Norman Allan : the story for Ezra
book three: towards joy
chapter three:
"Dr. Allan's Medicine Show"

"Rape seed" was toxic. It caused fatty degeneration of the heart (if I remember correctly). So they bred the toxin out of the plant (sort of: see below) and renamed it "canola" (for Canadian oil)

"Canola was created (from Rape Seed) through plant-breeding in order to get rid of two undesirable components of rapeseed...

"In the 1970s canola was created through traditional plant cross-breeding by removing two things found in the rapeseed plant: glucosinolates and erucic acid. Erucic acid was removed because it was believed to be inedible or toxic in high doses. The newly developed plant was renamed "canola" - a combination of "Canadian" and "Oil" (or ola) to make this difference apparent.
By definition, if a seed is labeled "canola" it has to have less than 30 micromoles of glucosinolates and less than 2% of erucic acid.
Canola oil is limited by government regulation to a maximum of 2% erucic acid by weight in the USA[25] and 5% in the EU,[26] with special regulations for infant food. These low levels of erucic acid are not believed to cause harm in human neonates

Brassica napus a cabbage family plant
Rapeseed oil is from the third most important crop grown here in the UK after wheat and barley

While studies done on laboratory animals in the early 1970s show that erucic acid appears to have toxic effects on the heart at high enough doses, an association between the consumption of rapeseed oil and increased myocardial lipidosis, or heart disease, has not been established for humans