The beefsteak plant, known botanically as Perilla frutescens, is not a single story when it comes to toxicity. Certain varieties contain a compound called perilla ketone that is genuinely dangerous to grazing animals and potentially harmful to humans, while other varieties of the same species have been eaten safely in East Asian cuisines for centuries. The answer depends heavily on which chemotype of the plant you are dealing with, who is eating it, and how much.
What Makes Some Beefsteak Plants Dangerous
The central concern with Perilla frutescens is perilla ketone, a compound found in the plant’s essential oil. A landmark study published in Science identified perilla ketone as a potent agent that causes fluid buildup in the lungs of laboratory animals and livestock, and noted that the plant’s widespread use in East Asian food and medicine raised questions about potential risks to people as well.1PubMed. Perilla ketone: a potent lung toxin from the mint plant, Perilla frutescens Britton Not every beefsteak plant produces dangerous amounts of this compound, though. A study testing five Perilla frutescens varieties found that only two of the five genotypes contained perilla ketone, and those two were judged unsuitable for consumption.2PubMed. Determination of toxic perilla ketone, secondary plant metabolites and antioxidative capacity in five Perilla frutescens L. varieties
This is a critical distinction that often gets lost in blanket warnings. The beefsteak plant is not uniformly poisonous. It is a chemically diverse species, and whether a given plant is toxic depends on its genetic makeup. The varieties bred and selected for culinary use in Japan, Korea, and China tend to belong to chemotypes that produce little or no perilla ketone. The varieties that grow wild, particularly in pastures across the southeastern United States, are often the ones that cause problems.
The Real Danger Is to Grazing Livestock
If there is one group for which the beefsteak plant is unambiguously hazardous, it is cattle. The plant is sometimes called purple mint in veterinary literature, and it has been responsible for documented cases of a condition called atypical interstitial pneumonia in cows. In one experimental study, researchers fed Perilla frutescens to calves and produced the syndrome in three out of five animals. The amount of plant material required varied widely, from about 2.3 kilograms of green seed-stage mint in one calf to over 15 kilograms in another. Necropsy showed pulmonary emphysema and edema, and microscopic examination revealed significant changes in the lung tissue of the affected animals.3PubMed. Intoxication of cattle by Perilla frutescens (purple mint)
The timing matters for ranchers. Perilla frutescens tends to be most toxic during its seed stage in late summer and early fall, which is exactly when pasture grasses thin out and cattle start browsing plants they would otherwise ignore. A cow is unlikely to seek out beefsteak plant when good forage is plentiful, but in drought conditions or overgrazed pastures, the risk climbs. The symptoms come on quickly: labored breathing, open-mouth panting, and sometimes death within days. Because the damage targets the lungs so specifically, animals that survive may still have compromised respiratory function afterward.
Other ruminants, including sheep and goats, can also be affected, though cattle seem to be the species most commonly involved in poisoning incidents in the field. Horses appear to be less commonly affected, partly because they tend to avoid the plant and partly because their lung tissue may respond somewhat differently to the toxin.
How Perilla Ketone Damages the Lungs
Perilla ketone does not act like a typical poison that accumulates in the liver or kidneys. It targets lung tissue specifically. After being absorbed from the gut, the compound is processed by enzymes in the lung itself, and the resulting metabolites damage the cells lining the air sacs. This leads to fluid leaking into spaces where air should be, producing the pulmonary edema that veterinarians see at necropsy. Research into species differences in susceptibility has pointed to the lung’s own enzyme system as the reason some animals are hit harder than others; the very act of metabolizing the compound in lung tissue is what creates the toxic byproduct.4Journal of Animal Science. Species Susceptibility to the Pulmonary Toxicity of 3-Furyl Isoamyl Ketone (Perilla Ketone)
This mechanism explains why the poisoning looks so different from other plant toxicities. A cow that eats enough perilla ketone-containing material does not show the liver failure, neurological signs, or gastrointestinal distress you might expect from other toxic plants. Instead, the animal essentially drowns from within as fluid fills the lungs.
Is It Safe for Humans to Eat?
Millions of people eat beefsteak plant regularly without harm. In Korean cuisine, perilla leaves (known as kkaennip) are eaten fresh as wraps, pickled, or added to stews. Japanese cuisine uses a closely related variety called shiso, which is the garnish on sashimi platters and an ingredient in umeboshi. Vietnamese and other Southeast Asian cuisines also incorporate the leaves and seeds. These culinary varieties have been selected over generations for flavor and aroma profiles that happen to correspond to low or absent perilla ketone content.
A recent multidimensional analysis of perilla leaf varieties confirmed this pattern. The study found that perilla ketone posed a potential risk in certain chemotypes, while heavy metal and pesticide residues in commercial perilla leaves were within safe limits. The varieties identified as safest and highest quality were those with a double-sided purple phenotype, southern geographic origins, and crucially, non-perilla-ketone chemotypes.5Journal of Food Composition and Analysis. Evaluation of edible and medicinal varieties based on multidimensional quantitative data: A case study of perilla leaf In other words, the varieties you find at an Asian grocery store have been chosen precisely because they do not produce the problematic compound.
The practical takeaway for anyone eating commercially sold perilla leaves or seeds is that the risk from perilla ketone is very low. These products come from cultivated, food-grade varieties. The risk is concentrated in wild-growing plants of unknown chemotype, which no one should be foraging and eating without expert identification.
Perilla Seed Oil and Acute Toxicity Testing
Perilla seed oil, which is rich in alpha-linolenic acid (an omega-3 fatty acid), has been gaining popularity as a dietary supplement and cooking oil. Safety testing in rodents is reassuring. In an acute oral toxicity study, mice given perilla seed oil showed no deaths, maintained normal behavior, ate and drank normally, and displayed healthy fur and good condition throughout the observation period, with no signs of toxicity at any dose tested.6PubMed Central. Systematic Evaluation of the Nutritional Quality, Elemental Safety, and Preventive Effects of Perilla Seed Oil on Hyperlipidemia and Gut Microbiota Dysbiosis in High-Fat Diet-Fed Rats This makes sense because the oil extraction process concentrates fatty acids rather than the volatile compounds like perilla ketone that make certain plant parts dangerous.
Perilla seed oil is a different product from the plant’s essential oil. Essential oil extraction captures the volatile aromatic compounds, including any perilla ketone present, in concentrated form. Perilla seed oil pressed for culinary or supplement use does not concentrate these volatiles to the same degree. This distinction matters if you are comparing products on a store shelf.
Allergic Reactions Are a Separate Risk
Even with safe, food-grade varieties, some people are allergic to perilla. Two documented cases of anaphylaxis from perilla seeds illustrate how serious this can be. Both patients developed widespread hives, wheezing, difficulty breathing, and dizziness immediately after eating food containing perilla seeds. Skin prick testing with perilla extracts produced strong positive responses in these patients but none in ten healthy controls. To confirm the connection, the patients were given a small oral dose of perilla seeds under medical supervision and rapidly developed severe symptoms including facial swelling and throat swelling.7The Journal of Allergy and Clinical Immunology. Two cases of anaphylaxis caused by perilla seed
Perilla allergy is not common, but it is worth knowing about if you are trying the seeds for the first time, especially if you have existing food allergies. The allergic reaction is an immune response to a protein in the seed and has nothing to do with perilla ketone. You could be eating the safest, most thoroughly vetted culinary variety and still have an allergic reaction if your immune system happens to recognize and overreact to that specific protein.
Beneficial Compounds in the Same Plant
The beefsteak plant is not just a toxicity story. The same species that produces perilla ketone in some varieties also produces rosmarinic acid in abundance, a compound with well-documented antioxidant and anti-inflammatory properties. Researchers have found that Perilla frutescens leaves are an unusually rich source of rosmarinic acid, and extracts from these leaves have shown protective effects in animal studies.
One study demonstrated that a rosmarinic acid-enriched fraction from perilla leaves strongly protected against drug-induced stomach ulcers in rats. The extract and its active fraction contained very high concentrations of rosmarinic acid.8PubMed Central. Rosmarinic Acid Enriched Fraction from Perilla frutescens Leaves Strongly Protects Indomethacin-Induced Gastric Ulcer in Rats Another study found that two key compounds in perilla leaves, caffeic acid and rosmarinic acid, reduced markers of liver damage when given to animals before exposure to a toxic oxidative challenge. Both compounds lowered indicators of liver injury and improved the activity of antioxidant enzymes.9PubMed. The hepatoprotection of caffeic acid and rosmarinic acid, major compounds of Perilla frutescens, against t-BHP-induced oxidative liver damage
Research has also explored cognitive effects. In a mouse model of cognitive impairment, perilla extract and rosmarinic acid improved performance on memory and learning tasks. Animals given these compounds performed better in maze and object recognition tests compared to untreated controls, and the treatment reduced markers of oxidative stress in the brain.10Nutrition Research and Practice. Perilla frutescens var. japonica and rosmarinic acid improve amyloid-β25-35 induced impairment of cognition and memory function These findings are in animal models and have not been confirmed in human clinical trials, but they do help explain why perilla has a long history in traditional medicine across East Asia.
The coexistence of a lung toxin and a potent antioxidant in the same species is one of the more interesting quirks of plant chemistry. It underscores why “is this plant poisonous” is rarely a yes-or-no question. The answer depends on which part of the plant, which variety, and which compound you are asking about.
Cats, Dogs, and Other Pets
Most of the veterinary toxicology literature focuses on livestock because that is where the economic damage and the clinical cases occur. Reports of perilla poisoning in dogs and cats are rare in the published literature, partly because companion animals are less likely to encounter and eat large quantities of the plant. That said, any animal with lungs could theoretically be affected by perilla ketone if it consumed enough of the right plant variety. The prudent approach with pets is to treat wild-growing perilla the way you would treat any unfamiliar plant in the garden: keep animals away from it.
If you grow ornamental perilla (sometimes sold under names like “magilla” or as a decorative foliage plant), it is worth noting that ornamental varieties have been selected for appearance, not necessarily for low perilla ketone content. Their chemical profile may differ from food-grade cultivars. If your dog likes to chew on garden plants, consider relocating ornamental perilla to a spot the dog cannot reach.
How Cooking Affects Safety
In many traditional preparations, perilla leaves are cooked rather than eaten raw. Cooking in general is known to reduce various antinutrient and potentially harmful compounds in wild edible plants. Research on wild edible plants from northeastern India found that both boiling and microwave cooking significantly reduced antinutrient levels, with microwave cooking producing the larger reductions in most cases.11Academia.edu. Effect of Boiling and Microwave Cooking on Nutritional, Anti-Nutritional and Toxicity of Wild Edible Plants of North-Eastern Region in India The specific volatile compounds in perilla, including perilla ketone, are heat-sensitive and would be expected to degrade or evaporate during cooking, although direct measurement of perilla ketone breakdown during cooking is limited in the published literature.
For practical purposes, cooking perilla leaves as part of a stew, stir-fry, or braise likely reduces whatever small amount of volatile compounds they contain. Eating raw leaves of a known culinary variety is also considered safe, as those varieties produce negligible perilla ketone to begin with. The combination of choosing the right variety and cooking it offers a double layer of reassurance.
Wild Perilla in North American Pastures
Perilla frutescens has naturalized across much of the eastern United States, from Texas to New England. It thrives in disturbed soils, forest edges, roadsides, and the margins of pastures. For anyone who keeps livestock, identifying and managing this plant is more immediately useful than understanding its chemistry. The plant grows one to three feet tall, has square stems typical of the mint family, and produces leaves that are often deeply purple on the underside, though green-leaved forms also exist. It flowers in late summer with small spikes of white to purple blossoms, and it is during and after flowering, at the seed stage, that the plant is at its most toxic to cattle.
Manual removal before the plant sets seed is the most straightforward control method. Mowing can reduce populations but may not kill established plants if done too late in the season. Herbicide application in spring, when the plants are young and actively growing, is the most effective chemical control. For horse and cattle owners in regions where perilla grows wild, walking pastures in late July and August to pull or spray any plants before they mature is one of the most cost-effective ways to prevent losses.