Tag Archives: vitamin d

Another Benefit of moderate, non burning Sun Exposure: any Damage is quickly repaired.

Benegits of sun exposure by Marc Sorenson, EdD…

For those who follow my writings, it should now be obvious that the risk of melanoma is decreased by regular sun exposure, and that the evidence for the health benefits of safe sun becomes clearer by the day. I opine that millions of lives could be saved yearly by regular, non-burning sun exposure for the entire population.

Another benefit of moderate sun exposure, or other ultraviolet radiation (UVR), is that it does not cause sufficient DNA damage to prevent efficient repair. A study published in the British Journal of Dermatology reviewed the impact of repeated low level sunlight exposures on vitamin D status and DNA damage/repair in light and brown skinned individuals.[1] The UVR doses were equivalent to 13-17 minutes of midday exposure in the UK. The study reported that no evidence existed for these low-level exposures leading to accumulated DNA-damage, indicating that any damage was quickly repaired. The research also showed that the exposures led to sufficient vitamin D levels in the participants. In addition, it has been shown that “Regular exposure to UV leads to an almost complete disappearance of DNA damage in the basal and suprabasal layers of the epidermis, where the initiating of skin cancer occurs.[2] It is no wonder that regular sun exposure is associated with less melanoma! Soak up some moderate, non-burning sun!

[1] Felton SJ, Cooke MS, Kift R, Berry JL, Webb AR, Lam PMW, de Gruijl FR, Vail A, and Rhodes LE. Concurrent beneficial (vitamin D production) and hazardous (cutaneous DNA damage) impact of repeated low-level summer sunlight exposures. Br J Dermatol. 2016 Jul 14. doi: 10.1111/bjd.14863. [Epub ahead of print]

[2] van der Rhee H, de Vries E, Coomans C, van de Velde P, Jan Willem Coebergh JW. Sunlight: For Better or For Worse? A Review of Positive and Negative Effects of Sun Exposure. Cancer Research Frontiers. 2016 May; 2(2): 156-183.

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Health Benefits of Tanning Beds shown in new Study.

By Marc Sorenson, EdD, Sunlight Institute, for sensible tanning bed use

The online magazine, Life Science Daily, just posted an article regarding the health benefits of UV light from tanning beds. Surprisingly, they were quoting from research published in the British Journal of Dermatology. I say “surprising,” because so many dermatologists and dermatological organizations are vehemently opposed to a single ray of sunlight touching the skin. And heaven forbid someone should use a tanning bed.

Three times weekly, adult subjects were exposed to a tanning bed that emitted 95% UVA rays and 5% UVB rays, which is approximately the amount of UVA and UVB that midday summer sunlight emits. Each exposure lasted six minutes. Here are some of the salient points reported in the article:

  • Any damage caused by the light exposure was repaired by the by the skin.
  • One of the positive benefits of the light was the production of nitric oxide, which improves blood flow and reduces blood pressure.
  • Another positive benefit was the productions of beta-endorphins, which reduce depression.
  • A third benefit, of course, is the production of vitamin D, necessary for growth and bone strength, as well as asthma prevention.

Here is one of the important quotes from the article, from Dr. Michael Holick:  “What this study shows is that you can get a reasonable amount of sunlight that would make enough vitamin D in your skin living in the U.K. Yes, the DNA is somewhat damaged, but because the body has adapted to its environment, it has the ability to repair it.”  Dr. Holick also suggested that people become educated about the wide range of health benefits from modest sun exposure, which is superior to taking vitamin D supplements.

Step by step, the truth is overcoming the powers of darkness! Seek the sun, and let a tanning bed enhance your health in the winter.

Click here to read the article. https://lifesciencedaily.com/stories/19743-study-shows-health-benefits-non-burning-exposure-uv-light/

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Stay well! Sun exposure enhances immunity independently of vitamin D.

Sun exposure and health By Marc Sorenson, EdD, Sunlight Institute…

New research shows that sunlight boosts the effectiveness of T-cells, an integral part of the immune system.[1] T-cells are a type of lymphocyte that recognizes and binds to foreign invaders, thereby rendering them harmless. This is an important new finding, which demonstrates another beneficial effect of sun—one that has no relationship to vitamin D.

The key player in this action is the blue-light spectrum of sunlight that stimulates hydrogen peroxide production. The hydrogen peroxide (HP) causes T-cells to move to the site of infection, and it (HP) is also involved in the killing of noxious bacteria. Dr. Gerard Ahern, one of the primary investigators, stated it in this way: “T cells, whether they are helper or killer, need to move to do their work, which is to get to the site of an infection and orchestrate a response. This study shows that sunlight directly activates key immune cells by increasing their movement.”

Also interesting is the fact that the skin has a large share of the total T-cells in humans, about twice the number circulating in the blood. Think about this magnificent body of ours! It is programmed to immediately respond to any invasions that may occur in the skin, and sun exposure, if we take full advantage of it, immediately accelerates the process. Then, when the t-cells are activated by the blue light, they can move rapidly to other body areas where they can be utilized.

Sun exposure has also been found to have an exceptionally important and positive effect on autoimmune diseases such as lupus, MS, rheumatoid arthritis and others, many of which have been found to associate with low solar radiation and vitamin D.[2] In this case, a different type of T-cell, called a regulatory T-cell, attacks the body’s own tissue, mistaking it for a foreign invader, and causes severe damage. The mechanism of autoimmune disease prevention by sunlight may be the suppression of regulatory T cells, in a manner that impedes the immune system’s attacks on its own tissues.[3] [4]

Sunlight is one of God’s (or Nature’s) greatest miracles. Be sure to receive your full contingent of wonderful, non-burning sun.

[1] Thieu X. Phan, Barbara Jaruga, Sandeep C. Pingle, Bidhan C. Bandyopadhyay, Gerard P. Ahern. Intrinsic Photosensitivity Enhances Motility of T Lymphocytes. Scientific Reports, 2016;6:39479

[2] Schwalfenberg GK. Solar radiation and vitamin D: mitigating environmental factors in autoimmune disease. J Environ Public Health. 2012;2012:619381.

[3]ArtukovićM1, Ikić M, Kustelega J, Artuković IN, Kaliterna DM. Influence of UV radiation on immunological system and occurrence of autoimmune diseases. Coll Antropol. 2010 Apr;34 Suppl 2:175-8.

[4]Marsh-Wakefield F, Byrne SN. Photoimmunology and Multiple Sclerosis. Curr Top Behav Neurosci. 2015;26:117-41.

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High Sun Exposure may reduce Kidney Cancer Risk.




Sun exposure Information by Marc Sorenson, EdD. Sunlight Institute.

There are 62,700 cases of kidney cancer and 14,240 deaths annually. Kidney cancer incidence has tripled since the early 1980s, and some researchers have felt that environmental factors may have played a part in that worrisome increase. One of those factors may be sun exposure, which may be vital to the prevention of the disease. The newest research measured sun exposure, which was based on the average number of hours per day outdoors in the summer, during different periods of life.[1] The researchers also took into consideration the age of the subjects and adjusted the data for other factors that may associate to kidney cancer.

These were some of the research results:

  • Higher summer sun exposure at age 40+ years, but not at younger ages, was associated with a significantly lower risk of thyroid cancer. When comparing the highest quartile (fourth) of sun exposure to the lowest quartile, there was a 44% reduction in risk.
  • Average lifetime sun exposure was not associated with thyroid-cancer risk.
  • Recent summer sun exposure was closely associated with a decreased risk of thyroid cancer.

One of the salient points, in my mind, is that the best sun exposure is that which is habitual or consistent. In the case of kidney cancer, sun exposure in the past does not indicate that the disease will be avoided in the future. Only recent sun exposure provides protection. However, this is not necessarily true of other diseases; in the case of breast and prostate cancers, childhood sun exposure is associated with a lesser risk of the diseases in adulthood.

Previous research has also confirmed the importance of sun exposure on kidney-cancer prevention. There is a strong inverse correlation between sun exposure and kidney cancer. For example, one study that used NMSC as a measure of sun exposure, determined that sun exposure reduced the risk of several cancers, including kidney cancer, from 35% to 42%.[2] Kidney cancer mortality rates were found to be strongly inversely correlated with solar UVB doses in Dr. William Grant’s 2002 and 2006 ecological studies.[3] [4]

Recent research by Dr. Sara Karami and colleagues, demonstrates that in women, there is a significant reduction in kidney cancer with high levels of sun exposure.[5] Those women with the highest fourth of sun exposure showed a 33% reduction in risk. Interestingly, the data was adjusted for vitamin D intake, and the results still showed sun exposure to have a stand-alone protective influence on kidney cancer—another indication that sun exposure has protective effects beyond vitamin D production

Remember that a lifetime habit of non-burning sun exposure will always provide the best health outcomes.

[1] Rachel D Zamoiski, Elizabeth K. Cahoon, D. Michal Freedman, et al. Prospective study of ultraviolet radiation exposure and thyroid cancer risk in the United States. Cancer Epidemiol Biomarkers Prev Published Online First December 2, 2016.

[2] Tuohimaa P, Pukkala E, Scélo G, Olsen JH, Brewster DH, Hemminki K, Tracey E, Weiderpass E, Kliewer EV, Pompe-Kirn V, McBride ML, Martos C, Chia KS, Tonita JM, Jonasson JG, Boffetta P, Brennan P.  Does solar exposure, as indicated by the non-melanoma skin cancers, protect from solid cancers: vitamin D as a possible explanation.  Eur J Cancer 2007;43(11):1701-12

[3] Grant WB. An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B radiation. Cancer. 2002 Mar 15;94(6):1867-75.

[4]  Grant WB, Garland CF. The association of solar ultraviolet B (UVB) with reducing risk of cancer: multifactorial ecologic analysis of geographic variation in age-adjusted cancer mortality rates. Anticancer Res. 2006 Jul-Aug;26(4A):2687-99.

[5] Karami S, Colt JS, Stewart PA, Schwartz K, Davis FG, Ruterbusch JJ, Chow WH, Wacholder S, Graubard BI, Purdue MP, MooreLE.  Short Report: A case-control study of occupational sun exposure and renal cancer risk. Int J Cancer. 2015 Oct 27.

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Research again shows sun exposure reduces myopia.

By Marc Sorenson, EdD. For sun exposure…

It should be well-known by now, but the relationship between sun exposure and myopia (nearsightedness) is still being studied. And as before, the answer is the same: sun deprivation is associated to a greater myopia risk. The difference in this research was the study population, which was a random sample of participants 65 years and older from Europe.[1] Among the factors that the researchers considered important, were vitamin D blood levels, vitamin D polymorphisms, ultraviolet B radiation (UVB), and years in education. Of these factors, only ultraviolet B radiation (UVB) was associated with reduced odds for myopia, especially if higher UVB exposure occurred during adolescence and early adulthood. This is another research paper that shows sun exposure to be protective against a disease, independent of vitamin D.

The authors of the study made this conclusion: “This study, while not designed to determine cause and effect relationships, suggests that increased ultraviolet B exposure, a marker of sunlight exposure, is associated with reduced myopia.

This is one in a long line of studies that show the relationship of sun exposure to myopia, and it doesn’t take a rocket scientist to determine that myopia is caused by lack of sun exposure. The evidence has been building for years. For example, one of the studies showed that the lowest risk of myopia among 12-year-old students was found among those who reported the highest levels of outdoor activity.[2] Some might surmise that the key ingredient was exercise, but that idea was refuted by the fact that there was no association between indoor activity and myopia. Something besides exercise had to be leading to the lower risk of myopia among children who were actively outdoors; it had to be sun. The lower risk of myopia persisted after adjusting for genetic factors, ethnicity and the amount of near work. This is important, because for many years there was an assumption that long hours of study indoors, staring closely at books (near work) and never focusing on distant objects, led to myopia. This study belied that error.

This same research showed that the prevalence of myopia among Chinese children living in Singapore was 29.1%, whereas Chinese children living in Sydney, Australia, had a prevalence rate of only 3.3%. The children in Sydney spent about 13.8 hours per week outdoors compared to 3.05 hours in Singapore. In other words, the children who spent most or their lives indoors had 9.5 times the risk of developing myopia!

Depriving either adults or children of their time in the sunlight leads to myriad illnesses, only one of which is myopia. When will we learn?

[1] Katie M. Williams, FRCOphth; Graham C. G. Bentham, MA; Ian S. Young, MD; et al Association Between Myopia, Ultraviolet B Radiation Exposure, Serum Vitamin D Concentrations, and Genetic Polymorphisms in Vitamin D Metabolic Pathways in a Multicountry European Study. Published Online: December 1, 2016. doi:10.1001/jamaophthalmol.2016.4752

[2] Rose KA, Morgan IG, J, Kifley A, Huynh S, Smith W, Mitchell P. Outdoor activity reduces the prevalence of myopia in children. Ophthalmology 2008 Aug;115(8):1279-85.

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Diet, sun exposure and arthritis: a forgotten study confirms what we know now.

Sun exposure By Marc Sorenson, EdD… Sunlight Institute…

Nearly thirty years ago, I talked to many “experts” who told me that our mostly vegetarian diet could not help those who suffered from arthritis, because “diet has nothing to do with arthritis.” However, I was able to find one or two pieces of research that indicated that arthritis was indeed associated with poor nutrition and could be ameliorated or reversed by proper nutritional habits.

Then, during our many years in the health and fitness resort business, we observed many seeming miracles with our arthritic attendees. One woman, who could not play piano due to her arthritic hands, was able to play again in less than two weeks. Her reduction in inflammation was visible and her increase in range-of motion was remarkable. Her husband, who could not walk more than about a hundred yards when they arrived, was walking a mile after two weeks as his arthritic hips recovered range of motion and his muscles gained strength.

Through serendipity, a few days ago, a piece of research appeared to me—a study that I wished I had known about 30 years ago. It was published in 1935, and was titled, THE TREATMENT OF CHRONIC ARTHRITIS BY DIET AND SUNLIGHT.[1] The author studied a group of seventy-two arthritic patients whom he treated with diet, calling his program the “depletion diet.” The diet was bulky and very high in protective foods, but contained very little protein and fat. He stated that “Thus in seventy-two cases treated by diet, five were not improved, thirteen were slightly improved, thirty-nine were much improved, and fifteen were completely relieved.”

Other treatment included sunbathing, and the doctor considered it so important that he had his patients move to an area where they could sunbathe for at least eight weeks per year. He felt that it was almost indispensable.

Our program was somewhat similar, although our diet was much stricter. We were fortunate that we already operated our resort in an area where the sun shines about 260 days per year.

Other research has shown a correlation between arthritis and sun exposure. A paper by Dr. Viera and colleagues demonstrated that at high latitudes, where sun exposure is considerably less available, the rate of rheumatoid arthritis (RA) is much higher than at lower latitudes.[2]  RA is also more severe in winter,[3] a time of less sun exposure.

So give up the junk food and safely embrace the sun. Your joints will love it!


[2]Vieira VM, Hart JE, Webster TF, Weinberg J, Puett R, Laden F, Costenbader KH, Karlson EW. Association between Residences in U.S. Northern Latitudes and Rheumatoid Arthritis: A Spatial Analysis of the Nurses’ Health Study. Environ Health Perspect. 2010 Mar 25. [Epub ahead of print]

[3]Cutolo M, Otsa K, Uprus M, Paolino S, Seriolo B.  Vitamin D in rheumatoid arthritis.  Autoimmun Rev 2007;7:59-64

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More Truth about Sun Exposure

By Marc Sorenson, EdD… Sun exposure benefits…

A very important paper regarding the necessity for sun exposure has recently been published by the journal Medical Hypothesis.[1] It is entitled Regular sun exposure benefits health, and it discusses the pros and cons of sun exposure. One of the salient statements in the paper is that intermittent sun exposure may increase the risk of skin cancer, whereas regular exposure to sunlight might benefit health. For those of us who have for years studied the beneficial effects of sun exposure, the use of the word “might” is the only drawback to the statement. There is no doubt that for the majority of the population, regular sun exposure absolutely protects and enhances health.

Among the diseases mentioned as being reduced or prevented by regular sun exposure are the following:

  1. Cancers: Colon, breast, prostate and non-Hodgkin lymphoma
  2. Multiple sclerosis
  3. Hypertension
  4. Diabetes

As the authors mention, most of these positive effects of sun exposure were previously ascribed to Vitamin D, but they point out that immune system function is enhanced by sun exposure beyond the effects of vitamin D, and list other non-vitamin D benefits of the sun, including:

  1. Production of nitric oxide
  2. Production of melatonin
  3. Production of serotonin
  4. Regulation of the circadian clock

I have discussed most of these items on the Sunlight Institute web site, but it was good to see new research that, in particular, separated the health benefits of sun exposure from vitamin D production. The idea that has become popularized during the past decade, that all benefits of sun exposure come from increased vitamin D production, is simply not true and can lead to the supplementation of vitamin D as a “cure” for diseases that may not be influenced by that hormone.

Of course, vitamin D is an exceptionally important photoproduct, and the only natural way to attain it is by exposure to the sun or to other sources of UVB light (such as a sunlamp or a tanning bed). The beauty of using these sources, rather than a vitamin-D capsule, is that all of the benefits of nitric oxide, melatonin, serotonin and circadian entrainment are included in the package.

Safely enjoy the sun, and you then will also safely enjoy better health. Remember not to burn, and to gradually develop a good tan.

[1]  van der Rhee H, de Vries, E, Coebergh, J. Regular sun exposure benefits health. Medical Hypotheses 97 (2016) 34–37

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Sun Exposure may be superior to Vitamin D for reducing Colon-Cancer Risk.

The importance of sun exposure for colon cancer

By Marc Sorenson, EdD, Sunlight Institute…

In 1980, Cedric and Frank Garland published a seminal paper showing a relationship between colon cancer and geographical location.[1] They observed dramatically higher rates of colon cancer in the Northeast, where there is a paucity of sun exposure, compared with the South and West where sun is more prevalent. They hypothesized that vitamin D, stimulated in the skin by sun, reduced the risk of colon cancer. They pointed out the correlation between colon cancer and UVR exposure, stating particularly that “New Mexico and Arizona had the highest statewide mean solar radiation values (500 gm-cal/cm2). These states experienced colon cancer rates for white males of 6.7 and 10.1 per 100 000 population, respectively, over the period 1959–61.  New York, New Hampshire, and Vermont had the lowest statewide mean solar radiation values (300 gm-cal/cm2) and experienced colon cancer rates for white males of 17.3, 15.3, and 11.3 per 100 000 populations, respectively, during the same period.”

Other studies have corroborated the correlation between high sun exposure and low colon cancer rates. Japanese research demonstrated that people in the areas of highest solar radiation exhibit the lowest rates of colon cancer, with those living in the areas of highest sun exposure having about half the colon cancer rate as those living in the lowest.[2]A significant aspect of this research is that sun correlated to a reduced risk of cancer even where vitamin D consumption was high, indicating that sun exposure (as noted with prostate cancer and breast cancer, above) may have beneficial influences on cancer beyond its stimulation of vitamin D production, or that vitamin D produced in the skin by sun exposure may have advantages over that consumed through food or supplements. 

The research by Dr. Mizoue is not the only investigation that differentiated the effects of UV light exposure and vitamin D/colon cancer. A six-week study by Dr. Rebel and colleagues used mice with intestinal tumors—tumors that often progress to cancers.[3] It was shown that the mice given either UV radiation or vitamin-D supplementation reduced the tumor load when compared to mice who received no treatment. However, only the UV treatments prevented the tumors from progressing to cancer. Still other recent research has demonstrated that sun, not vitamin D, may produce all of the positive effects on colon cancer. The researchers performed a 140-day investigation involving rats that had colon adenomas (a precursor to full-blown colon cancer) induced in their colons.[4] The rats were given either vitamin D3 as supplements, or the stored form of vitamin D, 25(OH)D3, in differing amounts. With low dose vitamin D in either form, no reduction in either existing adenomas or emerging tumors were seen. In higher doses, there was a dose-dependent increase in colon tumor numbers in both male and female rats. The researchers said the following in their concluding statement: “Thus, the association between sun exposure and the incidence of colon cancer may involve factors other than vitamin D concentrations. Alternative hypotheses warrant investigation. Furthermore, this study provides preliminary evidence for the need for caution regarding vitamin D supplementation of humans at higher doses, especially in individuals with sufficient serum 25(OH)D3 concentrations.” The takeaway from this research is this: sun is protective against colon cancer in rats (and probably in humans), independent of vitamin D—another reason to safely embrace the sun.

These studies again demonstrate that we cannot substitute vitamin D pills for sun in many cases. UV light from sun or sun lamps is always the best option to cover all prevention and healing possibilities.

[1] Garland CF, Garland FC. Do sun and vitamin D reduce the likelihood of colon cancer?  Int. J. Epidemiol 1980;9:227–31.

[2] Mizoue, T.  Ecological study of solar radiation and cancer mortality in Japan.  Health Phys 2004;87:532-38.

[3] Rebel H1, der Spek CD, Salvatori D, van Leeuwen JP, Robanus-Maandag EC, de Gruijl FR. UV exposure inhibits intestinal tumor growth and progression to malignancy in intestine-specific Apc mutant mice kept on low vitamin D diet. Int J Cancer. 2015 Jan 15;136(2):271-7.

[4] Irving AA, Plum LA, Blaser WJ, Ford MR, Weng C, Clipson L, DeLuca HF, Dove WF. Cholecalciferol or 25-hydroxycholecalciferol neither prevents nor treats adenomas in a rat model of familial colon cancer. J Nutr. 2015 Feb;145(2):291-8.


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Sun Exposure reduces Obesity; Vitamin D does not.

By Marc Sorenson, EdD. Sunlight Institute…

Sun exposure reduces the risk of obesity, and that relationship has been credited to vitamin D. However, one study, conducted on mice, shows that vitamin D may have nothing to do with reducing or preventing obesity.[1] The animals were placed on a high-fat diet to cause obesity. Then they were subjected to long-term exposure to ultraviolet radiation (UVR), (which is the same sunlight spectrum that leads to the production of vitamin D and other photoproducts). The UVR significantly suppressed weight gain and other measures of the metabolic syndrome (MetS), including glucose intolerance, insulin resistance, fasting insulin levels, fatty liver disease and serum cholesterol levels.

Interestingly, when the animals were supplemented with vitamin D, no such benefits occurred, meaning that UVR created the positive protections independently. However when nitric oxide was applied to the skin of the animals, the positive effects on weight loss and metabolic syndrome were again observed. Nitric oxide, of course, is another photoproduct of sun exposure, which has many positive health effects.

Other research showed that early-morning sun exposure was correlated to lower body-mass index (BMI) which is a measure of body fatness.[2] The authors of that research suggested that the mechanisms involved in weight control by early light exposure could be the following: (1) resetting the circadian rhythm (internal clock), (2) the greater quantity of blue light in morning sun and (3) effects on melatonin production. Whatever the mechanisms, we now know that early-morning sun is important to weight control. It may also be important to other health issues. But before we begin to think that sun exposure is the cure-all for obesity, realize that poor nutritional habits and lack of exercise are much more important. Nevertheless, sun exposure can furnish one more arrow in the quiver of protection from obesity.

Get your sun exposure and stay slim! Be careful not to burn.

[1] Geldenhuys S, Hart PH, Endersby R, Jacoby P, Feelisch M, Weller RB, Matthews V, Gorman S. Ultraviolet radiation suppresses obesity and symptoms of metabolic syndrome independently of vitamin D in mice fed a high-fat diet. Diabetes. 2014 Nov;63(11):3759-69.

[2] Reid KJ, Santostasi G, Baron KG, Wilson J, Kang J, Zee PC. Timing and intensity of light correlate with body weight in adults. PLoS One 2014;2;9(4)


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Athletic performance and sun exposure.

Athletic Performance and sun exposure.

Almost no one realizes the dramatic improvement that sun exposure can make on athletic performance. Years ago I helped Dr. John Cannell obtain translations of many esoteric and decades-old studies that had been forgotten, probably due to the fact that sun lamps were used to create some of the improvements in athletics, and have fallen out of favor due to the sunscare movement. I co-authored a paper with Cannell, called Athletic Performance and Vitamin D.[1] That paper is the source of much of the material covered here, and it demonstrates the remarkable, positive effect of sun or other ultraviolet (UV) exposure on human performance. I would also strongly suggest that the readers avail themselves of Dr. Cannell’s book on the subject, called The Athlete’s Edge, which discusses in far greater detail the materials introduced here.

One of the salient studies on UV exposure took place in 1957 and assessed the influence of sun exposure on strength and performance over a two-year period.[2] During that time six subjects were able to increase athletic performance and muscle trainability through systematic UV exposure. But when vitamin D3 was used, it not only did not work, it inhibited the performance-enhancing effect of the UV. I sometimes fear the public is beginning to believe that if sun exposure is proven to enhance human health, one needs only to take a vitamin D pill. Don’t get pulled into that idea. Sun exposure will always be more important than any of the photoproducts whose production it stimulates.

Here are some of the other salient studies on sun exposure and performance. In 1938, Russian researchers demonstrated that a series of four UV treatments improved speed in the 100-meter dash compared to four non-irradiated students, when both groups were undergoing daily physical training.[3] The times improved from 13.51 seconds to 13.28 seconds in the non-irradiated group and from 13.63 to 12.62 seconds in the irradiated group. In other words, the UV-treated group improved by three-fourths of a second more than the non-UV group. That may seem like a relatively small improvement, but three-fourths of a second better time in a 100-meter dash could be the difference between first and last place!

German research from 1944 showed that the exposure of 32 medical students to UV, twice weekly during for six weeks, associated with a 13% improvement in endurance, whereas performance of a control group was unchanged.[4]

Other German research shows that the ability of a muscle to gain strength (trainability) is much better in summer than winter, and peaks in September.[5] In fact, the trainability in September was 2½ times higher than the average monthly trainability for the entire year.

So you who love athletics, don’t avoid the sun. It may make you a winner. But don’t burn.

Reaction time has also been shown to improve significantly in the sunnier months.[6] [7]

When we consider reaction time, muscle and bone strength, speed and endurance, we should realize that these measurements are not only important for athletes; they are important for all aspects of living for all people. Everyone wants to be stronger, quicker, and faster, as well as have more endurance in daily activities. So embrace the sun, but do it safely and don’t burn.


[1] 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.

[2] E. Seidl and Th. Hettinger. The Effect of Vitamin D3 on the Strength and Performance of a Healthy Adult. International Journal Physiology, including Industrial Physiology, Vol. 16, Pages 365-372 (1957).

[3] Gorkin Z, Gorkin MJ, Teslenko NE. [The effect of ultraviolet irradiation upon training for 100m sprint.] Fiziol Zh USSR. 1938;25:695-701.

[4] Lehmann G, Mueller EA. [Ultraviolet irradiation and altitude fitness.] Luftfahrtmedizin. 1944;9:37-43. [Article in German].

[5] Hettinger T, Muller EA.  Seasonal course of trainability of musculature.  Int Z Angew Physiol. 1956;16(2):90-4.

[6] Sigmund, R. The effect of ultra-violet rays on the human reaction time.  Strahlentherapie. 1956;101(4):623-9.

[7] Seidl E. [The effect of ultraviolet irradiation on reaction time.] Int Z Angew Physiol. 1958;17(4):333-40.

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