Our bodies produce vitamin D when exposed to sunlight. However, according to dermatologist Richard Weller, the benefits of sunlight are not limited to this. A new study by his team shows that nitric oxide — a chemical transmitter that is stored in the skin in huge reserves, — can be released from UV radiation, providing great benefits for blood pressure and the cardiovascular system. How?
dermatologist
Before becoming a dermatologist, I worked in general medicine, like many dermatologists in the UK. At that time, it was about 20 years ago, I visited Australia. Having been in Australia, I realized that the spirit of competition is in the blood of the Australians, and they do not show generosity to the defeated. I often heard: "You Brits don't know how to play cricket and rugby." I basically agree with this.
But let's get back to our topic. At that time, we had weekly reading club meetings, a kind of get-together in the circle of doctors, dedicated to reviewing and discussing scientific medical articles. At the second meeting, the issue of mortality from cardiovascular diseases was discussed. Pretty dry stuff — statistics of deaths from heart disease, indicators. The Australians went back to their own: “Oh, you Englishmen! You're ahead of the planet in heart disease rates!"
And of course they were right. The incidence rate among Australians is three times lower than among the British — fewer deaths from heart attacks, heart failure, angina attacks ... Australians generally have better health. They, of course, claimed that they owed their good health to their incredible strength of mind, intensive sports, just because they are Australians, and we are frail English, and all that kind.
However, it is not only the Australians who have better health than the British. In the UK itself, incidence rates vary. We are talking about the standardized mortality rate — Simply put, the likelihood of death. Here are the figures from 20 years ago, but they are still relevant today. Let's compare mortality rates at the parallel of 50 degrees north latitude — these are the southern regions, London and other cities — and data for areas located 5 degrees north, and this is where Glasgow is located. I am from Edinburgh myself. It's too early for me to rejoice — Edinburgh at the same latitude.
So what is the reason for this difference in rates for settlements located in the vastness of southern Scotland and to the southern regions of England? We all know about the dangers of smoking, french fries and chocolate bars — typical Glaswegian diet. All this is well known to us. But this schedule has already been drawn up taking into account all these risk factors. Smoking, income level, diet and other risk factors were taken into account. The question remained unresolved: what is the reason for the increase in mortality rates as we move further north?
Of course, we took into account the intensity of sunlight. Ever since the media started talking about the benefits of vitamin D, a lot of people have been concerned about this issue. Humans really need vitamin D. For children, there are even established norms for its consumption. My grandmother grew up in Glasgow, then in the 20s and 30s rickets was a real scourge of this city, it was then that fish oil was first used. This really helped prevent the spread of rickets in Glasgow. As a child, my grandmother fed me fish oil. It is impossible to forget this incomparable taste.
There is a connection: the higher the content of vitamin D in the blood, the lower the risk of developing both heart disease and cancer. The conclusions of so many studies testify to the benefits of vitamin D. And it is really useful — to prevent the development of rickets, for example. But it turns out that vitamin D intake has no effect on reducing the rate of heart disease. The same is true for cancer prevention. Apparently, vitamin D alone doesn't make a difference. Vitamin D alone cannot prevent the development of heart disease. I believe that the high content of vitamin D — only an indicator of the effect of sunlight on the body, and the sunlight used in the methodology that I will tell you about has a beneficial effect on heart patients.
So, I returned from Australia, and despite the obvious health risks, I settled in the city of Aberdeen. In Aberdeen I was trained in dermatology. Then I became interested in scientific activities, in particular, my attention was attracted by this substance — nitric oxide. Here are three scientists — Furchgott, Ignarro and Murad — received the 1998 Nobel Prize in Medicine. They were the first to describe the action of this new chemical mediator — nitrogen oxides. Nitric oxide dilates blood vessels, thereby lowering blood pressure, and also dilates the coronary arteries, thereby preventing an attack of angina.
What's really surprising is that previously, when talking about chemical mediators in the human body, we thought about complex substances like estrogen and insulin, or about the transmission of impulses through the nervous system. These are very complex processes involving complex chemicals and very complex receptors. But the incredibly simple molecular structure — compound of nitrogen and oxygen — nevertheless, it is of great importance for lowering blood pressure, transmitting nerve impulses and many other processes, but first of all — for the work of the cardiovascular system.
We began research and came to the unexpected conclusion that our skin is capable of producing nitric oxide. That is, not only the cardiovascular system generates this substance, but also the skin. So, we published the results of our research, and we asked ourselves, what is the function of this substance? How can pressure be reduced through the skin? After all, it's not about the heart. So what's the deal?
Then I went to the USA, like many scientists who are going to do research, and spent several years in Pittsburgh. I have been studying these incredibly complex systems. It has been suggested that nitric oxide is somehow related to cell death, cell survival and their resistance to various influences. At first I started growing cells, then I did experiments on mice with "knockout" genes — that is, with mice carrying the desired gene mutation. A mechanism was developed in which nitric oxide contributed to increased cell survival.
I then returned to Edinburgh. Here, experiments were not made on experimental animals, but on our medical students. This species is close in its characteristics to humans, and has a number of advantages compared to the mouse. They live in the wild, they don't need to be shaved, they get their own food, and animal advocates don't shout slogans like "For the humane treatment of medical students" under the windows of our laboratory! Therefore, they are, in fact, ideal for experiments.
But here's what we found — we were not able to achieve the same results that were obtained in experiments with mice. It seemed that we could not turn off the function of nitric oxide production in human skin. We applied creams to the skin that block oxide-producing enzymes, we gave injections. But it was not possible to stop the production of oxide.
The reason was found only after 2-3 years of research, it turned out that the skin contains huge reserves of not nitric oxide itself, because nitric oxide — it's a gas, and it's released — (Puff!) — and after a few seconds it is already gone, but it can be stored in a different form: in the form of nitrate — NO3, nitrite — NO2, or nitrosothiol. These substances are more stable, that is, human skin contains huge reserves of nitric oxide. By imagining man as a huge store of this substance, we set out to find out if sunlight could activate these stores and cause them to be released from the skin, which contains 10 times more of this substance than the circulatory system. Can sunlight help release these stores into the circulatory system,
Since my area of research — dermatology, I decided to see what effect sunlight would have on the test subjects. We exposed some of the subjects to ultraviolet light using UV lamps. But we had to be very careful, because when exposed to UVB rays, vitamin D is produced — we wanted to exclude the effect of vitamin D on the results of the experiment. Therefore, we used UV-A rays: they do not lead to the production of vitamin D.The duration of artificial exposure of the subjects was equivalent to 30 minutes of exposure to the sun on a summer day in Edinburgh, the results of the experiments showed an increase in the content of nitric oxide in the circulatory system. So we exposed the test subjects to UV radiation, and the level of nitric oxide in the blood increased, and their blood pressure decreased. At the individual level, this reduction is not that great, but it is high enough for the whole population to lead to an overall reduction in the rate of heart disease in the population. However, if we irradiated the skin with UV rays or raised the temperature of the subjects to a level equivalent to irradiation with lamps, without allowing direct exposure of the skin to UV rays, this effect did not appear. So exposure to UV rays on the skin is a must.
So we continue to collect data. And there is some good news. The effect of exposure to UV rays is more pronounced in older people. I can't say exactly how much. One of the subjects was my mother-in-law, of course I have no idea how old she really is. But it is absolutely certain that for people older than my wife, the effect of exposure to UV rays is more pronounced. I would also like to note that there is no change in the concentration of vitamin D in the blood. This effect is not associated with vitamin D. Thus, vitamin D is useful as a prevention of rickets and calcium metabolism disorders. But the mechanism we have considered is not tied to vitamin D.
One of the problems associated with the study of blood pressure — it is your body doing its best to maintain a constant level of blood pressure. If you have a leg amputated and you are losing a lot of blood, the blood vessels in your body will constrict, your heart rate will increase, and all the processes in the body will be directed to increase pressure. This is one of the fundamental principles of physiology.
So the next step was to study the process of dilating blood vessels. We took measurements again. Note that the tail and hairline are missing — in front of you is a medical student. This is how the amount of blood flow in the arm is measured by determining the degree of its swelling when a certain volume of blood enters it. We found that when simulating UV irradiation — which corresponds to this thick line — those. when irradiating the hand with UV rays to increase its temperature, so that the rays themselves do not fall on the covered area of \u200b\u200bthe skin. The amount of blood flow does not change, as does the degree of vasodilation. But during direct exposure to UV rays and within an hour after the session, vasodilation occurs. This is the mechanism for lowering blood pressure, due to which the expansion of the coronary arteries also occurs, so that blood flows freely to the heart. It also turned out that UV radiation — sunlight — has a beneficial effect on blood flow and the cardiovascular system.
We have created a special model. UV radiation in different parts of the world at different times of the year is different, so you can calculate the amount of nitric oxide reserves — nitrates, nitrites, nitrosothiols in the skin — which decompose with the release of nitric oxide. Different wavelengths of light have different effects on these processes. You can first consider the waves of the wavelength that are necessary for this. So, if you live at the equator, the sun's rays passing through a very thin layer of the atmosphere fall directly on the top of your head. In winter and summer, the intensity of lighting is the same. But in our latitudes, in summer, the rays fall almost perpendicularly, and in winter they pass through a very thick layer of the atmosphere and a very large part of the ultraviolet is scattered, and the wavelength ranges of light waves reaching the Earth's surface are varies from winter to summer. We can multiply these values by the amount of nitric oxide released, and thereby calculate how much nitric oxide will be released from the skin into the circulatory system.
So, if you live on the equator — on the graph, these are red and purple lines — amount of released nitric oxide — it's this area under the curve, the area in this space. Therefore, if you are a resident of the equator, whether it is December or June, huge amounts of nitric oxide are released from your skin. The city of Ventura is located in southern California. In summer, it's like being at the equator. This is great. Huge amounts of nitric oxide are released. In Ventura, the middle of winter — Still, the volumes are quite significant. Edinburgh in summer — the area under the curve is quite significant, and now Edinburgh in winter — volumes of nitric oxide released are close to zero, a small amount.
So what's next? We continue research, develop this theory, get new data. We believe that our research is very important. We believe that this is the reason for the different levels of health in the north and south of the UK. This dependence is very important for us. We know that the skin contains huge stores of nitric oxide in many different forms. We assume that most of the nitric oxide enters the body with foods such as leafy vegetables, beets, lettuce, which contain large amounts of nitric oxide. We believe that the nitric oxide obtained from food is then stored in the skin, and the sun's rays promote the release of these reserves, which has a beneficial effect on the body.
Research continues, but dermatologists — that is, to me as a dermatologist — Every day you have to tell your patients, “You have skin cancer. Its reason — sunlight. Don't go out into the sun. But, in fact, I think it's more important to convey to people that sunlight can be both beneficial and dangerous. Yes, sunshine — a major risk factor for skin cancer, but death from heart disease is a hundred times higher than death from skin cancer. I think people should be aware of this and find that risk/benefit ratio.
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