Health studies about vitamin D, sunlight, and cancer:

Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women: A Randomized Clinical Trial (2017)

Conclusion: 2,064 elderly women were given either a daily dose of 2,000IU of vitamin D and 1,500mg of calcium or a daily placebo for 4 years. The cancer rates were measured over the course of the study and the vitamin D group had a slightly lower cancer rate. One possible reason for why the vitamin D group had only a slightly lower rate is that the women actually had decent vitamin D levels going into the study, possibly making the effects of supplemental vitamin D not as powerful as if the women had been deficient.


Vitamin D and Cancer: A Review of Molecular Mechanisms (2015)

Note: This is an overview of the multitude of complex mechanisms by which vitamin D prevents cancer.


Protective Role of Vitamin D Signaling in Skin Cancer Formation (2013)

Conclusion: Proper vitamin D receptor function protects against tumor formation and allows for DNA repair.


Association Between Ultraviolet Radiation, Skin Sun Sensitivity and Risk of Pancreatic Cancer (2013)

Conclusion:  “Being born in or living in areas of higher ambient UVR [ultraviolet radiation] (compared to lower ambient UVR) was associated with about 30-40% lower risk of pancreatic cancer. People with fair skin colour had 47% lower risk of pancreatic cancer than those with dark skin colour (95% CI 0.37-0.75). There was some suggestion of increased risk with increased average number of hours spent outside at work. This study suggests that people with light skin colour or those born or living in areas of high ambient UVR have lower risk of pancreatic cancer. Our analysis supports an association between UVR and pancreatic cancer, possibly mediated through production of vitamin D.”


Is Prevention of Cancer by Sun Exposure More Than Just the Effect of Vitamin D? A Systematic Review of Epidemiological Studies (2013)

Conclusion: “We found that almost all epidemiological studies suggest that chronic (not intermittent) sun exposure is associated with a reduced risk of colorectal-, breast-, prostate cancer and NHL.”


Ecological Studies of the UVB–Vitamin D–Cancer Hypothesis (2012)

Note: This article covers many studies providing strong evidence that a lack of UVB exposure / vitamin D is strongly associated with colon cancer, rectal cancer, breast cancer, gastric cancer, non-Hodgkin’s lymphoma, Hodgkin’s lymphoma, bladder cancer, ovarian cancer, pancreatic cancer, esophageal cancer, lung cancer, cervical cancer, renal cancer, vulvar cancer, gallbladder cancer, brain cancer, multiple myeloma, leukemia, prostate cancer, laryngeal cancer, thyroid cancer, melanoma, and pharyngeal cancer.


Serum Levels of 25-Hydroxyvitamin D and Survival in Norwegian Patients with Cancer of Breast, Colon, Lung, and Lymphoma: A Population-Based Study (2012)

Conclusion: A 24-year study of 658 cancer patients in Norway found that those with higher vitamin D levels at the time of diagnoses had higher survival rates.


Association Between Ambient Ultraviolet Radiation and Risk of Esophageal Cancer (2012)

Conclusion: 995 esophageal cancer patients in Australia were analyzed along with 1471 population controls. The cancer patients reported having less sun exposure over their lifetimes and tended to live in less sunny areas than the controls.


Association Between Ambient Ultraviolet Radiation and Risk of Epithelial Ovarian Cancer (2012)

Conclusion: 1,500 ovarian cancer patients and 1,459 healthy female controls in Australia were analyzed. The top third of all the women who reported having the most sun exposure over their lifetimes and who lived in the sunnier areas of Australia had the lowest risk for ovarian cancer. Those in the bottom third for lifetime sun exposure had the highest risk for ovarian cancer. “Women who spent their lives in areas with higher levels of ambient UVR [ultraviolet radiation] had a lower risk of developing epithelial ovarian cancer than those living in areas with lower levels of ambient UVR.”


Vitamin D and Cancer (2012)

Conclusion: “In clinical studies, an impact of vitamin D has been reported in different types of cancer. A low vitamin D activity is associated with an increased cancer risk and a more aggressive tumor growth, while high activity of this pathway induces antitumoral effects. In particular, serum circulating levels of 25(OH)D levels <20 ng/ml seems to expose to the risk of developing mammary and colorectal cancer.”


A Positive Feedback Signaling Loop between ATM and the Vitamin D Receptor Is Critical for Cancer Chemoprevention by Vitamin D (2012)

Note: This is a technical overview of how vitamin D prevents cancer.


Differences in Vitamin D Status May Account for Unexplained Disparities in Cancer Survival Rates Between African and White Americans (2012)

Conclusion: Compared to white Americans, black Americans generally have significantly lower vitamin D levels, significantly higher rates of vitamin D deficiency, and suffer much more from cancer (which vitamin D-deficiency has been found to be a major culprit in), with worse cancer survival rates than whites.
“This review offers evidence to explain cancer survival differences between AAs [African Americans] and WAs [White Americans]. AAs’ lower serum 25(OH)D concentrations [vitamin D] (mainly from reduced vitamin D photoproduction owing to darker pigmentation) may account for much of the unexplained survival disparity.” Emphasis added.


Exposure to Ultraviolet Radiation: Association with Susceptibility and Age at Presentation with Prostate Cancer (2011)

Conclusion: “A positive association between latitude and prostate cancer mortality has been interpreted to indicate that ultraviolet radiation (UVR) protects against development of this cancer.”


Prevalence of Serum Vitamin D Deficiency and Insufficiency in Cancer: Review of the Epidemiological Literature (2011)

Conclusion: “This review confirms a high prevalence of vitamin D deficiency in multiple cancer sites.”


How Strong is the Evidence that Solar Ultraviolet B and Vitamin D Reduce the Risk of Cancer? (2009)

Note: Comprehensive overview on the evidence of vitamin D and UVB’s anti-cancer benefits.


Vitamin D Receptor, UVR, and Skin Cancer: A Potential Protective Mechanism (2008)

Conclusion: Although UVB exposure can cause non-melanoma skin cancer, it’s also the same UV spectrum necessary for the epidermal vitamin D synthesis that prevents other cancers.


Vitamin D and Calcium Supplementation Reduces Cancer Risk: Results of a Randomized Trial (2008)

Conclusion: In a four-year population-based, double-blind, randomized placebo-controlled trial involving 1179 postmenopausal Nebraska women, women receiving a daily dose of 1500mg/day of supplemental calcium and 1100 IU/day of Vitamin D had a 77% lower risk for all types of cancer compared to the placebo group.


Low Serum Levels of 25-Hydroxyvitamin D Predict Fatal Cancer in Patients Referred to Coronary Angiography (2008)

Conclusion: This study measured the vitamin D levels of 3,299 Germans. Over the course of the study and follow ups, those with lower vitamin D levels had the highest rate of fatal cancer.


Circulating 25-hydroxyvitamin D Levels Predict Survival in Early-Stage Non-Small-Cell Lung Cancer Patients (2007)

Conclusion: 447 early-stage non-small-cell lung cancer patients were observed for an average of 6 years and it was found that those with higher vitamin D levels and higher vitamin D intake had higher survival rates than those with lower vitamin D levels and lower vitamin D intake.


Photoprotection by 1,25 Dihydroxyvitamin D3 Is Associated with an Increase in p53 and a Decrease in Nitric Oxide Products (2007)

Conclusion: Vitamin D and UV exposure “induce high levels” of the anti-cancer, tumor-suppressing, DNA-repairing p53 protein.


Vitamin D and Calcium Supplementation Reduces Cancer Risk: Results of a Randomized Trial (2007)

Conclusion: 4-year study had 1,179 elderly white Nebraska women take a daily calcium supplement, calcium + vitamin D, or a placebo. The calcium plus vitamin D group had the lowest cancer incidence. “Improving calcium and vitamin D nutritional status substantially reduces all-cancer risk in postmenopausal women.”


Vitamin D and Cancer (2006)

Conclusions: Two groups of mice were given subcutaneous implantations of mouse colon cancer cells. One group was severely vitamin D-deficient, the other group had much higher vitamin D levels. 19 days later the vitamin D-deficient mice had tumors that were 60% larger than the mice with the better vitamin D levels.


Does Sunlight Prevent Cancer? A Systematic Review (2006)

Conclusion: “From our review, it becomes clear that there is an increasing evidence of sunlight having a preventive effect on the initiation and/or progression of different kinds of cancer.”


Lower Vitamin-D Production from Solar Ultraviolet-B Irradiance May Explain Some Differences in Cancer Survival Rates (2006)

Conclusion: Black Americans have higher cancer rates than other races at least partly because of lower vitamin D levels as a result of a reduced ability to synthesize vitamin D from solar UVB exposure.


Prospective Study of Predictors of Vitamin D status and Cancer Incidence and Mortality in Men (2006)

Conclusion: Men with higher vitamin D levels have a lower cancer incidence and mortality rate compared to men with lower vitamin D levels.


The Role of Vitamin D in Cancer Prevention (2006)

Conclusion: Sun exposure and vitamin D prevent colon, breast, prostate, and ovarian cancer


Solar ultraviolet-B exposure and cancer incidence and mortality in the United States, 1993-2002 (2006)

Conclusion: For the period of 1993 to 2002, satellite-measured solar UV-B levels, 3+ million cancer incidences, and 3 million cancer deaths in America were analyzed. There was a correlation between lower UVB levels and an increased rate of  “bladder, colon, Hodgkin lymphoma, myeloma, prostate, rectum, stomach, uterus, and vulva” cancer, and to a lesser extent for “breast, kidney, leukemia, non-Hodgkin lymphoma, pancreas, and small intestine” cancer.


The Association of Solar Ultraviolet B (UVB) with Reducing Risk of Cancer: Multifactorial Ecologic Analysis of Geographic Variation in Age-Adjusted Cancer Mortality Rates (2006)

Conclusion: A study of American cancer mortality rates from 1950-1969 and 1970-1994 found that cancer mortality rates have been higher in areas of American with weaker UVB solar radiation (i.e. northern latitudes).


Ultraviolet Radiation, Dietary Vitamin D, and Risk of Non-Hodgkin Lymphoma (2006)

Conclusion: Study examined 551 people with non-hodgkin lymphoma and 462 controls and found that those who received more UV exposure through sunlight and tanning lamps had a slightly reduced risk for NHL.


Do Sunlight and Vitamin D Reduce the Likelihood of Colon Cancer? (2005)

Conclusion: Within the U.S., the states with the highest amount of solar radiation (New Mexico, Arizona, Florida, California, Texas – low latitudes) have the lowest rates of colon cancer mortality and the states with the lowest solar radiation (New York, New Jersey, Rhode Island, Connecticut – high latitudes) have the highest rates of colon cancer mortality. Lower latitude populations tend to have higher vitamin D levels than higher latitude populations.


Phytoestrogens and Vitamin D Metabolism: A New Concept for the Prevention and Therapy of Colorectal, Prostate, and Mammary Carcinomas. (2004)

Conclusion: Optimization of vitamin D levels is important for tumor prevention.


Prevalence of Vitamin D Deficiency in Patients Attending an Outpatient Cancer Care Clinic in Boston (2004)

Conclusion: This study compared the vitamin D blood levels of 56 middle-aged Boston cancer patients and 50 age-matched health control. 48% of the cancer patients were clinically deficient in vitamin D versus only 12% of the healthy controls. More alarming was that those who were deficient were deficient during summer when people’s vitamin D levels tend to be the highest.


Vitamin D3 from Sunlight May Improve the Prognosis of Breast-, Colon- and Prostate Cancer (2004)

Conclusion: 115,096 cases of breast, colon, and prostate cancer diagnosed over a 28-year period were observed. Researchers found that patients diagnosed in the summer and fall, when population vitamin D levels are highest, had the lowest cancer fatality rate. “The results suggest that a high level of vitamin D3 at the time of diagnosis, and thus, during cancer treatment, may improve prognosis of the three cancer types studied.” The study also found that men and women who received medium to high levels of occupational sun exposure had an extraordinarily lower cancer fatality rate compared to people with low occupational sun exposure.

Epidemiologic Evidence for Different Roles of Ultraviolet A and B Radiation in Melanoma Mortality Rates (2003)

Conclusion: People who get more exposure to strong UVB sunlight have lower rates of melanoma mortality.


Sunlight and Mortality From Breast, Ovarian, Colon, Prostate, and Non-Melanoma Skin Cancer: A Composite Death Certificate Based Case-Control Study (2002)

Conclusion: Sun exposure lowers your risk of developing breast, ovarian, prostate, and colon cancer


An Estimate of Premature Cancer Mortality in the U.S. Due to Inadequate Doses of Solar Ultraviolet-B Radiation (2002)

Conclusion: Lack of midday sun exposure increases one’s risk for developing and dying from breast, colon, ovarian, prostate, bladder, esophageal, kidney, lung, pancreatic, rectal, stomach, and uterine cancer.


Sunlight, Vitamin D, and Ovarian Cancer Mortality Rates in U.S. Women (1994)

Conclusion:  “Sunlight may be a protective factor for ovarian cancer mortality.”


Beneficial Effects of Sun Exposure on Cancer Mortality (1993)

Conclusion: “The research studies presented here suggest that dermal activation of vitamin D from regular, moderate sun exposure has a strong protective effect in the prevention of breast and colon cancer; has a weaker protective effect in melanoma, leukemia, and lymphoma; and acts to lower overall cancer death rates.”


Geographic Patterns of Prostate Cancer Mortality. Evidence for a Protective Effect of Ultraviolet Radiation (1992)

Conclusion: There are lower prostate cancer mortality rates in the southern regions of America compared to the northern regions due to the south receiving stronger sunlight with more vitamin D-producing UVB radiation.


The Relation of Solar Radiation to Cancer Mortality in North America (1940)

Conclusion: Sun exposure increases immunity to cancer


Also see studies specifically on sunlight and vitamin D’s prevention of:

Breast Cancer

Colon Cancer

Esophageal Cancer

Lung Cancer


Non-Melanoma Skin Cancer

Ovarian Cancer

Pancreatic Cancer

Prostate Cancer


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