In this paper of the WHO, there is a distinction between intrinsic sugars, who are incorporated within the structure of intact fruit and vegetables, and sugars naturally present in fruit juices. (page 15/59)

What are the differences between those two sugars? How an intrinsic sugar can become another one when making a juice?

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    $\begingroup$ From the document: "Higher intakes of free sugars threaten the nutrient quality of diets by providing significant energy without specific nutrients ". The sugar is the same, but it comes with or without other nutrients (and fiber). Also, it is easier to drink the juice of 4 oranges (roughly a cup) than to eat 4 oranges, so the sugar is released into the blood stream at a different rate. $\endgroup$ – Karsten Theis Jul 25 '19 at 23:16
  • $\begingroup$ In addition juice you buy may not always be pure but contain added sucrose to make it sweeter. $\endgroup$ – porphyrin Jul 30 '19 at 9:17

Your question has a broad scope. Yet, I'll try to give a simple answer. Basically, naturally occurring sugars or sugars contained within unprocessed foods including vegetables and fruits are considered intrinsic sugars. Examples for the most common intrinsic sugars are glucose, fructose, lactose, and sucrose. Besides them, other minor amount of natural sugars in foods such as galactose and maltose are also considered intrinsic.

The other type of sugar (e.g., the sugar in a juice) is called extrinsic sugars. Extrinsic sugars include processed sugars or sugars that are added to food. Extrinsic sugars include syrups such as honey, added sugars in soft drinks, and artificial sweeteners. However, there is no clear difference between intrinsic versus extrinsic sugars (Ref.1):

Development of caries in man is associated with dietary sugars, but the relationship between sugar contents of individual foods and their cariogenic potential is unclear. A recent report categorized dietary sugars as intrinsic (mainly fruit and vegetable) and extrinsic (mainly added sugars, milk, and fruit juices) and concluded that consumption of extrinsic sugars (except milk) should be replaced with that of intrinsic sugars. This paper examines briefly the dental consequences of the recommendations.

Yet, Live Strong recommends following:

According to the American Heart Association, intrinsic sugars should be limited to at least half of your daily intake of carbohydrates and extrinsic sugars should be limited to no more then half of your maximum daily amount.


  1. W. M. Edgar, "Extrinsic and Intrinsic Sugars: A Review of Recent UK Recommendations on Diet and Caries," Caries Research 1993, 27(suppl l), 64-67 (https://doi.org/10.1159/000261605).
  • $\begingroup$ If I correctly understand your answer, there are no extrinsic sugar in 100% pure juice despite it is juice, right? $\endgroup$ – Pierre Jul 24 '19 at 18:57
  • $\begingroup$ If the bottle says "no added sugar", then you are right. Otherwise, it contains some extrinsic sugar. $\endgroup$ – Mathew Mahindaratne Jul 24 '19 at 19:21
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    $\begingroup$ The WHO document does not distinguish extrinsic and intrinsic, but instead recommends limiting "free" sugar. "Free sugars include monosaccharides and disaccharides added to foodsand beverages by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates." So for the WHO document, it does not matter if it is 100% pure juice or lemonade, they recommend limiting intake of both. $\endgroup$ – Karsten Theis Jul 26 '19 at 13:47
  • $\begingroup$ @KarstenTheis So, WHO recommends limiting intake of 100% pure juice despite the fact that the sugar in it is the same as the sugar in the fruit, right? $\endgroup$ – Pierre Jul 31 '19 at 18:28
  • $\begingroup$ Yes, it’s not just about the kind of sugar, but also what it comes with. To give a current and tragic example, what is in a pulverized oxycontin pill is exactly the same as what is in the original pill. The effect on the person ingesting it is very different, though. $\endgroup$ – Karsten Theis Jul 31 '19 at 19:14

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