By Dr. Mercola
Recent research blaming sunlight exposure for the growing incidences of melanoma, the deadliest form of skin cancer, has failed to consider crucial information that could turn the entire concept on its head, according to Dr. William Grant, an epidemiologist writing for the Vitamin D Council.
One important point the research missed was that sometimes sunscreen can actually increase your risk of melanoma, especially in the Northern Hemisphere.
There are other studies showing that chronic UV (ultraviolet) light exposure may actually reduce the risk of melanoma. Allow me to explain …
Are Rates of Melanoma Really Increasing?
The first point that needs to be addressed is whether melanoma cases are really on the rise. As Dr. Grant stated:
“Two recent papers blame increased ultraviolet (UV) exposure for the growing rates of melanoma in the UK. Not considered were other possible explanations for the rising rates of melanoma, including the use of sunscreen, especially at latitudes above 40º, and a combination of underdiagnosis in the past with over diagnosis more recently. [Melanoma mortality rates changed little in the U.S. between 1986 and 2001 while incidence rates more than doubled.”
Further research published in the British Journal of Dermatologyi shows that the sharp increase in melanoma rates over the last three decades may actually be "an artifact caused by diagnostic drift." Diagnostic drift, according to the study, refers to a hefty increase in disease that is being fueled by non-cancerous lesions.
During the study period from 1991 to 2004, there were nearly 4,000 cases of melanoma included in the report, with an annual increase of 9.39 to 13.91 cases per 100,000 per year. The researchers revealed that, rather than being fueled by increasing exposure to sunlight as is commonly suggested, the increased incidence was almost entirely due to non-cancerous lesions misleadingly classified as “stage 1 melanoma.” Even the distribution of the lesions reported did not correspond to the sites of lesions caused by sun exposure, leading researchers to conclude:
"These findings should lead to a reconsideration of the treatment of 'early' lesions, a search for better diagnostic methods to distinguish them from truly malignant melanomas, re-evaluation of the role of ultraviolet radiation and recommendations for protection from it, as well as the need for a new direction in the search for the cause of melanoma."
Sensible Sunlight is Protective Against Melanoma
Exposure to sunlight, particularly UVB, is protective against melanoma -- or rather, the vitamin D your body produces in response to UVB radiation is protective. As written in The Lancet:ii
"Paradoxically, outdoor workers have a decreased risk of melanoma compared with indoor workers, suggesting that chronic sunlight exposure can have a protective effect."
A study in Medical Hypothesesiii suggested that indoor workers may have increased rates of melanoma because they're exposed to sunlight through windows, and only UVA light, unlike UVB, can pass through window glass. At the same time, these indoor workers, who get three to nine times less solar UV exposure than outdoor workers, are missing out on exposure to the beneficial UVB rays, and have lower levels of vitamin D. The study even noted that indoor UV actually breaks down vitamin D3 formed after outdoor UVB exposure, which would therefore make vitamin D3 deficiency and melanoma risk even worse. A number of associations between sun exposure and melanoma can be found in the medical literature, such as:
- Occupational exposure, such as farmers and fishermen, and regular weekend sun exposure are associated with decreased risk of melanoma
- Sun exposure appears to protect against melanoma on skin sites not exposed to sun light, and melanoma occurring on skin with large UV exposure has the best prognosis
- Patients with the highest blood levels of vitamin D have thinner melanoma and better survival prognosis than those with the lowest vitamin D levels.
Vitamin D Reduces Your Risk of Cancer
This is an important point, because if you are shunning the sun for fear of skin cancer, you are, ironically, missing out on one of the most potent natural cancer protections available. Vitamin D's protective effect against cancer works in multiple ways, including:
- Increasing the self-destruction of mutated cells (which, if allowed to replicate, could lead to cancer)
- Reducing the spread and reproduction of cancer cells
- Causing cells to become fully differentiated (cancer cells often lack differentiation)
- Reducing the growth of new blood vessels from pre-existing ones, which is a step in the transition of dormant tumors turning cancerous
A study by Dr. Grant found that about 30 percent of cancer deaths -- which amounts to 2 million worldwide and 200,000 in the United States -- could be prevented each year with higher levels of vitamin D. As he stated in the featured article, the potential lives saved from optimizing vitamin D levels through safe sun exposure (or a safe tanning bed) far outweighs the reported number of melanoma deaths:
“In 2007, there were 988 male and 837 female deaths from melanoma in the UK, and a total 71,336 male and 65,458 female cancer deaths. Thus, melanoma accounted for 1.4% of male cancer deaths and 1.3% of female cancer deaths. Assuming a 15% reduction in all-cancer incidence and mortality rates with adequate solar UVB exposure would imply 20,500 reduced cancer deaths in 2007, which is 11 times the number of melanoma deaths.”
Similarly, in a review of the health effects of sun exposure, tanning beds and vitamin D, researchers again noted that the benefits of vitamin D production outweigh the potentially increased risk of melanoma:iv
“The overall health benefit of an improved vitamin D status may be more important than the possibly increased CMM [cutaneous malignant melanoma] risk resulting from carefully increasing UV exposure.”
Again, there’s compelling research showing that sun exposure will indeed protect you against melanoma, as a very low level of vitamin D is a major risk factor for this disease. This is, by the way, also a primary reason why using sunscreen every time you go outdoors may actually accelerate, rather than prevent, cancer.
How to Optimize Your Vitamin D While Minimizing Your Risk of Skin Damage
Sun exposure is the best way to optimize your vitamin D levels, because when you expose your skin to sunshine or a safe tanning bed, your skin synthesizes vitamin D3. I believe this is a very compelling reason to really make a concerted effort to get ALL your vitamin D requirements from exposure to sunshine, or by using a safe tanning bed. If neither of these are feasible options, then you should take an oral vitamin D3 supplement. For more information, see my recent video below on how to know if you are getting enough vitamin D from sun exposure.
- i Br J Dermatol. 2009 Sep;161(3):630-4. Epub 2009 Jun 9.
- ii The Lancet, Volume 363, Issue 9410, Pages 728 – 730, 28 February 2004
- iii Medical Hypotheses Volume 72, Issue 4 , Pages 434-443, April 2009
- iv Public Health Nutr. 2012 Apr;15(4):711-5. Epub 2011 Oct 24.