New research has found that spending time in the sun may prevent people from suffering heart failure or stroke. Sunshine could even save lives. It all has to do with the effect of the sun’s UVA rays on the skin, and blood pressure.
The new research study, published late January in the Journal of Investigative Dermatology, states that both cardiovascular disease and hypertension (high blood pressure) have been seen to increase during winter months. Since there is no proven reason for this phenomenon, the study set out to uncover the truth. Remarkably, it found that the skin plays a vital role in lowering blood pressure through UVA irradiation. In simple terms, sunshine lowers the risk of high blood pressure, which in turn lowers the risk of stroke and heart failure.
Researchers started with the hypothesis that because there is an abundance of nitric oxide (NO) in human skin, when skin is exposed to UVA (the sun’s ultraviolet long-waves), the NO is mobilized into the circulation in a way that benefits the heart and its blood vessels. NO is a “signaling molecule” that is able to protect various body organs, and its mobilization is completely independent from the absorption of vitamin D into the skin from the sun.
The study presents evidence that exposure to the sun can change nitric oxide levels in the blood. What happens is that as the NO levels increase, there is a definitive drop in blood pressure, the study states. The cells that line the inner surface of blood vessels dilate and relax when NO is produced. This dilation is the key to overcoming high blood pressure (or hypertension), which as the American Heart Association warns, can damage and scar the arteries if it is not treated.
However, researchers were surprised to find that the “acute dietary intervention” they thought would have an effect on the availability of NO, did not have any effect on changes in circulation that were UV-induced. This showed them that effects on the cardiovascular system were not directly altered by the nitrite in the bloodstream. Instead, the effects of UVA irradiation on the skin boosted blood flow on its own, indicating that it used NO that had already formed in the skin.
Based in the United Kingdom, the researchers gave 24 volunteers doses of UVA in a laboratory that were the equivalent of what they would absorb if they were in the sunshine for half an hour during a southern European summer. Generally, the blood vessels of all participants dilated, and there was a decrease in blood pressure, indicating that UVA prevents people from suffering heart failure and stroke.
One of the researchers, Prof. Martin Feelisch said that the potential contribution of sunlight and the skin to reducing hypertension has not previously been highlighted in research studies. Based at the University of Southampton, he said that it was still not 100 percent clear how exposure to the sun lowers blood pressure. However, he said there was evidence that large storage pools of NO are found in skin, and that this is mobilized when the skin is exposed to sunlight. Once mobilized, the NO molecules move out of the skin into the bloodstream, dilating blood vessels and in this way lowering blood pressure.
High Blood Pressure
High blood pressure can be a killer. Apart from leading to stroke, heart failure and heart attacks, it can be the cause of permanent damage to other organs including the kidneys, brain and eyes.
All organs in the body need oxygen; if they do not get sufficient oxygen the body simply will not survive. The heart, which is really just a pump, beats and creates sufficient pressure to push the blood in the body through arteries and veins. In between this pumping movement, which is seen as a heart beat, the heart rests. If it pumps too forcefully or too rapidly, blood pressure will be high. Over any period of time, if the flow of blood is too high, the artery walls will be excessively stretched leading to vascular weakness and scarring, as well as an increased risk that blood clots will form, plaque will build up, and various other organs and body tissue will be damaged.
The American Heart Association likens high blood pressure to a water pressure system that gets clogged. Blockages have the effect of narrowing pipes, and this increases the pressure in the water pressure system. Similarly, when arteries start losing their flexibility, it is more difficult for the heart to pump blood into the arteries, and so the heart has to work harder. This can damage the valves and the muscles in the heart, as well as the heart itself. Damage to other organs is caused when there is not sufficient blood being pumped to them.
Just a little sunlight can have a significant effect on people who have relatively normal blood pressure, by lowering it, and in this way minimizing the possibility of stroke and heart failure. However, one of the senior researchers, dermatologist Dr. Richard B. Weller, warns that exposure to sunshine and sunbathing is not enough for people suffering from high blood pressure, even if it prevents some effects short-term. Based at Scotland’s University of Edinburgh, he says that if a person’s blood pressure is high, it must be medically controlled.
By Penny Swift