Pure orange juice could help regulate appetite, blood sugar throughout the day: TMU study

A new study conducted at the Toronto Metropolitan University (TMU) suggests that the benefits of 100 per cent orange juice go far beyond a daily dose of vitamin C.

The study was aimed at finding out the effects of drinking pure orange juice versus orange-flavoured sugary drinks on how much food a person might eat during their next meal, the effect on their blood glucose level, average appetite, emotions and sensory characteristics in normal-weight adults.

Explaining the purpose of the study, author Dr. Nick Bellissimo, associate Professor and director of Nutrition Discovery Labs at TMU, says it stems from the idea that reducing sugar intake is a healthy choice.

“There’s a number of dietary guidelines and recommendations, not just in Canada, but throughout the world around sugars reduction,” he says.

For example, the study cites that the World Health Organization suggests decreasing the intake of free sugars to 10 per cent or less of your daily energy intake in order to reduce the risk of unhealthy body weight and dental issues.

Bellissimo says based on such suggestions, some national guidelines recommend reducing all types of sugar.

“This implies essentially all glycemic carbohydrates, right? … [But] does the source matter and does the form matter? These are the basic things that we’re looking at in our experiment,” he says.

The experiment: Orange juice vs. soda vs. water

The study recruited 36 adults between the ages of 18 and 45 with average body mass index, considered to be healthy by all regular standards.

They participated in three separate test sessions about five days apart.

On the morning of each test session, participants arrived at the TMU laboratory at 8 a.m. after fasting for 10 to 12 hours and were fitted with continuous glucose monitors.

They were served breakfast in the lab and two hours later, they were all given 100 per cent orange juice during the first session, an orange soda during the second and water during the third.

About 60 to 90 minutes later, the participants were served lunch.

“We gave them a meal and we said, ‘eat until you’re comfortably full.’ And we actually measured how many calories they consumed at lunch,” says Bellissimo.

Thereafter, the participants were sent home and asked to record everything they ate for the rest of the day.

“We have the continuous glucose monitors on, so we were able to measure their blood glucose levels, or what I call the excursions – the changes in their blood glucose, for the rest of the day,” he says.

Bellissimo says changes in blood glucose levels have wide ranging impacts on how a person feels including mood, memory, performance, appetite and how many calories they end up consuming in the day.

“So the idea [of the experiment] is what should you be consuming as a mid-morning snack if you’re looking to a suppress your appetite and food intake and to potentially help regulate your blood glucose levels?,” says Bellissimo.

Bellissimo says it’s not about restricting food intake per se, which is not a recommended practice, but rather about healthy choices that work with the body’s biology to remain satiated.

“I think people in general are looking to make healthy choices in their daily routine … people don’t want to overeat. So we’re trying to figure out what should we be giving our body in real time, so it’s satisfying, and that you don’t end up overeating throughout the day. Ask anyone who tries to calorie restrict at breakfast, at lunch, in the evening. You’re just setting yourself up to really overeat at the end of the day. And so our idea here is can we do things early in the day and consistently that can help an individual self-regulate better?”

The findings: not all sugars are made equal

Bellissimo says even though the two beverages had similar sugar content, when participants drank 100 per cent orange juice, they consumed fewer calories at lunch time compared to when they drank the processed beverage.

Participants also consumed fewer calories throughout the day, which leads to lower blood sugar levels.

“The source [of sugar] matters,” he says.

Bellissimo says there are a combination of factors that may explain the effect of orange juice on appetite and subsequently blood glucose.

“[Orange juice] has a little fibre. We know that the orange juice digests more slowly than some of these sugary sweetened beverages. So you are reducing gastric emptying — that’s essentially how quickly food will empty from your stomach and move into the small intestine — and I think then also helps regulating your blood glucose levels.”

He adds that if blood glucose isn’t well regulated, hunger might return more quickly.

“And then next thing you know, you make poor decisions because … from a cognitive performance perspective you’re not making the best decisions because your biology is kind of overriding your ability to restrain your energy intake,” he says.

“I think every single person has been hangry at some point. And then when you’re in that state of mind, you’re less likely to make nutritionally sound decisions.”

The takeaway: orange juice is probably better for you than you thought

Bellissimo says the study provides a good deal of practical information.

“There’s something about the ratio of glucose and fructose in various beverages that can be utilized to actually potentially improve outcomes in terms of appetite, in terms of suppressing food intake,” says Bellissimo.

He says that the study points out that when considering reducing your sugar intake, the source of the sugar is key. Having just a bit of that sugar in 100 per cent orange juice could potentially help decrease your overall sugar consumption.

“A little bit of sweetness in the morning … had very strong and very evident, clear functional benefits in terms of appetite suppression, food intake suppression, and overall glucose control for the day,” he says.

“We’re not recommending this as a weight loss solution. This is about feeling good about choices that you make because it’s giving you a functional advantage in real time and it’s going to contribute to better self-regulation.”

He adds that the findings do not apply to groups the study did not include, such as those with diabetes, people living with obesity, children or older adults.

“But it opens up the door for additional experimental trials, especially some longer term studies that I think we need to do,” he says.