Do potatoes and onions stored together release toxic chemicals?

Kerala has numerous curries that use potatoes and spices together as ingredients. They are also used as fried, steamed, sautéed, and even powdered forms in many preparations across our country and beyond. Still, a video claiming that storing these vegetables together is dangerous often circulates on our social media platforms. The video is even accompanied by claims that it has led to the deaths of several children. What's the truth behind it?

The viral claim
The social media video shows visuals of children lying on hospital beds and floors, with adults seen wailing nearby. It alleges that ethylene gas released by onions reacts with potatoes, causing them to sprout rapidly and produce `toxic chemicals' such as solanine and chaconine. It further claims that consuming such potatoes can lead to ulcers, gastric inflammation, food poisoning and nervous system failure and that this could prove fatal for children. The video also includes screenshots of a report purportedly published by the Dainik Bhaskar, a while ago. That said, the video states that the visuals of children lying on hospital beds and the scenes of adults wailing are unrelated to one another. 

Credibility of the reports
To verify the claims, our fact-check team conducted an initial keyword-based search. However, they found no credible reports from anywhere indicating that children had died after consuming sprouted potatoes stored near onions. This clearly shows that the viral video has no factual link to the claims made in the post. 

We then examined studies on whether onions release ethylene gas. Research by the United States National Centre for Biotechnology Information confirms that onions do emit ethylene gas, which can affect nearby produce. Potatoes naturally contain glycoalkaloids such as solanine and chaconine, especially in the skin and sprouted portions. When consumed in large quantities, these compounds can be toxic to humans.

When are they toxic
According to reports by the European Food Safety Authority, symptoms of poisoning have been reported in humans not with moderate consumption, but when such compounds are ingested in excessive amounts. Other studies have also documented symptoms of human poisoning linked to the consumption of green coloured or damaged potatoes. 

Further searches revealed that the Dainik Bhaskar article featured in the viral video cites the National Capital Poison Centre, a US-based organisation. According to the organisation, fresh potatoes that have not sprouted are safe to consume, while green or sprouted potatoes are best avoided. The report explains that green or sprouted potatoes may contain higher levels of two naturally occurring toxins, solanine and chaconine, which is why they are considered unsafe.

What health experts say
The health experts we spoke to explained that sprouted or green potatoes can produce natural compounds known as glycoalkaloids, mainly solanine, which serve as a plant’s natural defence mechanism. These compounds tend to increase when potatoes are stored for long periods or begin to sprout. When consumed in large quantities, they can irritate the stomach and, in rare cases, cause more serious symptoms. However, experts emphasised that an average person is unlikely to fall ill from accidentally consuming one or two sprouted potatoes. What is generally advised is to avoid potatoes with green skin or deep sprouts as a precaution.

Based on the available evidence, it is clear that onions do release ethylene gas and that green or sprouted potatoes may contain glycoalkaloids. Consuming large quantities of green or sprouted potatoes may pose health risks. However, the claim that storing onions and potatoes together is dangerous or that it has caused deaths is false. The visuals circulated alongside this claim are unrelated and misleading.