Although many cultures consider animal brains a delicacy or staple, it's safest to avoid consuming them, especially mammal brains, because prion diseases are more common among herbivorous mammals that eat foliage or grass. While the disease can be transmitted through any part of the animal, brains tend to have higher concentrations of prions, increasing the risk. Additionally, although prions generally need time to adapt to different species, some can do so more quickly. The transmission of mad-cow disease to humans through contaminated beef led to Creutzfeldt-Jakob disease (vCJD), a fatal, degenerative brain disorder caused by prions. Worse still, prion disease has no cure or treatment; the best doctors can do is to make your final days as comfortable as possible.