A recent study published within the Nutrients Journal evaluated the results of elderberry juice (EBJ) consumption on indirect calorimetry (IC) and insulin sensitivity/ glucose tolerance measures in a  placebo-controlled, randomized, crossover pilot study.

Study: One-Week Elderberry Juice Treatment Increases Carbohydrate Oxidation after a Meal Tolerance Test and Is Well Tolerated in Adults: A Randomized Controlled Pilot Study. Image Credit: TYNZA/Shutterstock.com

Background

Estimates from the USA (US) Centers for Disease Control and Prevention (CDC) indicate that there are twice more states with adult obesity rates of 35% or higher in 2022 than in 2018.

The associated medical authorities call for higher access to healthcare, physical activity, and healthy foods to slow/reverse the obesity epidemic.

Berries fall under healthy foods and are wealthy in polyphenols, especially anthocyanins, and flavonoids. Prospective cohort studies show an association of anthocyanin consumption with reduced risk of type 2 diabetes, heart problems, and mortality. Further, short-term clinical studies report glucose tolerance improvements with berry interventions.

In regards to the study

In the current study, researchers evaluated the results of consuming EBJ on insulin sensitivity and oxidation in obese or chubby adults. Adults aged 22-75 with a body mass index (BMI) of 25 kg/m2 or higher were recruited between July 2021 and August 2022. Subjects were screened for eligibility using health history questionnaires.

Individuals were excluded in the event that they were pregnant, lactating, or had delivered previously yr. Eligible subjects were screened using an automatic self-administered 24-hour (ASA24) dietary assessment tool for unusual food regimen patterns. Participants continued their habitual food regimen and shunned taking dietary supplements throughout the five-week study period.

Participants got an inventory of high-polyphenol foods and asked to avoid eating listed items. The team implemented a randomized placebo-controlled crossover study design with two treatments. Every one-week intervention period was separated by a three-week washout period.

Participants consumed 100% EBJ or a sugar/flavor-matched placebo beverage for one week. Subjects were randomized to sequence one (EBJ then placebo) or two (placebo then EBJ).

Participants reported to the clinical laboratory on the eighth day of treatment for indirect calorimetry (IC) and meal tolerance test (MTT) examination. Two baseline samples were obtained 10 minutes apart, followed by a test meal and the (treatment) beverage. Blood samples were collected every half-hour after the meal for 3 hours, concurrent with IC testing.

Participants also performed a low-intensity exercise (treadmill walk) for half-hour after the last blood sampling. Serum glucose and insulin response curves were plotted from the MTT. The incremental area under the curve (iAUC) was computed. Linear mixed models tested differences between treatments.

Findings

Overall, 10 subjects were randomized to the protocol. One was excluded as a consequence of uncontrolled diabetes indicated by fasting glucose levels. Each treatments were well tolerated, without reports of gastrointestinal distress. Seven participants were females, and two were males. On average, participants were aged 55.3 and had a BMI of 29.8 kg/m2.

Several technical failures during MTT led to an unbalanced dataset. Nonetheless, statistical analyses included all (partial) datasets. The team observed significant differences between treatments for mean respiratory quotient (RQ) and the corresponding carbohydrate and fat oxidation across IC intervals.

EBJ treatment significantly increased the typical interval RQ, corresponding to a rise in carbohydrate oxidation and a decrease in fat oxidation. There have been no treatment effects on the typical energy expenditure (EE).

IC measures were similar through the treadmill walk, albeit statistically insignificant. No significant differences between treatments were observed in iAUC for serum glucose and insulin.

Conclusions

EBJ treatment didn’t affect serum glucose/insulin after taking the test meal. Nevertheless, it significantly increased the mean carbohydrate oxidation, with a concomitant decrease in fat oxidation. There have been no treatment differences in EE.

Taken together, seven-day consumption of EBJ caused a rise in postprandial carbohydrate oxidation, following a high-sugar MTT, without affecting serum glucose/insulin levels. Moving forward, further studies are essential with an increased sample size to find out the utility of EBJ on these outcomes.