Is there any way I can prevent my 4-year-old's recurring pneumonia?
Three episodes of pneumonia in one child in one year is cause for concern. If he is in group child care he is more likely to come down with infections, but those are usually colds and stomach flu rather than pneumonia. If he's basically healthy, growing and developing normally, his diet and vitamins are not factors.
Is there a history of allergies and asthma in your family? Does he have a persistent or recurrent nighttime cough? Has he had episodes of wheezing that your pediatrician has had to treat with inhaled medication? Controlling asthma can reduce the risk of pneumonia.
Did he have an X-ray between episodes that showed complete clearing of the pneumonia? If not, and if the pneumonia was always in the same part of the lung, it is possible either that he inhaled something that is lodged there or there is some anatomical abnormality such as a narrowed air tube that keeps triggering the infection.
Cystic fibrosis causes recurring lung infections and can be diagnosed with a painless skin test.
There are other, less common conditions that can cause recurring pneumonia. I think your child deserves some basic tests to eliminate some of these.