Solanine, Green Potatoes and Arthritis

Solanine is a toxic chemical found in members of the nightshade family, also known as the Solanaceae family. Solanine is a natural pesticide. The plants produce solanine to protect themselves from insects and fungi that might attack the plant. Solanine has been found in potatoes, tomatoes, eggplants and peppers (except for black pepper. which belongs to a different plant group). It produces unpleasant and even deadly effects in humans and has been implicated in some cases of arthritis.

Solanine is classified as a glycoalkaloid. All parts of the potato plant contain solanine, but the largest amounts are in the sprouts and in green potatoes, especially in their skin. If a potato has sprouted, all the sprouts should be removed before the potato is cooked. Green patches in potatoes represent areas where chlorophyll has been produced. Chlorophyll is the green pigment that plants use to absorb light energy and produce their food, and is safe to eat. However, the presence of chlorophyll indicates that the potato, which normally grows underground, is reacting to the presence of light. The green color is often accompanied by the production of solanine, which the exposed potato produces to protect itself from attack by pests. To complicate matters, not all green potatoes contain a high level of solanine, although the risk is greatly increased, and potatoes do not have to be green to develop a lot of solanine. The solanine will give a bitter taste to the potatoes, but even without this bitter taste you shouldn’t eat a green potato, because it may still contain enough solanine to cause harmful effects.

Solanine poisoning affects the digestive tract and the nervous system. Symptoms of mild solanine poisoning include headache, dizziness, a burning sensation in the mouth, stomach cramps, nausea, vomiting and diarrhea. Severe solanine poisoning causes drowsiness, weakness, confusion, vision problems, hallucinations, weak pulse, low blood pressure and rapid breathing. Solanine ingestion may be fatal. The symptoms of poisoning may appear within minutes after ingesting the solanine or may not appear until hours later.

Always check for green spots on potatoes before you buy them. It’s better to buy loose potatoes instead of bagged potatoes, since it’s easier to check loose potatoes for green areas. It’s also easier to check whether brown or yellow skinned potatoes have turned green than to check red or purple skinned varieties of potato. If you grow potatoes, check that they stay covered by soil as they develop. When you are storing potatoes in your home, keep them in a cool and dark place to reduce solanine formation. Once potatoes are cooked, solanine can no longer form because essential enzymes needed for its production are destroyed. However, any solanine made before the potatoes were cooked will remain. Solanine cannot be destroyed by boiling, steaming, baking, microwaving or frying potatoes. Deep frying at very high temperatures partially destroys solanine.

The bodies of most people can break down the small amounts of solanine found normally in nightshade food plants but are poisoned by the larger amounts that are in potato sprouts and may be present in green potatoes or potatoes exposed to light. However, some people seem to be especially sensitive to solanine and cannot tolerate even small amounts, possibly because their digestive tract is unable to break down the solanine. Most scientists claim that there is no connection between arthritis and eating specific foods, but the experiences of plenty of arthritis sufferers indicates something different. There are many anecdotal reports from people who have found that their joint pain correlates with their ingestion of tomatoes, for example. Some scientists say that the solanine-like chemical in tomatoes is not really solanine but is a related chemical called tomatine.

An exclusion diet, also called an elimination diet, could be used to discover whether the nightshade family affects your arthritis, but if you decide to go on this diet you must make sure that you still eat nutritious food. In an exclusion diet a suspect food is no longer eaten and observations are made about the body’s response to the food’s elimination. Some people find that eliminating all nightshades improves their arthritis, while some find that only one particular kind needs to be excluded. You don’t want to eliminate foods unnecessarily from your diet.

While you are on an exclusion diet, keep a daily record of what you eat and how your arthritis responds. After several weeks on the exclusion diet, if your pain is better the eliminated food should be reintroduced for several days to see if symptoms reappear. If they do, then you’ve just found a food that you’re sensitive to and by eliminating that food from your diet your symptoms will improve or disappear. If your pain didn’t improve on the elimination diet and reintroducing the food makes no difference to the intensity of your pain, then you know that the food that you eliminated doesn’t need to be removed from your diet.

A suspect food must be eliminated from your diet for a long time so that all traces of the food and its metabolites can be removed from your body. In the case of a nightshade exclusion diet, it also takes time to discover if only one nightshade or if all nightshades need to be eliminated from your diet. All the time and effort is well worthwhile, however, if the result is pain reduction or relief.