Nutrition Diet: Which potatoes have solanine? Identifying and Avoiding the Toxin

October 30, 2025 •

4 min read

According to the National Institutes of Health, solanine poisoning is a rare but serious condition that can occur from ingesting high levels of glycoalkaloids found in potatoes. Knowing which potatoes have solanine is crucial for food safety and maintaining a healthy diet, particularly by recognizing visual and taste cues that indicate a high concentration of this natural toxin.

Quick Summary

Solanine is a natural defense compound in potatoes that increases under stress from light, heat, or damage. High levels are indicated by green skin, sprouting, and a bitter taste. Proper storage in a cool, dark place and careful preparation are key to preventing solanine accumulation and ensuring potatoes are safe to eat.

Key Points

Identify Green Skin: Green discoloration indicates light exposure and a likely increase in solanine levels, a natural potato toxin.
Discard Sprouted Potatoes: Sprouts contain a high concentration of solanine, and potatoes that have begun to sprout should be generously trimmed or discarded.
Taste for Bitterness: A bitter flavor is a reliable sign of high solanine content. If a potato tastes bitter after cooking, do not eat it.
Store in a Cool, Dark Place: To prevent solanine build-up, store potatoes in a cool, dark, and dry environment, like a pantry or cellar.
Peeling is Key: Since solanine is concentrated in the skin, peeling can significantly reduce the toxin level, particularly in potatoes with minor greening.
Cooking is Not a Solution: Solanine is heat-stable and is not effectively removed by boiling, baking, or microwaving. Rely on peeling and discarding affected parts instead.
Watch for Damage: Bruised or damaged potatoes may have higher solanine concentrations due to the plant's stress response.

What Exactly is Solanine?

Solanine is a type of glycoalkaloid, a naturally occurring toxin found in plants of the nightshade family, which includes potatoes, tomatoes, and eggplants. In potatoes ($Solanum tuberosum$), solanine acts as a defense mechanism against pests and diseases. Normally, the concentration of solanine in healthy, properly stored potatoes is very low and considered safe for human consumption. However, under certain conditions, the level of this toxin can increase significantly, turning a nutritious food into a potential health risk.

How Solanine Levels Increase in Potatoes

High solanine levels are not linked to a specific potato variety but rather to environmental and storage factors. The conditions that can cause a potato to produce more solanine are well-documented.

Exposure to Light: The most common trigger for solanine production is exposure to light, which also causes the potato to produce chlorophyll, the harmless green pigment. While the green color itself isn't toxic, it serves as a strong indicator that solanine levels may also be elevated, as both are stimulated by the same conditions.
Mechanical Damage: Bruising, cuts, and other physical injuries to potatoes, which can occur during harvest or transport, cause the plant to produce more glycoalkaloids as a stress response.
Sprouting: As potatoes age and begin to sprout, their solanine content naturally increases, concentrating in the sprouts and the area around them.
Improper Storage: Storing potatoes in warm or humid conditions, rather than a cool, dark, and dry place, can accelerate sprouting and greening, leading to higher solanine levels.

Identifying and Handling Potatoes with High Solanine

Identifying a potato with elevated solanine is crucial for preventing illness. There are several clear signs to look for:

Green Discoloration: Any greening on the skin or just under it indicates light exposure and a probable increase in solanine. This is the most visible warning sign.
Sprouts or 'Eyes': Potatoes that have started sprouting contain higher levels of the toxin and should be generously trimmed.
Bitter Taste: A bitter or off-putting flavor is a more direct and reliable indicator of high glycoalkaloid content than greening alone. If a cooked potato tastes bitter or causes a burning sensation in your mouth, do not eat it.
Visual Damage: Bruised or damaged spots are areas where the potato has attempted to protect itself by producing more of the toxin.

Safe Handling and Storage Practices

Follow these tips to minimize your risk of solanine exposure:

Store in Darkness: Always keep potatoes in a cool, dark place, away from sunlight and artificial light, to prevent greening and sprouting.
Inspect Before Cooking: Before preparing, thoroughly check each potato for green spots, sprouts, and damage. Discard any potatoes that are extensively green or have a strong bitter taste.
Generously Peel and Trim: If a potato has only a few small green spots or sprouts, peel the skin and cut away the affected areas with plenty of margin. Since solanine is concentrated in the outer layer, peeling can remove 30–80% of the toxin.
Avoid Damaged Potatoes: Do not use bruised or damaged potatoes. Even if the visible damage is removed, higher solanine levels may exist in the rest of the tuber.
Do Not Reuse Cooking Water: Since solanine is water-soluble, some of the toxin can leach into the cooking water when boiling. Discard this water after cooking.
Peel for Children: Because children have smaller bodies and are more sensitive to toxins, it is best to always serve them peeled potatoes.

Effects of Cooking on Solanine

Many people wonder if cooking can destroy solanine. The short answer is that cooking is not a reliable method for removing this toxin. Solanine is heat-stable and only breaks down at very high temperatures (over 170°C or 338°F), and even then, some remains. Peeling and careful trimming are far more effective at reducing the risk. Frying potatoes at high heat (210°C/410°F) for ten minutes may reduce solanine by about 40%, but milder methods like boiling and microwaving have a negligible effect. Therefore, relying on cooking alone is a dangerous mistake.

Comparison: Safe vs. High-Solanine Potatoes


Characteristic	Low Solanine Potato (Safe)	High Solanine Potato (Risky)
Appearance	Uniform, healthy skin color, no greening.	Greenish patches on the skin, indicating light exposure.
Taste	Neutral, earthy flavor.	Distinctly bitter or burning sensation, especially in the mouth.
Sprouts/Eyes	Few, small, or no sprouts; firm texture.	Long, numerous, or shriveled sprouts.
Storage	Stored in a cool, dark, and dry environment.	Found near windows, in sunlight, or in warm, humid areas.
Damage	Undamaged, firm, and blemish-free.	Bruises, cuts, or soft, damaged spots.

Conclusion: The Final Word on Potato Safety

Ultimately, potatoes do not naturally contain dangerous levels of solanine, and no particular type of potato is inherently high in the toxin. The risk is created by environmental factors and improper handling. To safely enjoy potatoes as part of a nutritious diet, focus on proper storage and preparation. Discard any potatoes that show significant greening or sprouting, and if a cooked potato tastes bitter, err on the side of caution and throw it out. With careful attention, you can enjoy all the benefits of this versatile vegetable without worry.

For more detailed information, consult the resource on glycoalkaloids in potato tubers from the Oregon State University Extension Service.

Frequently Asked Questions

Symptoms of solanine poisoning primarily include gastrointestinal issues like nausea, vomiting, stomach cramps, and diarrhea. In severe cases, it can cause neurological problems such as headaches, hallucinations, and paralysis.

Not necessarily, as the green color comes from harmless chlorophyll, but it signals that the potato has been exposed to light, which also increases the toxic solanine level. If a potato is green, it's best to either peel it generously and trim the green parts or discard it entirely if the greening is extensive.

Peeling is an effective way to reduce solanine levels, as the toxin is most concentrated in the skin. However, if the potato has extensive greening or tastes bitter, the risk may extend deeper into the flesh, and it's safer to discard it.

You can, but you must completely and generously cut away the sprouts and the area around them, as solanine concentrates there. If a potato is heavily sprouted or shriveled, it's safer to throw it away.

Store potatoes in a cool, dark, and dry place, such as a pantry or cellar. Avoid storing them in direct light or in the refrigerator, as low temperatures can also increase solanine production.

No, solanine is heat-stable and not reliably destroyed by common cooking methods like boiling or microwaving. While very high-heat frying can reduce levels slightly, it is not a safe way to deal with high-solanine potatoes.

The skin of potatoes, especially new ones, often contains a higher concentration of solanine than the flesh. While safe in low concentrations, consuming peels from green or damaged potatoes is riskier.

No, sweet potatoes are from a different plant family and do not contain solanine. Solanine is specific to members of the nightshade family, including regular white potatoes.