Vitamin D3 Doesn't Prevent Diarrhea in Kids: Study

randomized-controlled-trial PMID: 24019420

Quick Summary: A study in Afghanistan found that giving high doses of Vitamin D3 to babies every three months didn't prevent them from getting diarrhea. This means Vitamin D3 supplements, in this specific way, didn't help reduce diarrhea in this group of children.

What The Research Found

Researchers looked at whether giving babies Vitamin D3 could stop them from getting diarrhea. They found that babies who took Vitamin D3 didn't get diarrhea any less often than babies who didn't. The Vitamin D3 didn't seem to make a difference in how often the babies got sick.

Study Details

Who was studied: 3,046 babies aged 1 to 11 months old in Kabul, Afghanistan. These babies were considered at higher risk for getting sick.

How long: The study lasted for 18 months.

What they took: Some babies received a high dose of Vitamin D3 (100,000 IU) every three months. Others received a placebo (a dummy pill).

What This Means For You

This study doesn't mean Vitamin D3 is useless. It just means that giving high doses of Vitamin D3 every few months didn't help prevent diarrhea in this specific group of babies. If you're concerned about your child's health, talk to your doctor. They can give you personalized advice based on your child's needs.

Study Limitations

The study was done in a place where diarrhea is common. This might have made it harder to see if Vitamin D3 had a small effect.

The babies only got Vitamin D3 every three months. It's possible that giving it more often could have a different result.

The researchers didn't check the babies' Vitamin D levels before the study.

Key Findings

This randomized controlled trial found that quarterly high-dose vitamin D3 supplementation (100,000 IU) did not reduce the incidence of diarrheal illness in infants aged 1–11 months in Kabul, Afghanistan. Over 18 months, there was no significant difference in time to first diarrhea episode (log rank P = 0.55) or recurrent episodes (intention-to-treat HR = 1.05; 95% CI: 0.98–1.17; P = 0.15). Similar results were observed in per-protocol analysis (HR = 1.05; 95% CI: 0.98–1.12; P = 0.14). Stratification by age, nutritional status, or season did not reveal any subpopulation benefit.

Study Design

The study was a double-blind, placebo-controlled RCT involving 3,046 high-risk infants in urban Kabul. Participants were randomized to receive six quarterly oral doses of vitamin D3 or placebo over 18 months. Diarrheal episodes (defined as ≥3 loose/liquid stools in 24 hours) were tracked via active surveillance (weekly home visits) and passive reporting. Kaplan-Meier plots analyzed time-to-first-event, while Poisson regression models assessed recurrent episode incidence.

Dosage & Administration

Infants received 100,000 IU of cholecalciferol (vitamin D3) orally every 3 months for 18 months. Placebo recipients followed the same dosing schedule. Supplements were administered under supervision to ensure adherence.

Results & Efficacy

Incidence rates: 3.43 episodes/child-year (95% CI: 3.28–3.59) in the placebo group vs. 3.59 (95% CI: 3.44–3.76) in the vitamin D3 group.
Time to first diarrhea: No significant difference (log rank P = 0.55).
Recurrent diarrhea risk: Vitamin D3 showed no protective effect in intention-to-treat (HR = 1.05; P = 0.15) or per-protocol analyses (HR = 1.05; P = 0.14).
Subgroup analyses: No efficacy observed across age groups, nutritional statuses, or seasons.

Limitations

The study’s high-risk population in a region with endemic diarrhea (baseline incidence ~3.5 episodes/child-year) may have limited the ability to detect modest benefits. Quarterly dosing might not maintain optimal vitamin D levels consistently, as seasonal and nutritional variability were not fully mitigated. Potential biases include reliance on caregiver-reported outcomes and lack of baseline vitamin D status measurement. Future research could explore daily/more frequent dosing, younger infants, or populations with documented deficiencies.

Clinical Relevance

In high-risk urban Afghan infants, quarterly 100,000 IU vitamin D3 supplementation did not prevent diarrhea. These results suggest such regimens may not be effective in similar low-income settings with high diarrheal disease burden. Clinicians should prioritize proven interventions (e.g., hygiene, nutrition) over this dosing strategy for diarrhea prevention in this demographic. Further studies in populations with different baseline vitamin D levels or dosing frequencies are warranted.