Yangon, Myanmar (CNN) -- Heavy users of betel quids reveal their addiction when they smile. Their teeth are stained a reddish-black, dyed from years of chewing potent parcels of areca nuts and tobacco, wrapped in a lime-coated betel leaf. "Some people after they eat they're drinking coffee or tea; always after eating I'm chewing the betel nut. I like it," says Myo Min Than, a 28-year-old noodle seller at a market in Myanmar's largest city, Yangon. Like tea or coffee, betel quids -- or "nuts" as they're often referred to -- give users a lift. But unlike tea or coffee, they also give them oral cancer.
@highlight
Hundreds of millions of people chew betel quids, mostly in Asia
@highlight
Research shows that chewing the parcels raises the risk of oral cancer
@highlight
Betel quids are parcels of areca nuts and tobacco wrapped in a lime-coated betel leaf
@highlight
In Myanmar, they're popular with taxi drivers who use them to stay awake on the roads
They're predominantly chewed in @placeholder, where their use isn't limited to adults.