Iron supplementation alone may not be enough. A new study published in Nutrients (2025) reveals the causal relationships between Vitamin A, Vitamin D, iron status, and childhood anemia, offering fresh insights into prevention strategies.
Background
Anemia is a common clinical condition characterized by reduced red blood cell volume. It remains a major global public health issue, with a prevalence of 24.3% worldwide (affecting nearly 1.9 billion people). In China, approximately 136 million individuals suffer from anemia, including a significant proportion of school‑aged children.

Childhood anemia leads to growth delays, higher infection rates, impaired cognition and motor development, ultimately reducing learning efficiency and social participation, while negatively impacting economic development.
Study Design
| Component | Details |
|---|---|
| Cross‑sectional data | 1,725 children (6–17 years) in Hunan Province |
| Indicators | Demographics, diet, outdoor activity, serum micronutrients (Vitamin A, 25‑hydroxy Vitamin D, ferritin, zinc) |
| Analysis | Multivariable logistic regression |
| Genetic analysis | Mendelian Randomization (MR) using GWAS datasets |
| Outcomes | Causal links between micronutrients and anemia risk |
Lifestyle Factors
| Factor | Effect on Anemia Risk |
|---|---|
| ≥30 min outdoor activity | ↓ 47–63% |
| Daily/occasional milk intake | ↓ 38–53% |
| Rural residence | ↑ risk |
| Picky eating | ↑ risk |
| Ferritin deficiency | ↑ risk |
Micronutrient Associations

| Micronutrient | Observational Findings | MR Findings |
|---|---|---|
| Vitamin A | Higher levels (≥0.44 μg/mL) → lower anemia risk | No clear causal effect |
| Ferritin | J‑shaped curve:Strong protective causal effect | |
| Serum Iron | Deficiency increases risk | Strong protective causal effect |
| Vitamin D | No significant association | Weak protective effect after removing outliers |
| Zinc | No significant association | No causal effect |
Implications
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Vitamin A may reduce anemia risk by supporting red blood cell production, iron metabolism, and immune function.
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Vitamin D may play a role in erythropoiesis and iron homeostasis, with MR analysis providing new evidence of its protective potential.
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Ferritin and serum iron are confirmed as key biomarkers and intervention targets for childhood anemia.
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Lifestyle factors such as outdoor activity and milk consumption indirectly lower anemia risk by improving overall health and immunity.
Conclusion
This study highlights that iron supplementation alone is insufficient. A holistic approach involving Vitamin A, Vitamin D, iron status, and healthy lifestyle factors is essential to reduce childhood anemia. Public health strategies should integrate nutritional diversity, outdoor activity, and targeted supplementation to achieve better outcomes.
Reference: Tang, J.; Tan, Y.; Chen, Y.; Wang, F.; Wang, T.; Sun, M.; Luo, M.; Chen, Y.; Wen, Y.; Li, Z.; et al. Vitamin A, Vitamin D, Iron, and Zinc in Relation to Anemia Risk: Observational Evidence and Mendelian Randomization. Nutrients 2025, 17, 3220.
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