[david-given]

Potatoes are quite toxic --- they're related to deadly nightshade. The versions we eat are heavily engineered so that the tubers produce survivably small quantities of toxin. (Wild potatoes produce it as a defense mechanism.) However it's possible to stimulate otherwise safe potatoes into producing high quantities of the stuff via mishandling. People have died.

http://www.smithsonianmag.com/arts-culture/horrific-tales-of...

In the 1960s some potato breeders accidentally produced a poisonous breed of potato by crossing two perfectly harmless versions, and some people (mostly the potato breeders themselves!) were quite ill before anyone realised what was going on.

http://boingboing.net/2013/03/25/the-case-of-the-poison-pota...

Also, seriously don't eat potato berries.

[cmarschner]

Same thing with Zucchini, cucumbers and other pumpkin derivatives which originally produced the toxin Cucurbitacine. We just had a case where a man died after a pie made of home-grown Zucchini which tasted unusually bitter. Apparently the plants can start producing the toxine when under stress (e.g. heat wave). There's a reason why children avoid anything bitter-tasting.

[MrBuddyCasino]

Same thing with Zucchini. Resently someone died here in Germany because a neighbour gave him a home grown one. Don't eat them if they taste bitter!

[greggman]

And yet peopl eat "bitter gourd" in China and "Goya" in Okinawa, both super bitter. Are those bad too and they just don't know any better?

[kragen]

We taste a lot of different chemicals as bitter, including cucurbitacin, persin, quinine, solanine, strychnine, momordicin, cyanide, and benzaldehyde, and consequently amygdalin. Apparently we have 25 or more different bitter taste receptors sensitive to more than 500 different bitter chemicals. The lethal doses of these chemicals in proportion to their bitterness vary enormously, and of course they also vary according to the situation: the momordicins in bitter melons are fine most of the time, but bitter melons are an abortifacient (possibly due to an effect of the momordicins) so you shouldn't eat them if you're pregnant. (There are other inexpensive means of abortion, such as misoprostol, which have been carefully studied and shown to be safe in the first trimester.) And different chemicals extracted from bitter melons have been shown to be cytotoxic in vitro and might be useful against cancer; some hepatotoxicity has also been shown. https://www.mskcc.org/cancer-care/integrative-medicine/herbs...

So I would say, no, they're not bad. But don't go overboard.

[sdrothrock]

Completely different plant. The bitterness is caused by momordicin, which is fine to consume.

[cmarschner]

Good timing :-)