Association between total calcium intake and depressive symptoms in cancer survivors based on the National Health and Nutrition Examination Survey (NHANES) 2007–2018: a cross-sectional study

Abstract Though previous studies have explored the relationship between Ca intake and depressive symptoms, epidemiological evidence on cancer survivors remains limited. This study aimed to investigate the association between estimated total Ca intake and depressive symptoms among cancer survivors in the USA. This study analysed data from 2204 cancer survivors in the National Health and Nutrition Examination Survey 2007–2018. Participants with the Patient Health Questionnaire (PHQ-9) scores ≥5 were defined as having depressive symptoms. Total Ca intake was defined as the sum of dietary Ca and Ca supplements, estimated through the first 24-h dietary recall, and was grouped into four ranges [Q1 (≤606·5 mg/day), Q2 (606·5–962·5 mg/day), Q3 (962·5–1476·0 mg/day) and Q4 (>1476·0 mg/day)] according to quartiles. Logistic regression and restricted cubic spline (RCS) were used to assess the relationship. In this study, 25·6 % of participants showed depressive symptoms, with moderate to severe depressive symptoms accounting for 9·7 % among all participants. After adjusting for all relevant confounding variables, compared with Q1, the odds of depressive symptoms in Q3 and Q4 were 40 % lower (OR:0·60, 95 % CI: 0·40,0·89) and 44 % lower (OR: 0·56, 95 % CI: 0·35,0·89), respectively ( P for trend = 0·003). RCS further depicted the negative association between total Ca intake and depressive symptoms. Higher estimated total Ca intake was associated with lower odds of depressive symptoms among US adult cancer survivors. However, total Ca intake was estimated using a single 24-h dietary recall, which may not capture usual long-term intake. Prospective studies using repeated dietary assessments and clinically validated mental health outcomes are needed to confirm these findings.