While we often think of potatoes as a harmless pantry staple, they are actually members of the infamous deadly nightshade family. Because of this biological lineage, potatoes produce natural defense chemicals called glycoalkaloids—specifically solanine and chaconine. When a potato develops a green tinge, it’s a forensic signal that these toxins are increasing. This mega-FAQ is designed to move past the “old wives’ tales” and provide a deep dive into the science of green potatoes, including how much is truly dangerous, why the toxin is there in the first place, and the best ways to keep your kitchen safe.
Potatoes, like tomatoes, are a member of the infamous deadly nightshade family. They contain solanine, which is a toxic substance. We are often told that the toxin is only in the potato plant itself, but never in the potato. This is not actually true. In reality, there are large amounts of the toxin in the plant and only small, trace amounts, in the potato, with more being in the skin, and hardly any at all in the flesh. A green tinge on a potato or just under the peel can indicate the presence of more of this toxin.
- What causes potatoes to turn green?
- Will eating a small amount of green on a potato make me sick?
- Should I remove the green part from a potato?
- Does a green color on a potato mean the potato is not ripe?
- How often do people get solanine poisoning from potatoes?
- Why is solanine toxic to humans?
- What is the Upper Safe limit of solanine?
- Does Cooking Destroy Solanine in Potatoes?
- How can you prevent a green tint from forming on potatoes?
- Why do I often find the green color on potato chips?
- Do potato eyes (sprouts) have toxic solanine?
Green Potato Mega FAQ
What causes potatoes to turn green?
The green tint that sometimes forms on potatoes is due to the production of harmless chlorophyll. But this also signals the presence of toxic glycoalkaloids like solanine and chaconine. Potatoes produce these toxins in response to sunlight or other harsh light exposure, damage, and diseases such as fungal blight or bacterial infection.
Will eating a small amount of green on a potato make me sick?
No, if you only ate a small amount of the green part from a potato then it is highly unlikely you will become ill from the small amount of solanine and chaconine you ingested. You would need to eat a large amount of potatoes with a green tinge to be in any true danger from solanine poisoning.
Should I remove the green part from a potato?
Yes, if you are going to cook a potato that has some green tint on the skin, it is best to peel away this part. The green may extend a few millimeters below the peel, so peel away all this green, too. Although you are not likely to get sick from a small amount of green on potatoes, there is a bitter taste present and it’s best to be cautious.
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Read more: Why Are Sweet Potatoes Sweet?
Does a green color on a potato mean the potato is not ripe?
The green color that sometimes forms on potatoes has nothing to do with whether the potato is ripe. There is no such thing as an unripe potato. When harvesting potatoes, some of the spuds are sometimes found exposed to the sunlight when they should be under the soil. These potatoes may be green due to the sunlight exposure. But this phenomenon has led to the myth that green potatoes are potatoes that have been harvested too soon and are unripe. This is also the origin of the term ‘sunburned potato.’
How often do people get solanine poisoning from potatoes?
We do not have exact information on the rate of solanine poisoning in humans, but it is extremely rare relative to the amount of potatoes consumed worldwide. This is because you must consume a large amount of compromised potato to be in danger from the toxin. It is possible for sub-acute toxicity to occur, which can cause some gastrointestinal symptoms like nausea or diarrhea.
Why is solanine toxic to humans?
Solanine is a problem for humans because it is an inhibitor (moderate) of acetylcholinesterase (AChE). Acetylcholinesterase is an enzyme that breaks down the neurotransmitter acetylcholine in our bodies. When AChE is inhibited, as by solanine, the levels of acetylcholine in the body increase. This can lead to the nerve cells being overstimulated, thus leading to various effects such as muscle spasms, paralysis, and even respiratory failure. This is very rare, however.
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What is the Upper Safe limit of solanine?
Estimates of the upper safe limit of solanine vary but according to this paper in the Journal of Experimental and Basic Medical Sciences, “Research has shown that doses of solanine found in potatoes ranging from 2-5 mg/kg body weight can cause toxic symptoms, while doses of 6 mg/ kg-1 body weight and above can lead to fatal outcomes.”
This means that a person weighing 60 kg/132 pounds would have to ingest 350 mg of solanine to have a fatal outcome. This is a huge amount. On the other hand, 120 to 300 mg could lead to symptoms of toxicity. Animal studies, however, have indicated that solanine is poorly absorbed.
Does Cooking Destroy Solanine in Potatoes?
Although there is some mixed evidence, it is generally accepted that regular potato cooking temperatures and durations do not degrade solanine a significant amount as solanine is quite heat stable. According to the 1990 paper, Effect of Cooking on the Contents of α-Chaconine and α-Solanine in Potatoes:
“Reduction in concentration of α-chaconine (CHA) and α-solanine (SOL), toxic glycoalkaloids in potatoes, during cooking by 3 procedures was investigated. Raw or cooked potato samples (2 g) were extracted twice with 5% acetic acid solution. The extract was purified on Sep-Pak C18 and CHA and SOL contents were determined by HPLC. Recoveries of CHA and SOL from raw potatoes were 96.5 and 98.2%, respectively, vs. 96.2 and 96.7% from cooked potatoes. >93.9% of CHA and 95.9% of SOL remained in potatoes after boiling. Contents of both were reduced by 15% on microwave treatment. On deep-frying alkaloid contents varied according to temperature. At 157°C, both alkaloids were unaffected; at 170°, potatoes showed a large variation in residual alkaloids. At 210°, alkaloids were partially decomposed; after 10 min heating, 64.9% of CHA and 59.7% of SOL remained. It is suggested that the critical temperature for decomposition of both alkaloids in potatoes may be around 170°. Results confirmed the relatively high stability of CHA and SOL in potatoes under normal home cooking conditions.”
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How can you prevent a green tint from forming on potatoes?
To prevent your potatoes from developing a green tint, store your potatoes properly. Most of the time, the reason potatoes get a green tint at home is because of exposure to light. Store your potatoes in a breathable container in a cool, dark place, like a pantry. A plain paper bag is great for storing potatoes. You can also purchase breathable cloth bags for the purpose. Do NOT store potatoes in a plastic bag!
Why do I often find the green color on potato chips?
Finding some green on potato chips/crisps is common. Sometimes you’ll find a lot of it. This happens because potatoes destined to become potato chips are sometimes stored in bad conditions and subject to prolonged exposure to light. The cooking process will not destroy all of the potential toxins, although frying at high temperatures does seem to degrade solanine better than other methods. It is quite safe to eat a couple of green potato chips. If most of the bag contains chips/crisps with green on them, it’s probably best not to eat them.
Do potato eyes (sprouts) have toxic solanine?
Yes, potato eyes, which are what we call the beginning of potato sprouts, have increased levels of solanine in them. It is best to remove any eyes or sprouts from potatoes before preparing them. This can be done by peeling the eye away or digging it out with the scoop tool at the end of a potato peeler.
Advanced Science: Understanding Potato Defense Mechanisms
While the basics of green potatoes are well-understood, these deeper scientific details explain the “why” behind the toxicity.
- Is solanine only found in the plant, never the potato? It is a common misconception that the edible root is toxin-free. While the highest concentrations are in the leaves and stems, trace amounts of solanine and chaconine are always present in the potato. A green tinge indicates these levels have spiked beyond the baseline.
- Why do potatoes turn green in response to light? Light triggers chlorophyll (the green color), but it also acts as a biological “alarm clock.” As a root, the potato’s purpose is to grow a new plant; it produces solanine as a chemical shield to discourage fungi and pests from consuming the energy stores before it can sprout.
- Does solanine build up in the human body? Whether glycoalkaloids can result in chronic sub-toxicity is still an area of active study. Because they are not always eliminated immediately, maintaining intake below the Upper Safe Limit (approx. 100–200mg) is essential for long-term safety.
Further Reading
- The Michael Pollan Fallacy: The Truth About the ‘Unpronounceable Food’ Rule
- Mold on Foods: When to Remove and Eat or Discard
- Are Today’s Fruits and Vegetables Less Nutritious?
- Acheta Powder: A Fact-Based Examination of the Cricket Protein Rumor