H., Price, M.L., Arlett, C.F., Green, M.H.L. (1997). Induction of mutagenic DNA damage in human fibroblasts after exposure to artificial tanning lamps. British Journal of Dermatology 1997; 137: 687-692.
[11](
www.motherearthnews.com/Natural-Health/2008-02-01/Vitamin-D-Sunshine-Supp...)
About the author
Tom Mosakowski, B.S. Biochemistry.
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