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Article review: The effects of orange juice in a reduced-calorie diet
“Orange juice allied to a reduced-calorie diet results in weight loss and ameliorates obesity-related biomarkers: A randomized controlled trial”
In their recent article published online in the peer-reviewed journal Nutrition, Carolina Ribeiro et al. of the School of Pharmaceutical Sciences in Sao Paolo (Brazil) assess the effects of the “combination of a reduced-calorie diet (RCD) and 100% orange juice” on weight loss, glucose and lipid metabolism, or diet quality in obese subjects.
Two groups, each containing 39 obese patients (with an average BMI of 33, average age 36), were randomly assigned to either a ‘Reduced-Calorie Diet’ (RCD) that included 500ml of 100% orange juice per day, or a control group RCD (which replaced juice with an energy-equivalent amount of food) for a 12-week period. To establish the RCD, the study first measured Total Energy Expenditure, before subtracting 500 kcal per day (equivalent to a Total Energy Expenditure reduction of 30%).
The two groups had similar outcomes with regards to their resulting body composition. They lost an equal amount of weight (6 to 7kg), lean mass, fat mass, % body fat and reduced their waist and hip circumference comparably. The authors conclude from this that “the addition of 100% orange juice does not affect the weight loss induced by a reduced-calorie diet.”
However, compared to the control group, the group consuming 100% orange juice decreased insulin by 18%, HOMA-IR (Homeostasis Model Assessment) by 33%, total cholesterol by 24%, low-density lipoprotein cholesterol by 24% and hs-CRP (ultra-sensitive C-reactive protein; a marker for increased risk of coronary events) by 33% (all with a p-value equivalent to 0.05 or less, in other words statistically significant for at least 95%). The reductions in insulin and HOMA-IR were especially higher at weeks 8 and 12 compared with the control group and similarly significant for total cholesterol and hs-CRP at week 12. It is significant to point out here that up until week 7, changes in these metabolic markers were similar in both groups, going in the same direction, but from week 8 onwards the changes stagnated in the control group. Research therefore that does not extend beyond 8 weeks might have missed out on this longer-term effect.
The 100% orange juice group demonstrated significantly increased vitamin C and folate intake with (respectively) 163% and 62% increases compared to the levels measured from the control group.
The statistically significant differences between the two groups on several markers show that a randomized controlled trial with two groups of this size is sufficient base for results in this instance, especially when the research period extends beyond 8 weeks. However, it is debatable whether complementing a reduced-calorie diet with 500 ml of 100% orange juice per day is advisable, as this exceeds common recommended portion sizes for 100% pure fruit juices in Europe. Nevertheless, the results are important as this raised level of 100% orange juice does not hinder weight loss.
Johan De Rycker
The study is funded by Citrus BR and Citrosuco S.A. by an unrestricted grant, though this influences neither the results or conclusions outlined by the authors. The study is declared on ClinicalTrials.com under the number NCT02914249.
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