You’re browsing the grocery store and you end up in the root vegetables section as you’re gearing up for some fall recipe classics. Your gaze lands on the potatoes, and you contemplate whether to bag the mini varietals or stick with good ol' russets, but then something catches your eye—Yukon Gold potatoes with a touch of green coloring to them. Wait, green potatoes? What gives?

Before you write them off as an act of nature and bag them anyway, take a moment to learn about why you might come across green potatoes and how safe it is to consume them. 

Why are my potatoes turning green? 

Isabelle Huang

As you've probably learned in your high school biology class, chlorophyll is the main pigment found in plants that makes them green. The compound uses energy from the sun during photosynthesis. While potatoes themselves aren't usually green, when exposed to enough sunlight, chlorophyll begins to work its way onto the surface.

Meanwhile, solanine, a chemical naturally found in potatoes and in the nightshade family, thrives 

Solanine helps contribute flavor to potatoes and acts as the tuber's natural defense against the environment. However, eating potatoes with too much of this chemical can prove toxic to the body, an illness termed "green potato poisoning."

People with green potato poisoning often face gastrointestinal distress, such as: nausea, vomiting, diarrhea, and in more extreme cases delirium, shock and paralysis. Doesn't sound too fun, does it?

If the skin is too green, can't I just peel it?

Helena Lin

The short answer is no. While solanine is more active in the skin, the compound might have penetrated into the main body of the potato without you knowing. If the flesh of the potato is green, raise the red flags. But let's not wait to find that out later, and just eliminate the option all together.

Unfortunately, while many toxins can be inactivated by heating, solanine is not. It only takes 2 mg of it to get the average person's stomach turning. Whether you are boiling or roasting the tubers, solanine is there to stay. 

How can I prevent potatoes from greening?

Isabelle Huang

If you've already shirked the option of purchasing green potatoes, there's still the danger of them turning. The best thing you can do is to store your potatoes in a cool, dark environment far away from sunlight alongside some other best-in-the-pantry foods.

Just remember, green potatoes = higher solanine content. If potatoes are a regular staple in your diet, be sure to inspect before you buy. It's better to be safe than sorry.