New research suggests that higher levels of vitamin D could significantly reduce the severity of dengue fever. A recent clinical study, published in the Indian Journal of Medical Research in late December 2025, found that patients with lower vitamin D levels experienced more severe forms of the mosquito-borne illness. This finding holds particular importance for regions where both dengue and vitamin D deficiency are common, impacting health systems worldwide.[vax-before-travel+2]
Research Uncovers Key Connection
The study, originating from Colombia, analyzed blood samples from nearly 100 laboratory-confirmed dengue patients. Researchers categorized these patients based on the severity of their disease: mild, those with warning signs, and severe dengue. They then compared these groups with healthy individuals. The results showed that patients with milder dengue consistently had higher vitamin D levels. In contrast, those experiencing warning signs or severe disease showed a significant deficiency in vitamin D.[timesofindia+1]
Scientists measured serum levels of 25-hydroxyvitamin D [25(OH)D], which is the main form of vitamin D circulating in the body. They also looked at various inflammatory markers. The study found significantly higher levels of tumor necrosis factor-alpha (TNF-α) in dengue patients, a marker often linked to severe outcomes globally. Interleukin-6 (IL-6) levels were especially high in severe dengue cases, contributing to increased endothelial permeability, which is a critical factor in severe dengue complications. Interferon-gamma (IFN-γ) also increased in severe cases, indicating a heightened state of inflammation.
The research team observed a clear link between lower 25(OH)D levels and increased levels of these inflammatory markers, including TNF-α, IL-6, and IFN-γ. Additionally, circulating miRNA-155, a molecule that regulates immune and inflammatory responses, increased with disease severity. There was an inverse relationship between 25(OH)D levels and miRNA-155, suggesting that vitamin D may help control inflammation. These findings indicate that vitamin D status is closely tied to how the immune system reacts during a dengue infection. Low vitamin D levels could lead to more severe disease.[vax-before-travel+1]
How Vitamin D May Help
Vitamin D is known for its strong immunomodulatory effects, meaning it can influence the body's immune response. Researchers believe vitamin D may play a role in reducing dengue virus replication and controlling the inflammatory response. This could prevent the excessive immune reaction, often called a "cytokine storm," that drives severe dengue cases characterized by plasma leakage, bleeding, and organ damage.
A systematic review published in January 2025 further supports these ideas. It concluded that vitamin D3 can help manage dengue by inhibiting the inflammatory response and boosting the immune system. This could lead to a decrease in viral load and overall disease severity. Studies suggest vitamin D may limit the early replication of the dengue virus, which then leads to lower production of inflammatory cytokines and chemokines in primary human macrophages.[vax-before-travel+2]
"What this study adds is a possible disease mechanism through microRNA-155, which is involved in immune dysregulation," Dr. R. Goswami, a professor of endocrinology at the All India Institute of Medical Sciences, said about the findings. He emphasized that maintaining normal vitamin D levels is a sensible approach.[journals+1]
Global Impact and Next Steps
Dengue remains a significant global health concern, affecting millions of people. As of January 26, 2026, the U.S. CDC identified 11 countries reporting dengue outbreaks, including cases in Florida, United States. In many dengue-endemic areas, vitamin D deficiencies are widespread, making this research particularly relevant for public health strategies.[vax-before-travel]
The research team behind the recent study noted that while vitamin D supplementation shows promise, more clinical trials are necessary. These trials would help determine if correcting vitamin D deficiencies can directly improve outcomes for dengue patients. Maintaining sufficient vitamin D levels, either through diet or supplementation, might offer protection against severe dengue illness.[vax-before-travel+1]
Further research is crucial to fully understand the mechanisms and confirm the benefits of vitamin D in preventing severe dengue. These studies could pave the way for new therapeutic options and better management strategies for this widespread viral infection.[vax-before-travel+2]
