Pomegranates and Blood Glucose Control
It is the season to eat pomegranates. I like to eat pomegranates. Pomegranates are so tasty, who doesn't like them? I can watch TV while mindlessly eating one seed after another, before I know it, a whole pomegranate is eaten.
One observation I had from my regular consumption of pomegranates is that I fell into sleep easier on the days that I ate some pomegranates than the days that I did not eat any pomegranates. When I first shared this with my aunt, who had trouble with falling to sleep, and suggested her to eat some pomegranates, she responded that "it had too much sugar" since she had high blood glucose levels that she would like to keep her sugar intake low.
Is there any connection between pomegranates and sleep? I wondered and searched for PubMed. I did not find any papers on pomegranates and sleep specifically, but I found some reports on pomegranates and blood glucose. That is useful information that may help people who have high glucose levels.
One randomized, crossover, controlled study recruited 16 healthy volunteers to have a high-glycemic food (white bread) with pomegranate juice or a fruit acids-containing control solution (same pH as pomegranate). During the glucose measurements throughout the 3 hours after the food consumption, compared with the control solution containing the equivalent amount of sugars, pomegranate juice significantly reduced the area under the curve for blood glucose (-33%, p< 0.05) and blood glucose peak (-25%, p<0.05) (1).
Patients with type 2 diabetes (n=85, 40 male and 45 female), who were between 37 and 60 years of age, were recruited into a randomized clinical trial. The study participants were given fresh pomegranate juice at a dose of 1.5 mL/kg body weight. The juice was consumed within a 5-minute time frame. Blood samples were collected at 1 and 3 hours after the juice consumption. The results showed that pomegranate juice consumption decreased fasting blood glucose, increased β-cell function, and decreased insulin resistance among diabetic participants, 3 hours after pomegranate juice administration (p < .05). The hypoglycemic response depended on initial fasting glucose levels. Compared with those who had higher fasting glucose levels (8.8-15.8 mmol/L or 159-285 mg/dL), participants with lower fasting glucose levels (7.1-8.7 mmol/L or 128-157 mg/dL) had a greater hypoglycemic response (p < .05). The effect of pomegranate juice was not affected by the sex of the patient and was less potent in elderly patients. It is important to note that not everybody in the study had the glucose-lowering effect after pomegranate juice consumption since one in five of the study participants' glucose levels did not respond to pomegranate juice. These study results suggested that pomegranate juice consumption could be an effective way to control glucose levels (2).
Diabetes is associated with increased oxidative stress and atherosclerosis development. Healthy subjects (controls) and type-2 diabetes patients (n=10 each group) who consumed pomegranate juice (50 ml per day for 3 months) participated in a study (3). Pomegranate juice consumption did not affect blood glucose, cholesterol, and triglyceride levels, and it resulted in a significant reduction in serum lipid peroxides and TBARS levels (both are oxidative stress biomarkers) by 56% and 28% (p < 0.05). Pomegranate juice consumption also significantly reduced cellular peroxides (by 71%) and increased glutathione levels (antioxidant biomarker by 141%) in the patients' monocytes-derived macrophages. Pomegranate juice consumption by diabetic patients did not worsen the diabetic parameters, resulted in anti-oxidative effects on serum and macrophages, which could contribute to attenuation of atherosclerosis development in these patients (3).
Although pomegranate juice contains a significant amount of sugar, these sugars may not exacerbate type-2 diabetes variables shown in previous studies (1-3). Such findings are contrary to sugars with other fruit juices (for example, grape juice). A rodent study (4) concluded that the pomegranate sugar fraction, unlike a white grape juice sugar fraction, decreased macrophage oxidative stress under both normal and diabetic conditions. These differing data may be due to the presence of unique sugars in pomegranate juice. The sugar fraction of pomegranate juice reportedly contains polyphenolic antioxidants (anthocyanins and tannins), which may contribute to the exceptional properties of pomegranate sugars (4). However, many of these unique sugars are still unidentified (4).
Sleep disorders are common in diabetic patients and negatively affect the control of diabetes. Studies have reported the presence of sleep disorders in approximately 50-70% of diabetic patients. One study included 585 type-2 diabetic patients showed that 54.40% of patients experienced excessive daytime sleepiness, and 64.30% experienced poor-quality sleep. HbA1c levels correlated significantly with the Sleepiness Scale and Sleep Quality Index results (p < 0.05) and were higher in those with obstructive sleep apnea syndrome (p < 0.05). These results showed that the higher HbA1c levels, the more likely a patient might experience sleep disorders. Addressing sleep disturbances in patients who have difficulty controlling their blood glucose can improve diabetes control, and better diabetes control can improve sleep (5).
A study examined the impact of glycemic derangement on sleep patterns among children with type-1 diabetes. The results showed that nocturnal hypoglycemia was positively correlated to deep sleep duration, while hyperglycemia was correlated to the number of awakenings, sleep-onset latency, and light sleep duration (6). In another word, a person with a lower blood glucose level may sleep longer and deeper.
I typically eat half or one pomegranate each time. As mentioned earlier, healthy subjects who drank 200 ml of pomegranate juice with white bread had a significant overall glucose reduction (-33%) and peak reduction (-25%) (1). Say if one pomegranate may press out about half a cup of juice (~125 ml) then I might have experienced some glucose-lowering effect from consuming pomegranates. Lowered glucose levels may be the reason why I fell into sleep more easily. Other benefits of pomegranates like lowering blood pressure, reducing atherosclerosis, and enhancing weight loss, and more can wait for future blogs. I am heading out to buy more pomegranates.
​References:
1. 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, 106(6), 1384–1393.
2. Banihani, S. A., Makahleh, S. M., El-Akawi, Z., Al-Fashtaki, R. A., Khabour, O. F., Gharibeh, M. Y., Saadah, N. A., Al-Hashimi, F. H., Al-Khasieb, N. J. (2014). Fresh pomegranate juice ameliorates insulin resistance, enhances β-cell function, and decreases fasting serum glucose in type 2 diabetic patients. Nutrition Research, 34(10), 862–867.
3. Rosenblat, M., Hayek, T., & Aviram, M. (2006). Anti-oxidative effects of pomegranate juice (PJ) consumption by diabetic patients on serum and on macrophages. Atherosclerosis, 187(2), 363–371.
4. Rozenberg, O., Howell, A., & Aviram, M. (2006). Pomegranate juice sugar fraction reduces macrophage oxidative state, whereas white grape juice sugar fraction increases it. Atherosclerosis, 188(1), 68–76.
5. Bilge, U., Keskin, A., Ünalacak, M., Yildiz, P., Güler, S., Selçuk, E., & Bilgin, M. (2015). Effects of Sleep Disorders on Hemoglobin A1c Levels in Type 2 Diabetic Patients. Chinese Medical Journal, 128(24), 3292.
6. Salah, N. Y., Abido, A. Y., & Rashed, H. R. (2020). Relationship of glycemic derangement using continuous glucose monitoring system with sleep pattern among children with type 1 diabetes mellitus. Diabetes/Metabolism Research and Reviews.