Low levels of vitamin D are associated with multimorbidity: Results from the LifeLines Cohort Study

<i>Background.</i> The prevalence of multimorbidity (≥ 1 disease within an individual) is rapidly increasing. So far, studies on the relationship between vitamin D and morbidity are mainly focusing on effects on single disease domains only, while vitamin D biology is associated with several diseases throughout the human body.<i>Methods.</i> We studied 8,726 participants from the LifeLines Cohort Study (a cross-sectional, population-based cohort study) and used the self-developed composite morbidity score to study the association between vitamin D levels and multimorbidity.<i>Results.</i> Study participants (mean age 45 ± 13 years, 73% females) had a mean plasma vitamin D level of 59 ± 22 nmol/L. In participants aged between 50 and 60 years, 58% had ≥ 2 affected disease domains, while morbidity score increased with age (70–80 years: 82% morbidity score &gt; 1; &gt; 80 years: 89% morbidity score &gt; 1). Each incremental reduction by 1 standard deviation (SD) of vitamin D level was associated with an 8% higher morbidity score (full model OR 0.92, 95% CI 0.88–0.97, <i>P = </i> 0.001). Participants with vitamin D levels &lt; 25 nmol/L were at highest risk for increasing morbidity prevalence (versus &gt; 80 nmol/L, OR 1.34, 95% CI 1.07–1.67, <i>P = </i>0.01).<i>Conclusions.</i> Low levels of vitamin D are associated with higher prevalence of multimorbidity, especially in participants with vitamin D levels &lt; 25 nmol/L. Collectively, our results favor a general, rather than an organ-specific, approach when assessing the impact of vitamin D deficiency.