Is sunlight really bad for you? It seems like that's about all we hear these days. When was the last time you read an article telling about the benefits of sunlight? Unless you've been reading Second Opinion, it's probably been a long time — if ever.
Sunlight comes in two flavors: ultraviolet B (UVB) and ultraviolet A (UVA). Both of them are supposed to cause skin cancer. And so we are constantly warned to cover our skin and apply sunscreens that block both UVB and UVA. But skin cancer is not the number one killer of people these days. In fact, it's fairly low on the list. The number one killer is cardiovascular disease. And now a surprising new study is showing that not getting enough UVA may be a cause for both high blood pressure and cardiovascular disease.
The authors of the study begin their report by noting that the likelihood of getting high blood pressure and cardiovascular disease is uniformly increased in higher latitudes. It is also increased in the lower latitudes during the winter. So what do these two conditions have in common? They both result in a lower exposure to sunlight. So here's what the researchers did.
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They took 24 healthy men and women and using the same technology that is used in tanning booths they irradiated their skin with UVA. Why UVA instead of UVB? It's because UVA penetrates deeper into the skin. In a moment, you'll see why this is important. UVB does not penetrate deep enough into the skin. The result was that the UVA lowered the blood pressure in all the subjects. But that's not all.
The researchers also measured the amount of nitric oxide before and after the UVA exposure. And what they found was amazing. The UVA caused the skin to release its nitric oxide stores in a dose-dependent manner. That means that the more UVA they were exposed to, the more nitric oxide they released. You may remember that nitric oxide is a product of oxygen metabolism that lowers blood pressure and decreases cardiovascular disease. Exercise and eating green leafy vegetables increases nitric oxide levels. And this is certainly one of the reasons for why they are known to lower blood pressure and decrease cardiovascular disease. But it gets even better.
The researchers discovered that the nitric oxide released from UVA exposure was not produced in the same way that nitric oxide is produced from exercise and green leafy vegetables. The skin has its own separate mechanism for releasing nitric oxide. So all three of these good lifestyle habits, exercise, diet, and now sunlight exposure are synergistic. They each lower blood pressure and decrease the risk of cardiovascular disease in their own way. In other words, they can be combined for a maximum effect. So how does it work?
In a surprising discovery the researchers found out that the deeper layers of the skin actually store nitric oxide. And when these layers are exposed to UVA, they release these stores. UVB does not have the same effect because it does not penetrate deep enough. According to Thomas Michel, a professor of medicine and biochemistry at Harvard Medical School, "This study provides suggestive evidence that skin-derived nitric oxide metabolites may have a role in reducing blood pressure upon UVA exposure." And one of the researchers Martin Freelisch went even further.
He said that the results of the study show that, "Avoidance of sunlight may be a new risk factor for cardiovascular disease that's never been on the map." So if not getting enough sunlight increases your risk of cardiovascular disease, and if getting too much sunlight increases your risk of skin cancer, what should you do? The researchers used a dose of UVA that was equivalent to 30 minutes of sun exposure at noon on a clear day in Southern Europe. I can see two lessons here.
First, since it is known that sunburn can cause a non-life threatening skin cancer called basal cell, it makes sense to do whatever it takes to prevent your skin from sunburn. People with lighter skin need to be more careful. Repeated exposure to sunlight over time will darken most skins — the tanning effect. This will allow longer exposures to the beneficial effects of UVA without the dangers of sunburn. So tanning without sunburn is one of the best ways to go.
Second, if you have to be exposed to a potentially excessive amount of sunlight feel free to use a UVB/UVA sunblock. Of course this will also block the beneficial effects of the UVA, so don't make this a regular habit. Only use it when there is no other way to protect yourself from sunburn. And one last point.
If you have white-white-white skin like mine, feel free to take plenty of Green Tea Extract whenever you are going to be out in the sun. Green Tea Extract has been shown to be protective against the cancer causing effects of sunburn. I like to take two to three tablets before I go out on my boat or take a long bike ride in the summer sun.
Yours for better health,