Vitamin D2026-07

From the Vitamin D Paradox to Precision Nutrition: Targeted Supplementation, Assay Pitfalls, and Clinical Decision-Making.

Dalamaga Maria, Tsilingiris Dimitrios, Petropoulou Dimitra, Emfietzoglou Rodopi et al. — Current nutrition reports

Summary

This review explores the complex role of vitamin D, noting that while low levels are linked to many diseases, broad supplementation often doesn't show universal benefits in trials. It emphasizes that vitamin D is most crucial for those with true deficiencies, especially for bone health. The paper advocates for targeted supplementation and testing, rather than routine use, to ensure effective and safe clinical management.

AI-generated summary — read the original

Key points

Vitamin D benefits are most clearly observed in individuals who are genuinely deficient, particularly for bone health.
Routine vitamin D screening is generally not recommended for healthy adults; testing should be reserved for specific clinical situations.
Supplementation should be targeted to individuals with evidence-based needs, rather than used as a universal preventative measure.
Daily or weekly vitamin D dosing is preferred over infrequent high-dose regimens, which may carry risks like increased falls and fractures.

What the study looked at

**What question the study asked:** This review examined the complex role of vitamin D in health, specifically addressing why many large-scale clinical trials have not consistently confirmed the broad health benefits suggested by observational studies linking low vitamin D levels to various chronic diseases. It aimed to provide practical guidance for healthcare professionals on how to best manage vitamin D status in patients. **How it was studied (design/participants):** This was a comprehensive review paper, meaning the authors analyzed and synthesized findings from a wide range of existing scientific literature. They considered both observational studies, which identify associations, and randomized controlled trials, which test cause-and-effect, along with guidelines and research on vitamin D testing methods and genetic factors. **What it found:** The review concluded that vitamin D's benefits are most significant for individuals with a true deficiency, especially concerning bone health. While some specific groups, such as older adults or those at high risk for diabetes, might benefit from supplementation, it's not a universal preventative for everyone. The paper highlighted challenges with vitamin D testing accuracy and emphasized that supplementation should be targeted to specific, evidence-based needs, rather than being given routinely. It also suggested that daily or weekly dosing is safer than infrequent, very high doses.

Dietary takeaway

This review suggests that while vitamin D is vital, its benefits are most pronounced when addressing an actual deficiency. For everyday food choices, focus on incorporating natural sources like fatty fish (salmon, mackerel) and fortified foods (milk, cereals) to maintain adequate vitamin D levels. If you're considering supplements, especially if you have specific health concerns or risk factors for deficiency, it's best to consult a healthcare provider to determine if targeted supplementation is appropriate for you. Remember, this is a review of existing research, and individual needs vary; one paper alone doesn't provide definitive dietary advice for everyone.

Abstract

PURPOSE OF REVIEW: Vitamin D is a pleiotropic secosteroid with established skeletal functions and proposed extraskeletal effects; however, its clinical application remains contentious. Despite extensive observational evidence linking low 25(OH)D concentrations to chronic diseases, randomized controlled trials (RCTs) have largely failed to confirm many of these associations. This review focuses on the practical clinical management of vitamin D, integrating determinants of vitamin D status, assay-related limitations, targeted testing, evidence-based supplementation, and decision-making within a precision-nutrition context. RECENT FINDINGS: The discordance between observational and interventional evidence is partly explained by the inclusion of vitamin D-replete populations in major trials, background supplementation, non-linear dose-response relationships, and assay variability. For skeletal outcomes, clinically meaningful effects are mainly observed in deficiency, whereas selected benefits have been reported in specific populations, including mortality reduction in adults aged ≥ 75 years, a modest reduction in cancer mortality, and reduced progression to diabetes in adults with high-risk prediabetes. The 2024 Endocrine Society guideline recommends empiric supplementation for selected groups and discourages routine screening in healthy adults. Daily or weekly dosing is preferred to intermittent high-dose regimens, which may increase falls and fractures. Standardization initiatives have improved 25(OH)D measurement accuracy, but inter-method variability persists, complicating thresholds and cross-study comparisons. Genetic polymorphisms in GC, CYP2R1, CYP24A1, and VDR contribute to variability in supplementation response, although precision-nutrition approaches remain investigational. Vitamin D should be viewed as a context-dependent, threshold-driven nutrient rather than a universal preventive therapy. Clinically, priority should be given to preventing and correcting severe deficiency (< 12 ng/mL [< 30 nmol/L]), a threshold below which adverse skeletal outcomes are well documented. Supplementation should target evidence-based indications, and laboratory testing should be reserved for situations in which results inform management. Bridging evidence and practice requires trials in deficient populations, improved assay harmonization, and integration of individualized risk factors into clinical decision-making.

View on PubMed →DOI: 10.1007/s13668-026-00780-2