"Virgin boy eggs" or eggs boiled in the urine of prepubescent boys preferably under the age of 10 are a popular spring time snack in China’s northeast city of Dongyang located in the middle of Zhejiang Province.

The eggs are believed to provide remarkable health benefits such as reducing body heat, enhancing blood circulation and reinvigorating the body.

"If you eat this, you will not get heat stroke. These eggs cooked in urine are fragrant," Ge Yaohua, 51, owner of one of the most popular "virgin boy eggs" stalls, told Reuters. "They are good for your health. Our family has them for every meal. In Dongyang, every family likes eating them."

Ge, who has been making the snack for more than twenty years, sells each egg for 1.50 yuan, which is about $0.24 - twice the price of the regular eggs he also sells. He says that the "Tong Zi Dan" eggs are popular because of their fresh and salty taste.

Vendors collect buckets of the key ingredient from primary school toilets, and while there is no real explanation for why the urine has to come from young boys below the age of 10, the tradition has lasted for centuries.

It takes about a day to make these "virgin boy eggs," because they are marinated and boiled in pots of urine and after the egg is cooked, the hard-boiled eggs are then cracked and put back into pots of urine to simmer for hours. 

The vendors must keep pouring urine into the cooking pot and controlling the fire to prevent the eggs from being overheated and overcooked. 

Many of Dongyang’s residents believe in the ancestral tradition that these eggs offer medicinal qualities that treat a variety of health conditions.

"By eating these eggs, we will not have any pain in our waists, legs and joints. Also, you will have more energy when you work," Li Yangzhen, 59, who bought 20 eggs from Ge, told Reuters.

Many local residents are also known to personally collect buckets of urine of young boys from nearby elementary schools to cook the eggs at home, and due to the popularity of these unique treats, the local government has listed the "virgin boy eggs" as an intangible cultural heritage.

However, some Chinese medical experts warned about sanitary issues in using urine to cook the eggs.

Not everyone in Dongyang eats the urine-soaked eggs though, and some of the local residents even hate them.

"We have this tradition in Dongyang that these eggs are good for our health and that it would help prevent things like getting a cold," Wang Junxing, 38, told Reuters. "I don't believe in all this, so I do not eat them."