While many berries offer nutritional benefits and are a delightful part of various diets, some berries found in nature contain compounds that are harmful to humans. Some wild berries harbor potent toxins.
Toxic Compounds in Berries
The toxicity of certain berries stems from specific chemical compounds they produce, which interfere with human biological processes. These compounds are broadly categorized and affect the body in different ways.
Alkaloids are diverse nitrogen-containing compounds often found in poisonous berries. Tropane alkaloids, for example, are known for their effects on the nervous system, leading to symptoms such as hallucinations, confusion, and heart rate irregularities. Deadly nightshade contains tropane alkaloids like atropine and scopolamine.
Glycosides represent another class of toxins, characterized by a sugar molecule attached to a non-sugar component. Cyanogenic glycosides, for instance, release hydrogen cyanide when metabolized, which inhibits cellular respiration and can be lethal. Cardiac glycosides, found in plants like lily-of-the-valley, directly impact heart function by interfering with the sodium-potassium pump in cardiac cells, leading to irregular heartbeats or cardiac arrest.
Saponins are compounds that create a soap-like foam when mixed with water. These can cause gastrointestinal irritation, leading to nausea, vomiting, diarrhea, and abdominal pain. Larger quantities can be toxic and may interfere with nutrient absorption.
Oxalates are found in various plants, including some berries. When ingested, oxalates can bind with minerals like calcium, potentially leading to kidney stone formation and interfering with mineral absorption. High oxalate intake can cause discomfort.
Evolutionary Reasons for Toxicity
Toxic compounds in berries are primarily an evolutionary adaptation, serving as a defense mechanism for the plant. This strategy helps ensure the plant’s survival.
Toxicity protects immature seeds. Unripe berries frequently contain higher concentrations of toxins to discourage consumption before seeds are ready for dispersal. This allows seeds to mature fully. Once mature, the fruit often becomes edible, attracting animals that disperse the seeds.
Plants have evolved these compounds to target specific threats. Some toxins may be effective against insects or certain mammals, while posing less threat to birds, which are often seed dispersers. This allows plants to selectively deter unwanted consumers while encouraging those that aid in propagation.
General Principles for Identifying Unsafe Berries
Caution is essential when encountering wild berries. Never consume them unless their identification is absolutely certain. Relying on appearance, such as color, can be misleading, as both edible and poisonous berries can share similar hues.
Avoid berries that appear unusually colored, have a bitter or soapy taste, or grow on plants with spines or milky sap. While some colors like blue or black are often safer than white, yellow, or green, these are not foolproof rules. Many highly toxic berries can be red or purple.
Do not assume a berry is safe just because animals are observed eating it. Animals often have different digestive systems and tolerances to toxins than humans. Teach children never to eat any wild berries without adult supervision, and always adhere to the principle: “if in doubt, leave it out.”
Symptoms and Emergency Response
Ingesting poisonous berries can lead to a variety of symptoms. Common signs include nausea, vomiting, abdominal pain, and diarrhea. Some toxins can cause more severe reactions, affecting neurological functions, leading to dizziness, confusion, weakness, or seizures. Cardiac issues can also occur.
If someone is suspected of having eaten poisonous berries, call a poison control center or emergency services. In the United States, the national toll-free Poison Help hotline is 1-800-222-1222.
When contacting poison control, provide information including what was eaten, the estimated quantity, and any symptoms observed. If possible, gather a sample of the plant or a photograph to aid in identification. Do not attempt to induce vomiting unless advised by a medical professional, as this can sometimes worsen the situation. Keeping the affected individual calm and still can also be helpful.