Vitamin E may increase or decrease the risk of pneumonia, depending on smoking and exercise

In laboratory studies, vitamin E has influenced the immune system. In several animal studies vitamin E protected against viral and bacterial infections. However, the importance of vitamin E on human infections is not known.

Dr. Harri Hemilä and Prof. Jaakko Kaprio, of the University of Helsinki, Finland, studied the effect of vitamin E on the risk of pneumonia in the large randomized trial (Alpha-Tocopherol Beta-Carotene Cancer Prevention Study) which was conducted in Finland between 1985-1993. There were 898 cases of pneumonia among 29,133 participants of the study.

Vitamin E had no overall effect on pneumonia risk. However, vitamin E decreased pneumonia risk by 69% among participants who had the least exposure to smoking and exercised during leisure time. In contrast, vitamin E increased pneumonia risk by 79% among those who had the highest exposure to smoking and did not exercise.

Over half of the participants were outside of these two subgroups and vitamin E did not affect their risk of pneumonia. Thus, the beneficial and harmful effects of vitamin E are restricted to fairly small parts of the population. The researchers concluded the role of vitamin E in susceptibility to pneumonia in physically active nonsmokers warrants further study.