A dietary study by University at Buffalo nutrition researchers has shown that lutein and zeaxanthin, rather obscure antioxidant vitamins in the carotenoid family, have a significant positive effect on lung health.

Study participants who ate half the average amount of foods containing lutein and zeaxanthin showed a reduction in lung function equivalent to 1-2 years of aging, results showed.

The study, published in the 1 March issue of the American Journal of Epidemiology, shows that dietary carotenoids other than beta-carotene, the most frequently investigated nutrient in that family, are associated positively with lung function.

Carotenoids are antioxidant vitamins found primarily in orange, red, green and yellow vegetables and fruits. Green leafy vegetables such as spinach, kale and collard greens are good sources of lutein and zeaxanthin.

The researchers also found a strong association between dietary intake of foods containing the antioxidant vitamins C and E and healthy lung function, results that supported their previous research. In a study published last May, they reported that high blood levels of vitamins C and E and the carotenoids lutein, zeaxanthin and beta-cryptoxanthin were associated with better pulmonary function in a general population.

"The importance of this study is that it strengthens the hypothesis that carotenoids are antioxidant vitamins that play a significant role in maintaining respiratory function, and that beta-carotene may not be the 'one' important carotenoid," said Holger Schunemann, M.D., Ph.D., UB assistant professor of medicine and social and preventive medicine and lead author on the study.

"Impaired lung function is associated with an increased risk of dying, so it is important to determine the factors that could influence lung function," he said. "This information may be even more important for smokers, who have a heavy free-radical burden."

This study was based on dietary records and interviews obtained from 1,616 randomly selected residents of Western New York ages 35-79 who were free of respiratory disease. All participants performed standard lung-function tests, which measured the volume of air they could expel in one breath -- forced vital capacity (FVC) -- and the volume forcibly expelled in one second (FEV1).

Of the several carotenoids prevalent in the diets of participants, lutein and zeaxanthin showed the strongest association with pulmonary function, Schunemann said.

"We also found a positive association between pulmonary function and dietary intake of vitamins C and E, but when we considered these antioxidant vitamins simultaneously, only vitamin E correlated significantly with FEV1 and only lutein and zeaxanthin with FEV." Taking vitamin C and E supplements didn't change these results significantly.

"Further studies are needed to confirm these results," he said, "and longitudinal studies could help to clarify whether this association is related to lung development in childhood and adolescence, or whether it's the result of an accumulation of protective effects against oxidative damage throughout life."

Additional UB researchers on the study, all from the Department of Social and Preventive Medicine, were Susan McCann; Brydon JB Grant, MD, (also from the Department of Medicine); Maurizio Trevisan, MD, professor and chair; Paola Muti, MD, and Jo L. Freudenheim, PhD.

The study was supported in part by a grant from the National Institutes of Health and the German Research Foundation.