Say I'm eating peanut butter out of a jar with a spoon, thus presumably transferring some of my saliva into the bottle.

Some research indicates that this sort of double-dipping might be a health hazard if the food is then going to be consumed by others.

But are there any meaningful risks of contamination if I'm the only one who will be eating the peanut butter?

  • 5
    I would say yes, because you are introducing bacteria into the jar, some of which might not be beneficial --there are unfriendly bacteria in your mouth at times.
    – larry909
    Commented Oct 17, 2018 at 2:19

2 Answers 2


In addition to actually adding unwanted species, you're also adding moisture to a food that's otherwise very low in water. This will change its ability to support the growth of mould and bacteria in the damp bits.

If you polish off a jar in a few days and always eat the bit you previously got saliva on, I'm sure the risks will be vanishingly small. If you leave it for a couple of weeks after dipping in a well-licked spoon, I'm less confident.

As a practical measure it would seem easy to spoon out as much as you want into another container, then eat that. That also means you have the option of sharing it rather than having to refuse on the basis that you might as well have spat in it.

  • 10
    As a practical measure it would seem easy to spoon out as much as you want into another container, then eat that. - Do you think that people who eat PB directly out of the jar have a clear imagination of how much they are going to eat? ;D
    – Ian
    Commented Oct 17, 2018 at 10:43
  • 2
    @Ian: Scoop it out with a bigger spoon, then eat it with a second spoon. While some saliva transfer to the first spoon is possible, it will be on the inside of the spoon, which only comes into contact with the PB that you're immediately scooping out.
    – Flater
    Commented Oct 17, 2018 at 11:12
  • @Ian you're probably right, but some people have it as a post-workout snack and they may be a little more willing to measure
    – Chris H
    Commented Oct 17, 2018 at 11:13
  • 1
    @Ian maybe that's just what some eaters would like to have - an easy way to prevent themselves from eating more than intended, by first creating the portion and then eating it.
    – rumtscho
    Commented Oct 18, 2018 at 9:04
  • 2
    @rumtscho That is perfectly possible. My comment was a rather humorous remark about the usual association with eating PB or Nutella right out of the jar. I myself am guilty of having done that before. Nutella never went bad after doing that, by the way.
    – Ian
    Commented Oct 18, 2018 at 9:28

Even if you eat it all by yourself, and all the bacteria is sourced from you; you still have food safety concerns. As those bacteria might multiply in the jar, and start producing toxins as well.

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