When people are very sick in the hospital with digestive problems, they receive vitamins through special nutrition support. Researchers studied 478 critically ill patients to see how their bodies handled nine different water-soluble vitamins (like vitamin C and B vitamins). They discovered something important: not everyone’s body responds the same way to the same vitamin dose. Patients with high inflammation in their bodies couldn’t hold onto vitamin C and B9 well, while patients with kidney problems built up too much of vitamins B2, B5, and B6. This means doctors may need to give different vitamin amounts to different patients based on their inflammation levels and kidney function, rather than using a one-size-fits-all approach.

The Quick Take

  • What they studied: Whether critically ill hospital patients with digestive disease absorb and maintain water-soluble vitamins the same way when given identical vitamin supplements through IV nutrition
  • Who participated: 478 hospitalized patients with serious digestive system diseases who were receiving IV nutrition support with added vitamins
  • Key finding: Patients’ bodies handled vitamins very differently: 80% were low in vitamin C and 78% were low in B9 (folate), but 35% built up too much B2 and smaller numbers accumulated B5 and B6. The key factor was inflammation level and kidney function—not the vitamin dose itself
  • What it means for you: If you’re hospitalized with serious digestive illness, your doctor may need to customize your vitamin doses based on blood tests showing inflammation and kidney function, rather than giving everyone the same amount. This is especially important if you have high inflammation or kidney problems

The Research Details

Researchers measured nine different water-soluble vitamins in the blood of 478 hospitalized patients with serious digestive diseases. All patients received the same vitamin supplements through IV nutrition (called parenteral nutrition or PN). The researchers took blood samples and used statistical analysis to figure out which patients were getting too little or too much of each vitamin. They also looked at whether inflammation levels and kidney function affected how patients’ bodies handled the vitamins. To confirm their findings, they analyzed data from a large national health survey (NHANES) that tracked Americans’ vitamin levels from 2003 to 2020.

This approach is important because it shows that giving everyone the same vitamin dose doesn’t work equally well for all patients. By understanding which patients are at risk for vitamin deficiency or buildup, doctors can adjust treatment to match each person’s specific needs. This personalized approach could help critically ill patients recover better.

The study included a large number of patients (478), which makes the findings more reliable. The researchers used multiple statistical methods to analyze the data and confirmed their results using a separate large national database. However, the study only looked at hospitalized patients with digestive disease, so results may not apply to other patient groups. The study was observational, meaning researchers watched what happened rather than randomly assigning patients to different treatment groups.

What the Results Show

The most striking finding was that vitamin C and B9 (folate) deficiency were extremely common—affecting about 8 out of 10 patients even though they were receiving vitamin supplements. In contrast, some vitamins accumulated to high levels: about 1 in 3 patients had too much B2, and about 1 in 9 had too much B5 or B6. When researchers looked at what caused these problems, they found two main culprits: inflammation and kidney function. Patients with high inflammation couldn’t maintain adequate vitamin C and B9 levels no matter how much was given. Patients with kidney problems couldn’t get rid of excess B2, B5, and B6, causing dangerous buildup. The researchers created prediction models that could identify which patients would have these problems with reasonable accuracy (the models were 69-89% accurate depending on the vitamin).

The study confirmed that water-soluble vitamins behave differently in critically ill patients compared to healthy people. The NHANES database analysis showed similar patterns in the general population, suggesting these findings aren’t unique to hospitalized patients. The research also showed that standard vitamin supplementation protocols—the same dose for everyone—don’t work well for patients with inflammation or kidney problems.

Previous research has shown that vitamins matter for patient outcomes, but this study goes further by explaining why some patients don’t respond well to standard vitamin doses. It bridges the gap between knowing vitamins are important and understanding how to actually deliver them effectively to different patients. The findings align with what doctors know about inflammation and kidney disease affecting nutrient metabolism, but this is one of the first studies to quantify exactly how much this matters for water-soluble vitamins in critically ill patients.

The study only included hospitalized patients with digestive diseases, so results may not apply to other patient groups or to healthy people. The researchers observed what happened but didn’t randomly assign patients to different vitamin doses, so they can’t prove that changing doses would definitely help. The study was done at specific hospitals, so results might differ in other settings. Additionally, the study measured vitamin levels at one point in time rather than tracking changes over the entire hospital stay.

The Bottom Line

For hospitalized patients with high inflammation: vitamin C and B9 doses should be higher than standard amounts (moderate confidence). For hospitalized patients with kidney problems: avoid routine B2, B5, and B6 supplementation; if these vitamins are necessary, use lower doses or give them every other day instead of daily (moderate-to-high confidence). All critically ill patients should have their vitamin levels monitored with blood tests to guide personalized dosing (high confidence).

This research matters most for doctors treating critically ill patients with digestive diseases, kidney disease, or high inflammation. It’s also relevant for patients in these situations and their families who want to understand why their vitamin supplements might be adjusted. The findings may also apply to other critically ill patients, but more research is needed to confirm this. This research does NOT apply to healthy people taking regular vitamin supplements.

If vitamin doses are adjusted based on these findings, blood vitamin levels could normalize within days to weeks depending on the specific vitamin and the patient’s condition. However, the time needed to see clinical improvement (better recovery, fewer infections) would depend on the individual patient and their overall health status.

Want to Apply This Research?

  • If you’re a hospitalized patient or caregiver, track vitamin blood test results (C, B1, B2, B3, B5, B6, B7, B9, B12) along with inflammation markers (like CRP) and kidney function tests (creatinine, eGFR) to see patterns in how your body handles vitamins
  • Work with your medical team to request personalized vitamin dosing based on your blood test results rather than standard doses. Ask your doctor to check your inflammation and kidney function when adjusting vitamin supplements
  • Request regular vitamin level monitoring (weekly or as clinically indicated) during hospitalization. Keep a record of which vitamin doses you receive and your corresponding blood test results to help your medical team identify your individual vitamin needs

This research describes patterns in hospitalized patients with serious digestive diseases and should not be used to self-treat or change your own vitamin supplementation without medical supervision. If you are hospitalized or have kidney disease, inflammation, or digestive problems, discuss any vitamin supplementation changes with your doctor or registered dietitian. This study provides information for healthcare providers to consider when prescribing vitamins to critically ill patients, but individual treatment decisions should be based on your specific medical situation, blood test results, and professional medical advice. Do not stop or change prescribed vitamins without consulting your healthcare provider.