Day 66: Can the sun prevent against heart disease?



When Richard Weller moved ‘down under’, he was surprised by how competitive Australians were. This competitiveness extended into his workplace, where he was teased by other doctors about the higher rates of heart disease in the U.K. On average Australians suffer from about a third less cardiovascular illnesses such as stroke and heart attacks.


Within Britain there is a gradient of health, indicating a far greater chance of dying from a heart attack in Glasgow than in London. Research has accounted for known risk factors, leaving a missing space of increased deaths as one moves North.

As a dermatologist, Weller decided to study the effects of sunlight on this phenomenon. Sunlight is known to be necessary to enable production of Vitamin D and higher levels of blood Vitamin D are associated with lower levels of cancer. Yet Vitamin D supplementation doesn’t change the rates of heart disease. In this talk, Weller describes how high Vitamin D is simply a marker for sunlight exposure and this exposure is preventative against heart disease.

Nitric oxide was first described as a chemical transmitter in Aberdeen in 1998, where Weller began his dermatology training. Nitric oxide serves to dilate blood vessels, lowering blood pressure. It also dilates the coronary arteries, stopping angina. Weller began to conduct his own research and discovered that nitric oxide is produced by the skin.

Weller used mice as specimens in Pittsburgh, before moving onto medical students. He discovered it was difficult to turn off nitric oxide in humans, and wondered what could cause its release into the circulation. They exposed their subjects to UVA rays, which don’t make vitamin D and observed a rise in circulating nitric oxide after thirty minutes under a UV lamp. Without the UV but in the presence of the same heat as the lamps produced, the conversion failed to occur. There was also no change in Vitamin D. Next they examined the effects of UV rays versus heat on blood vessel dilation, once again yielding a positive result.

Work on this is ongoing. Weller’s job is not only to tell people to avoid skin cancer, but also to convey the message that there are benefits as well as risks to sunlight. Deaths from heart disease are a hundred times higher than those from skin cancer. Future studies should aim to further quantify the risk-benefit ratio of sunlight exposure.


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