I agree that peanut butter may not be a good oil or fat, but butter contains butyric acid. Butyric acid is a component of GABA as well - Gamma-Amino Butyric Acid.
The anti-fungal and anti-tumor effects of butyric acid, a short chain fatty acid, are unique to butter. Butyric acid is an energy source for the cells lining the colon, where it plays a part in development and maintenance. It reduces chronic inflammation of the colon, and high fecal levels correlate with decreased colon cancer risk. In people with compromised immune systems, undifferentiated cell growth can be inhibited by butyric acid.
Butyric acid is found in butter, parmesan cheese, vomit, and as a product of anaerobic fermentation (including in the colon and as body odor). Yes, our own friendly flora produce it.