Nonmigraine headache is associated with low levels of serum 25-hydroxyvitamin (OH) D, according to results from the sixth survey of the Norwegian Tromsø Study, Tromsø 6.
Marie Kjaergaard, MD, University Hospital of North Norway, Tromsø, Norway, and colleagues found that the incidence of nonmigrainous headache was 20% higher in participants who had the lowest levels of serum 25(OH)D than in those with the highest levels.
In contrast, no association between serum 25(OH)D and migraine was identified in the same large population sample.
"[T]he VDR [vitamin D receptor] and 1-alfahydroxylase, which hydroxylates 25(OH)D to the active metabolite 1,25-dihydroxyvitamin D, are found in areas in the brain which are thought to be involved in the pathophysiology of headache and migraine, thereby indicating a role of vitamin D in these tissues," the authors write. "We found that low level[s] of serum 25(OH)D were associated with non-migraine type of headache, and the association remained significant after adjustment for possible confounders."
The study is published in the November/December 2012 issue of Headache.
Few Case Reports
As investigators point out, only a few case reports have described the effect of vitamin D on headache, and no adequate intervention studies have been done.
Because others have reported a high prevalence of headache in association with high latitude, the authors felt these findings suggest a relationship between headache and vitamin D.
They subsequently explored this potential relationship in 11,614 participants in the sixth survey of the prospective Tromsø study.
The Tromsø Study began in 1974. This epidemiologic, prospective study of health problems and chronic diseases serves as a resource for the surveillance of disease risk factors. The study initially focused on cardiovascular disease but through the years also included several other chronic diseases and conditions, such as vitamin D status and chronic pain.
Participants were asked in a questionnaire whether they had experienced headache in the last year. If the answer was yes, they were asked to specify whether the headache was migraine or another type of headache, along with the average frequency, duration, intensity, and type.
A total of 725 participants indicated on the questionnaire that they suffered from migraines, although only about half of these fulfilled the group's criteria for migraine.
Another 3336 participants reported that they had another type of headache, but of these, 1051 fulfilled the group's migraine criteria.
The data were also stratified according to smoking status because the method of measurement used in the study was found after the study was completed, to overestimate serum 25(OH)D in smokers. "To adjust for this, we chose to divide the study population into current smokers and non-smokers," they write, with former smokers included in the nonsmoking group.
"In model 1 with adjustment for age, gender, BMI [body mass index] and chronic diseases, the non-smokers had a significantly higher OR [odds ratio] for non-migraine type of headache in the lowest quartile," investigators report. "This finding remained significant in model 2 when additional adjustment was done for the possible confounders physical exercise, alcohol consumption, and educational level."
In contrast, no association between headache and serum 25(OH)D was found in the current smoker group.
Risk for Headache Across Serum 25(OH)D Quartiles in Nonsmokers
|Serum 25(OH)D ||Migraine Headache (Nonsmokers)||Nonmigraine Headache (Nonsmokers)|
| Model 1|
| 4th quartile ||Reference ||Reference|
| 1st quartile ||1.14 (0.76 - 1.71)|| 1.31 (1.14 - 1.49)|
| Model 2|
| 4th quartile ||Reference ||Reference|
| 1st quartile ||1.03 (0.67 - 1.57) ||1.20 (1.04 - 1.39)|
As investigators note, it is important to consider confounding variables in a study such as this one because serum 25(OH)D levels reflect lifestyle and nutritional habits as well, both factors that can affect or be affected by headache.
Physical exercise, alcohol consumption, education level, and some chronic diseases also influence serum(OH)D levels.
The study was supported by the North Norway Regional Health Authority. The authors have disclosed no relevant financial relationships.
Headache. 2012;52:1499-1505. Abstract
Pam Harrison • Medscape Medical News © 2013 WebMD, LLC