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Can you Eat Green Potatoes? Dangers and Symptoms

By Liam McAuliffe Updated on

Have you ever come across a potato with a green tint? While this may seem harmless, green potatoes can actually be dangerous to consume. 

The green color means that a plant toxin called solanine is present. It’s produced when potatoes are exposed to light for extended periods of time. 

In this article, we’ll explore the science behind green potatoes and the potential health risks associated with consuming them. 

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A Story of Green Potato Poisoning

It was a lovely autumn day in South London in 1979 when suddenly 78 schoolboys and their monitors fell violently ill

Some were vomiting, others keeled over with abdominal pain or rushed to the toilet with diarrhea. A few soon became totally incapacitated, went comatose, or convulsed violently. 

After a few hours, a few of the boys had to be rushed to the emergency room as parts of their circulatory systems shut down. Days later a few students were still suffering hallucinations. 

The good news is that eventually, all the boys and their caretakers recovered. 

What caused this horror show of maladies? The humble green potato. Or, more accurately, an entire bag of humble green potatoes that had been stored improperly since the previous summer.

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Why do Potatoes Get Green? 

The green hue that potatoes can get is from chlorophyll. It forms through photosynthesis when potatoes are exposed to light. AKA when they’re improperly stored. Traditionally, potatoes were stored underground in root cellars to protect them from light exposure. 

Ironically, chlorophyll isn’t toxic. Rather, it’s a sign that natural plant defenses called glycoalkaloids that form alongside chlorophyll are present. In green potatoes, these compounds are solanine and chaconine. 

These plant toxins are found most concentrated in the skin, sprouts (eyes), and around any blemishes. But they can also be found in the flesh just beneath the skin, as studies of the schoolboy poisoning revealed.

How Many Green Potatoes Does It Take to Harm You? 

After reading the anecdote above, you may be wondering just how poisonous green potatoes can be. 

The amount of green potatoes it takes to cause poisoning depends on things like your age, body weight, and overall health. 

Some people can experience symptoms of toxicity from consuming as little as 1 mg of solanine per kilogram of their body weight. And 3 milligrams per kilogram (2.2 pounds) can be enough to kill.

This comes out to around 68 milligrams of solanine to produce toxicity symptoms in a 150-pound person. For that same person, 302 mg can be a fatal dose.

The chart below lists the chaconine and solanine levels in popular potato products.

POTATO CHIPS (1 OZ BAG).36-.88 mg.29-1.4 mg 2.7 -12.4 mg/ 28 gram bag
FRIED POTATO SKINS (4 OZ)4.4-13.6 mg2.0-9.5 mg6.4- 23.1 mg/4 oz

It’s worth noting that the American Food and Drug Administration has not established upper levels of solanine allowed in foods. But Health Canada has determined a maximum of 20 mg per 100 grams of potatoes.   

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How do Green Potatoes Affect the Body?

When you consume green potatoes, the solanine can enter the bloodstream, where it weakens and breaches the membranes of red blood cells. Once within the cells, the solanine destroys the part of the cell that creates its energy–the mitochondria. 

This cell-rupturing process is one of the factors linking solanine intake with a condition called intestinal permeability. ]

Intestinal permeability, AKA “leaky gut,” is identified as one of the root causes of systemic inflammation and autoimmune disorders. When your gut lining is compromised, pathogens, including solanine itself, easily enter the bloodstream and are carried throughout the body. 

Though low-level exposure to toxins in green potatoes is not likely to cause acute toxicity, consuming small doses of plant toxins over time can lead to them accumulating in your body. This is especially true for solanine which studies show takes a long time for your body to break down and eliminate.

In addition to your intestinal membrane, solanine can damage another lesser-known but equally important membrane called the glycocalyx. This thin hair-like membrane surrounds every cell in your body, and the health of the glycocalyx is linked to critical bodily functions from heart health to fertility. 

Not surprisingly, animal studies have found that consuming glycoalkaloids, including solanine, can cause birth defects.  

Symptoms of Green Potatoe Poisoning 

Consuming 1 kg of green, damaged, and/or sprouting potatoes can result in acute symptoms of solanine poisoning. 

Mild to moderate solanine poisoning is associated with symptoms, including

  • Headache
  • Vomiting
  • Diarrhea
  • Apathy
  • Restlessness
  • Drowsiness
  • Fever
  • Low blood pressure
  • Weakness
  • Tremors

Symptoms of extreme solanine poisoning include

  • Birth defects, including spina bifida
  • Heart failure
  • Death

Cognitive impairments associated with solanine poisoning include

  • Confusion
  • Rambling
  • Incoherence
  • Stupor
  • Hallucinations
  • Dizziness
  • visual disturbances 

What Do You Do with Green Potatoes?

To avoid exposure to plant toxins from green potatoes, it’s best simply to discard them. Potatoes are inexpensive and easy to find for most people. 

Though the USDA states that it’s okay to consume green potatoes as long as you peel the skins, remove the sprouts, and slice away any green color, it’s better not to risk it. 

It’s worth noting that if you improperly prepare green potatoes or simply miss some areas where solanine is present, it is neutralized by cooking like other food contaminants. 

One way to tell if solanine is present in a cooked potato is to be aware of the bitter flavor–the more bitter, the more likely the potato is contaminated. 

How to Properly Store Potatoes?

As we touched on above, root cellars have existed for thousands of years because roots must be stored in cool, dark environments. 

We’re talking zero light and a temperature between 45º to 50º Fahrenheit. 

Though potatoes can be stored for months, It’s best to consume potatoes within 3 to 5 weeks at the very longest. 

And since there’s no way to know how long store-bought potatoes have been sitting in industrial “root cellars” before you purchased them, it’s best to seek fresh potatoes from local farmers and farmer’s markets. 

Green Potatoes: The Bottom Line

When it comes to potatoes, green does not mean go!

The green color of potatoes is a sign of the presence of solanine–a potentially harmful plant toxin. 

If you eat a lot of green potatoes at once, you can experience symptoms including nausea, vomiting, diarrhea, and more severe reactions like hallucinations, convulsions, and, in the worst cases, even death. 

Low-dose chronic exposure to green potato toxins can damage your intestinal lining, opening the way for widespread systemic inflammation. 

To reduce the risk of consuming green potatoes, store them in a cool, dark place and eat only fresh potatoes. It’s always a good idea to inspect all potatoes and make sure there are no green hues and that all sprouts have been removed.

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