Can Sunshine Ward Off a Heart Attack?

Hypertension and heart attack risk may be reduced by some time in the sun

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) While too much exposure to the sun’s rays may lead to skin cancer, soaking up some sun may brighten your health by lowering blood pressure and cutting the risk of heart attack and stroke.

The old Irish saying “May the sunshine brighten your heart” may have more truth to it than you might think.

Research has shown that exposure to the sun’s rays can lift a person’s mood, but it may also release a heart healthy compound—and it’s not vitamin D, according to a new study.

"Walk in the sunshine to boost heart health."

Richard Weller, senior lecturer in dermatology at the University of Edinburgh in Scotland, and his colleagues measured the blood pressure of 24 volunteers who sat beneath tanning lamps for two sessions of 20 minutes each.

In one session, the volunteers were exposed to both the UV (ultraviolet) rays and the heat of the lamps. In the other, the UV rays were blocked so that only the heat of the lamps affected the skin.

Blood pressure dropped for one hour following exposure to UV rays but not after the heat-only sessions.

The results show that it is the sun’s UV rays that may lead to health benefits, according to the study authors.

The volunteers’ vitamin D levels remained unaffected in both sessions. While vitamin D is vital for the body, scientists attribute the drop in blood pressure to an increased production of nitric oxide in the body rather than from vitamin D. This may explain why dietary vitamin D supplements alone may not compensate for lack of sunlight.

Nitric oxide is a chemical transmitter stored in huge reserves in the skin, and can be released by UV light. Nitric oxide dilates blood vessels and the coronary arteries, so it may help stop angina. Angina is chest pain or discomfort you get when your heart muscle does not get enough blood.

Dr. Weller told the dailyRx News, "The effect was small at 2 mm Hg and lasted less than an hour so I am not advocating this as a measure for blood pressure control based on the current study. The importance is that it demonstrates a new mechanism separate from vitamin D by which sun may exert beneficial effects. We are moving on to a study looking at more frequent administration of UV to see if that will produce a clinically useful long-term fall in blood pressure but we are not there yet."

He added that regarding sun protection, the standard advice holds. Excess sun is the major preventable cause of skin cancer, according to Dr. Weller.

In a separate lecture on this topic, Dr. Weller pointed out that Scots get sick more often than Australians, and the less frequent sunshine in Scotland may explain why.

Heart disease and stroke linked to high blood pressure are estimated to lead to around 80 times more deaths than those from skin cancer in the UK, according to the authors.

This study raises the question: Do the heart benefits of sun exposure outweigh the risks of skin cancer?

“We now plan to look at the relative risks of heart disease and skin cancer in people who have received different amounts of sun exposure,” said Dr. Weller. “If this confirms that sunlight reduces the death rate from all causes, we will need to reconsider our advice on sun exposure.”

The study was presented on May 9 at the International Investigative Dermatology conference in Edinburgh.

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Review Date: 
May 7, 2013
Last Updated:
October 16, 2013