A comprehensive data analysis suggests that 100% fruit juice does not have a significant effect on fasting blood glucose, fasting blood insulin, or insulin resistance, according to a new study.
The findings are consistent with previous research indicating that 100% fruit juice is not associated with an increased risk of developing type 2 diabetes mellitus (T2D) and support a growing body of evidence that 100% fruit juice has no significant effect on glycemic control.
Juice is good food
Pure, 100% fruit juices can be nutrient-dense foods providing potassium, magnesium, folate, calcium, vitamins A and C, and soluble fiber, as well as an array of bioactive substances, including carotenoids and flavonoids. “Nutritional guidance encourages consumption of fruit as part of a balanced and healthy diet, although guidance often recommends limited consumption of fruit in the form of juice citing concerns over a lack of fiber and the potential for excessive energy intake. Juices also tend to have moderately high-glycemic index ratings, indicating a relatively rapid and high post-prandial glucose response as compared with foods with a lower glycemic index,” stated the researchers, led by Mary M. Murphy of the Center for Chemical Regulation & Food Safety in Washington, DC.
Diets lower in these types of simple carbohydrates may be relevant for the prevention and management of some chronic diseases, including type 2 DM.
The researchers published their results online December 15, 2017 in Journal of Nutritional Science.
A systematic review quantitatively summarized results from randomized controlled trials (RCT) examining the effects of 100% fruit juice on glucose–insulin homeostasis. Using data from 18 RCT, meta-analyses evaluated the mean difference in fasting blood glucose (16 studies), fasting blood insulin (11 studies), the homeostatic model assessment of insulin resistance (HOMA-IR; 7 studies) and glycosylated hemoglobin A1c (HbA1c; 3 studies) between the 100% fruit juice intervention and control groups.
The results show 100% fruit juice, as compared with the control group, had no significant effect on:
- Fasting blood glucose (−0.13 mmol/L)
- Fasting blood insulin (−0.24 pmol/L)
- HOMA-IR (−0.22) or HbA1c (−0.001)
Results from stratified analyses and univariate meta-regressions also largely showed no significant associations between 100% fruit juice and the measures of glucose control.
“The available RCT indicate that repeated intake of 100% fruit juice does not have a significant effect on glycemic control or measures of insulin resistance,” the researchers stated. “These findings from RCT of markers for diabetes are consistent with findings from some observational studies suggesting that consumption of 100% fruit juice is neutral regarding risk of type 2 DM.”
Although the mechanism by which 100% fruit juice imparts a favorable effect on glycemic control is not clearly known, some evidence, largely from in vitro and animal studies, indicates that polyphenols may favorably affect glucose–insulin homeostasis in a variety of ways. The researchers point specifically to:
- Inhibition of glucose absorption
- Stimulation of insulin secretion from the pancreas and change in glucose release from the liver
- Activation of insulin receptors and glucose uptake by cells
- Modulation of cell signaling pathways and gene expression