Healthy women’s pneumonia risk not reduced by vitamins

Well-nourished women who get a lot of vitamins through their diet or supplements are at no less risk for community-acquired pneumonia than other women, a large prospective study suggests.

However, the study, which looked at more than 80,000 women, did find that smokers face a lower risk for pneumonia if their diet includes a lot of vitamin A.

Previous studies have found that specific vitamins lower people’s risk for pneumonia and respiratory infections, but most looked at elderly or malnourished individuals.

Mark Neuman (Children’s Hospital, Boston, Massachusetts, USA) and colleagues studied the effects of vitamin intake in 83,165 women from the Nurses’ Health Study II.

They focused on nurses who were 27–44 years of age in 1991, when the information on dietary and supplemental intake of vitamins was first collected.

Nutrient intake was assessed through self-administered questionnaires, and updated every 4 years.

The participants were followed-up for incident cases of community-acquired pneumonia for 10 years.

During 650,377 person-years of follow-up, 925 new cases of pneumonia were diagnosed. A case was considered to be physician-diagnosed pneumonia if confirmed by chest radiography.

In adjusted analyses, neither dietary nor total intake of any vitamin was associated with risk of community-acquired pneumonia.

These analyses adjusted for age, cigarette smoking, body mass index, physical activity, total energy intake, and alcohol consumption.

The vitamins studied included vitamins B12, A, C, D, and E, along with total carotenoids, alpha-carotene, beta-carotene, beta-cryptoxanthine, lycopene, lutein, and zeaxanthin.

However, when the researchers studied the association between vitamin intake and community-acquired pneumonia among smokers, they found a significant link.

After excluding smokers who took vitamin E supplements, they found that the risk of community-acquired pneumonia among women in the top quintile of dietary vitamin E intake was cut by more than half (relative risk [RR] = 0.45), compared with women in the lowest quintile.

Neuman et al conclude in the American Journal of Medicine: “Vitamin intake does not alter community-acquired pneumonia risk in healthy young and middle-aged women.

“Among smokers, higher intake of foods rich in vitamin E may reduce the risk of community-acquired pneumonia.”