WASHINGTON: Spending time in out in the sun in childhood is really a good thing, for a new study has found that it can lower the risk of developing Multiple Sclerosis (MS) in later life.

The study was conducted by Talat Islam, MBBS, PhD, and Thomas Mack, MD, MPH, with the Keck School of Medicine of the University of Southern California in Los Angeles.

The researchers analysed 79 pairs of identical twins with the same genetic risk for MS in which only one twin had MS as a part of their study.

They asked the twins to specify whether they or their twin spent more time outdoors during hot days, cold days, and summer, and which one spent more time sun tanning, going to the beach and playing team sports as a child.

They found that the twin who spent more time out in the sun as a kid had had a 25 to 57 percent reduced risk of developing MS depending on the amount of time spent outdoors.

The researchers now state that sun exposure has a positive effect on MS.

"Sun exposure appears to have a protective effect against MS. Exposure to ultra violet rays may induce protection against MS by alternative mechanisms, either directly by altering the cellular immune response or indirectly by producing immunoactive vitamin D," they state.

"Our findings note the importance of sun exposure among people with identical genetic risk for MS. High priority should be given to research into how sun exposure reduces MS risk if we are to unravel the mystery of what causes MS," Dr Mack added.

The study is published in the July 24, 2007, issue of Neurology , the medical journal of the American Academy of Neurology.