Exposure to sunshine may help reduce blood pressure —Experts 

Public health experts have urged Nigerians to embrace regular exposure to sunshine, particularly early morning sun, noting that it can help lower blood pressure levels and even help reduce mortality from cardiovascular issues.

The experts noted that there is a link between exposure to the sun and lower blood pressure levels

According to them, exposure to sunlight triggers the skin to release its reserves of nitrogen oxides, which expand blood vessels, lower blood pressure, and may have a protective effect against metabolic syndrome.

The experts, a Professor of Public Health at the University of Ilorin, Prof. Tanimola Akande, and a public health physician, Dr. David Adetola while speaking exclusively with PUNCH Healthwise, said exposure to sunlight can help boost the body’s vitamin D supply. 

Prof. Akande explained that the early morning sun between 7 am to 9 am is the most beneficial to generate Vitamin D, adding that it helps to boost its supply in the body. 

The former National Chairman, Association of Public Health Physicians of Nigeria, however, stressed that sunlight after 10 am may be harmful, noting that excessive exposure to sunlight depending on the individual’s type of skin can be hazardous.

He further said, “Studies show that 5 to 15 minutes of sunlight is enough to get the optimum effect of sunlight. For dark-skinned people, it can be as long as 30 minutes. Individuals can stay out longer and get the same effect, preferably with the use of sunscreen.

“Lack of sunlight can lead to deficiency in Vitamin D which is important in the growth of bones. In children, it can result in rickets; there is growth retardation and bone deformities classically in the form of bow legs. Even in adults Vitamin D is important for bone health. Exposure to the sun improves bone health. 

“There are reports that exposure to sunlight can decrease blood pressure and increase blood flow, which is extremely beneficial to our cardiovascular system. Some studies have also shown that exposure to sunlight can reduce some autoimmune diseases.” 

In his submission, Dr. Adetola noted that moderate amounts of sunlight are beneficial to an individual’s overall health, noting that the Vitamin D generated by the exposure helps prevent different diseases. 

He stressed, “Studies have proven that those who obtain enough vitamin D as children have a lower risk of acquiring type 1 diabetes as adults. In one specific study, children who received the right amount of vitamin D had an 80 per cent lower risk of getting type 1 diabetes than those who were vitamin D deficient, who had a fourfold higher risk.

“To prevent diseases that are more likely to arise if people do not obtain the right amount of vitamin D required for their bodies, it is advised that people should acquire small quantities of sun exposure.

“You only need to spend 12 to 15 minutes in the noon sun, or 15 to 30 minutes if you have darker skin, to get enough vitamin D into your system.” 

A study published in the Journal of Investigative Dermatology also indicated that exposing skin to sunlight may help to reduce blood pressure and thus cut the risk of heart attack and stroke. 

The research which was carried out at the Universities of Southampton and Edinburgh shows that sunlight alters levels of the small messenger molecule, nitric oxide (NO) in the skin and blood, reducing blood pressure.

While limiting sunlight exposure is important to prevent skin cancer, the authors of the study, including Dr. Richard Weller of the University of Edinburgh, suggest that minimising exposure may be disadvantageous by increasing the risk of prevalent conditions related to cardiovascular disease.

During the study, the skin of 24 healthy individuals was exposed to ultraviolet (UVA) light from tanning lamps for two sessions of 20 minutes each. In one session, the volunteers were exposed to both the UVA rays and the heat of the lamps. In another, the UV rays were blocked so that only the heat of the lamps affected the skin.

The results suggested that UVA exposure dilates blood vessels, significantly lowers blood pressure, and alters NO metabolite levels in the circulation, without changing vitamin D levels. Further experiments indicate that pre-formed stores of NO in the upper skin layers are involved in mediating these effects. The data are consistent with the seasonal variation of blood pressure and cardiovascular risk at temperate latitudes.

Another study carried out in 2016 by the Medical Research Council Centre for Inflammation Research, University of Edinburgh, Queen’s Medical Research Institute, Edinburgh, UK found that there is a correlation between increased sun exposure and reduced population blood pressure and cardiovascular mortality.

The study discovered that individuals with high serum vitamin D levels are at reduced risk of hypertension, cardiovascular disease, and metabolic syndrome. 

The study which was published on Karger Open Access reads partly, “Sunlight has beneficial effects on cardiovascular risk factors independently of vitamin D. Sunlight is a risk factor for skin cancer, but sun avoidance may carry more of a cost than benefit for overall good health.” 

Similarly, a study titled; “Sunlight and Vitamin D: Necessary for Public Health” and published on Taylor and Francis Open Access noted that exposure to sunlight goes beyond the production of vitamin D, adding that it helps in the release of nitric oxide, production of beta-endorphin, and regulation of circadian rhythms which are all important components of lifelong health and well-being.

The study further read, “Physiological responses go beyond the production of vitamin D. When the skin is stimulated with UVA radiation, nitric oxide is released, stimulating vasodilation and lowering of blood pressure. During active exposure to UVA, diastolic blood pressure in one study fell by roughly 5 mmHg and remained lower for 30 minutes after exposure citation. 

“A reduction of diastolic blood pressure by 5 mmHg decreases risk for stroke by 34% and coronary heart disease by 21% Citation.

“Another physiological response of skin exposure to sunlight is the thickening of the stratum corneum (the outermost layer of the epidermis) and increased skin pigmentation through the production of melanin.” 


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