Why Do Sprouted Potatoes Become Toxic? What You Need to Know Before Eating Them

Potatoes are one of the world's most popular foods, but when they begin to sprout, many people wonder whether they're still safe to eat. While small sprouts don't instantly make a potato poisonous, sprouting is a sign that the potato is producing higher levels of natural toxins that can be harmful if consumed in large amounts.

Here's why sprouted potatoes become potentially toxic and how to handle them safely.

1. Potatoes Naturally Contain Glycoalkaloids

Fresh potatoes naturally contain compounds called glycoalkaloids, primarily:

• Solanine

• Chaconine

These natural chemicals help protect the potato from insects, fungi, and other pests.

In healthy potatoes, glycoalkaloid levels are usually low enough to be considered safe for consumption.

2. Sprouting Triggers an Increase in Toxins

When a potato begins to sprout, it starts using stored nutrients to grow new shoots.

During this process, the concentration of glycoalkaloids—especially solanine—increases, particularly around:

• The sprouts.

• The eyes of the potato.

• The skin.

• Green areas exposed to light.

As toxin levels rise, the potato becomes less safe to eat.

3. Sunlight Makes the Problem Worse

Exposure to sunlight or bright indoor light causes potatoes to produce chlorophyll, turning parts of the potato green.

Although chlorophyll itself is harmless, green potatoes often contain increased levels of glycoalkaloids.

For this reason, a green potato is a warning sign that toxin levels may also be elevated.

4. Solanine Is Heat-Stable

Unlike many bacteria, solanine is not easily destroyed by cooking.

Boiling, baking, frying, or microwaving will not completely eliminate the toxin.

This means cooking a heavily sprouted or green potato does not necessarily make it safe to eat.

5. Eating Too Much Solanine Can Cause Poisoning

Consuming potatoes with high levels of glycoalkaloids may lead to food poisoning.

Possible symptoms include:

• Nausea.

• Vomiting.

• Stomach pain.

• Diarrhea.

• Headache.

• Dizziness.

Symptoms usually appear within several hours after eating contaminated potatoes.

6. Severe Cases Are Rare but Possible

Although uncommon, consuming very high amounts of glycoalkaloids may affect the nervous system.

Serious symptoms can include:

• Confusion.

• Weakness.

• Low blood pressure.

• Difficulty breathing.

• Seizures in extremely rare cases.

Children are generally more vulnerable because of their smaller body size.

7. Small Sprouts May Not Always Mean You Must Throw the Potato Away

If the potato is still:

• Firm.

• Not green.

• Free of mold.

• Only has tiny sprouts,

it may be possible to remove the sprouts, eyes, and a generous portion of the surrounding flesh before cooking.

However, if the potato is heavily sprouted, green, shriveled, soft, or has a bitter taste, it is safest to discard it.

8. Bitter-Tasting Potatoes Should Never Be Eaten

A bitter or burning taste is often a sign of elevated glycoalkaloid levels.

If a potato tastes unusually bitter, stop eating it immediately.

9. Proper Storage Helps Prevent Sprouting

To reduce sprouting, store potatoes:

• In a cool place (about 45–50°F or 7–10°C).

• In a dark environment.

• In a dry, well-ventilated area.

• Away from direct sunlight.

Avoid storing potatoes in warm kitchens or near windows, where they sprout more quickly.

10. Don't Store Potatoes Next to Onions

Potatoes and onions release gases that can accelerate each other's spoilage.

Keeping them in separate containers may help extend their shelf life.

How to Tell If a Potato Should Be Thrown Away

Discard potatoes if they are:

• Heavily sprouted.

• Green over large areas.

• Soft or wrinkled.

• Moldy.

• Giving off an unpleasant odor.

• Bitter when tasted.

When in doubt, it's safer to replace the potato than risk food poisoning.

Can You Cut Off the Sprouts?

If the potato is still firm and has only a few small sprouts, removing:

• The sprouts.

• The eyes.

• Any green portions.

• A thick layer around the affected area

may reduce glycoalkaloid exposure.

However, this is not recommended if the potato is extensively sprouted or green, as toxins may be distributed more widely throughout the tuber.

The Bottom Line

Sprouted potatoes become potentially toxic because they produce higher levels of natural compounds called glycoalkaloids, especially solanine and chaconine. These toxins help protect the growing potato but can cause nausea, vomiting, diarrhea, and neurological symptoms if consumed in excessive amounts.

A firm potato with only tiny sprouts may sometimes be salvaged by removing the sprouts and any green areas. However, potatoes that are heavily sprouted, green, soft, moldy, or bitter should be discarded to avoid the risk of food poisoning.