There’s cyanide lurking in your apples.
And those juicy peaches, too.
Your potatoes can be deadly if you’re not careful. Same goes for the leaves on those beautiful, tart rhubarb stalks. And that amaretto flavoring in your morning coffee? It has killer origins.
In fact, several edible plants have poisonous parts or parts that can turn poisonous in the wrong conditions. Here’s a look at a few of the most dangerous of the edibles.
• Rhubarb leaves, kale, spinach and other greens. Yes, dark, leafy greens are fabulous for you — full of vitamins A and C, iron and calcium — but too much of the wrong kind can make you sick.
Those leaves contain a chemical called oxalic acid that, in humans, can cause several undesirable symptoms, including burning of the throat, diarrhea, vomiting, difficulty breathing, convulsions, coma and death.
The leaves of edible rhubarb stalks have the highest concentration of oxalic acid of any of the greens commonly grown in northeast Kansas. But don’t count out the prized spring vegetable on an inedible technicality, says Jennifer Smith, horticulture extension agent for the Douglas County-Kansas State Extension Office, 2110 Harper St.
“Rhubarb leaves are not as poisonous as people think. They will make you sick if you eat a bunch, but it’s like if you eat a bunch of spinach, it’ll make you sick, too,” Smith says. “Rhubarb leaves, and especially the oldest leaves, contain the highest concentration of (oxalic acid).”
According to www.rhubarbinfo.com, it is estimated that it would take 11 pounds of rhubarb leaves to kill a 145-pound person. Those leaves would contain about 24 grams of oxalic acid. Before it would kill you, you’d likely get too ill to finish all 11 pounds of the leaves, though.
That said, too much oxalic acid in one’s everyday diet can create kidney stones and aggravate symptoms of diseases such as gout and rheumatoid arthritis.
• Pits, seeds and almonds. The pits of stone fruits like peaches and apricots, the seeds of apples and certain types of almonds all contain amygdalin, a compound containing sugar and cyanide, a highly toxic substance that robs those who ingest it of their ability to carry oxygen in their blood, thus killing them by asphyxiation.
“I think someone figured out it’s about a cup of apple seeds that could possibly kill an adult,” says Ward Upham, an extension associate at Kansas State Research and Extension in Manhattan. “And so it’s not something you need to be overly concerned with unless you just eat the seeds themselves. If you happen to eat one, it’s not going to cause any problems.”
That is, unless you ingest seeds or pits on purpose, as was the case in the late 20th century, when the cancer drug Laetrile went on the market.
“Laetrile was used to treat cancer probably back in the ’70s, and it was derived from (apricot) pits,” Upham says. “And it wasn’t something that was mainstream — it was one of those, kind of on the side type things, and the active ingredient was cyanide.”
Another direct ingestion example is the Italian amaretto liqueur, which is often made from bitter almonds that would be toxic otherwise. That’s because bitter almonds differ from the common almonds found in a grocery stores. Our everyday almonds are safe thanks to their genetics, Upham says.
“Almonds are a type of peach that has undergone a mutation so that the pits, or the nuts inside those pits, no longer contain cyanide,” he says.
• Potatoes and tomatoes. Though potatoes and tomatoes themselves aren’t toxic (unless you eat green potatoes), their plants are.
“Every once in a while you actually get fruit on potatoes, they’re little small, probably the size of a quarter maybe at most, those are toxic,” Upham says. “And all parts of a tomato except the fruit are toxic.”
Those fruits on the potato plant contain high amounts of the alkaloid solanine, which is also the chemical found in green potatoes. Alkaloids are naturally occurring chemicals and the more famous members of the family include caffeine, nicotine, quinine and morphine.
“I don’t think anyone has ever been killed by it, but it can make you sick,” Upham says.
Similarly, the leaves and stems of the potato’s nightshade cousin, the tomato, contain an alkaloid called tomatine that can do nerve damage and cause severe stomach distress.
• Ornamentals. There are some technically edible plants like certain types of sweet potatoes and plums that Upham says are perfectly plate ready, but can be harmful if they’ve been treated like every other nonedible in a conventional garden.
“Sometimes, I get questions on sweet potatoes — they have ornamental varieties of sweet potatoes — they want to know if those are edible. And they are,” Upham says. “And the same thing holds for purple plum trees. Every once in a while we’ll get fruit on those, and that also is edible, it’s just that they have to be a little bit careful, because if it’s been sprayed as an ornamental, what has been used as a spray may not be something you want to eat the fruit from.”