Insufficient sunlight associates in a dose-response manner to higher risk of hypertension and earlier death. By Marc Sorenson, EdD. 
Understanding hypertension
Hypertension, or chronic high blood pressure, depends on the amount of blood the heart pumps and resistance to arterial blood. Thus, the tighter the arteries, the higher the blood pressure. The top number on a blood-pressure measurement, and stated in millimeters of mercury (mm/Hg), is systolic pressure. In addition, the lower number is diastolic pressure, another critically important measurement. Hypertension occurs when blood pressure is greater than 140/90 mm/Hg. Thirty-one percent of US adults are hypertensive. Hypertension can damage arterial walls and can eventually lead to an increased risk of death from heart disease, heart failure, and other arterial diseases. It also associates to a higher risk of kidney disease, irregular heart rhythms, osteoporosis, cognitive dysfunction, painful intercourse and stroke.
Does insufficient sunlight exposure influence hypertension?
Conventional textbook theory holds that the brain, blood vessels, and kidney regulate blood pressure. However, recent evidence suggests that the skin could also regulate hypertension, and insufficient sunlight plays a role in increasing it.
Insufficient sunlight, as mentioned, leads to a spate of diseases and disorders. In addition, some of those diseases have a dose-response relationship with sun exposure.
Hypertension is one of those diseases and can lead to disability and death. Blood pressure between 80 (diastolic pressure or lowest pressure) and 120 systolic (higher pressure), is in normal ranges. When blood pressure rises substantially above either of these figures and stays elevated, it is a danger signal.
Understanding the dose-response relationship.
So, what is a dose-response relationship (DRR)? This is where changes in one measured factor produces a predictable, consistent change in another measured factor. Thus, if I increase my exercise a certain amount weekly, I probably hope for a dose-response outcome: predictably better endurance. Consequently, if my body increases its endurance each week, my exercise produces a dose response relationship with endurance. Conversely, if someone stops exercising and loses a predictable amount of endurance, this is also a DRR (negative DRR).
An illustrative example of positive sunlight (rather than insufficient sunlight) and DRR.
My friend Wayne had severe hypertension when checking in at our former resort. After sunbathing each day for a month, hypertension decreased profoundly.
Wayne arrived with blood pressure of 157 systolic and 97 diastolic (157/97). Both of these measurements are dangerously high. Four weeks later, without medication, and while taking no vitamin D, the numbers dropped to 125/54. He had progressed from very high stroke risk to very low stroke risk. In addition, his vitamin D levels climbed to 103 ng/ml, a number I considered impossible without supplementation. I learned much, especially about sunlight, vitamin D levels and hypertension. Sufficient sunlight is a key to optimal levels of blood pressure. Many people believe that older persons cannot raise vitamin D levels. Yet, Wayne was in his seventies. Furthermore, insufficient sunlight was obviously a major cause of his hypertension. Wayne’s DRR occurred with the increased sun exposure and produced optimal blood pressure.
The latest research regarding insufficient sun exposure and hypertension
This latest research on insufficient sun exposure began by noting another important, but misleading fact. An inverse association exists between cardiovascular disease (CVD) and vitamin D levels. Yet, as the authors mentioned, trials of vitamin D supplementation seem to show no benefits for CVD. In addition, they state that benefits of high vitamin D levels for CVD might be a marker for something else. That something, of course, is probably sunlight. In their research, carried out by questionnaire, 23,593 women answered questions regarding melanoma. In addition, they also related factors of possible interest for hypertension. Those factors included detailed sun exposure habits, marital status, education, smoking, alcohol, BMI, exercise and chronic stress. Hypertension-medication use from 2005-2007 became the measurement tool used to determine hypertension incidence among members of the study group.
All subjects filled out a questionnaire to determine sun-exposure and sun-bed habits:
- Do you sunbathe during summer?
- Do you sunbathe during winter vacation?
- Do you travel south to sunbathe?
- Do you use a sun bed?
The investigators deemed that women answering ‘yes’ on one or two questions had moderate sun exposure. Those answering ‘yes’ on three or four questions had the greatest sun exposure.”
The main goal was to assess hypertension risk associated with sun exposure, after adjusting the data for any confounding factors.
Here are the results:
- When compared with women with high sun exposure, those with low sun exposure were 41% were more likely to have hypertension. For moderate sun exposure, the women were 15% more likely to have hypertension. Hence, this is another example of a dose response relationship (DRR). The lower the sunlight exposure, the greater the risk of hypertension.
- Other risk factors for hypertension were lack of exercise, darker skin, chronic high stress and lack of university education.
- The researchers concluded, “That in our observational design sun exposure was associated with a dose-dependent reduced risk of hypertension…. [This] might partly explain the fewer deaths of [from] cardiovascular disease with increasing sun exposure.”
Hypertension is serious, and a major cause of death, which is inversely associated to sun exposure. Therefore, regular, non-burning sun exposure can provide one of the best protections against this insidious disease.
For more information on sunlight and health: https://sunlightinstitute.org/ and read the book, Embrace the Sun.
Insufficient sunlight destroys health. By Marc Sorenson, EdD
Insufficient sunlight is wreaking havoc on health and ruining the enjoyment sunlight provides. Yet, we choose to live in air-conditioned homes, play many of our sports in covered buildings and drive covered cars. In addition, advertisements persuade us that we must wear sunscreen anytime we venture outdoors. Some also suggest that we wear it at night. Thus, they think we can prevent “sun damage” that continues after daytime outdoor sun exposure. It is obvious that the greater part of our population suffers sunlight deprivation. Or, as a recent scientific review called it, “insufficient sun exposure.”
The paper, Insufficient Sun Exposure Has Become a Real Public Health Problem, exposes the damage done due to sun deprivation.
First of all, the authors begin by stating that deaths due to insufficient sunlight are staggering. They amount to 340,000 yearly deaths in the U.S. and 480,000 in Europe. They then delineate the source of those deaths, first declaring a list of major maladies that spread illness and misery. The list includes breast and colorectal cancer, hypertension, CVD, metabolic syndrome, MS, Alzheimer’s, autism, asthma, type 1 diabetes and myopia. In addition, excessive mortality (death) was also on the list due to of insufficient sunlight. Yet, although the list of these sun-sensitive diseases is impressive, I must say I was disappointed. They did not mention another 15 cancers and other diseases associated closely to insufficient sunlight. For those cancers, and additional diseases, read the book, Embrace the Sun, which I wrote with Dr. William Grant.
For decades, scientists designated vitamin D as the only photoproduct of sunlight that produced benefits.
One of the paper’s salient points regarding insufficient sunlight and is transcendentally important. I have been emphasizing the point for years, yet much of the world ignores it. The point is that vitamin D is a vital and important photoproduct of sun exposure. Yet, other photoproducts of sunlight are equally vital. This statement by the authors tends to clarify the truth about Vitamin D and its place with human health. “Vitamin D has long been considered the principal mediator of beneficial effects of sun exposure. However, oral vitamin D supplementation has not been convincingly shown to prevent the above conditions; thus, serum 25(OH)D as an indicator of vitamin D status may be a proxy for and not a mediator of beneficial effects of sun exposure.”
The authors also mention that nitric oxide, and direct effects of ultraviolet radiation, may work independently of vitamin D. For example, nitric oxide is a colorless gas, formed by sunlight exposure to endothelial cells in the skin. It acts as a potent vasodilator and lowers blood pressure. In addition, it is also a potent antioxidant. Of course, insufficient sunlight leads to a lack of nitric oxide, vitamin D and other vital photoproducts.
Here are the explanations used in the review regarding different diseases associated with insufficient sun exposure. Nevertheless, these diseases do not necessarily improve due to vitamin D supplements. Note: the term nmol/L means nanomoles/ per liter, and U.S. measurements are in ng/ml (nanograms per milliliter). To convert nmol/L to ng/ml, multiply by 2.5.
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All-cause mortality (death) Effects of insufficient sunlight
The review also states that insufficient sunlight is a risk factor for death similar to that of smoking. In addition, people with serum vitamin D levels less than 22 nmol/L, have twice the risk of all-cause death. That is, compared to those whose levels were greater than 125 nmol/ (about 50 ng/ml). Remember, vitamin D levels in these cases are really proxies for sun exposure.
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Breast cancer. Effects of insufficient sunlight
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The review quotes research showing a 400% increased breast cancer risk is associated with vitamin D levels less than 50 nmol/L when compared to levels greater than 150 nmol/L. Think sunlight. The vitamin D levels are surrogate measurements for sun exposure.
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Colorectal cancer. Effects of insufficient sunlight
The authors quote a meta-analysis showing a 104% higher risk associated with vitamin D levels less than 30 nmol/L compared to those with levels higher than 82 nmol/L. Interestingly, another study, using animals, showed that neither vitamin D nor UVR (sunlight) was associated with the number of cancer tumors. Nevertheless, ultraviolet radiation (UVR), but not vitamin D, appeared to reduce progression to malignancy. Insufficient sun exposure then, could lead to colorectal cancer.
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Cardiovascular disease (CVD), our number-one killer. Effects of insufficient sunlight
In their review, the authors note CVD has been the leading cause of death globally for the last three decades. In addition, hypertension, or high blood pressure is the number-one risk factor for (CVD). The review states that a growing body of evidence shows an inverse relationship between sunlight exposure, blood pressure and CVD. The authors indicate that a mediator other than vitamin D probably contributes to CVD mortality. Thus, nitric oxide, a sun-exposure product and potent vasodilator, may be the chemical that lowers blood pressure and reduces CVD. The researchers further state that those with habitual low sun exposure double the risk of cardiovascular death compared with those who receive the greatest sun exposure. Obviously, insufficient sunlight can be a deadly contributor to CVD due to an inability to produce sufficient nitric oxide.
5. Metabolic syndrome (MetS). Effects of insufficient sunlight
MetS is a cluster of maladies including glucose intolerance, insulin resistance and high fasting insulin levels. MetS also may include nonalcoholic fatty liver disease, obesity, and cholesterol. All of these factors contribute to heart disease and diabetes. The review noted that UVR suppressed obesity and type 2 diabetes, yet, vitamin D supplementation did not produce the same benefits. The review also suggested that sunlight exposure is an effective suppressor of obesity and MetS through vitamin D-independent mechanisms.
Other diseases, due to insufficient sunlight, to follow later:
Other diseases in the review also indicated an association to insufficient sunlight. I will expatiate on those diseases in a future blog. Until then, be sure to obtain your share of non-burning, regular sun exposure to your skin. In addition, as autumn arrives, you will need a different source of vitamin D production. This is due to the sun’s UVB light being unavailable in autumn and winter in mid to high latitude areas. Therefore, the suggestion is to use a sunbed, which produces vast quantities of vitamin D. Sunbeds also produce vast quantities of UVA light that stimulate nitric oxide in the skin. Therefore, sunbeds are the perfect answer for those times when there is little sunlight availability.
For more information on the healthful effects of sun exposure, visit Sunlight Institute and read my book, Embrace the Sun.