Rare sugars are – as you might well expect – rare. That is to say that they occur naturally, often in things like fruit, dairy, or even in insects, but they have traditionally been very hard and costly to produce at volume. Fortunately, recent, awesome discoveries over the last twenty years or so have enabled the science magicians to reproduce a number of these at volume, often through fermentation or enzymatic conversion of much more standard food items like corn or starch.
It’s worth bearing in mind that rare sugars are still actually sugar – but the difference is in their effects, their structure at a molecular level, and how our bodies react to them. All of the sugars listed below are available to buy, so technically are no longer ‘rare’, but it’s a convenient category to put them in.