Young lesbian, gay and bisexual smokers may be more at risk of acute respiratory illnesses than their straight counterparts, a study suggests.

American researchers found that gay and lesbian smokers between the ages of 18 and 24 were more likely to have had strep throat, a bacterial infection, while bisexual smokers were more likely to have had a sinus infection, asthma or bronchitis, in contrast to their heterosexual peers.

Previous studies have found that gay people are more likely to smoke than heterosexuals.

This study, published in the journal Lung last month by researchers from West Virginia University, used data from a 2006 US college health assessment.

The respondents, aged between 18 and 24, included 69,723 heterosexuals,1,259 gays and lesbians, 1,717 bisexual people and 1,128 people who were unsure of their sexuality.

It found that 18.4 per cent of gay respondents and 21.8 per cent of bisexual respondents had ever smoked, compared to 16.5 per cent of straight people.

Gays and lesbians had a 42 per cent increased risk for strep throat compared with their heterosexual counterparts.

Bisexual men and women had a 36 per cent increased risk for asthma, 18 per cent increased risk for sinus infection, and 30 per cent increased risk for bronchitis compared to straight people.

The study also surveyed people who were unsure of their sexuality. These people had no increased risk of acute respiratory illness.

Researchers said further study was needed to show whether gay and bisexual people were disproportionately affected by more serious chronic respiratory illnesses such as lung cancer and emphysema.