Higher Vitamin D Levels Associated With Reduced Mortality Risk in Middle-Aged and Older Adults: Study Shows
USA: A recent prospective cohort study published in PLOS One has highlighted a significant link between serum 25-hydroxyvitamin D [25(OH)D] levels and mortality risk among middle-aged and elderly individuals in the U.S. Conducted by Yaowen Hu and colleagues from the Center for General Practice Medicine, Zhejiang Provincial People’s Hospital, the research underscores the protective role of optimal vitamin D levels against all-cause, cardiovascular, and cancer-related deaths.
The study utilized data from the National Health and Nutrition Examination Survey (NHANES), spanning 2001–2018, which involved 22,130 participants aged 40–70 years. Researchers measured serum 25(OH)D concentrations and analyzed their association with mortality outcomes. Vitamin D deficiency, defined as a level of ≤50.00 nmol/L, was found in 33.59% of participants, while 71.74% had levels indicating insufficiency (≤75.00 nmol/L), reflecting a widespread public health concern.
The study revealed the following notable findings:
- A nonlinear, L-shaped relationship existed between vitamin D levels and mortality.
- Participants with moderately low vitamin D levels (25.00–49.99 nmol/L) had a 22% lower risk of all-cause mortality compared to those with severe deficiency (<25.00 nmol/L).
- The risk of all-cause mortality was reduced by 41% in individuals with insufficient levels (50.00–74.99 nmol/L) and by 46% in those with sufficient levels (≥75.00 nmol/L).
- A similar pattern was observed for cardiovascular mortality.
- Significant reductions in cancer mortality were noted only in participants with insufficient and sufficient vitamin D levels compared to the severely deficient group.
- The study found that the protective effect plateaued beyond a specific threshold, indicating that very high serum 25(OH)D concentrations may not offer extra survival benefits.
- Results highlighted the importance of maintaining adequate—but not excessive—vitamin D levels to lower mortality risks.
The authors emphasized several limitations that may influence the interpretation of findings. Vitamin D status can be affected by factors such as dietary intake, occupational and environmental exposure to sunlight, use of sunscreen, and supplementation habits. The study did not fully account for differences in supplement absorption and utilization, nor did it adjust for seasonal variations in UV-B exposure, which could impact serum levels. Additionally, reliance on self-reported health and socioeconomic data introduces potential bias and residual confounding.
Despite these limitations, the research provides compelling evidence of the association between serum vitamin D concentrations and mortality among middle-aged and older adults in the U.S. The findings advocate for increased attention to vitamin D status in public health strategies, especially considering the high prevalence of deficiency and insufficiency reported in the study population.
The authors concluded that while adequate vitamin D levels are clearly linked to lower mortality risks, more studies are needed to clarify causality and uncover the biological mechanisms driving these associations. They stressed the importance of balanced vitamin D optimization through dietary sources, supplementation, and safe sun exposure, while cautioning against excessive intake without medical supervision.
Reference:
Hu, Y., Gao, F., Yang, Y., Yang, W., He, H., Zhou, J., Zhao, Y., Chen, X., Zhao, W., & He, X. (2025). Serum 25(OH)D levels and mortality risk among middle-aged and elderly populations in the U.S.: A prospective cohort study. PLOS ONE, 20(7), e0328907. https://doi.org/10.1371/journal.pone.0328907
