
Declared the poisonous plant of 2025! What's so bad about the nut that protects the brain, heart and prevents some types of cancer?
Boiled or baked, salted or caramelized, it is mostly healthy, but it also has its dark side.
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We love it as a healthy snack, because it is rich in unsaturated fats, proteins, fibers, essential vitamins and minerals. Like any nut, we know that we should eat it in moderation because they are usually very caloric, so the limit is no more than 10 pieces per day. This nut is also particularly rich in vitamin B6, which in one hundred grams contains enough to satisfy 20 percent of the daily requirement for this vitamin, which is necessary for normal brain function, preventing skin disorders and slowing down aging.
It is also rich in selenium, one hundred grams contains 12 micrograms of this mineral, which is a good antioxidant and helps prevent heart disease and even some types of cancer. It also contains iron, zinc, copper, calcium, magnesium, potassium and vitamin E. Then there are the proteins and polyphenols that provide our body with significant health benefits – from good heart health, stroke prevention, blood sugar regulation, improved brain health and its better functioning to healthy eyes and bones, as well as a stronger immune system. We attribute all of this to cashew nut, which was declared a poisonous plant in 2025.

Selection of the German Botanical Garden
The competition is traditionally organized by German botanical garden "Wandsbeck" to provide information about the toxic effects of plants that people commonly use without knowing their special properties. The dark side of the cashew nut lies in the fact that its shell is poisonous.
– Cashews in Europe are only found in grocery stores and are completely non-toxic for human consumption because they are processed before reaching the stores. Namely, the fruit, which originates from northeastern Brazil and is now cultivated in Africa, Asia, Latin America and India, contains cardol oil, which negatively affects the mucous membrane and can cause serious colic and skin allergies, which are – according to the Wandsbeek botanical garden – "comparable to second-degree burns."

Harmful cardol
– Raw cashews should not be consumed. The shell of the cashew is hard and contains a poisonous oil (cardol), which leads to health problems after consumption. Purchased cashews are usually harmless, because the outer shell, which contains the largest amount of cardol, is removed before sale. They are then fried or steamed. These processes render the poisonous cardol harmless. Cashews processed in this way are real sources of energy and offer a number of health benefits. They are rich in unsaturated fatty acids, proteins, fibers, vitamins and minerals. They are especially rich in magnesium, copper, zinc and vitamin B – states the Botanical Garden.
They point out that cashews purchased in stores as ready-made products may, however, contain salt or sugar, so they advise making sure they are unsalted and contain as little sugar as possible.
Also, Cashews contain histamine. People with histamine intolerance should limit their consumption, warn German botanists, who are now calling for nominations for the next poisonous plant of the year from the list of toxic plants on their website. If a poisonous plant is not on the list, it can be suggested, the list will be updated, and voting will be possible from June. The plant that receives the most votes will be declared the poisonous plant of 2026, and the public will have the opportunity to learn more about its dark side.