New York, Bisexual young people are more likely to smoke than their straight counterparts, say researchers.

Published in the journal JAMA Pediatrics, the study followed 7,843 youths and young adults over three years, finding that those who came out as bisexual were twice as likely as consistently-heterosexual participants to start smoking.

Coming out as lesbian, gay, or another non-heterosexual identity, or having a consistent LG+ identity, was not associated with being more likely to smoke.

"Bisexual young people may face unique forms of discrimination and stigma that increase their risk for smoking or other substance use behaviours," said study author Andrew Stokes from the Boston University in the US.

"For example, they may experience stigma from heterosexual individuals as well as from within the LGB+ community. There's also prior research that shows that bisexual populations have worse mental health outcomes than LG+ populations," Stokes added.

"The findings point to a need for public health interventions specifically designed to address the unique needs, experiences, and stressors associated with coming out and identifying as bisexual."

For the study, the researchers used data from the first four waves of the nationwide Population Assessment of Tobacco and Health (PATH) study, which surveyed the same 14-29-year-olds three times between 2013 and 2018.

By the third wave, 14 per cent of the respondents had smoked at some point, and six per cent were current smokers.

The researchers found that the same sexual identity patterns held true both for having smoked at any point in the study period and for being a current smoker.

Compared to a consistent heterosexual identity, coming out as bisexual was associated with being more than twice as likely to smoke, they found.

Participants with LG+ identities in the first wave who shifted to a bisexual identity, or vice versa, were twice as likely to smoke.

On the other hand, participants with a consistent LG+ identity throughout the three waves of the study and participants who started out identifying as heterosexual and came out as LG+ were not more likely to smoke.

"The study is unique because it asks youth about their sexual orientation and gender identity. Most national surveys do not," the stud authors wrote.