The activated charcoal food trend is lit, but safe?

(AP Photo)

(AP/Meredith) -- At a recent food fest in San Francisco, charcoal was added to everything from corn dogs to cookie dough - part of a trend toward charcoal-tinted food.

"Food that's normally a certain color, you turn it jet black and people go crazy over it," said Cole Mayer of DOUGHP Cookie Dough.

Often made from burning coconut shells or bamboo, adding activated charcoal powder to foods has captured the attention of social media.

"The charcoal came right after the unicorn rainbow trend and people were like, we're done with the whole rainbow thing. We want black," said Laura Athuil of Choux Bakery

Charcoal doesn't seem to change the taste of food, but it can affect the texture.

"I wouldn't say grit but a heartier, chunkier taste," said festival customer, Shea Steinbacher.

But for many charcoal enthusiasts before tasting, snapping a photo first is the priority before eating.

"That's how it works. Photos first," declared Carla Sigua, as she prepared to dig in to her carefully chosen charcoal samples.

"Don't touch it. Let me fix it, then dig in after that."

But is eating charcoal safe? Doctors do prescribe activated charcoal to treat poisoning and overdoses. But they say eating too much on your own can cause severe constipation and other health problems.

"If someone takes medication within two hours of taking activated charcoal, the effectiveness could be greatly reduced or completely reduced. Also, when it's added to all these foods, essentially a person isn't getting any nutrients out of those foods because the vitamins and minerals are being absorbed or held onto by the activated charcoal," Akilesh Palanisamy, an integrative medicine specialist at Sutter Health.

In June, the New York City Health Department banned charcoal in food because of those concerns, but so far there are no other reports of other cities following suit.