A few years ago I heard about some chemical effect which takes place in food containing high amounts of sugar. The outcome of it allegedly makes the food become unconsumeable within a few months. When I searched for more information on the WWW, I only found converse information: sugar does not deteriorate, is even used for conservation of food. So does my memory deceive me?

  • What do you mean by "uneatable" or "unconsumeable"? Are you asking whether it turns into poison, or whether it gets yucky-tasting?
    – Sneftel
    Commented Oct 16, 2023 at 16:02
  • As far as I remember some chemical reaction caused formation of an unhealthy substance (like frying causes Acrylamide).
    – Shakesbeer
    Commented Oct 16, 2023 at 16:07
  • 1
    This question, as written, is too vague to be answerable. Among other things, none of us can give the state of your memory.
    – FuzzyChef
    Commented Oct 16, 2023 at 17:55
  • 1
    You might be thinking of fermentation, which is when microbes digest the sugars. If uncontrolled, this can be bad, but it’s also how we get beer, wine, hard cider, etc
    – Joe
    Commented Oct 16, 2023 at 19:35

2 Answers 2


Either your memory deceives you or someone else did.

Sugar by itself does not degrade into anything toxic or otherwise inedible. On the contrary, sugars can preserve food nearly as well as salt or vinegar (with some caveats), and in particular, cultures have been using honey as a preservative for thousands of years. It may seem counterintuitive since yeasts and bacteria love sugar as a food source, but as it turns out, an environment of too much sugar acts very similarly to salt by extracting the moisture from the cells, killing the micro-organism in the process.

So while there are many reasons why food with sugar as a component can go bad over time, but the sugar in and of itself is not one of those reasons.

  • Doesn't honey contain some anti-bacterial compounds, making it an even better preservative than sugar? Commented Oct 20, 2023 at 21:17
  • @PeterShor I'd argue that "more resilient" is a more applicable description than "better". Sugar is a perfectly good preservative that will probably last forever under ideal circumstances. That being said, honey's anti-bacterial properties (as well as it being much easier to get ahold of for ancient civilizations) does make it "better" from a historical standpoint. Also, if the circumstances are less than ideal (such as being exposed to high levels of humidity for an extended period of time) then sugar can quickly change from being a toxic environment for microbes to being a playground.
    – Abion47
    Commented Oct 22, 2023 at 22:14

Well, there's two questions there: does sugar spontaneously transform into something else over time, and if so, is that something else unhealthy.

The only normal change I know of that sugar undergoes over time in food, is the hydrolysis of disaccharides like sucrose (table sugar) into monosaccharides (such as glucose and fructose) in a low-pH environment. Neither glucose nor fructose is poisonous. Of course, there's also the fermentation of sugar into other things, but that's not a chemical process.

The question of whether high-sugar foods are unhealthy -- either immediately, or after a while -- is a medical one, and off-topic for this site.

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