By Marc Sorenson, EdD, for sun exposure…
A new research paper on sun exposure and cancer has some interesting observations and some errors. It is entitled, Does Sunlight protect us from cancer? Here is the abstract of the article, verbatim.
“The Ultraviolet (UV) radiation contained in sunlight is a powerful mutagen and immune suppressant which partly explains why exposure to solar UV is the biggest risk factor for the development of cutaneous tumors. Evidence is building that sunlight may be protective against some internal malignancies. Because patients with these tumors are often vitamin D deficient, this has led some to propose that vitamin D supplementation will be beneficial in the treatment of these cancers. However, the results from already completed trials have been disappointing which has given weight to the argument that there must be something else about sunlight that explains its cancer-protecting properties.”
The first sentence, of course, is false. The idea, that sun exposure is the biggest risk factor for skin cancer, is erroneous. We have presented materials many times, proving that melanoma is not caused by sun exposure, and that sun exposure is protective against that disease. And as regards common skin cancers, we have shown that high-fat nutrition, lack of antioxidants, meat consumption and alcohol intake are all risk factors. Search the blogs on this site to read the different articles.
The statement is correct, of course, that sunlight is protective against many internal cancers. Dr. Bill Grant and I are finishing our book, Embrace the Sun, where we present nearly all of the research on the protective influence of sun exposure against cancer.
The statement that vitamin D research has been disappointing is both true and false. Randomized controlled studies (RCTs) have shown the vitamin D supplements do have a protective effect against internal cancers, contrary to the statement by the researchers.
Finally, let’s look at the statement that there is something beyond vitamin D that explains the cancer-protecting properties of sun exposure. That is partially true. Beyond vitamin D, the sun causes the production of nitric oxide, serotonin, endorphin and BDNF, all of which are vital to human health, and may have their own cancer-protective properties.
The bottom line? Eat correctly (avoid junk), REGULARLY soak up some sun around midday and get plenty of exercise. That advice will be a boon to your health in myriad ways.
Sun and cognitive ability by Marc Sorenson, EdD, Sunlight Institute…
If you have depression, you may also have cognitive impairment, according to older research that I just became aware of. The researchers measured cognitive abilities among approximately 14,000 depressed subjects and then exposed them to either one day of sunlight or two weeks of sunlight. They then determined if cognitive disabilities were associated with the sun they obtained.
The results were impressive: Those who were sun-deprived for two weeks had 2.5 times the risk of being cognitively impaired, compared to those who had sufficient sunlight. A one-day exposure made no significant difference in cognition.
Results of other research, based on a 15-year residential history of varying degrees of sun exposure, has also shown that cognitive impairment in persons who were below the median exposure to sun, was 88% greater than those who were above the median. The researchers mentioned vitamin D as a possible mechanism by which sun positively influenced cognition, but they also remarked that regulation of the circadian rhythm by sunlight could be a factor.
Several other studies showed a close, positive association between vitamin D levels and cognition, and as we know, vitamin D levels in most cases are a surrogate measurement for sun exposure.
The message is to get plenty of sunlight to improve mental clarity. Happy thinking!
 Shia T Kent, Leslie A McClure, William L Crosson, Donna K Arnett, Virginia G Wadley and Nalini Sathiakumar. Effect of sunlight exposure on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study. Environmental Health 2009, 8:34
 Kent ST, Kabagambe EK, Wadley VG, Howard VJ, Crosson WL, Al-Hamdan MZ, Judd SE, Peace F, McClure LA. The relationship between long-term sun radiation and cognitive decline in the REGARDS cohort study. Int J Biometeorol. 2014 Apr;58(3):361-70.
In a new scientific paper, Dr. MS Razzaque shows that there may be some downsides to vitamin D supplementation, including “cardiovascular events and beyond.” He also states that “since hypovitaminosis D status usually reflects reduced sunlight exposure, the obvious primary replacement should be safe sunlight exposure, and not exogenous supplements.”
The paper specifically mentions that avoiding sunlight exposure may influence the initiation and progression of different types of tumors [cancer], high blood pressure, type 1 diabetes and multiple sclerosis. It also points out that there may be some deleterious consequences of vitamin D supplementation, although in my opinion, the dosage would need to by quite high.
As I have indicated in many of my posts on the Sunlight Institute site, sun exposure is the most natural way to obtain vitamin D, and it has no toxicity, since it is self-regulated.
What wasn’t mentioned was the production of health-promoting substances when sun touches the skin, e.g. endorphins and nitric oxide. And of course, the sun helps the brain to produce serotonin and BDNF, which are critical for proper brain function.
So soak up your sunlight but don’t burn.
 Razzaque MS. Sunlight exposure: Do health benefits outweigh harm? J Steroid Biochem Mol Biol. 2016 Sep 16. [Epub ahead of print].
By Marc Sorenson, EdD. Sunlight Institute
Although I occasionally try to balance the messages about tanning beds, this blog is meant neither to discourage nor promote their use. The readers should make up their minds after weighing the evidence. In a recent blog, I mentioned some positive messages about tanning-bed use, which included the following: Note: all references for the following list are found in the blog under footnote 1.
- Tanning-bed use is associated with a reduced risk of clots.
- Tanning-bed use is associated with increased vitamin D levels.
- Tanning-bed use is associated with stronger bones
- Tanning-bed use can cure psoriasis and eczema and tanning beds are often recommended by dermatologists.
- Tanning-bed use more than three times yearly is associated with a 40-50% reduced risk of endometrial cancer.
- Tanning-bed use is associated to lower breast-cancer risk.
After I posted the above information, a friend from Canada reminded me of research by Dr. Pelle Lindqvist and his colleagues, which demonstrated that both sun exposure and tanning-bed exposure reduced the risk of death during a 20-year study. Women who used tanning beds were 23% less likely to die of any cause than women who did not use them.
In addition, I remembered an older study that showed that tanning beds were able to take winter vitamin D levels up to summer levels in a period of five weeks.
So, along with the bad rap tanning beds are receiving, there is some good news. Who wouldn’t want to live longer in better health? Still, as with all decisions, weigh the evidence and then decide.
 Lindqvist P. Epstein E, Landin-Olsson M, Ingvar C, Nielsen K, Stenbeck M, Olsson H. Avoidance of sun exposure is a risk factor for all-cause mortality: Results from the Melanoma in Southern Sweden cohort
 Moan J, Lagunova Z, Cicarma E, Aksnes L, Dahlback A, Grant WB, Porojnicu AC. Sunbeds as vitamin D sources. Photochem Photobiol. 2009 Nov-Dec;85(6):1474-9.
By Marc Sorenson, EdD, Sunlight Institute…
In the previous blog, we noted that sun exposure was associated with a reduced risk of the deadly bacterial infection called sepsis. In reality, UV therapy was used to treat many kinds of infections decades ago, when sun exposure was widely known as a bactericide.
Dr. Zane Kime, in his book, Sunlight could Save Your Life, reviewed the results of research conducted between 1886 and 1909 and showed that the following bacteria were killed by ultraviolet light: anthrax, plague, streptococci, tubercle bacillus, cholera, staphylococcus, colon bacillus and dysentery bacillus. Sun was virtually forgotten with the advent of antibiotic drugs, but now the interest has returned.
While watching a newscast, I noticed the news ticker along the bottom of the screen announcing, “Sunshine is the most effective anti-infection therapy.” But is this really news? Dr. Kime cites several early studies on sun and infectious diseases that were performed about the same time as the advent of antibiotics. Reports in the scientific literature in the 1940s showed that sun killed infectious bacteria or viruses. Kime states …“a number of patients, having such various infections and diseases as blood poisoning [septicemia], childbirth infections, peritonitis, viral pneumonia, mumps, and bronchial asthma were treated with ultraviolet light therapy to their blood.”          They were, in fact, treated very successfully.
Dr. Kime also cited research showing that UV therapy killed the flu virus outside the body and destroyed cancer-producing viruses. He reported good results in his own practice in treating fungal infections with sun therapy.
The ancients knew of the marvelous healing effects of sun exposure, and Dr. Kime knew even more in 1980 as he reviewed the literature. We need more people who are willing to promulgate the truth about our kindly friend, the sun.
 Kime, Z. Sunlight Could Save Your Life. World Health Publications, Penryn, CA 1980 pp 180-81.
 Miley, G. The Knott technic of ultraviolet blood irradiation in acute pyogenic infections. New York J Med 1942;42:38.
 Miley, G. The Knott technic of ultraviolet blood irradiation in acute pyogenic infections. New York J Med 1942;42:38.
 Rebbeck, E. Ultraviolet irradiation of auto-transfused blood in the treatment of puerperal sepsis. Amer J Surg 1941;54:691
 Rebbeck, E. Ultraviolet irradiation of autotransfused blood in the treatment of postabortal sepsis. Amer J Surg 1942;55:476.
 Rebbeck, E. Ultraviolet irradiation of the blood in the treatment of escherichia coli septicemia. Arch Phys Ther 1943;24:158.
 Rebbeck, E. The Knott technic of ultraviolet blood irradiation as a control of infection in peritonitis. Amer J Gastroenterol 1943;10:1-26
 Hancock, V. Irradiated blood transfusions in the treatment of infections. Northwest Med 1934;33:200.
 Barrett, H. Five years experience with hemo-irradiation according to the Knott technic. Am J Surg 1943;61:42
 Barrett, H. The irradiation of auto-transfused blood by ultraviolet spectral energy: results of therapy in 110 cases. Med Clin N Amer 1940;24:723
 Miley, G. The present status of ultraviolet blood irradiation. Arch Phys Ther 1944;25:357.
 Hollaender, A. The inactivating effect of monochromatic ultraviolet radiation on influenza virus. J Bact 1944;48:447.
 Heding LD, Schaller JP, Blakeslee JR, Olsen RG. Inactivation of tumor cell-associated feline oncornavirus for preparation of an infectious virus-free tumor cell immunogen. Cancer Res 1976;36:1647.
By Marc Sorenson, EdD, Sunlight Institute
After coming across some research having to do with sun exposure and the seasonality of fractures, I thought it wise to share it with my readers.
In high latitude areas, which have far less sun availability than lower latitude areas, we would expect rates of hip fracture to be high, and such is the case. Sweden is a country that has large differences in latitude, and in research performed there it was shown that the higher the latitude and the lesser the sun exposure, the greater was the risk of hip fracture. In other words, significantly more hip fractures occurred in the northern part of the country compared to the middle and southern parts. Another Swedish investigation demonstrated that in men, hip fracture risk was 37.5% lower in summer than winter. Women had a 23.5% reduced risk in summer.
Research from Norway showed similar results. Hip fracture risk in men was 40% higher in winter than summer, and in women the risk was 25% higher.These fluctuations in seasonal hip fractures indicate a loss of bone mass during periods of low sun exposure (winter) and an increase in bone mass during periods of high sun exposure (summer). In other words, sun exposure is able to reverse bone loss, or osteoporosis. Other studies show similar patterns of bone strength based on sun exposure or lack thereof.
The importance of sunlight in maintaining and producing strong bones has been known since antiquity. Dr. Richard Hobday, author of The Healing Sun, writes the following comments and a history in an online article. “Traditionally, sunlight deprivation has been linked with weak or brittle bones. One of the earliest references to this was made more than two thousand years ago by the Greek historian Herodotus (480-425 BC), who noted a marked difference between the remains of the Egyptian and Persian casualties at the site of battle of Pelusium which took place in 525 BC:
‘At the place where this battle was fought I saw a very odd thing, which the natives had told me about. The bones still lay there, those of the Persian dead separate from those of the Egyptian, just as they were originally divided, and I noticed that the skulls of the Persians were so thin that the merest touch with a pebble will pierce them, but those of the Egyptians, on the other hand, are so tough that it is hardly possible to break them with a blow from a stone. I was told, very credibly, that the reason was that the Egyptians shave their heads from childhood, so that the bone of the skull is indurated by the action of the sun — this is why they hardly ever go bald, baldness being rarer in Egypt than anywhere else. This, then, explains the thickness of their skulls; and the thinness of the Persian’s skulls rests upon a similar principle: namely that they have always worn felt skull-caps, to guard their heads from the sun.’ Herodotus, ‘The Histories’”
The message is this: Don’t hide yourself from the sun; rather, embrace it in a safe manner, and that will protect your bones.
 Nilson F, Moniruzzaman S, Andersson R. A comparison of hip fracture incidence rates among elderly in Sweden by latitude and sun exposure. Scand J Public Health. 2014 Mar;42(2):201-6.
 Odén A, Kanis JA, McCloskey EV, Johansson H. The effect of latitude on the risk and seasonal variation in hip fracture in Sweden. J Bone Miner Res. 2014 Oct;29(10):2217-23.
 Solbakken SM1, Magnus JH, Meyer HE, Emaus N, Tell GS, Holvik K, Grimnes G, Forsmo S, Schei B, Søgaard AJ, Omsland TK.
 Grønskag AB1, Forsmo S, Romundstad P, Langhammer A, Schei B. Incidence and seasonal variation in hip fracture incidence among elderly women in Norway. The HUNT Study. Bone. 2010 May;46(5):1294-8.
 Richard Hobday. The Healing sun: Sunlight, Brittle Bones, and Osteoporosis. http://sunlightenment.com/the-healing-sun-sunlight-brittle-bones-and-osteoporosis/. (accessed February 5, 2016)
By Marc Sorenson, EdD Sunlight Institute…
A most interesting research paper demonstrates that nitrate supplements, combined with exposure to sunlight, increases performance of cyclists. The researchers state that “dietary nitrate supplementation has been shown to increase nitric oxide (NO) metabolites, reduce blood pressure (BP) and enhance exercise performance.” And, as we have discussed in this blog, sun exposure reduces BP by increasing the production of NO. It was theorized that sun exposure might enhance the athletic performance induced by the dietary nitrate supplementation.
The theory proved to be correct; although sun exposure did not improve cycling times by itself, when combined with the nitrate supplementation, cycling times improved significantly.
It may surprise some people to realize that ultraviolet radiation (UVR) from sun beds or sun lamps has been used since before 1950 to enhance athletic performance. As early as 1938, Russian researchers reported that a course of UVR significantly improved speed in the 100-meter dash among four students when compared with controls that did not have the radiation, although both groups were undergoing identical daily training. The non-irradiated group improved by 1.7% but the irradiated group improved by 7.4%. Another study conducted over ten weeks showed that cardiovascular endurance improved remarkably among athletes in training who were irradiated vs. those who were not. The irradiated athletes improved by 19.2% compared to 1.5% among the non-irradiated group.
There are numerous studies from Germany showing the efficacy of UVR on athletic performance, most of them from the early days before the idea of sun-lamp produced UVR fell into disrepute because of the attack on tanning beds. What a shame. This method of athletic assistance could produce an impressive improvement in sports performance for so many people, athletic or not. Strength improves, stamina improves, quickness improves and speed improves with UVR radiation, which of course is also part of sunlight. The mechanism for this improvement is likely a combination of vitamin D and nitric oxide.
Safely enjoy the sun!
 Muggeridge DJ, Sculthorpe N, Grace FM, Willis G, Thornhill L, Weller RB, James PE, Easton C. Acute whole body UVA irradiation combined with nitrate ingestion enhances time trial performance in trained cyclists. Nitric Oxide. 2015 Aug 1;48:3-9.
 Cannell JJ, Hollis BW, Sorenson MB, Taft TN, Anderson JJ. Athletic performance and vitamin D. Med Sci Sports Exerc. 2009 May;41(5):1102-10.
 Gorkin Z. Gorkin MJ, Teslenko NE. The effect of ultraviolet radiation upon training for the 100-meter sprint.
 Allen R, Cureton T. Effects of ultraviolet radiation on physical fitness. Arch Phys Med 1945;10:641-4.
By Marc Sorenson, EdD Sunlight institute…
Recent research shows that there is a higher risk of leukemia in countries that are at high latitudes in the north or low latitudes in the south. The risk is twice as high at these latitudes as at latitudes closer to the equator. Dr. Cedrick Garland, one of the authors of the research, stated that “these results suggest that much of the burden of leukemia worldwide is due to the epidemic of vitamin D deficiency we are experiencing in winter in populations distant from the equator.” Since persons living far from the equator have much less exposure to the sun’s rays, due to shorter sunlight seasons and more cloudiness, the statement regarding vitamin D deficiency makes sense; UVB from sun exposure, or another source such as tanning lamps, is necessary to stimulate the skin to produce vitamin D—hence the association between latitude and vitamin D.
However, Dr. William B Grant sent me an interesting paper that leads me to believe that some things that seem to make sense may not necessarily be true. The paper showed that there was little difference among vitamin D levels in countries at different latitudes, with levels being close to 20 ng/ml on average. This would lead me to believe that vitamin D was not the factor that caused the reduced risk of leukemia among the countries that received more sunlight.
We are then left to determine the cause of the reduced risk of leukemia in the sunny countries. There are really only two factors that come to mind. First, sunlight, through the eyes, stimulates the production of serotonin/melatonin, which have been associated with protection against cancer in some studies. Sunlight also stimulates the skin to produce nitric oxide and endorphin, which could have an impact. Second, populations residing in areas closer to the equator are likely to have access to year-round fruits and vegetables, which have been shown to associate to a lower risk of cancer. Whatever the reason, this is one more example of better health among people who receive more sunlight. And remember, even those fruits and veggies need sunlight to thrive. So let’s safely embrace the sun.
 Cuomo RE, Garland CF, Gorham ED, Mohr SB. Cuomo RE, Garland CF, Gorham ED, Mohr SB. Low Cloud Cover-Adjusted Ultraviolet B Irradiance Is Associated with High Incidence Rates of Leukemia: Study of 172 Countries. PLoS One. 2015 Dec 4;10(12).
 Jennifer Hilger, Angelika Friedel, Raphael Herr, Tamara Rausch, Franz Roos, Denys A. Wahl, Dominique D. Pierroz, Peter Weber and Kristina Hoffmann. A systematic review of vitamin D status in populations worldwide. Br J Nutr. 2014 Jan 14;111(1):23-45.
By Marc Sorenson, EdD Sunlight Institute…
The obesity pandemic, brought about by horrendous eating patterns, lack of exercise and lack of sunlight, has spawned millions of nutritionally bizarre diet programs and numerous strange medical procedures. One of the strangest is gastric bypass surgery, a procedure that cuts calorie absorptions by bypassing part of the stomach and intestinal area that absorbs nutrients. It is another case, similar to open-heart bypass, of a surgery that “bypasses” the real problem: preposterous lifestyle habits.
Any thinking person realizes that a surgery that reduces the calorie absorption also reduces the absorption of calcium and dietary vitamin D. It is a recipe for osteoporosis and hip fractures; these nutrients are essential for optimal bone health. Research by Dr. J Fleischer and colleagues showed that one year after gastric bypass, bone loss at the hip was 8%.[i] Just how important is this finding? One assessment showed that the risk of fracture increases two to three times for every 10 percent drop in bone density,[ii] and another showed that for every loss of 0.12g (.043 oz) per square centimeter (.15 square inch) of bone mass, the risk of a fracture increased by 360% in women and 340% in men.[iii]
Remember that this bone loss was reported only one year after the bypass surgery. If this rate of bone loss continued for several years, it would weaken the skeleton to the point that the slightest movement would cause a fracture. The bypass procedure is a horror, and the bone loss brought on by lack of absorption of calcium and vitamin D is even worse.
In the case of decreased absorption of vitamin D, increased dietary intake of vitamin D may not work to improve bone strength; it is likely that only a very small quantity of the increased intake would be absorbed into the system, meaning that the only way to ensure adequate vitamin D levels in the blood is to expose the skin to sunlight around midday in summer or light from sunlamps in winter. Vast quantities of vitamin D are produced in this manner, and the entire quantity is delivered to the blood, where it can work to increase calcium absorption in both the intestine and the bone. Calcium absorption in the intestine, for example, is 65% higher in people whose vitamin D levels are at the high end of “normal” when compared with those who are at the low end of normal.[iv]
Osteoporosis is not inevitable, and it is to a certain extent reversible. It is a problem caused by sunlight deficiency, excessive protein consumption, smoking, and lack of activity. Now we have added another revolting cause: the doctor’s scalpel. I wonder just how many doctors advise their patients about bone loss, sunlight and vitamin D before performing this atrocity. Interestingly, however, sunlight exposure has a positive influence on gastric bypass. Adverse effects of these surgeries are directly associated with the season and latitude in which they occur.[v] Seasons or latitudes of low sunlight availability were inversely correlated to prolonged stays in the hospital (39.4% longer stay), increased dehiscence (bursting open of a surgically closed wound) and wound infection. This surgery is a horror to begin with, but if it must be done, it appears that one should have it done in a sunny season of the year, or at a sunny latitude.
An ounce of prevention is worth tons of cure in the case of obesity. Good nutrition and ample sunlight exposure is essential to optimal human health.
[i] Fleischer J, Stein EM, Bessler M, Della Badia M, Restuccia N, Olivero-Rivera L, McMahon DJ, Silverberg SJ. The decline in hip bone density after gastric bypass surgery is associated with extent of weight loss. J Clin Endocrinol Metab. 2008 Oct;93(10):3735-40.
[ii] Nguyen T, Sambrook P, Kelly P, Jones G, Lord S, Freund J, Eisman J. Prediction of osteoporotic fractures by postural instability and bone density. BMJ 1993;307:1111-15.
[iii] Nguyen ND, Pongchaiyakul C, Center JR, Eisman JA, Nguyen TV. Identification of high-risk individuals for hip fracture: a 14-year prospective study. J bone Miner Res 2005;20:1921-28.
[iv] Heaney RP, Dowell MS, Hale CA, Bendich A. Calcium Absorption Varies within the Reference Range for Serum 25-Hydroxyvitamin D. J Am Coll Nutr 2003;22:142-46.
[v] Petersen L, Canner J, Cheskin L, Prokopowicz G, Schweitzer M, Magnuson T, Steele, K. Proxy measures of vitamin D status—season and latitude, correlate with adverse outcomes after bariatric surgery in the Nationwide Inpatient Sample, 2001-2010; a retrospective cohort study. 2015;9:88-96.
By Marc Sorenson, EdD, Sunlight Institute…
A short time ago, we posted a blog showing that little boys who had high sunlight exposure were about 82% less likely to develop prostate cancer than those who were not exposed. Now let’s take a look at additional interesting science on sunlight and prostate cancer.
Norwegian research has also demonstrated an inverse correlation between prostate cancer and sunlight when death rates from prostate, breast and colon cancer were compared to the season in which the cancer was diagnosed.[i] [ii] Over 36 months, study subjects diagnosed during summer and fall (times of the greatest sunlight exposure and vitamin D production) had much lower death rates than those diagnosed in winter and spring.
Another indication of the influence of sunlight on prostate cancer is research on prostate specific antigen (PSA). The higher the PSA level in the blood, the greater is the chance of cancer. When the prostate gland is undergoing changes that may lead to cancer, PSA levels generally rise. Men with the lowest levels of lifetime sunlight exposure have higher PSA levels than those with the highest levels of sunlight exposure.[iii]
Nevertheless, a recent meta-analysis of studies of serum vitamin D levels and prostate cancer showed no relationship between prostate cancer and vitamin D.[iv] The reason for the discrepancy between a lowered risk of prostate cancer correlating to higher sunlight exposure but not correlating to a higher serum level of vitamin D is unknown. It is probable that the beneficial influence of sunlight on prostate cancer goes beyond its stimulation of vitamin D production in skin. And according to Dr. Cannell, the reason for the lack of a relationship between blood levels of vitamin D and prostate cancer may be because the subjects in the studies received much of their vitamin D from cod-liver oil, high in vitamin A, which has been shown to thwart the beneficial effect of vitamin D on cancer,[v] possibly due to the fact that retinol (vitamin A) competes with activated vitamin D for receptor sites.[vi] Suffice it to say that sun exposure is the safest and surest way to reduce the risk of prostate cancer. Men, protect your health and your love-life by getting your share of the wonderful sun.
[i] Robsahm TE, Tretli S, Dahlback A, Moan J. Vitamin D3 from sunlight may improve the prognosis of breast-, colon- and prostate cancer (Norway). Cancer Causes Control 2004;15:149-58.
[ii] Lagunova Z, Porojnicu AC, Dahlback A, Berg JP, Beer TM, Moan J. Prostate cancer survival is dependent on season of diagnosis. Prostate 2007;67(12):1362-70.
[iii] Weinrich S, Elliaon, E, Weinrich, M, Ross, K, Reis-Starr, C. Low sun exposure and elevated serum prostate specific antigen in African American and Caucasian men. AM J Health Stud 2001;17:148-55
[iv] Lu Yin, Elke Raum, Ulrike Haug, Volker Arndt, Hermann Brenner. Meta-analysis of longitudinal studies: Serum vitamin D and prostate cancer risk. Cancer Epidemiology 2009;33: 435–45.
[v] Cannell, J. Vitamin D newsletter: February 28, 2010.
[vi] Bao Y, Ng K, Wolpin BM, Michaud DS, Giovannucci E, Fuchs CS. Predicted vitamin D status and pancreatic cancer risk in two prospective cohort studies. Br J Cancer 2010;102(9):1422-7.