Turkish Journal of Medical Sciences
Abstract
Background/aim: Major depressive disorder (MDD) is a common psychiatric condition characterized by depressive symptoms and suicide-related clinical features. Vitamin D status has been investigated as a potential clinical correlate of depression and suicidal ideation, but the direction and specificity of these associations remain uncertain. This cross-sectional study aimed to examine the associations among serum 25-hydroxyvitamin D [25(OH)D] levels, depressive symptom severity, suicidal ideation, and suicide-related cognitive–affective dimensions in adults diagnosed with MDD.
Materials and methods: This cross-sectional study included 97 adults aged 18–65 years who were diagnosed with MDD according to DSM-5 criteria. Depressive symptom severity and suicide-related outcomes were assessed using the Hamilton Depression Rating Scale (HDRS), Suicidal Ideation Scale (SIS), and Suicide Probability Scale (SPS). Vitamin D status was classified as deficient (<20 ng/ mL), insufficient (20–29 ng/mL), or sufficient (≥30 ng/mL). Associations were examined using multivariable generalized linear models adjusted for available sociodemographic and clinical covariates.
Results: Vitamin D deficiency was observed in 61.9% of participants and the mean serum 25(OH)D level was 18.4 ± 11.9 ng/mL. Lower serum 25(OH)D levels were significantly associated with higher HDRS, SIS, and SPS total/subscale scores. In adjusted models, higher serum 25(OH)D levels remained inversely associated with HDRS scores, SIS scores, and total SPS scores. Parental status was also associated with lower SIS scores, while a history of suicide attempts was associated with higher SPS–Suicidal Ideation scores.
Conclusion: Lower serum 25(OH)D levels were associated with greater depressive symptom severity and higher suicide-related scale scores in adults with MDD, particularly across cognitive–affective domains relevant to suicide probability. However, given the study’s cross-sectional single-center design, absence of a healthy control group, modest sample size, and adjustment limited to available covariates, these findings should be interpreted as associations rather than evidence of causality, directionality, or established biomarker utility.
Author ORCID Identifier
ELİF KÜÇÜK: 0000-0002-7567-5323
FERİDE UYSAL: 0000-0003-2562-2597
SEDA ŞENKARDEŞ KANDEMİR: 0000-0002-2135-0072
ÖZGÜR ÖZKALAYCI: 0000-0002-0486-5306
CANAY PAMUKÇU: 0009-0006-2329-2124
NİHAL TAŞTEKİN: 0000-0001-7737-552X
MERİH ALTINTAŞ: 0000-0001-7045-3046
DOI
10.55730/1300-0144.6371
Keywords
depression severity, Major depressive disorder, suicidal ideation, vitamin D
First Page
1264
Last Page
1273
Publisher
The Scientific and Technological Research Council of Türkiye (TÜBİTAK)
Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
KÜÇÜK, E, UYSAL, F, ŞENKARDEŞ KANDEMİR, S, ÖZKALAYCI, Ö, PAMUKÇU, C, TAŞTEKİN, N, & ALTINTAŞ, M (2026). Vitamin D deficiency, depression severity, and suicide risk: evidence from patients with major depressive disorder . Turkish Journal of Medical Sciences 56 (4): 1264-1273. https://doi.org/10.55730/1300-0144.6371