Strawberry Field's death through crude oil, though often derided as a clumsy homage to Jill's death, was more gruesome and realistic.
Watching through YOLT
on DVD again recently, I still think the emotional impact of Aki's death is underrated, but it doesn't help that the movie feels very fast paced for a 1960s movie, seemingly forgetting about her (maybe there should've been more breathing space, to let the impact of her death set in, like have a silently brooding Bond in the castle grounds watch Tiger's staff wheel away Aki's body in a shroud or body bag as the sun rises, before it cuts to the silly ninja training stuff and sham wedding).
From what I've read about poisoning, I get the impression that Aki died from a cyanide substance (first with her inability to breath properly, then her apparent cardiac arrest, followed by sudden unconsciousness and death within minutes).
And speaking of cyanide, I nearly forgot about poor Paula in Thunderball
(who in captivity took a hidden cyanide pill to avoid brutal interrogation).