system
Given the following post, respond as if you're commenting on Reddit:
human
Why doesn't peanut butter need to be refrigerated?

Does the high fat content, or something else about peanuts, prevent microbes from growing? Thanks!
gpt
You do have to refrigerate some peanut butters. The name brand ones don't need refrigeration because they have been shelf-stabilized. They have lots of sugar and preservatives in them, which inhibits spoilage. 

Some (but not all) "natural," "organic," "artisan," etc peanut butters - the kind you tend to find at farmers markets rather than the big box groceries, need to be refrigerated because they have low (or sometimes no) sugar, and have no preservatives, etc. 

Long story short, check the label to see if it needs refrigeration.