Eat Right and Breathe Easy
Participants were asked about smoking status (years of smoking, current number of cigarettes smoked per day, years since quitting) and about their diet and vitamin supplement intake in the preceding 24 hours. Each also was given a blood test to determine exact levels of the four vitamins.
"We found that people with high levels of antioxidants [in their diet] had better lung function," Hu tells WebMD. They also found the protective effect was different depending on the smoking status and varied with different antioxidants. "Beta carotene had a less protective effect for smokers. And the more they smoked, the less protected they are. In fact, beta carotene offered almost no protection for heavy smokers," Hu says. However, "selenium provides strong protection for smokers in general.
"Overall, it gives us another reason that eating fruits and vegetables is good," Hu tells WebMD. "The magnitude of effect is very strong, very significant" in the study, he says.
While the evidence regarding diet was encouraging, taking vitamin supplements did not seem to make a difference, Hu adds.
Why? One reason, says Hu, may be because people generally take vitamins when they are unhealthy. "So you may find that people who use supplements have lower lung function than those who did not."
He says that survey questions were too broad to provide a cause-and-effect between vitamins and lung protection. Questioners only asked whether vitamin supplements had been taken within the past month. "That reflects only recent intake but does not reflect long-term intake. [They] may have started taking because having a health problem," Hu says.
Lou Ann Brown, PhD, says that while you can't reverse lung disease by eating right, you may be able to prevent further decrease in lung function as you age. "Eating right can decrease the aging process of the lung by four years because antioxidants provide protection from pollutions in air. Particularly in metropolitan areas, we have lots of ozone and fumes and oxygen radicals in the air from everything," she tells WebMD. Brown, a biochemist and associate professor of pediatrics at Emory School of Medicine, has herself researched the issue.
"What mamma told you was right. Eat your fruits and vegetables," she says. "There probably are other protective agents we're not aware of yet that are in fruits and vegetables, and by just taking supplements, you don't get those. The National Institutes of Health says eat five fruits and vegetables a day, so this is in keeping with that policy."