New evidence
Vitamin C (500 mg/day) to pregnant smokers was linked to DNA methylation changes at 5 CpG sites that statistically explained a significant portion of the supplement's benefit on children's lung function at age 5 — but only in this specific clinical trial of 137 mother-child pairs.
This is the first strong hint that vitamin C might improve lung function in children through epigenetic changes, but with only 4 prior studies on the pairing and mixed results overall, we are far from a general recommendation — the finding needs replication.
In a double-blind trial, pregnant smokers who took 500 mg of vitamin C daily had children with better lung function at age 5 compared to placebo. The study found that the vitamin altered DNA methylation at several sites, and statistical analysis showed that changes at 5 of those sites accounted for a meaningful part of the lung function improvement. However, the effect was observed in a specific clinical population (smoking mothers), the sample was modest, and the broader body of evidence on vitamin C and lung function is still mixed (2 beneficial, 2 neutral) — so this is an intriguing lead, not a settled benefit.
Where this fits in the evidence
Pillser has synthesized 4 studies on Vitamin C for Improved Lung Function — overall evidence strength: Low.
Across 4 studies, 2 reported beneficial moderate-sized effects on lung function (one RCT in children of pregnant smokers, one narrative review), while 2 meta-analyses in adults with COPD and asthma found no significant effect. The only specific dose studied was 500 mg/day in the positive RCT, but the evidence is inconsistent and limited by varied populations and study designs.
The study
- Randomized Controlled Trial (RCT)
- n = 137
- 2025-10-03
- Clinical epigenetics
This is a plain-language summary of a research finding, not medical advice. Pillser surfaces research signals to help you decide what's worth investigating — always consult a qualified professional before changing what you take.