A recent study published in the journal Critical Care Medicine found that vitamin D sufficiency may improve recovery from sepsis by modulating the immune response.
Sepsis is a life-threatening complication caused by the body’s overwhelming response to infection. Sepsis occurs when chemicals released into the bloodstream to fight the infection cause widespread inflammation. The inflammation leads to blood clots and leaky blood vessels, which causes inadequate blood flow. This can deprive the body’s organs of nutrients and oxygen. In severe cases, sepsis leads to organ failure. In the worst cases, blood pressure drops and the heart weakens, resulting in septic shock, which is often fatal.
Sepsis is the most common reason for admission to intensive care units and the leading cause of death among critically ill patients. Approximately 750,000 U.S. patients are affected by sepsis annually, with a mortality rate of 25%. Despite large research efforts, a lack of effective interventions to treat and improve outcomes from sepsis remains.
Vitamin D possesses both anti-inflammatory and immune strengthening properties, making it a promising intervention to improve health outcomes among patients suffering from sepsis.
Available research indicates that vitamin D deficiency is highly prevalent in critically ill patients and is associated with adverse outcomes. Furthermore, meta-analyses have shown that vitamin D deficiency is linked with increased susceptibility for severe infection, sepsis and mortality among the critically ill.
In a recent study, researchers aimed to determine the prevalence and severity of vitamin D deficiency among patients with sepsis. A total of 61 patients were included in the study: 20 with mild sepsis and 41 with severe sepsis, categorized by the presence of one or more organ failure at admission.
The researchers compared the average vitamin D levels of the septic patients to the vitamin D levels of 20 healthy elderly adults.
Here is what he researchers found:
- Patients with severe sepsis had an average vitamin D status of 6.28 ng/ml, which is considered severely vitamin D deficient (VDC recommends a vitamin D status between 40-80 ng/ml).
- Patients with severe sepsis had significantly lower average vitamin D levels than both mild sepsis patients and healthy controls (6.28 ng/ml, 19.8 ng/ml and 26.6 ng/ml, respectfully; p = 0.0001).
- The average vitamin D levels of mild sepsis patients were lower than healthy adults, but the difference did not reach statistical significance (19.8 ng/ml vs 26.6 ng/ml).
- Twenty-two patients showed positive blood culture for bacterial growth, indicating the presence of infection. The median vitamin D status of patients with bacterial growth were significantly lower than patients without (6.6 ng/ml vs 14.2 ng/ml, p = 0.0023).
- Patients who died within 30 days had significantly lower vitamin D levels than those who survived (5.8 ng/ml vs 10.4 ng/ml, p = 0.025).
- Those with a vitamin D status below 8 ng/ml experienced a 4.71-fold increased risk of 30-day mortality compared to those with a vitamin D status above or equal to 8 ng/ml (p – 0.02).
The researchers conducted a secondary experiment using a mouse model of sepsis to explore the mechanism in which vitamin D may affect sepsis. Half of the mice were given a diet without vitamin D, while the other half received a normal diet for a total of six weeks. Then, researchers induced sepsis among the mice. They wanted to determine whether vitamin D deficiency affects the presence of bacteria and anti-microbial peptides. In addition, the study aimed to evaluate the effects of vitamin D deficiency on the immune system, specifically the ingestion of bacteria by a type of white blood cell called macrophages. This process, known as phagocytosis, plays a vital role in the recovery from infection.
The researchers discovered the following:
- Vitamin D deficiency was significantly associated with increased bacterial infection (p < 0.05).
- The induction of sepsis increased levels of cathelicidin, an anti-bacterial protein, among vitamin D sufficient mice.
- Significantly lower cathelicidin levels were seen in vitamin D deficient mice compared to vitamin D sufficient mice (p < 0.05).
- Phagocytosis was significantly reduced in vitamin D deficient mice compared to vitamin D sufficient mice (p = 0.029).
The researchers concluded,
“We have confirmed, in a cohort of hospitalized patients with sepsis, that [vitamin D deficiency] is common, severe, and is associated with disease severity, bacterial positive culture, and 30-day mortality.”
They went on to state,
“…We suggest that therapies aimed at restoring [vitamin D sufficiency] in patients at risk of deficiency when they are admitted to hospital need to be developed to try and prevent the increasing healthcare burden of sepsis patients.”
Due to the potentially fatal consequences of sepsis, this study’s findings may save lives. The results provide hope to sepsis patients that they can increase their likelihood of a full recovery through maintaining healthy vitamin D levels.
However, it is important to recognize the study’s limitations. The cross-sectional design restricts the results to only prove association and not causation. Furthermore, the results from an animal study are not necessarily replicable in humans. Therefore, randomized controlled trials need to evaluate the efficacy of vitamin D supplementation for the recovery of sepsis among humans.
Tovey, A. & Cannell, JJ. Healthy vitamin D levels may improve health outcomes of patients with sepsis. The Vitamin D Council Blog & Newsletter, 2016.