Could sun exposure help prevent onset of obesity and diabetes? Researchers found it did in mice fed a high-fat diet.
The research team, led by Dr. Shelly Gorman of Telethon Kids Institute in Perth, Australia, publish their findings in the journal Diabetes.
It is common knowledge that sunlight exposure - specifically, exposure to ultraviolet (UV) radiation - is a leading cause of skin cancer. As such, health organizations - such as the Centers for Disease Control and Prevention (CDC) - recommend that to reduce the risk of developing the disease, we stay in the shade, use sunscreen and wear protective clothing.
But could these measures cause us to miss out on potential health benefits? Sun exposure is the body's main source of vitamin D, and lack of this vitamin is believed to have negative implications for health. A recent study, for example, linked vitamin D deficiency to all-cause mortality and cancer prognosis.
And last year, Medical News Today reported on a study by Dr. Richard Weller and colleagues from the University of Edinburgh in the UK, which claimed moderate sun exposure poses heart benefits that may outweigh skin cancer risks.
Nitric oxide production attributed to slowed obesity, diabetes onset
To reach their findings, the researchers fed mice a high-fat diet to trigger the onset of obesity and diabetes. The mice were then exposed to moderate levels of UV radiation.
At the time of publication, MNT did not have access to information stating how long the mice were exposed to UV radiation.
However, the researchers say these mice showed reduced weight gain and had fewer indications of diabetes onset - such as high blood sugar levels and insulin resistance.
Further research showed that this effect was not down to vitamin D but a compound called nitric oxide, which the skin releases after sun exposure.
They reached this conclusion by applying a cream that contained nitric oxide to the skin of the mice, while other mice received vitamin D supplementation. The cream triggered the same obesity- and diabetes-slowing effects as UV exposure, while vitamin D supplementation had no effect.
The researchers note that previous research has suggested that nitric oxide production from UV exposure can lower blood pressure. "These observations further indicate that the amounts of nitric oxide released from the skin may have beneficial effects, not only on heart and blood vessels, but also on the way our body regulates metabolism," says study author Dr. Martin Feelisch, of the University of Southampton in the UK.
Dr. Gorman says the team's findings are important because they indicate that alongside a healthy diet and exercise, moderate exposure to sunlight may aid obesity prevention in children - something that is a major concern in the US.
According to the CDC, rates of childhood obesity have more than doubled over the past 30 years. Around 18% of children aged 6-11 years are now obese.
Commenting on the overall findings, Dr. Weller says:
"We know from epidemiology studies that sun-seekers live longer than those who spend their lives in the shade. Studies such as this one are helping us to understand how the sun can be good for us.
We need to remember that skin cancer is not the only disease that can kill us and should perhaps balance our advice on sun exposure."
The team stresses, however, that since their study was conducted on mice - nocturnal animals covered in fur that have little exposure to sunlight - their findings should be interpreted with caution.
They say further studies are warranted to determine how UV exposure impacts onset of obesity and diabetes in humans.
MNT recently reported on a study from the University of California-Berkeley suggesting grapefruit juice could curb the effects of a high-fat diet.