Plasma carotenoid concentrations in relation to acute respiratory infections in elderly people.

A high plasma carotenoid concentration could improve the immune response and result in decreased risk of infectious diseases. However, data on the relationship of plasma carotenoid concentration with acute respiratory infections, which occur frequently in elderly people, are scarce. We investigated, therefore, the relationship of plasma concentrations of six major carotenoids (beta-carotene, alpha-carotene, beta-cryptoxanthin, lycopene, lutein and zeaxanthin) with the incidence and severity of acute respiratory infections. Baseline data from an intervention trial were used. Participants were 652 non-institutionalized elderly people (> or =60 years old) enrolled via two community-based sampling strategies in the Wageningen area of The Netherlands in 1998-99. Plasma carotenoid concentrations were divided into quartiles, the lowest being the reference. Frequency and severity of episodes during the previous 1 year, i.e. staying in bed, medical consultation and episode-related medication, were self-reported by means of a questionnaire. On average 1.6 episodes per person were recorded. The incidence rate ratio of acute respiratory infections at high beta-carotene status was 0.71 (95 % CI 0.54-0.92) as compared with the low beta-carotene concentration group. No association was observed between beta-carotene and illness severity. alpha-Carotene, beta-cryptoxanthin, lycopene, lutein and zeaxanthin were not related to incidence or severity of the infections. We conclude that elderly people with a high plasma beta-carotene concentration may have a lower occurrence of acute respiratory infections.