The lower gastrointestinal tract lacks the alcohol dehydrogenase enzyme present in the stomach and liver that breaks down ethanol into acetylaldehyde , which is actually more toxic than ethanol ( drinking alcohol ) and is responsible for most chronic effects of ethanol .
The lower gastrointestinal tract lacks the alcohol dehydrogenase enzyme present in the stomach and liver that breaks down ethanol into acetylaledhyde . 
 Acetylaldehyde is actually more toxic than ethanol ( drinking alcohol ) and is responsible for most chronic effects of ethanol .