The internet and social media has been awash with claims that fruit juice can cause sudden blood sugar ‘spikes’.
Pure fruit juice producers have felt the knocks of these assertions - more often than not spread by diet and lifestyle ‘gurus’ on platforms such as TikTok and Instagram.
A new study, however, has found that 100% orange juice delays and reduces the rise in blood sugars compared with sugar-sweetened drinks; in turn producing a slower rise and a lower ‘spike’ in blood glucose levels.
Researchers involved in the study – which was published in the peer-reviewed journal Food & Function - have welcomed the opportunity to highlight how natural sugars from fruit behave differently in the body than added sugars, due to the natural structure of the juice.
Lead researcher, Professor Francisco Tomás-Barberán, and dietitian Dr Carrie Ruxton, believe that these findings will help better inform dietary choices and public understanding of sugar in beverages.
Challenging misinformation
Firmly challenging the received knowledge around pure fruit juice and blood sugar spikes, the study shows 100% orange juice provides a slower, more controlled rise in blood sugars than sugar sweetened drinks, illustrating that not all sugary drinks will lead to similar blood sugar behaviours.
“People often assume that because fruit juice contains natural sugars from the fruit, it must act in the same way as a sugary soft drink. Our findings clearly show this is not the case,” Tomás-Barberán said.
“When sugars are consumed within the natural fruit matrix of 100% orange juice, absorption is slower and the early blood glucose peak is lower. Food structure matters.
He continued: “Although public health guidance often groups all ‘free sugars’ together, our study demonstrates that sugars naturally present in fruit juice do not produce the same metabolic response as exactly the same sugars added to drinks.”
The randomised controlled cross-over trial involved 25 healthy young men who consumed four different drinks on separate days: 100% orange juice, a 50% orange juice drink with added sugars, a sugar-sweetened water drink, and a pure glucose drink.
Consumption of 100% orange juice produced a slower rise in blood sugars compared with the sugar-sweetened drinks, which were matched exactly to the balance of sugars in natural orange juice.
While the rise and fall in blood sugars eventually evened out over two hours, the natural sugars from orange juice entered the bloodstream more gradually.
According to the study, this steadier absorption may help explain why some people experience a gradual feeling of energy after drinking 100% orange juice, compared with the sharper ‘spike and dip’ sometimes associated with sugar sweetened drinks.
Ultimately, scientists think that the difference most likely comes down to structure. While soft drinks generally deliver sugar in isolation, 100% orange juice contains what is known as a ‘fruit matrix’ — a natural mix of small fibre fragments, plant ‘bioactives’, and vitamins and minerals found in oranges and other whole fruit. This structure appears to moderate how quickly sugar enters the bloodstream.
Ruxton added: “People are now so worried about ‘sugar spikes’ that some are using wearable technologies, like glucose monitors, to test their reaction to different foods and drinks. While I don’t think this is helpful unless recommended by a doctor, it’s reassuring to know that 100% orange juice is better for blood glucose control than other types of sweet drinks.
“Even with the same overall sugars, the natural fruit matrix of 100% orange juice slows down absorption creating a more gradual rise in blood glucose levels. That could mean more sustained energy levels after your morning glass juice. The fruit matrix in 100% juices also delivers vitamin C for immune function and skin, potassium for blood pressure and a range of fruit bioactives for mental function and cardiovascular health”.
Like Ruxton, behaviour change specialist, Dr Heather McKee, agreed there has been an helpful growing preoccupation with monitoring blood glucose levels, with individuals using these devices even if they’re not diabetic.
“There’s definitely been a surge of interest in blood glucose monitoring, partly driven by influencers and wearable technologies,” she said.
“While glucose responses can be useful in clinical contexts, for most healthy individuals, the body is extremely good at regulating blood sugar. Focusing too heavily on short-term ‘spikes’ can sometimes distract from the bigger behavioural drivers of health, things like dietary patterns, movement, sleep, and stress.”
McKee welcomes the research’s findings, and points out the importance of understanding how different types of sugars interact with our bodies – but cautions against any black-and-white interpretations of food or drinks as purely ‘good’ or ‘bad’.
“Research like this is a useful reminder that not all sugars behave the same way in the body,” she continued.
“The ‘food matrix’ matters, meaning the natural structure of a food or drink can influence how quickly sugars are absorbed and how the body responds metabolically.
“However, it’s also important to keep the bigger picture in mind. While 100% fruit juice contains naturally occurring sugars and some beneficial nutrients, it’s still relatively easy to consume quickly and in larger quantities than whole fruit. From a public health perspective, the goal isn’t to label foods as ‘good’ or ‘bad’, but to encourage overall dietary patterns that support health.”
NPM update risks penalising healthy fruit drinks
The findings follow the publication of the Nutrient Profiling Model 2018 - which despite being reviewed and consulted on eight years ago, has only just been shared.
In the NPM 2018, free sugars replace total sugars, and sugar and energy-density thresholds have been lowered, reducing opportunities for high-sugar and high-calorie foods to pass as non-HFSS.
Speaking with registered dietician and director of Chickpea Marketing, Corrine Toyn, about the proposals - which Food Manufacture has been informed are very likely to go ahead - these new guidelines could see people discouraged from consuming 100% fruit juices, regardless of their clear health benefits.
“The proposed NPM changes risk penalising fruit juices despite their nutritional profile and contribution to five-a-day, which could have unintended consequences for public health messaging,” Toyn said.
“The Government’s recommendation is to consume no more than 150ml [of fruit juice and smoothies] a day, so perhaps the emphasis should be on portion size with clear regulation around the millilitres that’s promoted in marketing e.g. avoidance of large bottles and specific labelling on portion guidance.”
However, Toyn also noted that these changes would give brands an opportunity to “lead on education and clarify the science around fruit juice and sugar types, differentiating from sugary drinks”. Although she cautions that their messaging will need to be “clear and evidence-based to navigate new regulations”.
Where does the real opportunity lie?
Ultimately, McKee told Food Manufacture what’s really important is to focus on helping the average person develop concrete, healthy eating habits that can help them become more resilient and healthy in the long term. While reducing sugar intake is a key part of that, it is far from a silver bullet for the nation’s wellbeing.
“Policy decisions like the NPM proposals understandably aim to reduce excess sugar intake at a population level," she said.
“The challenge is balancing simplicity in policy with the biological complexity of foods. Research that explores how natural food matrices affect metabolism helps add nuance to that conversation.”
She concluded: “From a market perspective, we’re likely to see continued interest in products that promise ‘stable energy’ or ‘balanced blood sugar’, but the real opportunity from my point of view is helping consumers build sustainable habits rather than focusing on single nutrients in isolation.”
