How Much Cyanide Is In Almonds?

Nuts are one of those foods that are hard to stop eating once you've had a few. After grabbing a handful from that obscenely large Costco container, it's difficult to not go in for another handful. But are there nuts that you should stop eating?  

Almonds are a popular tree nut that come in two main varieties — sweet and bitter. The sweeter variety are the kind of almonds most easily found in stores today, but historically, bitter almonds were more common. This latter variety of almonds contains amygdalin, a compound that, when metabolized, breaks down into hydrogen cyanide, benzaldehyde, and other chemicals. While benzaldehyde gives bitter almonds its distinct taste, cyanide is a highly toxic poison. This bitter taste and poison help to protect almond trees in the wild by deterring threats, but they're also one of the many ways in which food can kill you.

According to a 2013 study published in International Scholarly Research Notices Toxicology, "...the consumption of 50 bitter almonds is deadly for adults. However, for young children, 5–10 almonds are fatal." Sweet almonds contain only trace amounts of cyanide, making them safe for consumption. While heating almonds — through methods like bakingor boiling — lowers cyanide, there is still a lack of conclusive studies confirming the effectiveness of these processes.

The difference between sweet and bitter almonds is largely responsible for the presence of cyanide. Sweet almonds have a low level of amygdalin and are safe to eat. In contrast, bitter almonds, which are used primarily for flavoring and extracts (a key ingredient in those pillow-soft Italian holiday treats, pignoli cookies), have significantly higher levels of amygdalin. As Dianne Velasco, a plant genetics researcher, told NPR, almond breeders cannot tell whether a tree will bear bitter or sweet almonds until the tree is ripe, which takes about three to five years.

If bitter almonds are ingested, the CDC recommends that you do not try to vomit. Symptoms of cyanide poisoning include dizziness, nausea, slowed heart rate, and low blood pressure. Cyanide is treated with antidotes, so the best option is to go to the emergency room as soon as possible.

Today, in California, where nearly 80 percent of the world's almonds are grown, sweet almonds are the focus of commercial almond production, ensuring that the almonds consumers buy are safe to eat. In 2014, a recall of imported almonds due to high cyanide levels highlighted the importance of distinguishing between sweet and bitter almonds.

Bitter almonds aren't the only types of almonds to be concerned about. Sprouted almonds are edible, but come with the risk of exposure to harmful bacteria like salmonella and food poisoning. Almonds may also contain toxic molds, along with other tree nuts like cashews and hazelnuts. This is more common in raw, unsalted nuts, whereas roasted or salted tree nuts tend to be safer to consume.