Post by lauryn on Mar 17, 2005 12:31:03 GMT -5
Vitamin D and Sunscreen
It’s hard to imagine that a vitamin could find itself in the midst of a controversy, but that is exactly the position vitamin D is in. The conflict is over risking sun exposure because of our bodies’ need for vitamin D. Vitamin D deficiency can be a serious health problem, most notably by blocking the absorption of calcium and phosphorus, causing a chronic imbalance and bone deterioration. As luck would have it, sunlight is the most abundant, natural source that helps our bodies make vitamin D.
You may be unaware that, despite the name, vitamin D is not actually a vitamin. It is a hormone known as calcitrol. When your skin is exposed to UVB light, it converts 7-dehydrocholesterol (present in your skin and bloodstream) into vitamin D, where the liver and kidneys activate it and it begins regulating and enhancing the absorption of the minerals calcium and phosphorus in the body. Since there are very few foods that naturally contain vitamin D (your best options are salmon, mackerel, and cod liver oil) most of us need to rely on either sun exposure or vitamin D-fortified foods (such as milk and cereals) to ensure we get enough.
Where the controversy takes place is that exposing our skin to the sun without sunscreen is dangerous, but there are those that believe sunscreen will cancel out the body's ability to manufacture vitamin D from sun exposure. This concern has been expressed from several seemingly reputable resources (Sources: www.intelihealth.com/IH/ihtIH/WSIHW000/325/20932/230636.html?d=dmtContent; www.cnn.com/2003/HEALTH/diet.fitness/10/28/vitamin.D.ap/; www.umm.edu/patiented/articles/what_sunscreen_guidelines_000020_4.htm; American Journal of Clinical Nutrition, December 2004, 80 (Supplement 6):1678S-88S; and Archives of Dermatology, December 1988, pages 1802-1804).
On the other side of this argument are proponents for sun avoidance (myself included) who encourage maintaining adequate levels of vitamin D through dietary sources and supplements without skimping on the sunscreen because sunscreen does not block the amount of UVB radiation needed to help the body manufacture vitamin D.
An article reprinted in PCI Journal, Volume 12, Number 4, November 2004, refers to comments by dermatologist Darrell S. Rigel, M.D., clinical professor, New York University Medical Center in New York City. He reports that as someone who sees and treats skin cancer patients on a daily basis, it is appalling to him that anyone in good conscience would claim that intentional sun exposure, regardless of length of time, is beneficial. It is a fact that skin cancer rates are rising and solid science supports the daily application of sunscreen as the best defense against the damaging effects of sunlight. The same article also mentioned a 1997 study published in the Journal of the National Cancer Institute. It concerned patients with xeroderma pigmentosa (a disease that causes multiple skin cancers in persons exposed to even small amounts of UV radiation). The study demonstrated that these patients, despite avid sun avoidance and constant UV protection, still had normal levels of vitamin D over a period of several years. There is also the issue that no sunscreen, regardless of active ingredients or how often or liberally it is applied, can provide 100% protection from UV radiation. The tiny amount of UVB light that sunscreens do not shield is enough to begin the synthesis of vitamin D (though depending on your skin color and climate, supplemental vitamin D will likely still be necessary).
Further, several large, controlled studies have shown that vitamin D deficiency does not result from ongoing regular sunscreen use. Vitamin D supplementation is a good idea because most people’s diets are naturally deficient in it, not to mention as we age our bodies’ ability to produce vitamin D naturally diminishes due to the decrease in 7-dehydrocholesterol (a component in skin that begins the conversion process for vitamin D) (Sources: The Journal of the American Osteopathic Association, Volume 103, Number 8, August 2003, pages 3-4; American Journal of Clinical Dermatology, March 2002, pages 185-191; Dermatology, January 2001, pages 27-30; British Medical Journal, October 1999, page 1066). Before beginning any new vitamin supplement program, make sure to consult your physician.
It’s hard to imagine that a vitamin could find itself in the midst of a controversy, but that is exactly the position vitamin D is in. The conflict is over risking sun exposure because of our bodies’ need for vitamin D. Vitamin D deficiency can be a serious health problem, most notably by blocking the absorption of calcium and phosphorus, causing a chronic imbalance and bone deterioration. As luck would have it, sunlight is the most abundant, natural source that helps our bodies make vitamin D.
You may be unaware that, despite the name, vitamin D is not actually a vitamin. It is a hormone known as calcitrol. When your skin is exposed to UVB light, it converts 7-dehydrocholesterol (present in your skin and bloodstream) into vitamin D, where the liver and kidneys activate it and it begins regulating and enhancing the absorption of the minerals calcium and phosphorus in the body. Since there are very few foods that naturally contain vitamin D (your best options are salmon, mackerel, and cod liver oil) most of us need to rely on either sun exposure or vitamin D-fortified foods (such as milk and cereals) to ensure we get enough.
Where the controversy takes place is that exposing our skin to the sun without sunscreen is dangerous, but there are those that believe sunscreen will cancel out the body's ability to manufacture vitamin D from sun exposure. This concern has been expressed from several seemingly reputable resources (Sources: www.intelihealth.com/IH/ihtIH/WSIHW000/325/20932/230636.html?d=dmtContent; www.cnn.com/2003/HEALTH/diet.fitness/10/28/vitamin.D.ap/; www.umm.edu/patiented/articles/what_sunscreen_guidelines_000020_4.htm; American Journal of Clinical Nutrition, December 2004, 80 (Supplement 6):1678S-88S; and Archives of Dermatology, December 1988, pages 1802-1804).
On the other side of this argument are proponents for sun avoidance (myself included) who encourage maintaining adequate levels of vitamin D through dietary sources and supplements without skimping on the sunscreen because sunscreen does not block the amount of UVB radiation needed to help the body manufacture vitamin D.
An article reprinted in PCI Journal, Volume 12, Number 4, November 2004, refers to comments by dermatologist Darrell S. Rigel, M.D., clinical professor, New York University Medical Center in New York City. He reports that as someone who sees and treats skin cancer patients on a daily basis, it is appalling to him that anyone in good conscience would claim that intentional sun exposure, regardless of length of time, is beneficial. It is a fact that skin cancer rates are rising and solid science supports the daily application of sunscreen as the best defense against the damaging effects of sunlight. The same article also mentioned a 1997 study published in the Journal of the National Cancer Institute. It concerned patients with xeroderma pigmentosa (a disease that causes multiple skin cancers in persons exposed to even small amounts of UV radiation). The study demonstrated that these patients, despite avid sun avoidance and constant UV protection, still had normal levels of vitamin D over a period of several years. There is also the issue that no sunscreen, regardless of active ingredients or how often or liberally it is applied, can provide 100% protection from UV radiation. The tiny amount of UVB light that sunscreens do not shield is enough to begin the synthesis of vitamin D (though depending on your skin color and climate, supplemental vitamin D will likely still be necessary).
Further, several large, controlled studies have shown that vitamin D deficiency does not result from ongoing regular sunscreen use. Vitamin D supplementation is a good idea because most people’s diets are naturally deficient in it, not to mention as we age our bodies’ ability to produce vitamin D naturally diminishes due to the decrease in 7-dehydrocholesterol (a component in skin that begins the conversion process for vitamin D) (Sources: The Journal of the American Osteopathic Association, Volume 103, Number 8, August 2003, pages 3-4; American Journal of Clinical Dermatology, March 2002, pages 185-191; Dermatology, January 2001, pages 27-30; British Medical Journal, October 1999, page 1066). Before beginning any new vitamin supplement program, make sure to consult your physician.
Jenn
