How to avoid solanine poisoning from your favorite vegetables

The potato originated in present-day Chile and was first cultivated by the Incas, who developed fields and irrigation systems on the slopes of the Andes.

Today, the potato is one of the most important crops in our climate zone. It is available in over a thousand varieties that differ in the size and shape of tubers, as well as the color of the skin or flesh—ranging from light to red and even bluish-purple.

Potatoes are a rich source of starch, easily digestible proteins, and vitamins, especially vitamin C (which strengthens the immune system and protects against the harmful activity of free radicals) and B vitamins, essential for the proper functioning of the nervous system. They also contain a lot of potassium and magnesium.

Despite the presence of valuable nutrients, potatoes contain compounds that protect the plant from pest attacks and diseases but are poisonous to humans. These include steroidal glycoalkaloids, particularly solanine. What is worth knowing about them?

Glycoalkaloids, produced in various parts of the plant (flowers, leaves, sprouts, tubers), develop primarily when the potato is exposed to sunlight. They also increase when potatoes are stored at temperatures above 50°F and packaged in materials that do not protect against light or chemical agents. Visible signs of solanine expansion include green spots and young shoots on the tubers.

Due to the high consumption of potatoes, the glycoalkaloids in them are among the most common sources of toxic substances in the human diet. The consequences of poisoning, usually 7-19 hours after a meal, can include typical stomach problems: nausea, vomiting, stomach aches, headaches, colic, diarrhea, excessive sweating, and fever. Occasionally, there may also be consciousness disorders, breathing problems, heart arrhythmia, and even hallucinations.

When the concentration of solanine in the blood remains high for a long time, symptoms such as tachycardia (very fast heartbeat), neck stiffness, partial paralysis, or coma can occur. In severe poisoning cases, hospitalization may be necessary.

The harmful compound causes changes in the functioning of many important organs and the nervous system. Even if it does not initially cause serious ailments, it accumulates in the liver, kidneys, and heart, leading to their gradual degeneration. Solanine irritates the mucous membrane of the mouth, esophagus, and stomach and can cause inflammation of the liver, kidneys, or gallbladder.

The harmful dose of solanine is 2-5 mg/kg of body weight. Under normal conditions, it is hard to exceed— a person weighing 132 lb would need to consume over 2.6 lb of potatoes daily to ingest a dangerous amount of glycoalkaloid. However, considering the rapid increase of this compound in sunlit tubers, this value decreases to as little as 0.9 lb of potatoes.

According to some studies, the concentration of glycoalkaloids decreases significantly when potatoes are peeled, while cutting and most processing methods, such as boiling, baking, frying, or drying, do not significantly affect the content of these compounds, as they break down only at temperatures above 500°F.

The advice? Avoid buying potatoes with green spots or sprouts—store potatoes in cool and dark places without access to sunlight. If you observe disturbing changes on the tubers, carefully cut them out, as most solanine accumulates just under the skin.

It is worth knowing that glycoalkaloids are not only found in potatoes. Carrots, especially the part of their root that protrudes above the ground and is usually right next to the greens, can be a rich source of solanine, as indicated by the characteristic greening. Therefore, before cooking, it should be cut off.

The dangerous compound is also hidden in eggplants. This vegetable, popular in Mediterranean cuisine, is becoming increasingly common in the U.S. Alongside its rising popularity, it is important to note that eggplants should not be eaten raw due to their solanine content. It is worth peeling them and salting them before preparing them, which additionally reduces the concentration of glycoalkaloids.

Green tomatoes are also rich in such compounds, especially in tomatoes. It is advisable to avoid eating them raw, especially in larger quantities. While tomatine, like solanine, is not neutralized by thermal processing, fried, boiled, or pickled green tomatoes are considered much healthier. However, children under the age of 10 and people with hypertension should avoid eating them. A better choice for them would be ripe red tomatoes.