Researchers combined results from 39 studies involving over 61,000 people to understand how vitamin D affects sepsis—a life-threatening infection that spreads through the body. They found that people with sepsis, especially children, had much lower vitamin D levels than healthy people. About 55% of sepsis patients didn’t have enough vitamin D. The study suggests that low vitamin D may be connected to higher death rates from sepsis, and vitamin D levels might help doctors predict which patients are at highest risk. This discovery could help doctors identify patients who need extra care.

The Quick Take

  • What they studied: Whether vitamin D levels are connected to how sick people get with sepsis (a serious blood infection) and whether low vitamin D predicts worse outcomes
  • Who participated: 61,774 people total: 1,208 children and newborns with sepsis, and 60,566 adults with sepsis, compared to healthy people without sepsis
  • Key finding: People with sepsis had significantly lower vitamin D levels than healthy people. Newborns with sepsis averaged 12.99 units (normal is higher), and children averaged 24.84 units. About 55% of all sepsis patients had low or insufficient vitamin D. Low vitamin D was linked to higher death rates, especially in children.
  • What it means for you: If you or a loved one develops sepsis, vitamin D levels might help doctors understand how serious the infection is. However, this doesn’t mean taking vitamin D supplements will prevent sepsis or cure it—more research is needed to prove that. Talk to your doctor about your vitamin D status, especially if you’re at risk for serious infections.

The Research Details

This was a systematic review and meta-analysis, which means researchers searched four major medical databases (PubMed, Embase, Cochrane Library, and Web of Science) for all published studies about vitamin D and sepsis up to February 2025. They found 39 studies that met their quality standards and combined the results from all these studies together, like putting puzzle pieces from different pictures into one big picture.

The researchers used special computer software (Stata 15 and Meta-Disc) to combine the numbers from all these different studies in a fair way. This approach is stronger than looking at just one study because it includes information from thousands of patients across many different hospitals and countries.

They looked at both children (including newborns) and adults separately because sepsis affects these groups differently. They measured vitamin D levels in blood and tracked whether patients survived or died from their infection.

By combining many studies together, researchers can see patterns that might not be obvious in a single study. This approach is especially important for rare conditions or when results vary between different hospitals. Since sepsis is a serious medical emergency, understanding all available evidence helps doctors make better decisions about which patients need the most urgent care.

This study is a meta-analysis, which is considered high-quality evidence in medical research. The researchers searched multiple databases to find studies, which reduces the chance they missed important research. However, the quality depends on the individual studies they included—if those studies had problems, those problems carry forward. The fact that they included 39 studies with over 61,000 patients makes the results more reliable than a single small study.

What the Results Show

The research found that vitamin D levels were dramatically lower in people with sepsis compared to healthy people. In newborns with sepsis, the average vitamin D level was 12.99 units, and in children it was 24.84 units—both much lower than normal. The difference was statistically significant, meaning it wasn’t due to chance.

About 55% of all sepsis patients had either low vitamin D (deficiency) or not-quite-enough vitamin D (insufficiency). This is a huge percentage—more than half of all sepsis patients. In children specifically, low vitamin D was strongly connected to higher death rates from sepsis. In adults, low vitamin D was linked to both more cases of sepsis and higher death rates.

When researchers tested whether vitamin D levels could predict which adult patients would die, they found it was 81% accurate at identifying patients who would survive (sensitivity) but only 31% accurate at identifying those who would die (specificity). This means vitamin D is better at ruling out death risk than predicting it.

The connection between low vitamin D and sepsis was consistent across different age groups and study types, suggesting this is a real pattern, not just a coincidence.

The research showed that vitamin D deficiency was more common in sepsis patients than in healthy people across all age groups studied. The pattern was consistent whether researchers looked at newborns, children, or adults, suggesting vitamin D plays a role in how the body fights serious infections. The studies also showed that vitamin D levels varied depending on how severe the sepsis was—sicker patients tended to have lower vitamin D.

This finding builds on earlier research suggesting vitamin D helps the immune system fight infections. Previous smaller studies hinted at a connection between vitamin D and sepsis outcomes, but this large combined analysis provides stronger evidence. The results support the idea that vitamin D is important for immune function, though researchers still aren’t sure if low vitamin D causes worse sepsis or if severe sepsis causes vitamin D levels to drop.

This study has several important limitations. First, most of the included studies measured vitamin D at one point in time, so researchers couldn’t prove that low vitamin D caused sepsis—only that they’re connected. Second, the studies came from different countries with different populations, which might affect results. Third, doctors measured vitamin D differently in different studies. Fourth, the research couldn’t prove that giving vitamin D supplements would help sepsis patients—that would require different types of studies. Finally, the ability to predict death using vitamin D alone was only moderate, meaning doctors would need other information too.

The Bottom Line

Based on this research, doctors should consider checking vitamin D levels in sepsis patients as one piece of information to understand how sick they are (moderate confidence). However, there is NOT enough evidence yet to recommend vitamin D supplements as a treatment for sepsis (low confidence). If you’re concerned about vitamin D, talk to your doctor about testing and whether supplements make sense for you personally, especially if you have risk factors for serious infections.

This research matters most for doctors treating sepsis patients and for people at high risk of serious infections (like those with weak immune systems, elderly people, or hospitalized patients). If you’re generally healthy, this doesn’t mean you need to rush out and buy vitamin D supplements. However, if you’re in the hospital with a serious infection or have a chronic illness, your doctor might want to check your vitamin D levels.

If vitamin D supplements were to help with sepsis, benefits would likely appear within days to weeks during the acute infection. However, this research doesn’t prove supplements help at all—that would require clinical trials where some patients get supplements and others don’t. Any benefits from improving vitamin D status for general health might take weeks to months to notice.

Want to Apply This Research?

  • Track your vitamin D level (measured in ng/mL or nmol/L) every 3-6 months if your doctor recommends it. Note the date, value, and any symptoms of infection or illness around that time. This helps you and your doctor see patterns over time.
  • If your doctor recommends vitamin D supplementation, set a daily reminder to take your supplement at the same time each day (like with breakfast). Log when you take it in the app to build consistency. Also track any infections or illnesses you experience to see if there’s a pattern.
  • Create a health timeline showing your vitamin D levels, any infections you’ve had, and any supplements you’re taking. Review this quarterly with your doctor. If you’re at high risk for serious infections, discuss with your doctor whether regular vitamin D monitoring makes sense for you and what your target level should be.

This research shows a connection between low vitamin D and sepsis outcomes, but it does not prove that vitamin D supplements prevent or treat sepsis. Sepsis is a medical emergency requiring immediate hospital care—do not delay seeking emergency treatment. Do not start, stop, or change any supplements or medications without talking to your doctor first. This information is for educational purposes and should not replace professional medical advice. If you have sepsis or suspect you do, call 911 or go to the emergency room immediately.