Many supplements have been studied for pneumonia, but there is little evidence to support their efficacy. For instance, a meta-analysis found that Vitamin C was ineffective in treating or preventing pneumonia.[1] Similarly, probiotics, specifically the strain Lactobacillus rhamnosus GG, failed to prevent ventilator-associated pneumonia.[2]
Although there is some evidence that low levels of vitamin D (measured by plasma 25-hydroxyvitamin D3) are associated with an increased risk of bacterial pneumonia[3], it’s unclear whether supplementation reduces this risk. Lastly, a randomized controlled trial found that N-Acetylcystine (NAC) supplementation, despite lowering markers of oxidative stress and inflammation, did not improve chest imaging results in people hospitalized with pneumonia.[4]
Conversely, zinc supplementation is associated with a reduced risk of pneumonia in children,[5] but adding zinc as an adjunct to antibiotic treatment in children who already have pneumonia does not improve time to recovery.[6][7]