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
High blood pressure (HBP, hypertension) is a plague in our society, with one in three adults in the U.S. having the condition. Although 61,762 people per year die from HBP per se, its influence on other diseases may be more dangerous that HBP itself; it is also implicated in increased risk of death from heart disease, heart failure, other arterial diseases, kidney disease, irregular heart rhythms, osteoporosis, cognitive dysfunction, painful intercourse and stroke. Although textbook theory holds that HBP is regulated by the brain, blood vessels, or kidney, recent evidence suggests that HBP could be regulated in the skin, and that sunlight exposure plays a role in in controlling the condition. The authors of the latest research on this subject (footnote 3) demonstrate that sunlight produces a dilation of the arteries (known as vasodilation) by stimulating the production of Nitric oxide (NO) in the skin. NO is a potent vasodilator, stimulated by the ultraviolet A (UVA) portion of sunlight, and has been known for several years to lower blood pressure. Dr. Oplander and his colleagues wrote the first paper on the UVA and blood pressure in 2009,  showing a dramatic reduction of blood pressure with UVA.
A study from China demonstrates that exposure to sunlight correlates to a lowered risk of HBP. In a randomly selected population of Chinese residents from Macau (where the rate of hypertension is very high), the following risk factors for hypertension were assessed: lack of sunlight exposure, low intake of fish, smoking, obesity and lack of exercise. An average of more than one-half hour of sunlight exposure per day, compared to none, predicted a 40% reduced risk for hypertension. Other factors such as smoking and poor nutrition, are of course very dangerous in producing HBP.
Dr. Grant has estimated that by doubling the dose of sun exposure, 400,000 lives could be saved yearly in the USA, with most of the reduction in mortality due to lives saved by lesser incidence of cancer and cardiovascular disease. HBP, of course is a major player in cardiovascular disease, and we know that regular sunlight exposure is associated with profoundly lower risk of about 18 major cancers. Do not neglect to get your regular, non-burning sun exposure. It could save your life!
 American Heart Association/American Stroke Association Statistical Fact Sheet/2013 update.
 Ann Pietrangelo. Healthline 2014 http://www.healthline.com/health/high-blood-pressure-hypertension/effect-on-body (accessed January 4, 2016).
 Johnson RS, Titze J, Weller R. Cutaneous control of blood pressure. Curr Opin Nephrol Hypertens. 2016;Jan25(1):11-5.
 Opländer C, Volkmar CM, Paunel-Görgülü A, van Faassen EE, Heiss C, Kelm M, Halmer D, Mürtz M, Pallua N, Suschek CV.. Whole body UVA irradiation lowers systemic blood pressure by release of nitric oxide from intracutaneous photolabile nitric oxide derivates. Circ Res. 2009;105:1031–40.
 Ke L, Ho J, Feng J, Mpofu E, Dibley MJ, Feng X, Van F, Leong S, Lau W, Lueng P, Kowk C, Li Y, Mason RS, Brock KE. Modifiable risk factors including sunlight exposure and fish consumption are associated with risk of hypertension in a large representative population from Macau. J Steroid Biochem Mol Biol 2013 Nov 1 [Epub ahead of print].
 Grant, W. In defense of the sun: An estimate of changes in mortality rates in the United States if mean serum 25-hydroxyvitamin D levels were raised to 45 ng/mL by solar ultraviolet-B irradiance. Dermato-endocrinology 2009;4:207-214.
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.
By Marc Sorenson, EdD
A new article on November 30, 2015, from the Daily Mail, discusses breaking research on the association between ED and vitamin D. The research from Johns Hopkins University, by Dr. Erin Michos and her colleagues, was conducted on 3,400 men over age 20, 30% of whom were vitamin D deficient, and 16% of whom reported symptoms of ED. Men with Vitamin D deficiency were 32% more likely to suffer ED than those whose levels were sufficient.
Although I, along with Dr. Grant, were the first to hypothesize that vitamin D deficiency could lead to ED, I have moderated my opinion somewhat. It is entirely possible that higher vitamin D levels are really a surrogate measurement for sunlight exposure. Although vitamin D probably has a positive affect on ED, the UVA portion of sunlight has a nearly immediate effect in dilating the blood vessels through the production of nitric oxide (NO), which is absolutely necessary for producing an erection. Viagra and other ED drugs work by inhibiting the breakdown of NO, which keeps NO in circulation for a longer period. But, they don’t always work and can have many deleterious side effects.
My hope is that research will be done to determine the effectiveness of sunlight exposure in alleviating the condition. Of course, the underlying cause of ED is consuming foods that occlude the arteries. Sunlight and/or vitamin D serve as palliatives to that occlusion, as do the ED drugs. A nutrition program filled with colorful fruits and vegetables,[i] along with ample sunlight exposure, would, in my opinion, produce the very best results in mitigating or perhaps reversing the disease.
[i] Esposito K, Giugliano F, Maiorino MI, Giugliano D. Dietary factors, Mediterranean diet and erectile dysfunction. J Sex Med. 2010 Jul;7(7):2338-45.
To read the Daily Mail article, please click this link. http://www.dailymail.co.uk/health/article-3321000/Could-daily-dose-vitamin-D-cure-erectile-dysfunction-Deficiency-means-man-32-likely-impotent.html
 Sorenson M, Grant WB. Does vitamin D deficiency contribute to erectile dysfunction? Dermato-Endocrinology 4;2:128–136.
 Opländer C, Volkmar CM, Paunel-Görgülü A, van Faassen EE, et al. Whole body UVA irradiation lowers systemic blood pressure by release of nitric oxide from intracutaneous photolabile nitric oxide derivates. Circ Res. 2009;105:1031–40.
 Burnett AL. The role of nitric oxide in erectile dysfunction: implications for medical therapy. J Clin Hypertens (Greenwich). 2006 Dec;8(12 Suppl 4):53-62
 Nitric Oxide and Viagra (no authors listed) Concepts in Biochemistry (accessed on November 30, 2015) at http://www.wiley.com/college/boyer/0470003790/cutting_edge/viagra/viagra.htm.
By Marc Sorenson, EdD, Sunlight Institute…..
Before proceeding with the discussion on sunlight addiction, it is important to review the truth about sunlight and melanoma, to understand why sunlight addiction may be a good thing.
A recent report on ultraviolet light and addiction is obviously meant to be a hit piece regarding sunlight exposure and tanning, as seen in the opening statement: “Despite widespread awareness that UV exposure is a major risk factor for all common cutaneous malignancies, skin cancer incidence relentlessly increases by ~3% per year.”
The “all common cutaneous malignancies” portion of this statement, of course, is patently false. Whereas the relatively benign common skin cancers are increased by exposure to sunlight, melanoma is increased by avoiding the sun. If the dramatic increase in melanoma over the past century were due to sunlight exposure, then sunlight exposure must also have increased dramatically during that time. To determine whether that has happened, we analyzed data from the Office of Occupational Statistics and Employment Projections, Bureau of Labor Statistics, (BLS) to determine if there was an increase or decrease in human sunlight exposure during the years from 1910 to 2,000. The statistics showed that indoor occupations such as “professional, managerial, clerical, sales, and service workers grew from one-quarter to three-quarters of total employment between 1910 and 2000.” BLS also stated that during the same period, the outdoor occupation of farming declined from 33% to 1.2% of total employment, a 96% reduction. The data also showed an approximately 66% decline in the occupation of farmers and 50% of the decline in the occupation of farm laborers.
The Environmental Protection Agency also determined that as of 1986, about 5 percent of adult men worked mostly outside, and that about 10 percent worked outside part of the time. The proportion of women who worked outside was thought to be even lower. These data demonstrate a dramatic shift from outdoor, sun-exposed activity to indoor, non-sun-exposed activity during the mid-to-late 20th Century.
Despite these facts, the Melanoma International Foundation (MIF) has stated that melanoma has increased by 30 times (3,000%) just since 1935! Here is the statement by the MIF: “Melanoma is epidemic: rising faster than any other cancer and projected to affect one person in 50 by 2010, currently it affects 1 in 75. In 1935, only one in 1,500 was struck by the disease.” Indeed, the American Cancer Society in 2014 reported that one in 50 now contracts the disease. That exponential increase in melanoma has been accompanied by a profound decrease in sunlight exposure, yet sunlight or other UV exposure is blamed for the melanoma increase—a totally counterintuitive argument! I submit that not only is sunlight not responsible for the exponential increase in melanoma, but that the decrease in sun exposure may be a major cause of that increase.
Here are other facts that belie the idea that melanoma is caused by sunlight exposure:
- Outdoor workers, while receiving 3-9 times the UVR exposure as indoor workers,  have had no increase in melanoma since before 1940, whereas melanoma incidence in indoor workers has increased steadily and exponentially.
- Most melanomas occur on areas of the body that are seldom or never exposed to the sunlight.  
- The use of sunscreen, which has increased steadily, has not resulted in a decrease in melanoma. In fact, melanoma has increased as sunscreen use has become more widespread. Since sunscreens block sunlight, it is evident that at best they are a waste of money and at worst may be contributing to the increase in melanoma.
Now, let’s discuss the research on the aforementioned addiction to sunlight. The researchers conducted various experiments on mice that showed behavior choices, such as desiring lighter rather than darker environments, were increased by regular exposure. These behavior choices were mediated by β-endorphins, peptide hormones which are similar to opiates. So is this all bad? This marvelous product, β-endorphin, is one of the feel-good hormones that decreases pain and increases a sense of well-being. The case the researchers make regarding addiction to sunlight is compelling, and why not? Sunlight exposure causes vitamin D production in the skin, which is essential to human health; it also stimulates the production of nitric oxide, which relaxes our vessels and lowers our blood pressure; it stimulates the production of serotonin in the brain, which is another feel-good hormone necessary for a happy mood and wellbeing. And considering the myriad additional effects of sunlight on health, including the prevention of cancer, the prevention and reversal of bone diseases and the reduction of heart disease, could it not be part of God’s (or Nature’s) master plan to develop a positive addiction to sunlight so than our health could be enhanced? I am a sunlight addict, and expose myself to it regularly for two reasons: (1) It marvelously improves my mood and (2) it protects me from disease and weakness. I am a light-skinned, blue-eyed Caucasian who has spent much of my seven decades on this earth seeking the sun. Yet, there have been no melanomas or even common skin cancer.
Nevertheless, the researchers summarize their paper on sun addiction with the following: “While primordial UV addiction, mediated by the hedonic [pertaining to pleasure] action of β-endorphin and anhedonic effects of withdrawal, may theoretically have enhanced evolutionary vitamin D biosynthesis, it now may contribute to the relentless rise in skin cancer incidence in man.”
That summary statement is claptrap, as can be seen by the research on melanoma and sunlight presented above. If sunlight is addictive and helps me to avoid melanoma, heart disease, bone loss and other maladies, I can only say, “hooray for the addiction!”
 Gillian L. Fell, Kathleen C. Robinson, Jianren Mao, Clifford J. Woolf, and David E.
Fisher. Skin β-endorphin mediates addiction to ultraviolet light. Cell. 2014 June 19; 157(7): 1527–1534.
 Ian D. Wyatt and Daniel E. Hecker. Occupational changes in the 20th century. Monthly Labor Review, March 2006 pp 35-57: Office of Occupational Statistics and Employment Projections, Bureau of Labor Statistics
 U.S. Congress, Office of Technology Assessment, Catching Our Breath: Next Steps for Reducing Urban Ozone, OTA-O-412 (Washington, DC: U.S. Government Printing Office, July 1989).
 Melanoma International Foundation, 2007 Facts about melanoma. Sources: National Cancer Institute 2007 SEER Database, American Cancer Society’s 2007 Facts and Figures, The Skin Cancer Foundation, The American Academy of Dermatology.
 American Cancer Society. Melanoma Skin Cancer Overview 9/16/2014. Accessed on 9/23/2014 at http://www.cancer.org/cancer/skincancer-melanoma/overviewguide/melanoma-skin-cancer-overview-key-statistics
 Godar D. UV doses worldwide. Photochem Photobiol 2005;81:736–49.
 Thieden E, Philipsen PA, Sandby-Møller J, Wulf HC. UV radiation exposure related to age, sex, occupation, and sun behavior based on time-stamped personal dosimeter readings. Arch Dermatol 2004;140:197–203.
 Garland FC, White MR, Garland CF, Shaw E, Gorham ED. Occupational sunlight exposure and melanoma in the USA Navy. Arch Environ Health 1990; 45:261-67.
 Rivers, J. Is there more than one road to melanoma? Lancet 2004;363:728-30.
 Crombie, I. Racial differences in melanoma incidence. Br J Cancer 1979;40:185-93.
 Phillippe Autier. Do high factor Sunscreens offer protection from melanoma? West J Med. 2000 Jul; 173(1): 58.
By Marc Sorenson, EdD, Sunlight Institute
In a new media release from Toronto, the Vitamin D Society asserts that “The importance of natural sunlight to human life cannot be understated.” It goes on to quote Dr. Reinhold Vieth, a scientist and professor at the University of Toronto. “There really is no substitute for natural sunlight in human health. Your skin is like a solar receptor and has the amazing capacity to manufacture all of the vitamin D your body needs. Everyone has the capability to generate vitamin D.”
There is a problem, however, as I posted recently. About a third of Canadians, about 12 million people, do not meet the minimum Health Canada guidelines for vitamin D levels. The reason? Sunlight deficiency.
Perry Holman, executive director of the Society, states that “This is not a call for people to ignore the warnings about over-exposure to sunlight but a call for people to exercise common sense and ensure they are not shutting themselves out from the vital health benefits of natural sunlight.”
Of course, in the winter, when no vitamin D production is available, it will be necessary to find another source of vitamin-D stimulating light. Sunlamps are ideal, provided they produce UVB light.
Also remember, that during winter, sunlight still raises serotonin levels and produces nitric oxide, both of which are necessary to human health. The value of sunlight goes far beyond its ability to promote vitamin D production in the skin.
For more information on the Vitamin D Society, visit www.vitamindsociety.org.
By Marc Sorenson, EdD
Drs. Asta Juzeniene and Johan Moan wrote a paper in 2012 that beautifully summarizes the effects of sunlight beyond the production of vitamin D. Here are the highlights of their paper, as stated in the abstract. They discuss the separate affects of Ultraviolet B light (UVB) and ultraviolet A light (UVA), which are, of course, components of sunlight.
- UVB induces cosmetic tanning (immediate pigment darkening, persistent pigment darkening and delayed tanning).
- UVB-induced, delayed tanning acts as a sunscreen.
- Several human skin diseases, like psoriasis, vitiligo, atopic dermatitis and localized scleroderma, can be treated with sunlight or artificial UV radiation (phototherapy).
- UV exposure can suppresses multiple sclerosis independently of vitamin D synthesis.
- UVA generates nitric oxide (NO), which may reduce blood pressure and generally improve cardiovascular health.
- UVA induced NO may also have antimicrobial effects.
- UVA induced NO may act as a neurotransmitter.
- UV exposure may improve mood through the release of endorphin.
It wasn’t mentioned in the paper, but we now know that sunlight also helps generate serotonin in the brain, which improves mood, and outside the body it is a potent disinfectant (see my recent blogs on those subjects). So those who claim that sunlight is harmful in any amount, must be living on a different planet. Embrace the Sun, but never burn.
 Asta Juzeniene and Johan Moan. Beneficial effects of UV radiation other than via vitamin D production. Dermato-Endocrinology 4:2, 109–117; April/May/June 2012.
By Marc Sorenson, EdD, Sunlight Institute
Does sunlight have an influence on the risk of having a stroke? It does.
Interesting research had as an objective to determine whether long-term or short-term sunlight exposure affected stroke incidence.1 Measurements of sunlight exposures were taken for 15-,10-,5-,2-, and 1-year exposures to sunlight among 16,606 people who were free on any coronary disease. It was found that shorter exposure periods exhibited slightly stronger protective relationships against stroke, but both long- and short-term exposures were effective. Those who were below the median sunlight exposure had an increased risk of stroke of 61%. The researchers said that they did not know the biological pathways for the protective relationship, but I surmise that the answer is sunlight-induced nitric-oxide production, which keeps the blood pressure down and keeps the vessels flexible.
Whatever the mechanism by which sunlight protects us against stroke, let’s celebrate the fact that the protection is available.
1. Kent ST, McClure LA, Judd SE, Howard VJ, Crosson WL, Al-Hamdan MZ, Wadley VG, Peace F, Kabagambe EK. Short-and long-term sunlight radiation and stroke incidence. Ann Neurol. 2013 Jan;73(1):32-7.
By Marc Sorenson, EdD Sunlight Institute
Recent research, again involving Dr. Richard Weller, demonstrates that Sunlight exposure may prevent liver inflammation in non-alcoholic fatty liver disease (NAFLD), which is the most prevalent liver disorder in western countries. The authors of this research state then state the following possible mechanism: “Following exposure to sunlight-derived ultraviolet radiation (UVR), the skin releases anti-inflammatory mediators such as vitamin D and nitric oxide.”
Though there has been no proof that sunlight works for humans (no research yet), the authors indicate that animal studies suggest that exposure to sunlight (UVR), can prevent the development of NAFLD.
They also note that most of the credit for these positive results has focused on vitamin D, yet clinical trials have yet to demonstrate a clear, beneficial effect of supplementation; therefore, they suggest that other mediators such as nitric oxide may be important. This is another of those studies that demonstrates the possibility that sunlight has positive affects on a disease independently of vitamin D. Future research may clarify that idea.
Until then, regular sun exposure may be good insurance for a healthy liver.
 Gorman S, Black LJ, Feelisch M, Hart PH, Weller R. Can skin exposure to sunlight prevent liver inflammation? Nutrients 2015 May 5;7(5):3219-39.
Marc Sorenson, EdD, Sunlight Institute.
Anything that causes arterial plugging or prevents the relaxation of blood vessels can contribute to cardiovascular diseases (CVD). Poor diet, little exercise and lack of sunlight exposure form a combination that devastates vessel health and reduces the flexibility of those vessels. Among the CVD are ischemic heart disease, intermittent claudication (painful oxygen restriction to the legs), ischemia of the brain leading to strokes, peripheral artery disease and erectile dysfunction. Yes, I said erectile dysfunction.
ED is considered one of the major predictors of CVD.[i] It is caused by inability of the corpus cavernosa, two cylindrical chambers that run the length of the penis, to become engorged with blood, causing erection. When the process takes place normally, the cavernosa are stimulated by nitric oxide (NO), they then relax, and blood flows into the penis, allowing erection to take place. Therefore, erection is a vascular event.[ii] The same effect is seen in blood pressure decreases caused by NO after sunlight exposure. Ultraviolet A (UVA) light stimulation of the skin causes the release of NO from pre-formed stores of NO in the skin. NO is a potent vasodilator, and when it is released into the arteries by UVA stimulation, causes increased blood flow and lowers blood pressure.[iii] The mechanism is much the same in both instances. This is another example of sunlight enhancing health without the benefit of vitamin D. UVA light, that stimulates nitric oxide release, does not stimulate the skin to produce vitamin D.
An early study assessed the affect of ultraviolet light (UV) exposure to cavernosal strips, which were obtained from men during penile prosthetic surgery.[iv] The strips showed relaxation in response to UV, and the relaxation increased with the duration of exposure. We expect that sunbathing, which would profoundly increase NO in the circulation, would also vasodilate the cavernosa to allow erection. The same nitric oxide mechanism that lowers blood pressure, would seem to be a good method to treat ED. After all, drugs for ED, such as Viagra and Cialis, work by enhancing the effects of nitric oxide.[v] Sunlight is free and is a much better choice.
[i] Pastuszak AW, Hyman DA, Yadav N, Godoy G, Lipshultz LI, Araujo AB, Khera M. Erectile dysfunction as a marker for cardiovascular disease diagnosis and intervention: a cost analysis. J Sex Med 2015 Apr;12(4):975-84.
[ii] Marc Sorenson and William B. Grant. Does vitamin D deficiency contribute to erectile dysfunction? Dermatoendocrinol 2012 Apr 1; 4(2): 128–136.
[iii] Liu D, Fernandez BO, Hamilton A, Lang NN, Gallagher JM, Newby DE, Feelisch M, Weller RB. UVA irradiation of human skin vasodilates arterial vasculature and lowers blood pressure independently of nitric oxide synthase. J Invest Dermatol. 2014 Jul;134(7):1839-46.
[iv] Kim SC, Oh CH, Park JK, Lee MY, Uhm DY. Effects of ultraviolet light on the tension of isolated human cavernosal smooth muscle from non-diabetic and diabetic impotent men. Urol Res. 1997;25(2):149-52.
[v] Mayo Clinic Online. http://www.mayoclinic.org/diseases-conditions/erectile-dysfunction/in-depth/erectile-dysfunction/art-20047821. Accessed July 3, 2015.