Science and the Sunbelt
Just last weekend, most people in the U.S. turned their clocks ahead one hour in the spring ritual known as daylight savings time. (Hawaii, Alaska, Indiana and Arizona abstain.) The official reason for the semi-annual change is to give farmers more daylight hours to do their work. But new research suggests that another hour of sunlight each day may benefit us all.
According to the National Cancer Institute, lifetime exposure to sunlight may reduce your risk of some of the most common types of cancer. In an analysis of death certificates from 24 states over an 11-year period, the NCI researchers found that people who lived in the sunniest parts of the country, and those exposed to the most sunlight through their jobs, had significantly lower rates of breast and colon cancer than matched controls.
Sun may cut risk of some cancer by 25 percent
The scientists identified cases through a database maintained by the NCI, the National Institute for Occupational Safety and Health, and the National Center for Health Statistics. The data was collected from 24 states from 1984 through 1995, and includes information on occupation, state of residence at birth and at death, and cause of death.
The researchers took significant measures to ensure the accuracy of their data. They only included people who were born and died in states in the same solar radiation range. And they classified farmers in their own occupational category, separate from other outdoor jobs, as they have been shown to have higher overall rates of certain types of cancer. They also narrowed down the cases substantially with a long list of exclusions.
Even after all those adjustments, the results were compelling. Overall, people who lived in the highest solar radiation range (in states like Arizona, Hawaii, Florida, and Texas) had less risk of dying of breast, ovarian, prostate, or colon cancer than those who lived in the lowest range (states like Maine, New Hampshire, Ohio, and Washington). The occupational difference was most significant in relation to cases breast and colon cancer; across all levels of solar radiation, people who worked outside had 20 to 25 percent less risk of these two types of cancer. And the benefits of outside work weren’t attributable to the amount of hard labor. Even after the researchers adjusted for level of physical activity, the reduction in risk remained.
Use common sense to balance benefits and risks
In their discussion, the NCI researchers theorize that sunlight offers cancer protection through its contribution of vitamin D. Recent laboratory tests have shown that vitamin D can slow or halt the proliferation of breast and colon cancer cells. And in other research, breast cancer patients showed lower serum concentrations of a form of vitamin D when compared with healthy controls.
In recent years we’ve all been trained to fear the sun, due to the threat of skin cancer. Now there is a growing belief that exposure to the sun may not actually cause skin cancer (we’ll continue to research this and send information as we uncover it). Either way, the fear of skin cancer shouldn’t keep you huddled indoors in the dark. According to Dr. William C. Douglass, you can reap the sun’s healthy benefits with as little as 20 minutes of exposure a day.
To Your Good Health,
Jenny Thompson
Health Sciences Institute
Source: Occupational and Environmental Medicine 2002;59:257-262
Copyright 1997-2002 by Institute of Health Sciences, L.L.C.
