British Heart Foundation – Is sunshine good for us?

 
 

Shedding light on new ways to lower blood pressure

By Sorrel Bunting, Senior Research Engagement Officer at the British Heart Foundation

High blood pressure affects around 16 million people in the UK, and 7 million of us don’t even know we have it. Researchers around the world are looking for ways to help lower high blood pressure, including one BHF-funded team in Scotland investigating if a sunny day could do more for our health than we previously thought.

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What is blood pressure?

Blood pressure is the pressure inside our blood vessels, caused by blood pushing on the walls of the arteries — the larger blood vessels that carry blood from your heart to the rest of the body. We need to have a certain amount of pressure to be able to pump blood around our bodies effectively, but too much can be a problem.

Typically we will be advised that our blood pressure should be under 140/90

When we have our blood pressure measured, we are given two numbers. The first one is the highest pressure your blood vessels feel when your heart contracts (or beats) and forces blood around the body. The second number is the lowest pressure your vessels will experience when your heart relaxes in between beats. Typically doctors will advise that your blood pressure should be under 140/90 (pronounced “140 over 90”).

Why is high blood pressure bad for us?

If you’re told by a doctor that you have high blood pressure, this means that the pressure of the blood in your arteries is consistently higher than it should be. High blood pressure is not usually something you can feel but over time — if it is not treated — the strain means that your heart can become enlarged and pump less effectively, which can lead to heart failure.

High blood pressure increases our risk of heart and circulatory diseases, in fact around 50% of heart attacks and strokes are associated with high blood pressure. Research teams are working to find ways to lower high blood pressure and reduce our risk of serious complications.

Why are we talking about sunshine?

Sunshine is known to increase the risk of developing skin cancer. But we also hear a lot about sunshine and vitamin D, and how getting enough exposure is important for us to absorb calcium to grow and maintain healthy bones. Studies have shown that people living closer to the equator also have lower blood pressure.

So is sunshine good for us or not?

Dr Richard Weller and his team at the University of Edinburgh think that the lower blood pressure seen in people living nearer to the equator could be linked to levels of a chemical in the blood called nitric oxide (NO). NO helps our blood vessels to relax and lower blood pressure. And it’s not just blood vessels that produce NO, our skin does too!

His team are investigating whether exposure to sunlight could cause the release of NO in our skin and help reduce blood pressure. They have found that giving people a dose of ‘artificial sunlight’ — UVA light — can reduce their blood pressure. Interestingly, this was separate from the effects of just being warmed up or from vitamin D, which forms after exposure to UVB light.

They are now carrying out a BHF-funded study to see if giving people a dose of UVA light twice a day could lower the blood pressure of those approaching an unhealthy level, and therefore reduce their risk of heart and circulatory diseases.

They hope that this might shed light on how we can lower blood pressure in a drug-free way.

“I actually think a far more important message is that there are benefits as well as risks to sunlight … we need to find the risk-benefit ratio. How much sunlight is safe, and how can we finesse this best for our general health” — Dr Richard Weller

Sorrel Bunting, Senior Research Engagement Officer at the British Heart Foundation

 
Mark Hosker