Asia's deadly secret: The scourge of the betel nut
It is used by almost a tenth of the world's population. It gives people a buzz equivalent to six cups of coffee and is used variously as a symbol of love, marriage and a cure for indigestion and impotence.
But it is also leading tens of thousands to an early grave.
The culprit? The humble betel nut.
Found across Asia, these nuts are harvested from the Areca palm and are chewed for their warming glow and stimulating properties.
Such is its effectiveness, that alongside nicotine, alcohol and caffeine, betel nuts are believed to be one of the most popular mind-altering substances in the world.
Although used by women and children, the nuts are especially popular among working-age men, who chew to stay awake through long hours of driving, fishing or working on construction sites.
But the short-lived benefits come at a terrible cost.
High rates of oral cancer are destroying the lives of many who buy betel nuts, often decades after their first taste.
Now in Taiwan, where the nuts are affectionately known as 'Taiwan's chewing gum', the government is taking action to curb this centuries-old habit and reduce the thousands of lives lost each year.
The betel nut is a key part of many Asian cultures and can be consumed dried, fresh or wrapped up in a package known as a quid.
Although the exact preparation varies across countries and cultures, the quid is usually a mixture of slaked lime, a betel leaf and flavourings such as cardamom, cinnamon and tobacco.
Worryingly, the International Agency for Research on Cancer lists each ingredient, with the exception of cardamom and cinnamon, as a known carcinogen - or cancer-causing agent.
The slaked lime is seen as a particular problem as it causes hundreds of tiny abrasions to form in the mouth. This is thought to be a possible entry point for many of the cancer-causing chemicals.
"About half of the men here still don't know that betel nuts can cause oral cancer," says Prof Hahn Liang-jiunn, an oral cancer specialist at the National Taiwan University Hospital.
"[This is despite] Taiwan's incidence or mortality rates for oral cancer ranking among the top two or three in the world."
'I started chewing because everyone else did'
Like most people, Qiu Zhen-huang, 54, was completely unaware of the risks.
A former gravel company worker, he chewed for ten years. Twenty years after quitting, he developed the disease.
"I started chewing betel nut because everyone at work did it," says Mr Qiu.
"We shared it with each other to build good relations."
Three years ago, a small hole developed in his left cheek and in just three months, the tumour grew to the size of a golf ball and completely changed his life.
"Whatever I ate flowed out. I had a gauze pad over it. It hurt," he said.
"It affected me a lot. I was so ashamed I avoided going out."
Each year, 5,400 Taiwanese men like Mr Qiu are diagnosed with oral cancer or pre-cancerous lesions and an estimated 80 to 90% of those also chew betel nuts.
An early symptom includes white or red lesions inside the mouth, but this can rapidly progress to grotesque flesh-eating tumours.
Unlike other cancers, these are difficult to hide, leaving sufferers physically and psychologically devastated.
"It's miserable for them," says Prof Hahn.
"Sometimes, even after surgery, they still can't perform basic functions, including expressing emotions through their face because the lower jaw also has to be cut depending on the scale of the cancer."
Tackling the scourge
Luckily for Qiu Zhen-huang, his cancer was treated and his cheek reconstructed.
But the Taiwanese government is helping people detect the disease more quickly by providing around one million free screenings and funding programs to help people quit betel nuts for good.
In 2013, these measures helped cut the usage rate among men by nearly half.
Critics argue that action should have been taken much sooner as the cancer risk of betel nuts has been known since 2003.
However, pressure from those working in the industry has provided strong opposition to change.
Now the government is trying to reduce the domestic supply of betel nuts by offering subsidies to farmers to cut down their trees and plant alternative crops.
Other countries such as India and Thailand have also launched campaigns to discourage betel nut chewing.
But there is still a way to go. At a recent presentation to elementary school children of fishing industry workers, nearly all raised their hands when asked whether their parents or relatives chewed betel nuts.
And as the cancer can take up to 20 years to appear, the current changes will have come too late for many people - a fact that Mr Qiu keeps close to his heart.
"I'm one of the luckier ones."