In a recent study, researchers in the United Kingdom investigated the effects of pomegranate juice on lowering blood sugar levels.
Pomegranates are rich in vitamins A, C, and E, as well as antioxidants. Pomegranates are also an excellent source of fibre and iron. It’s no wonder then that prior human intervention studies on the effect of pomegranate juice have yielded positive results, such as lowering blood pressure and the improvement of other health biomarkers. Most recently, a new research study set out to see whether pomegranate juice helps mediate the body’s response to sugar after consumption of a high-glycemic index food.
What is the Glycemic Index?
The glycemic index (GI) is a scale used to indicate how a particular food affects blood sugar levels. Foods are assigned a number that can be compared to pure glucose, which has the highest possible GI number of 100. The GI values of all foods can be classified as either high GI (70-100), medium GI (50-70), or low GI (below 50). The higher the GI value, the more quickly the carbohydrates are broken down in our bodies to be used or stored away. Carbohydrates that are lower on the GI index, such as vegetables or whole-wheat products, are broken down more slowly and result in a more gradual rise in blood sugar levels, while higher GI foods like soda or sweets cause a drastic spike in blood sugar accompanied by increased insulin release.
Because of the positive effects of pomegranate juice reported in previous studies, a UK research group hypothesized that pomegranate juice may actually modulate the body’s responses to high GI foods. This may be due to pomegranate’s abundance of punicalagin and punicalin, which are the polyphenols that contribute to the unique taste of the juice.
Does Pomegranate Juice Help Lower Blood Sugar?
Published recently in The American Journal of Clinical Nutrition, the study assessed the effects of pomegranate supplements, pomegranate juice, or a placebo solution that contained equivalent amounts of malic acid, citric acid, and potassium content of pomegranate juice. A total of 48 healthy volunteers were recruited to test the effects of the aforementioned on blood sugar levels after a meal consisting of 109 grams of white bread, a high GI food.
The volunteers were divided equally into the three groups. For all, a baseline blood glucose measurement was taken prior to consumption of the meal. A timer was started at the first bite or sip, and volunteers were given 15 minutes to consume the meal. Blood glucose measurements were taken again every 15 minutes for one hour, and every half an hour for an additional two hours. All such measurements were taken with a glucometer, a machine that analyzes blood sugar content from a finger-prick at each time-point.
Pomegranate Juice or Supplements?
The results showed that the consumption of 200 mL of pomegranate juice reduced the glycemic response of bread, resulting in slower breakdown and a decreased peak blood sugar level. Further testing showed that punicalagin, a pomegranate polyphenol, was an inhibitor of human α-amylase in vitro. Since α-amylase is an enzyme that breaks down carbohydrates, its inhibition by pomegranate’s punicalagin explains the observed mediated body response to white bread.
What’s more interesting is that only the pomegranate juice could produce these beneficial results, while both the supplement and the acidic solution both proved to be ineffective. The researchers speculate that this may have been due to the punicalagin in the supplement not mixing as well as the pure pomegranate juice in the stomach and small intestine in its encapsulated form.
In all, this study showcases the potential of pomegranate polyphenols to advance our understanding of glucose metabolism in order to develop medications and strategies to help those struggling with diabetes or obesity. Needless to say, the benefits of pomegranate juice merit further investigation. In the meantime, these results suggest that it can’t hurt to include a glass of pure pomegranate juice with your next cheat meal.
Written by Rebecca Yu
Kerimi, A., Nyambe-Silavwe, H., Gauer, J. S., Tomás-Barberán, F. A., & Williamson, G. (2017). Pomegranate juice, but not an extract, confers a lower glycemic response on a high–glycemic index food: randomized, crossover, controlled trials in healthy subjects. The American Journal of Clinical Nutrition, ajcn161968.
Babcock, J. (2017, June 20). Low Glycemic Diet: Benefits, Foods & Sample Plan. Retrieved October 26, 2017, from https://draxe.com/low-glycemic-diet