With all the hormones and whatnot inside. Dopamine, adrenaline, melatonin, whatever. Also, there’s this Hunter S. Thompson bit on the… pineal gland?
If it had an effect on you, wouldn’t it be a really messed up high, all over the place? With uppers, downers etc mixed? (Not including the emotional implications of eating raw human brains.)
Overall its very inconsistent due to the first pass effect of the liver as well. Anything absorbed from the alimentary canal goes through the liver first and the liver is very effective at breaking down lost hormones.