Are Green Potatoes Toxic? Safety, Risks, and How to Handle Them

If you’ve ever noticed green patches on your potatoes and wondered whether they’re safe to eat, you’re not alone. Green potatoes are a common concern for home cooks, and for good reason. The green coloration can indicate the presence of potentially harmful compounds that may affect your health if consumed in large quantities.

Understanding what causes potatoes to turn green, the associated health risks, and how to properly handle them can help you make informed decisions about food safety in your kitchen. This comprehensive guide will explain everything you need to know about green potatoes and whether they pose a real danger to your health.

What Causes Potatoes to Turn Green?

The greening of potatoes is a natural biological process that occurs under specific environmental conditions. When potatoes are exposed to light—whether natural sunlight or artificial lighting—they begin producing chlorophyll, the same green pigment found in leafy vegetables and other plants.

Chlorophyll itself is completely harmless and is the same compound that gives spinach, kale, and other green vegetables their color. In potatoes, this pigment develops as a protective response to light exposure, turning the flesh or skin from its normal white, yellow, or brown color to various shades of green.

This process can occur in potatoes of all varieties, though it’s more visible in lighter-skinned varieties. In potatoes with naturally dark or red skin, the greening may be less obvious from the outside but can still occur beneath the skin. You can check for hidden greening by gently scratching the surface of a dark potato to see if green coloration appears underneath.

The greening process is closely related to photosynthesis, the mechanism plants use to convert light energy into food. While chlorophyll production itself isn’t dangerous, the conditions that trigger it also stimulate the production of other compounds in the potato—some of which can be toxic to humans.

Understanding Solanine: The Toxic Compound in Green Potatoes

The real concern with green potatoes isn’t the chlorophyll but rather a toxic compound called solanine. Solanine belongs to a family of compounds known as glycoalkaloids, which potatoes produce naturally as a defense mechanism against insects, fungi, and bacteria.

Under normal conditions, potatoes contain low levels of solanine, primarily concentrated in the skin and eyes (sprouts). However, when potatoes are exposed to light, physical damage, or improper storage conditions, solanine production increases significantly—often in conjunction with chlorophyll production.

It’s important to understand that greening and solanine production are related but separate processes. While they typically occur together under the same conditions, a green potato doesn’t always contain dangerous levels of solanine, and a potato with high solanine levels isn’t always visibly green. However, the green color serves as a useful warning sign that solanine levels may be elevated.

Solanine is concentrated most heavily in the skin, sprouts, and any green portions of the potato. It has a distinctly bitter taste and can cause a burning or tingling sensation in the mouth and throat—nature’s warning system to stop eating the contaminated food.

Health Risks: How Toxic Are Green Potatoes Really?

The toxicity of green potatoes depends entirely on how much solanine they contain and how much you consume. In small amounts, solanine is generally harmless, as the human body can process and eliminate small quantities without issue. However, consuming potatoes with high solanine concentrations can lead to poisoning symptoms.

Common symptoms of solanine poisoning include:

• Nausea and vomiting
• Diarrhea and abdominal cramping
• Headaches and dizziness
• Excessive sweating
• Fever and confusion in severe cases
• Burning sensation in the mouth and throat

The severity of symptoms depends on several factors, including the amount of solanine consumed, individual body weight, and personal sensitivity. Children are particularly vulnerable due to their smaller body size and may experience symptoms from smaller amounts of solanine.

The good news is that serious cases of solanine poisoning are extremely rare in modern times. Food safety regulations in the United States and other developed countries set strict limits on acceptable solanine levels in commercially sold potatoes. The FDA limits glycoalkaloids to 200-250 milligrams per kilogram of raw potato, significantly below the levels that would cause severe illness in most people.

Research suggests that the toxic dose of solanine is approximately 1 milligram per kilogram of body weight, though this can vary between individuals. For context, this means a 150-pound person would need to consume about 68 milligrams of solanine to experience symptoms—roughly equivalent to eating a pound of potatoes with moderately elevated solanine levels.

Most cases of solanine exposure result in mild, temporary digestive symptoms that resolve on their own within 24 hours without medical treatment. Severe poisoning cases resulting in hospitalization or death are exceptionally rare and typically involve consumption of extremely large quantities of improperly stored or damaged potatoes.

How to Identify Potentially Dangerous Potatoes

Being able to recognize potatoes with potentially harmful solanine levels is an important food safety skill. Here are the key warning signs to look for:

Visual indicators: The most obvious sign is green coloration anywhere on the potato—skin or flesh. Even small green spots can indicate elevated solanine levels. Also check for sprouts or “eyes” beginning to grow, as these areas contain higher solanine concentrations.

Texture and condition: Potatoes that are wrinkled, soft, or show signs of damage or decay may have elevated solanine levels. Physical damage triggers increased solanine production as a defense response.

Taste test: If a cooked potato tastes unusually bitter or causes a burning sensation in your mouth, this is a strong indicator of high solanine content. Do not continue eating potatoes with these characteristics.

Smell: While solanine itself doesn’t have a strong odor, potatoes with very high levels may smell slightly off or musty.

Safe Preparation Methods for Green Potatoes

If you discover that your potatoes have small green spots or areas, you don’t necessarily need to throw them away immediately. Proper preparation can significantly reduce solanine content and make them safe to eat.

Peeling and Trimming

The most effective way to reduce solanine in green potatoes is through careful peeling and trimming. Studies show that peeling can remove 25-75% of the solanine content, as it’s primarily concentrated in and just beneath the skin.

When preparing potatoes with green areas:

• Peel the entire potato, removing all skin and a generous layer of flesh beneath
• Cut away any green-colored flesh, going at least 1/4 inch beyond the visible green area
• Remove all eyes, sprouts, and any damaged or bruised areas
• Discard the peels and trimmings where children or pets cannot access them

Cooking Methods

Cooking can further reduce solanine levels in potatoes, though it doesn’t eliminate them completely. Different cooking methods have varying effects:

Boiling: This method can reduce solanine levels, particularly if you discard the cooking water. Some solanine leaches into the water during boiling.

Baking and roasting: High-temperature cooking methods can break down some solanine, though they’re less effective than boiling at removing it.

Frying: While frying does reduce solanine somewhat, it’s generally less effective than other methods.

Microwaving: Similar to other cooking methods, microwaving can reduce solanine levels but won’t eliminate them entirely.

Remember that cooking cannot make a severely green or bitter potato safe to eat. If a potato is green throughout or still tastes bitter after cooking and proper preparation, it should be discarded.

When to Throw Away Green Potatoes

Not all green potatoes can be salvaged. Here are situations where you should discard potatoes without attempting to prepare them:

• The potato is extensively green, with green coloration covering more than 25% of the surface
• Green areas extend deep into the flesh of the potato
• The potato has numerous large sprouts
• After cooking, the potato tastes bitter or causes mouth irritation
• The potato shows signs of rot, excessive wrinkling, or soft spots in addition to greening
• You’re preparing food for young children, pregnant women, or individuals with compromised immune systems—in these cases, err on the side of caution

The small cost of discarding a questionable potato is far preferable to the risk of foodborne illness.

Proper Storage to Prevent Greening

Prevention is the best approach to dealing with green potatoes. Proper storage can prevent greening and solanine production, keeping your potatoes safe and fresh for weeks or even months.

Ideal Storage Conditions

Potatoes require specific conditions to remain in optimal condition:

Temperature: Store potatoes in a cool environment between 45-50°F (7-10°C). This is warmer than refrigerator temperature but cooler than average room temperature. A basement, root cellar, or unheated garage can be ideal.

Darkness: Light is the primary trigger for greening and solanine production. Store potatoes in complete darkness or in opaque containers.

Humidity: Moderate humidity (around 80-90%) prevents potatoes from drying out and shriveling while not promoting rot.

Ventilation: Good air circulation prevents moisture buildup and reduces the risk of mold and decay.

Storage Mistakes to Avoid

Refrigeration: Despite common belief, refrigerators are too cold for potato storage. Cold temperatures below 40°F can actually increase solanine production in some varieties and also convert starches to sugars, affecting flavor and texture.

Plastic bags: Storing potatoes in sealed plastic bags traps moisture and can lead to rot. Use paper bags, cardboard boxes, or mesh bags instead.

Near onions: Both potatoes and onions release gases that can accelerate spoilage in the other. Store them separately.

In direct light: Never store potatoes on countertops or in areas exposed to natural or artificial light.

Washing before storage: Moisture promotes decay. Only wash potatoes immediately before use.

Practical Storage Solutions

If you don’t have ideal storage conditions, consider these alternatives:

• Keep potatoes in a paper bag in the coolest, darkest cabinet or drawer in your kitchen
• Purchase smaller quantities more frequently rather than buying in bulk
• Use opaque containers with ventilation holes
• Monitor stored potatoes regularly and remove any showing signs of sprouting, greening, or decay

Shopping Tips: Selecting Safe Potatoes

Your first defense against green potatoes starts at the grocery store or farmers market. When purchasing potatoes:

• Inspect each potato individually for green coloration, sprouts, or damage
• Choose potatoes that are firm, smooth, and free of soft spots
• Avoid potatoes displayed under bright lights or in clear packaging exposed to light
• Select potatoes stored in cool, dark areas of the store
• Check the bottom of bags or bins where damaged potatoes might settle
• Purchase from reputable sources that practice proper potato storage
• When buying in bulk, plan to use them quickly or ensure you have proper storage conditions

Special Considerations for Different Potato Varieties

Different potato varieties can have varying baseline levels of glycoalkaloids and different susceptibilities to greening:

Russet potatoes: These have relatively low baseline solanine levels and show greening clearly due to their light skin.

Red and purple potatoes: The dark pigmentation can hide greening, so check carefully by scratching the surface or inspecting cut surfaces.

Yellow potatoes: Varieties like Yukon Gold can develop green tints that may be less obvious than in white potatoes.

New potatoes: These young potatoes typically have thinner skins where solanine can concentrate more readily.

Regardless of variety, the same safety principles apply: look for green coloration, trim thoroughly, and discard if extensively green or bitter-tasting.

Myths and Facts About Green Potatoes

Myth: All green potatoes are dangerous and must be thrown away.
Fact: Potatoes with small green spots can usually be made safe by thorough peeling and trimming.

Myth: Cooking completely removes solanine from potatoes.
Fact: While cooking reduces solanine levels, it doesn’t eliminate them entirely. Severely green potatoes remain unsafe even after cooking.

Myth: You can tell if a potato has dangerous solanine levels just by looking at it.
Fact: While greening indicates possible solanine presence, taste is a more reliable indicator—bitter flavor means high solanine levels.

Myth: Solanine poisoning is common and often fatal.
Fact: Serious solanine poisoning is extremely rare, and fatal cases are nearly unheard of in modern times due to food safety regulations.

Myth: Chlorophyll in green potatoes is toxic.
Fact: Chlorophyll itself is harmless—it’s the solanine that often accompanies it that can be problematic.

What to Do If You Suspect Solanine Poisoning

If you or someone in your household experiences symptoms after eating potatoes that may have been green or bitter:

• Stop eating the potato immediately
• Drink plenty of water to help flush your system
• Monitor symptoms—mild digestive upset typically resolves within 24 hours
• Rest and avoid other hard-to-digest foods
• Seek medical attention if symptoms are severe, worsen, or don’t improve after a day
• Call poison control (1-800-222-1222 in the United States) if you’re concerned about the severity
• Keep a sample of the potato if possible for identification purposes

Children, elderly individuals, or those with compromised health should be monitored more closely and may need medical evaluation sooner.

Frequently Asked Questions

Can you get sick from eating a small amount of green potato?

Most people won’t experience symptoms from eating a small amount of green potato, especially if it’s been properly peeled and cooked. However, sensitivity varies, and children may be more susceptible. When in doubt, it’s better to err on the side of caution.

How long does it take for potatoes to turn green?

Potatoes can begin showing green coloration within a few days of light exposure, though the timeframe varies depending on the intensity of light, temperature, and potato variety. This is why proper storage immediately after purchase is important.

Are organic potatoes less likely to turn green?

No, organic and conventional potatoes have the same biological response to light exposure. Both will produce chlorophyll and potentially solanine when exposed to light or stored improperly.

Can animals eat green potato scraps?

No, solanine is toxic to most animals including dogs, cats, horses, and livestock. Potato scraps with green areas or sprouts should be disposed of where animals cannot access them.

Do sweet potatoes turn green and produce solanine?

Sweet potatoes are not actually related to regular potatoes and do not produce solanine. If a sweet potato appears green, it’s usually just a natural color variation and is safe to eat.

The Bottom Line on Green Potato Safety

Green potatoes do contain a potentially toxic compound called solanine, but the risk can be effectively managed through awareness and proper handling. The green color serves as a helpful visual warning that solanine levels may be elevated, though it’s not a perfect indicator.

For most people, following these simple guidelines will ensure potato safety:

• Inspect potatoes before purchase and regularly during storage
• Store potatoes in cool, dark, well-ventilated conditions
• Peel and trim away any green areas, sprouts, and damaged portions
• Cook peeled potatoes thoroughly
• Never eat potatoes that taste bitter or cause mouth irritation
• Discard potatoes that are extensively green or heavily sprouted

The vast majority of potatoes available in stores are safe to eat, and serious solanine poisoning is exceptionally rare. With proper storage, preparation, and common sense, you can confidently enjoy potatoes while minimizing any potential health risks.

When in doubt, remember that the cost of discarding a questionable potato is minimal compared to the discomfort of potential illness. Trust your senses—if a potato looks extensively green, smells off, or tastes bitter, it’s better to throw it away than risk consuming elevated solanine levels.

Sources:

• National Center for Biotechnology Information – Potato Glycoalkaloids
• Nature – Scientific Reports on Solanine
• PubMed – Chlorophyll and Glycoalkaloid Production
• USDA – Green Potato Safety
• Missouri Poison Center – Potato Safety Information
• Food Safety Authority of Ireland – Green Potatoes