The flowering plant Hypericum perforatum, commonly known as St. John’s wort, is a perennial herb recognized by its bright yellow blooms. The plant is often found growing wild across temperate regions worldwide. As it develops, its distinctive flowers are replaced by structures that many people mistake for true berries, leading to questions about the edibility and safety of these fruit-like seed capsules.
Identification and Traditional Uses of St. John’s Wort
St. John’s wort is identified by several distinct physical features. The leaves appear covered with tiny, translucent dots when held up to the light, which is the origin of its species name, perforatum. Its five-petaled, star-shaped flowers are deep yellow and often have small black dots along the edges. When the flowers or developing fruit are crushed, they exude a distinctive reddish-purple oil or pigment.
The parts traditionally utilized are the flowers and the upper portions of the leaves and stems. These aerial parts contain the active compounds hypericin and hyperforin, which are the focus of most research. Historically, the plant has been used in folk medicine for treating wounds and, more recently, for mood support supplements. These compounds are extracted from the flowering tops, not the seed capsules, for commercial use.
The Direct Answer: Toxicity of the Berries
The structures commonly referred to as St. John’s wort “berries” are technically dried seed capsules, not botanical berries. These seed capsules are not considered edible and should not be consumed by humans or animals. The entire plant, including the seed capsules, contains the naphthodianthrone compound hypericin, which is its primary toxic component.
While the highest concentration of hypericin is found in the flowers and buds, the compound is present throughout the above-ground parts. Ingestion of any part of the plant can lead to photosensitization. This reaction is caused by hypericin circulating in the bloodstream, which then reacts to sunlight upon reaching the skin. St. John’s wort is officially listed as toxic to several species, including cats, dogs, and livestock.
Symptoms of Ingestion and Emergency Protocol
Ingestion of St. John’s wort seed capsules can result in adverse effects, primarily affecting the skin and the gastrointestinal tract. The most notable symptom is photosensitization, where the skin becomes extremely sensitive to light. Affected individuals, especially those with unpigmented skin, may develop severe redness, inflammation, blisters, and lesions after sun exposure.
Consuming the plant can also cause systemic symptoms like gastrointestinal distress, including vomiting, diarrhea, and stomach pain. More severe reactions, though less common, can include fever, lethargy, increased heart rate, and neurological signs like loss of coordination or convulsions. If ingestion is suspected, move the person or pet out of direct sunlight and promptly contact a local poison control center or seek veterinary care.