Tag Archives: Sunlight exposure

Sunlight exposure or vitamin D supplementation to lower cholesterol levels? A surprise.

Recent research enlightened me to a paradox in cholesterol research. It appears that vitamin D supplementation actually raises total cholesterol (TC) levels and “bad cholesterol” levels (LDL). Supplementation is also associated with a small rise in “good cholesterol” levels (HDL). The paradox lies in the fact that sunlight exposure is associated with a decrease in total cholesterol levels and LDL, while also producing a small rise in HDL. In both cases, vitamin D levels are raised significantly. Sunlight exposure reduces cholesterol.
The research, from India, was born of a concern that although India has abundant sunshine, vitamin D deficiency is common, because so many do not take advantage of sunlight exposure. The researchers decided to determine whether it was better to use sunlight exposure to increase vitamin D levels, or to instead use vitamin D supplementation. To do this, they formed three groups: a control group that had “normal” levels above 50 nmoL (20 ng/ml), and two vitamin D-deficient group with levels below 50 nmoL. One of the vitamin D-deficient groups increased their usual sunlight exposure by at least 20 minutes to their face and arms between 11 AM and 3 PM daily. The other deficient group received oral supplements of 1,000 IU of vitamin D (cholecalciferol), but did not increase sunlight exposure. The researchers also measured cholesterol levels. The study lasted for 6 months and the results were as described above: A decrease in TC level and LDL levels in the sunlight exposure group, an increase in TC and LDL in the supplementation group, and an increase in HDL in both groups.
It would have been interesting if the subjects in the sunlight-exposure group had experienced full-body exposure for 20 minutes, which can produce up to 20,000 IU of vitamin D; a few minutes on the face and arms is not sufficient to optimize vitamin D levels. Equally, the use of 1,000 IU daily of vitamin D is miniscule. I would have suggested at least 4,000 IU daily. Altering upward the dosages of both sunlight and vitamin D could have shown larger differences. More research needs to be done to determine whether or not these results can be replicated.

The indications of this study is that vitamin D supplementation may be harmful because it raises serum lipids in an adverse manner. There is also an indication that sunlight exposure improves lipid profiles while still raising vitamin D levels.
By what mechanism would sun exposure lower cholesterol levels? A type of cholesterol precursor called 7-DHC is stored in the skin. It is also used to produce vitamin D when under the influence of sunlight. Regular sunlight exposure would reduce this cholesterol store and thereby reduce cholesterol levels.
As to why vitamin D supplementation might increase cholesterol levels, it could be due to the fact that it is usually made by radiating lanolin from sheep. Animal products are known to raise cholesterol levels.
Whatever the reasons for the ability of sunlight to lower cholesterol levels, this study is one more indication that sunlight is a friend to nearly every system of the body. Be sure to obtain plenty of non-burning sunlight. Your heart and brain will thank you for it!

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Sun Exposure, artificial Light and Weight Control

Sun Exposure, artificial light and weight control. Marc Sorenson, EdD… Sunlight Institute

Sun exposure gives life and has so many positive effects, including anticancer, anti-heart disease, and anti-osteoporosis. Unnatural light, however can do exactly the opposite. In the case of obesity, artificial light at night (ALAN) can lead to weight gain, according to a study in the International Journal of Obesity.[1]

The hormone melatonin works in conjunction with serotonin during each daily physiological cycle, known as the circadian rhythm. Serotonin is a natural “upper” that awakens our senses and prepares us for our workday. Then, when the rhythms are properly synchronized, as evening comes, serotonin decreases and melatonin, a sleep inducer, takes over so that we can sleep soundly and awake refreshed as daylight and serotonin once more take over. However, a monkey wrench is often thrown into the works. It is called artificial light at night (ALAN), and it may be one of many factors that lead to obesity. ALAN inhibits melatonin production, a factor in both obesity and cancer.

The researchers looked at satellite images of 80 countries, assessed the amount of ALAN emitted from each country and then compared the rates of obesity in each. The data was adjusted to take into consideration the differing dietary patterns in each country, as well as the urban vs rural population and other factors that would influence obesity.

The results showed, that after all adjustments, ALAN emerged as a prominent predictor for obesity.

So how does this relate to sun exposure? One of my recent posts noted the results of research on early morning sun exposure and obesity, noting that early sun exposure inhibited obesity dramatically.[2] So not all light is good. Light at night is harmful; early morning sun exposure is wonderful. And if one wants to remain slim, it is imperative to eschew junk food, exercise and get plenty of non-burning sun exposure.

[1] Rybnikova NA, Haim A, Portnov BA. Does artificial light-at-night exposure contribute to the worldwide obesity pandemic? International Journal of Obesity. Int J Obes (Lond). 2016 May;40(5):815-23.

[2] Reid KJ, Santostasi G, Baron KG, Wilson J, Kang J, et al. Timing and Intensity of Light Correlate with Body Weight in Adults. PLoS ONE 2014 9(4): e92251. doi:10.1371/journal.pone.0092251

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Do you have High Blood Pressure? Could Sunlight save your Life?

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.[1] 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.[2] 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.[3] 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, [4] 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.[5] 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.[6] 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!


[1] American Heart Association/American Stroke Association Statistical Fact Sheet/2013 update.

[2] Ann Pietrangelo. Healthline 2014 http://www.healthline.com/health/high-blood-pressure-hypertension/effect-on-body (accessed January 4, 2016).

[3] Johnson RS, Titze J, Weller R. Cutaneous control of blood pressure. Curr Opin Nephrol Hypertens. 2016;Jan25(1):11-5.

[4] 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.

[5] 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].

[6] 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.

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Sunlight and Cognition

By Marc Sorenson, EdD Sunlight Institute

We have previously discussed information indicating that people who received more sunlight had better brain function, and noted the relationship between Alzheimer’s, autism and other mental disorders and lack of sun. A recent study compared cognitive impairment and sunlight in a 15-year residential history of varying degrees of sunlight exposure. It showed that cognitive impairment in persons who were below the median exposure to sunlight was 88% greater than those who were above the median.[1]

The researchers mentioned vitamin D as a possible mechanism by which sunlight positively influenced cognition, but also remarked that regulation of the circadian rhythm by sunlight could be a factor. These same investigators had previously shown that lower levels of sunlight exposure resulted in a 2.58-times higher incidence of cognitive impairment.[2]

So, if you would like to maintain your cognitive abilities, soak up a little non-burning sunlight!

[1] Kent ST, Kabagambe EK, Wadley VG, Howard VJ, Crosson WL, Al-Hamdan MZ, Judd SE, Peace F, McClure LA. The relationship between long-term sunlight radiation and cognitive decline in the REGARDS cohort study. Int J Biometeorol. 2014 Apr;58(3):361-70.

[2] Kent ST, McClure LA, Crosson WL, Arnett DK, Wadley VG, Sathiakumar N. Effect of sunlight exposure on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study. Environ Health. 2009 Jul 28;8:34

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Sunlight Exposure is Associated with a Reduced Risk of Stroke.

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.


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Sunlight and Food Allergy

By Marc Sorenson, EdD, Sunlight Institute

An August 15, 2015 review of research on sunlight, vitamin D and food allergy makes some interesting statements.[1] First, the researchers state that since 2007, most epidemiologic studies have supported low sunlight, as measured by season of birth and latitude, as a risk factor for food allergy. They then note that studies that looked directly at vitamin D status as measured by serum vitamin D levels are not nearly as consistent as the sunlight studies. They state: “Although conflicting, the vitamin D studies suggest a more complicated association than a linear dose response in all individuals, with some studies indicating different associations based on host characteristics (e.g. concomitant eczema, genetic polymorphisms, country of birth).”

Their summary is telling: “Many studies have linked sunlight with the development of food allergy but whether this is directly related to vitamin D status or a myriad of other sunlight-derived, seasonal and/or geographic factors remains uncertain. More studies are needed to investigate the role of sunlight and vitamin D status in food allergy because of their potential for primary prevention and disease modification.”

This is another of those scientific papers that illustrates that whereas sunlight exposure is nearly always protective against the studied disease, there is much more room for argument when vitamin D serum levels are used.

My takeaway? Get sufficient exposure to sunlight on a regular basis. That provides plenty of vitamin D when it is needed, but also provides nitric oxide, endorphins, serotonin, dopamine and other photoproducts that may yet be named. We must cease to equate sunlight exposure only with vitamin D production or we do a disservice to other healthful effects of sunlight.


[1] Rudders SA, Camargo CA Jr. Sunlight, vitamin D and food allergy. Curr Opin Allergy Clin Immunol. 2015 Aug;15(4):350-7.

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Viagra Use is Associated with a Profound increase in the Risk of Melanoma.

Recently, I posted that sunlight exposure, coupled with blueberry consumption, may be a better option than Viagra in terms of overcoming erectile dysfunction (ED)[1] but never mentioned that there might be a further association with Viagra and melanoma. Research now indicates a surprising newcomer to the melanoma equation: the use of sildenafil (Viagra) increases the invasiveness of melanoma cells, which may raise the risk of the disease.[2] In a study that was begun in 2000 and reported in 2014, it was found that recent use of Viagra was associated with an 84% increased risk of melanoma and that ever use of the drug was associated with a 92% risk. And among those who had no major chronic diseases at baseline, the risk was 124% higher for those who recently used the drug and 177% higher among those who had ever used the drug.

Noxious chemicals have many side effects, but who would have guessed that an ED drug would increase the risk of melanoma? Remember also that we have presented information showing that melanoma is not caused by regular sunlight exposure, and that sunlight is in fact protective against that disease. Sunlight, therefore, is a better choice for the prevention of both melanoma and ED.

[1] http://sunlightinstitute.org/sunshine-blueberries-nitric-oxide-and-peak-sexual-function-better-than-viagra-and-cialis/

[2] Li WQ, Qureshi AA, Robinson K, Han J. Sildenafil use and increased risk of incident melanoma in US men: a prospective cohort study. JAMA Intern Med. 2014 Jun;174(6):964-70C

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Sunlight Exposure Reduces the Risk of Heart Disease and does not Increase the Risk of Melanoma.

By Marc Sorenson, EdD, Sunlight Institute

An article in a South-East Asia online paper[i] has some good points on sunlight and disease, but is sullied by some unfortunate quotes by two people that I have great respect for, Drs. Richard Weller and Robyn Lucas. The article starts well enough by stating that health benefits of sun outweigh the risks. A statement by Dr. Weller is then quoted: “Dermatologists only think about the skin whereas the benefits of sunlight are predominantly in general health rather than skin health,” So far, so good. He also says that vitamin D tablets will not provide the same benefits as sunlight. That is also true.

Next, Dr. Weller says that the only major problem caused by sunlight is melanoma, but melanoma is often linked to sunburns that occur in childhood. The fact is, melanoma is not caused by sunlight, as I have reiterated in this blog many times. As people have moved out of the sunlight in the U.S., the risk of melanoma has increased exponentially; outdoor workers have a fraction or the risk of melanoma as indoor workers, and melanoma has increased only in indoor workers since 1940.

Later in the article, in trying to explain why melanoma incidence is low in South-East Asia, Dr. Lucas makes this statement: “this is probably due to the culture of not being sun-seeking in South-East Asia as well as a small contribution from having generally slightly darker skin. Even though the UV levels are high in these countries close to the equator, the burden of UV-related skin diseases is low” [italics mine]. Dr. Lucas has obviously bought into the idea that sunlight causes melanoma and must look for a reason to explain the fact that high sunlight exposure in South-East Asia associates with a low risk of the disease. In the italicized statement above she has answered the question. The reason that there is a low risk of melanoma in the area is because regular, high sunlight exposure prevents melanoma.

Nevertheless, the article is well-written until the last paragraph, which quotes a Dr. Emilie van Deventer:  “Sunlight exposure for the purposes of vitamin D is better earlier in the morning or later in the afternoon when the risk of skin damage caused by UV is much lower.” Anyone who makes such a statement has not read the research; almost no vitamin D is produced in early morning or late evening. Early-morning sunlight, of course, is associated closely with slimmer bodies, but not due to vitamin D.

So, I continue to fight this battle, separating the truth from the fiction, the gold from the dross. Regular, non-burning sunlight is good for us. Enjoy it safely and do not burn.

Read the article here: http://www.scidev.net/asia-pacific/health/news/sunlight-good-for-the-heart-researchers-say.html

[i] http://www.scidev.net/asia-pacific/health/news/sunlight-good-for-the-heart-researchers-say.html

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Early-Life Sun Exposure Affects the Age of Onset of Bipolar Disorder.

By Marc Sorenson, EdD

We are meant to be in the sunlight for both mental and physical health, and one of the most important phases for sunlight exposure is early life. We have previously discussed such diseases as autism, low bone strength and type-one diabetes as being related to lack of sunlight either in the formative years or even in the womb.

One of the latest pieces of research involves the onset of bipolar disorder (BD), a mental condition characterized by alternating mania and depression, usually interspersed with normal mood. The disorder was previously called manic-depressive illness.

In an 11-nation study, the U.S. was found to have the highest rate of BD and India lowest rate.[1] Or perhaps we should use the word “risk” rather than “rate.” Is it possible that greater sunlight exposure plays a part in India’s lower risk? Research has yet to determine that answer, but a recent study may “shed some light” on the subject. In the Journal of Psychiatric Research, a team of about 50 scientists studied the influence of light exposure during early life on the age of onset of BD.[2] The study covered 23 different countries at different latitudes and assessed light exposure in the early lives of 3896 BD patients. It was found that more sunlight exposure in the first three months of life was associated with a later onset of the disease. The researchers felt that sunlight during this time helped set the circadian rhythms later in life. The researchers concluded with this statement: “This study indirectly supports the concept that early life exposure to light may affect the long term adaptability to respond to a circadian challenge later in life.”

It would be interesting to know if the overall risk of BD is lower in countries or areas where people receive the most sunlight in infancy, of for that matter, during a lifetime. This research, however, shows us that our children, even our little ones, should receive regular, non-burning sunlight exposure.

[1] Amanda Gardner. U.S. has highest bipolar rate in 11-nation study. Heath.com. March 7, 2011. http://www.cnn.com/2011/HEALTH/03/07/US.highest.bipolar.rates/ Accessed July 21, 2015.

[2] Bauer M, Glenn T, Alda M, Andreassen OA, Angelopoulos E, Ardau R, Baethge C, Bauer R8, et al. Influence of light exposure during early life on the age of onset of bipolar disorder. J Psychiatr Res. 2015 May;64:1-8

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Sunlight and Your Liver: is Nitric Oxide at work again?

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.[1] 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.

[1] 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.

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