Nigerian medical doctor and health educator Chinonso Egemba, widely known on social media as Aproko Doctor, has raised concerns about the potential health risks associated with consuming improperly processed Garri, a staple food made from cassava.

In a video released on Monday, Egemba explained that cassava contains naturally occurring compounds called cyanogenic glycosides—specifically linamarin and lotaustralin—which, during inadequate processing, can convert into hydrogen cyanide. According to him, this compound can pose serious health risks if consumed in high quantities.

“This hydrogen cyanide can start to affect certain tissues in your body,” he said in the video. “One of the things it can affect is your eye—the optic nerve and the retina.”

Citing research findings, Egemba said there is evidence suggesting a correlation between frequent Garri consumption and reduced visual sharpness. “There is even research that showed that people who drink Garri more have less visual acuity than people who don’t,” he stated.

However, he clarified that the risk is not inherent in Garri itself but in the method of preparation. According to him, when cassava is properly fermented and dried during processing, the levels of hydrogen cyanide are significantly reduced.

“During proper processing—the fermenting, drying, all the processes involved—the hydrogen cyanide that is dangerous is reduced to the lowest amount possible. So if your Garri is properly processed, it will not lead to blindness,” he said.

Egemba advised consumers to pay attention to the texture and smell of Garri, noting that properly dried and slightly sour Garri is often safer. He warned that moisture or a lack of crispness could be signs of inadequate fermentation or drying.

He also recommended purchasing only sealed Garri with certification from the National Agency for Food and Drug Administration and Control (NAFDAC), urging the agency to strengthen market surveillance.

“The most important question you should be asking when it comes to your Garri is: Who processed it? Was it processed properly?” he said.