Sugar Showdown: Intrinsic vs. Extrinsic Sugars
Have you ever picked up a food item you thought was ‘naturally sugar-free’, only to glance at the food label and discover sugar in it? Although this can be confusing, it might be down to the difference between intrinsic and extrinsic sugar.
What are intrinsic and extrinsic sugars?
Intrinsic sugars are naturally found in the cellular structure of foods, like fruit and vegetables. Extrinsic sugars are found outside the cellular structure of a foods, and are sub-divided into Milk Sugars (e.g. lactose) and Non-Milk Extrinsic sugars (NMES). Intrinsic sugars and milk sugars are naturally occurring, whereas NMES are added during preparation and processing.
Why understanding the difference matters
Due to intrinsic sugars already being in a food item, they are accompanied by essential nutrients, which generally makes them healthier for consumption. For example, the fibre in fruit and vegetables assists with glucose regulation.
However, NMES are outside of a food product and have no nutritional value. When consumed in excessive amounts, research has shown that there is increased risk of obesity, chronic diseases of the lifestyle, tooth decay and poor oral health.
In essence, intrinsic sugars are okay for consumption, but NMES should be kept to a minimum. According to the World Health Organization, it is recommended to keep added sugar to less than 10% of total energy intake per day.
Spotting extrinsic sugars on food labels
When you’re trying to make healthier food choices, it’s important to read food labels carefully to spot extrinsic sugars. Focus on the ingredient list and words like “sugar”, “sucrose”, “corn syrup”, “honey”, “agave nectar”, or “brown sugar”, indicate there are extrinsic sugars in the product. Words like “fructose (fruit)” or “lactose (milk)” indicate that this type of product likely only contains intrinsic sugars, that occur naturally in the food.
What about fruit juice?
Fruit contains fructose, so you will always see sugar instead on the nutritional label of all fruit juices. What you want to look out for is the ingredient list. This list will guide you. If the ingredient list has concentrates listed on the label the added sugar is going to be higher than a label that only has oranges listed for example. Fruit juices that are blended with vegetable juices will also have a lower glycaemic index than plain fruit juices.
Now you understand the difference between intrinsic and extrinsic sugars, it’s easier to make informed choices about what you eat and drink. By being aware of where sugars come from in your food, you can better manage your intake and focus on nourishing your body with more intrinsic sugars. So, next time you’re reading a food label, remember to look beyond just the sugar content—think about the source and how it fits into your overall health goals. Your body will thank you for it!
References:
Prada, M. et al. (2022) Perceived associations between excessive sugar intake and health conditions, MDPI. Available at: https://www.mdpi.com/2072-6643/14/3/640 (Accessed: 16 February 2025).
Macdonald, I.A. (2019) Free sugars: Proceedings of the nutrition society, Cambridge Core. Available at: https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/free-sugars/9255FAED949871917C921BFF754CB3AC (Accessed: 16 February 2025).
Padovan, M. et al. (2024) Declaration of free sugars from fruits on food labels: A scoping review, British Food Journal. Available at: https://www.emerald.com/insight/content/doi/10.1108/bfj-05-2024-0547/full/html (Accessed: 16 February 2025).
Nguyen, M. (2024) Consumption of 100% fruit juice and body weight in children and adults: A Systematic Review and Meta-Analysis, Jama Pediatrics. Available at: https://jamanetwork.com/journals/jamapediatrics/fullarticle/2813987 (Accessed: 16 February 2025).
