The BBC's Richard Hannaford reports on the research

The study, published in the journal Thorax, analysed data taken in the 1960s and 1970s.

It found that the lung capacity or "forced expiratory volume" (FEV) of people with a high intake of two particular vitamins - C and E - was better than average.

Eating bread was also associated with improved lung health.

Scientists believe this effect is due to antioxidant properties of the vitamins, which help protect the tissues of the lung from damage.

The two vitamins are found abundantly in certain fruit and vegetables.

Reduces cancer risk

The properties are also thought to be responsible for protecting the lungs against the development of cancer, according to a separate study published this week.

Researchers found that high levels of vitamin E in the blood were associated with the lowest risk of lung cancer.

They stressed, however, that it was not proven that taking a vitamin E supplement could lower the risk.

The study involved 29,000 Finnish male smokers - those with the highest levels of alpha-tocopherol, the active form of vitamin E in the body, had 19% fewer cases of lung cancer.

Karen Woodson, who led the study for the National Cancer Institute in the US, said: "These findings suggest that high levels of alpha-tocopherol, if present during the early critical stages of tumour formation, may inhibit lung cancer development."

The precise mechanism by which this may occur is still to be unravelled, but scientists believe that antioxidants work by attaching themselves to, and rendering harmless, particles called "free radicals".

These circulate in the body and are thought to cause cell damage which can trigger cancer development.

Antioxidants have also been shown to encourage already damaged cells to "commit suicide".