A new Boston University study has found that women living in the Northeast are more likely to develop rheumatoid arthritis (RA) due to a lack of exposure to sunlight, suggesting a possible link between the condition and vitamin D deficiency.
For the study, Veronica Vieira, associate professor of environmental health, and her colleagues compared the medical data of 461 women suffering from RA to a control group of 9,220 healthy participants.
They were surprised to discover that women residing in states like Maine, New Hampshire and Vermont were at a significantly increased risk of developing the autoimmune disease than were those from sunnier climates who could absorb vitamin D naturally.
"The results were unexpected," Vieira said. "Prior to the analysis, we were more interested in the relationship with air pollution. I hadn’t given latitudes much thought."
She added that decreased solar exposure and vitamin D deficiencies have also been linked to several other autoimmune diseases, including multiple sclerosis and Crohn’s disease.
Good sources of the vitamin D include fish such as salmon, tuna and mackerel. The nutrient is also available as a dietary supplement.