By Concepta Merry, MB, BCh, BAO, BA
Associate Professor, Global Health, School of Medicine, Trinity College, Dublin
Dr. Merry reports no financial relationships relevant to this field of study.
- Low serum 25-hydroxyvitamin D levels were associated with a higher risk of frequent headaches in middle-aged/older Finnish men.
SYNOPSIS: Low vitamin D levels are associated with a range of neurovascular diseases, but little data are available on the association between vitamin D levels and headaches. This retrospective, cross-sectional study showed that low serum vitamin D levels were associated with a higher risk of frequent headaches in middle-aged/elderly Finnish men.
SOURCE: Virtanen JK, Giniatullin R, Mäntyselkä P, et al. Low serum 25-hydroxyvitamin D is associated with higher risk of frequent headache in middle-aged and older men. Sci Rep 2017;7:39697. Doi:10.1038/srep39697.
Vitamin D insufficiency is emerging as a global public health concern, especially for residents of the Nordic countries who have limited year-round access to ultraviolet B sun exposure.1 There is increasing evidence linking vitamin D insufficiency to a wide range of neurovascular disorders.2,3 Studies suggest that the prevalence of headache may increase with increasing latitude, which raises the possibility of a link between vitamin D insufficiency and headaches.4 However, to date, this is just a biologically plausible hypothesis rather than an evidence-based relationship.
The aim of this study was to investigate the relationship between serum 25-hydroxyvitamin D [25(OH)D] as a marker for vitamin D status and headaches.
This was a retrospective, cross-sectional, population-based cohort study using data from men (aged 42 to 60 years) in the Finnish Kuopio Ischaemic Heart Disease Risk Factor Study cohort. The Kuopio Ischaemic Heart Disease Risk Factor Study is a Finnish-based population study originally designed to evaluate the risk factors for cardiovascular disease, atherosclerosis, and related outcomes in randomly selected men.5
The authors of the Kuopio study collected data on 2,682 men 42 to 60 years of age between 1984 and 1989. Data were available on both 25(OH)D and headache for 2,601 of the 2,682 study participants. Consequently, this sub-study evaluated data on 2,601 men.
A diagnosis of frequent headache was defined as the presence of a headache weekly or daily over the previous year. The authors did not comment on the cutoff for low vitamin D level and did not differentiate between vitamin D insufficiency or deficiency. Serum 25(OH)D was measured using a validated high-performance liquid chromatography assay.
The study showed that the average serum 25(OH)D level was 17.4 ng/mL (standard deviation [SD], 7.6 ng/mL; min-max, 3.1-54.4 ng/mL). Of all participants, 67.9% had a serum 25(OH)D < 20 ng/mL, the cutoff for vitamin D insufficiency. In addition, 250 of the study participants (9.6%) reported frequent headaches as defined above. The average 25(OH)D level was statistically significantly lower among those who reported frequent headaches (14.4 ng/mL; SD, 7.5 ng/mL) as compared to those without frequent headaches (17.6 ng/mL; SD, 7.6 ng/mL), even after adjustment for age and month of blood draw (P < 0.001). After multivariate adjustment, men in the lowest vs. the highest serum 25(OH)D quartile had a 113% (95% confidence interval, 42; 218%; P for trend 0.001) higher odds ratio for frequent headache.
These are very interesting results, in that they pin a somatic complaint (headache) to a physiological measurement (serum 25(OH)D) that can arguably be improved by supplementation. That said, there are study limitations, such as the fact that the study demographic was limited to middle-aged/older men; there may be minimal generalizability of the results to women and younger men. Furthermore, the diagnosis of headache was based on self-report and did not differentiate between types or severity of headache. Also, this study merely associates headache and low vitamin D levels; there is no inference of causation, nor did the authors comment on the effect of vitamin D supplementation on the frequency or severity of headache in this population. To explore these effects, a well-designed clinical trial would be the logical next step.
In summary, this retrospective, cross-sectional study suggests that low serum 25(OH)D was associated with a higher risk of frequent headaches in the Kuopio study cohort. We can add these results to a growing list of connections between low (or elevated) serum 25(OH)D and health or disease states, not to mention compelling work showing the effect of supplemental vitamin D2 or D3. Does this change our clinical practice? Perhaps not, but for the next patient with frequent headaches, maybe hypovitaminosis D should be added to our differential diagnosis. If a patient with frequent headaches is found to have low serum 25(OH)D, then shared decision-making should explore what to do about it.
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- Prakash S, Mehta NC, Dabhi AS, et al. The prevalence of headache may be related with the latitude: A possible role of vitamin D insufficiency? J Headache Pain 2010;11:301-307.
- Salonen JT. Is there a continuing need for longitudinal epidemiologic research? The Kuopio Ischaemic Heart Disease Risk Factor Study. Ann Clin Res 1988;20:46-50.
