You might have seen a bottle of murky "black lemonade" standing out next to the bright green kale concoctions and vibrant red beet blends at the juice bar lately.
Or maybe a jar of it posed in a pre-workout shot from a fitness Instagrammer.
Juice made with activated charcoal has become a popular "detox" drink over the past year or so.
Lots of people swear by it.
Yoga teacher and blogger Victoria Moore drinks charcoal lemonade once or twice a week — making her own from lemon juice, organic maple syrup, Himalayan sea salt and activated charcoal powder. She hopes to purge toxins from processed food and environmental pollution and says the drink doesn't taste as bad as it looks.
"On days when I start off with a detox drink I notice I feel more clear-headed, less stressed and more energized throughout the day," Moore says.
Food and health blogger Whitney Benjamin created a whole cleanse around activated charcoal, drinking carbon lemonade once a day when she's cleansing or up to four times a day if she notices a problem with her digestion or immune system. She says it's refreshing, and that she thinks it cleans up her gut.
"I am hoping that any toxins or undigested food particles residing in my digestive tract are absorbed via the charcoal," she says.
But what's the truth about its benefits?
"Not everybody needs a lemonade charcoal Slurpee, but for different situations, charcoal can be extremely helpful," says Judy Fulop, a naturopathic physician at the Osher Center for Integrative Medicine at Northwestern Memorial Hospital in Chicago.
Because of activated charcoal's absorbent properties, Fulop sometimes suggests capsules of the special carbon to patients — including people who have been exposed to mold and athletes who get diarrhea when running marathons. In both cases, the idea is that charcoal adheres to problematic particles, moving with them out of the gastrointestinal tract.
That absorption isn't always a good thing.
But if you swig that carbon lemonade alone, can it have the promised detoxing effects?
Other claims: black lemonade can help with hangovers, and reduce gas or bloating.
Bottom line: activated charcoal is pretty harmless in very small amounts, according to Fulop.
But she warns it could cause constipation, and turn your tongue (and your poop) black. She also recommends addressing any underlying medical problems that black lemonade might soothe with a healthcare professional.
"It's not a panacea," Fulop says.