Background
Dietary guidelines often deal with 100% fruit juice (FJ) inconsistently because it represents a source of free sugars. However, FJ also provides bioavailable micronutrients and plant bioactive at levels similar to those found in whole fruits.
Aims
To verify the hypothesis that eating whole fruit is better than drinking 100% FJ for glycemic control. In this study we evaluate and compare the effect of consumption of 300-ml orange FJ and 300-gram of orange fruit on post-prandial glucose (PPG) levels measured after 1 hour and 2 hours.
Methods
15 type-2 diabetic patients volunteered from author’s online Diabetes Reversal Program to participate in the study. The volunteers were recruited online from Canada, USA, UK, Australia, Italy, and India. None of the patients were insulin dependent. On day 1, they drank 300-ml orange FJ on empty stomach in the morning and measured the difference between fasting blood glucose (FBG) and PPG. On day 2, they ate 300-gram whole orange fruit on empty stomach in the morning and measured the difference between FBG and PPG. The relative effect of consumption of 300-ml orange FJ and 300-gram whole orange fruit on glycemic control was compared to verify the hypothesis that eating whole fruit is better than drinking 100% fruit juice.
Results
The above tables and graph show the relative effect of consumption of 300 ml orange FJ and 300 g whole orange fruit on the blood glucose levels of the patients. On an average, a slight difference between 1 hr. PPG (11 mg/dl) of both meals was observed. However, there was negligible difference between 2 hr. PPG (5 mg/dl). When observed individually, majority of the participants had a higher glycemic response to orange FJ. The 1 hr. PPG for orange FJ had a significant spike (>60 mg/dl) for some patients (P6, P13, P15). Interestingly, in the comparison of 1 hr. PPG, some participants (P7, P9, P14) seemed to have a higher glycemic response to whole orange fruit than orange FJ. Furthermore, a negligible difference was observed between 2 hr. PPG after consumption of whole orange fruit and orange FJ in most of the participants. On an average, there was a negligible difference between the deviation of average 2 hr. PPG from average FBG, in orange FJ group (0), and whole orange fruit group (+5 mg/dl). One participant (P14) got mild episodes of cough after eating/drinking oranges. No other negative outcomes were reported by the participants.
Discussion
Fruit juices are a subject of controversy due to the presence of free sugars and less dietary fiber than in fresh fruits. However, a recent review of studies stated that moderate consumption of 100% juices not only does not have negative effects on human health, but on the contrary improves the health of the organism. [2] Its intake helps lower blood pressure and the content of highly sensitive C-reactive protein, thereby reducing the risk of cardiovascular diseases. There is no correlation between moderate juice consumption and type 2 diabetes onset. In a meta-analysis of 18 RCTs in 2017 it was found that 100 % fruit juice had no significant effect on fasting blood glucose, fasting blood insulin, insulin resistance, or HbA1c. [3] These findings are consistent with findings from some observational studies suggesting that consumption of 100 % fruit juice is not associated with increased risk of diabetes.
The glycemic index of the juices is low or medium, which distinguishes them from standard soft drinks containing sugar. The consumption of juices (100-500 ml/day) does not increase the risk of obesity in adults and children. Negative effects, such as weight gain and an increased risk of diabetic diseases, can only be observed with excessive consumption of juices. Based on data from some studies, individuals with high consumption of sugar sweetened beverages (SSBs) had a 26% greater risk of developing type 2 diabetes. [4] Results from a meta-analysis in 2014 suggested that a greater intake of sugar sweetened fruit juice was associated with a 14% higher risk of incident type 2 diabetes while 100% fruit juice had no effect. [5] In another study a higher percentage of fruit juice consumers met the average requirement for vitamin A, vitamin C, folate, magnesium, and potassium as compared to non-consumers. [6] In our present study, a negligible difference was observed between the deviation of average 2 hr. PPG from average FBG, in both the groups: orange FJ group (0), and whole orange fruit group (+5 mg/dl) highlighting that consumption of oranges (whether juiced or eaten whole) is well tolerated by majority of the participants. The findings from this study suggest that a moderate intake of both fruit juice and whole fruit is safe and well tolerable for diabetics and does not substantially raise the blood glucose levels in the average diabetic, however, individualized dietary modification certainly would be the best potential practice to achieve optimal health outcomes.
Conclusions
Eating whole fruit may provide a better 1 hr. PPG control as compared to 100% fresh fruit juice. However, the difference is negligible in the 2 hr. PPG levels. Overall, consumption of whole fruit seems to be a better choice for glycemic control as compared to 100% fresh fruit juices. A moderate intake of fruit juice is safe for diabetics, but individualized dietary modification is important to implement the observations.