Does sunlight exposure lower your blood pressure? A critical look at new research findings.
On Jul 28, 2013
Keypoint Tweet @CentralSkin: Sun tanning to lower blood pressure? Take this advice with a grain of salt and a dollop of sunscreen.
Study claims that sun tanning lowers your blood pressure
- The findings of a study that was presented at the International Investigative Dermatology conference is stirring up emotions. Researchers at Edinburgh University suggest that natural sunlight helps reduce blood pressure, and thereby cutting the risk of heart attacks and strokes, two of the biggest killers in USA and worldwide.
- The findings suggested that UV rays drop blood pressure by increasing the production of nitric oxide, a blood vessel dilating compound that has natural anti-hypertensive properties. Up until now, sunlight was mainly thought to have effects on Vitamin D production, as well as release of certain mood elevating chemicals. However, sunscreen does not lead to Vitamin D deficiency since we get the majority of our Vitamin D through food sources such as eggs and enriched milk and orange juice.
How did they come up with these results?
- The research involved 24 study subjects who were subjected to 20 minute sessions under tanning and heat lamps. In one session, 24 study volunteers were exposed to both UV rays and the heat of lamps. In another session, the UV rays were blocked so that only the heat from the lamps affected the patients. The results of the study showed that blood pressure dropped for an hour after 20 minute exposure to UV rays from tanning lamps but not after the heat-only sessions. Nonetheless, even the lead researcher of the study and a senior lecturer in dermatology at Edinburgh University said, Dr. Richard Weller admitted that the “blood pressure changes recorded in the experiment were small- not enough to make a big difference to one individual with hypertension.” Vitamin D levels, which are normally stimulated by sun exposure were similar in both groups.
What is the lead author of this study claiming?
- Commenting on the results of the study, Dr. Richard Weller said, “We suspect that the benefits to heart health of sunlight will outweigh the risk of skin cancer.” In addition, he stated that his work also "explains why dietary vitamin D supplements alone will not be able to compensate for lack of sunlight."
Critical analysis of these findings. Here is what we want our readers to consider:
- While organizations which support tanning and tanning bed operators may love these findings, we recommend that our readers be cautious consumers of new information. A study with just 24 subjects is very preliminary, and the results cannot fully be appreciated until a full clinical trial involving larger number of individuals is conducted. Also, the blood pressure drop is so small, as even admitted by the lead scientist, that the clinical benefit of such a change is far from evident. Moreover, lowering blood pressure in people with normal blood pressure is not going to decrease the risk for stroke and heart attacks. And in people who have elevated blood pressures, the effects of the sun may be so small, they will have no effect on lowering the risk of death from stroke and heart attacks. These people can benefit much more from blood pressure control through weight loss, a healthy diet, avoiding salt, and blood pressure medications if need be. In addition, sun exposure is the single most alterable risk factor for skin cancer, and reducing exposure to the sun is the single best way to prevent getting skin cancer.
- In his interview with ScienceOmega, Dr. Weller is much more measured in his evaluation of his own findings. "Our sample was just 12 or 24 people depending on which experiment you're looking at, and a one-off dose of UV lowered their blood pressure for an hour," he said. "That’s not going to be enough to stop them dying young. It shows that the mechanism exists, but it doesn’t say this is something we should be rushing out and doing now. The health message remains the same as it always was because all of the work that has been done on sunlight and skin cancer is solid, thorough and extensive.” So we recommend that our readers understand these findings, but take them with a giant grain of salt and a dollop of sunscreen.