For those who hate eating their vegetables, it’s easy to imagine that they’re actually toxic plants masquerading as food. But, as Ars has reported before, many of the common vegetables, fruits, spices, and other plant matter that we shovel in do in fact contain toxins—albeit at minor, generally harmless amounts.

This includes veggies in the Cucurbitaceae family also called cucurbits or gourds (see gallery of family members below), which contain a class of poisons called cucurbitacins. The toxic steroids are among the most bitter-tasting compounds biochemists have ever come across and, in the plants, they function as a defense against herbivores. Most domesticated varieties of gourds have had high levels of cucurbitacins bred out of them. But stressful growing conditions, such as droughts or high temperatures, can cause plants to boost production. Also, accidental cross-pollination with wild, bitter varieties can up toxin levels.

As such, consumers can occasionally come across super bitter gourds—and suffer what some researchers call toxic squash syndrome if they eat them. This may happen more often than people might think; a recent analysis in France tallied 353 cases between 2012 and 2016. Of those, more than 50 percent were due to squash consumed from a grocery store. That said, the Food and Drug Administration told me earlier that these cases are rare in the US.

When it does happen, toxic squash syndrome is usually marked by diarrhea (sometimes bloody), vomiting, and abdominal pain, which can sometimes lead to dehydration, low blood pressure, rapid heartbeat, headaches, and vertigo. If eaten in high enough levels, the poisons can lead to lethal fluid buildup in the lungs (pulmonary edema). But according to a recent case reported in JAMA Dermatology, there’s another puzzling symptom: hair loss.

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Doctor Philippe Assouly reported that two women in France were separately poisoned by toxic gourds, suffering standard gastrointestinal distress directly afterward. But days later, they experienced substantial hair loss, too.

The first woman got sick immediately after eating very bitter pumpkin soup, suffering nausea, vomiting, and diarrhea. Then a week later, she started losing chunks of hair from her scalp and pubic area. Her family had also had some of the soup and initially got sick, but they didn’t eat as much as she did and didn’t experience any hair loss.

Similarly, the second woman ate a meal with her family that included squash. While her family skipped the squash because it tasted bitter, the woman ate on—and experienced “severe vomiting” an hour later that lasted for hours. Three weeks later, she too lost large swaths of hair from her scalp, armpits, and pubic region.

Months later, some hair had regrown on both women. The hair that hadn’t fallen out showed signs of breakage and weakness.

Assouly didn't speculate how cucurbitacins may have affected the hair loss, though he noted that other toxic plants can do so by shutting down cell division. Unfortunately, there’s little work on cucurbitacins in general to help figure it out. There are also 12 different categories of cucurbitacins that show up in various types of gourds, all likely to have their own cellular effects. In the 1960s, researchers tried to study certain cucurbitacins as possible drugs to treat cancer because they’re particularly good at killing tumor cells. But the work was largely abandoned when researchers found that the compounds were simply too toxic to be used for any medical benefit.

Assouly says that the timing and length of hair regrowth in the two women “does not seem to leave a doubt” that the bitter gourds were behind their hair loss.

“It seems important and useful to be aware of this toxic association of alopecia with a common plant,” he concludes. But it may be more important and useful to make people aware that if their pumpkin or squash dishes taste extremely bitter, then they shouldn't eat them.

JAMA Dermatology, 2018. DOI:10.1001/jamadermatol.2017.6128 (About DOIs).