Red Raspberries - Improve Blood Glucose and Increase Satiety

Red raspberries offer an array of health benefits from improving glucose control, increasing satiety and reducing inflammation. Initial findings of several studies on the health benefits of red raspberries were presented at the 2017 Experimental Biology conference in Chicago. The studies included both human subjects and animals. Short-term trials conducted on humans showed that consumption of raspberries improved glucose control and satiety. Long-term animal trials showed positive effect on the gut microbiota. The results of the studies provide insights for future research on the potential benefits of red raspberries related to reducing the risk of inflammation, obesity and type 2 diabetes.

"We are excited about this new flurry of studies, which builds on previously published research aimed to understand the potential health benefits of red raspberries better. Our Council is committed to delivering the highest quality nutrition and health science that consumers can use to make informed choices when aiming for a healthy diet," said Tom Krugman, Executive Director of the National Processed Raspberry Council (NPRC).

Though further studies on humans are warranted, the initial findings of these studies suggest that vital nutrients, polyphenolic phytochemicals and fiber found in raspberries may play a key role in supporting metabolic functions, including anti-oxidative, anti-inflammatory and metabolic stabilizing activity.

How Raspberries Benefit Health

Control Blood Glucose Levels
Red raspberries are rich in dietary fiber and polyphenols that can improve the health of individuals at risk for developing diabetes mellitus. A research team at the Center for Nutrition Research, Institution for Food Safety and Health, Illinois Institute of Technology, Chicago conducted the effect of red raspberries on meal-induced postprandial metabolic responses. The study comprised of obese individuals with impaired fasting glucose and hyperinsulinemia (PreDM) and healthy weight individuals with normo-glycemia and insulinemia.

The findings of the study published in the FASEB Journal suggest that red raspberries improved insulin sensitivity in individuals with pre-diabetes and insulin resistance. Red raspberries have a role in post meal glycemic control in individuals with hyperinsulinemia.

Improve Satiety

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The study also had a secondary objective in assessing the effects of red raspberries in improving satiety. The research team found that the participants in the PreDM group who reported the highest level of hunger experienced greater satiety after the consumption of red raspberries. The participants in the healthy weight group were also given 2 cups of raspberries for breakfast. The participants experienced significantly greater hunger suppression, after a raspberry meal compared to the same calorie breakfast without raspberries.

Improve Gut Health

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A research team from the Institute for Food Safety and Health from the Illinois Institute of Technology conducted an eight-week pilot study to examine the impact of consumption of red raspberry purée on the gut microbiota. Consumption of red raspberry puree for four weeks resulted in decreased Firmicutes and increased Bacteroidetes.

The team found that a type of bacteria called Akkermansia, which is associated with metabolic health, increased only after the consumption of red raspberry purée. The preliminary results of the study are promising. However, further research is needed to show that consumption of raspberry purée may change the composition of the gut microbiota.

Another study was conducted to find out if red raspberries can modulate the fecal microbiota in obese mice with diabetes and dyslipidemia. Dr. Giuliana Noratto and colleagues of the Department of Food and Nutrition Science at Texas A&M University found that red raspberry supplementation increased the number of Lachnospiraceae. Lachnospiraceae is a family of bacteria that can be depleted during diseases of the intestinal tract such as inflammatory bowel disease Crohn’s disease and ulcerative colitis. The findings of the study provide a base for additional studies involving human participants.

Improve Insulin Sensitivity with Cardio-protective Effect

Red raspberries contain polyphenolics that promote adipose tissue browning and increase lipid oxidation. But the role of polyphenolics in skeletal muscle intracellular lipid accumulation and inulin resistance is unclear. A study conducted on mice found that supplementation of 5% dried raspberry for 12 weeks improved insulin resistance and reduced inflammation in skeletal muscle while consuming a high-fat diet. The findings of the study give support to a short-term study in humans conducted by Xiao and colleagues.

A research team from the University of Michigan studied the antioxidant and anti-inflammatory properties of red raspberries. A study was conducted to mice to explore the potential relationship between feeding freeze-dried whole raspberry powder and the risk of cardiometabolic risk in obese rats. They found that red raspberries upregulated the expression of specific cardiac-protective molecular proteins - myocardial adiponectin, its receptor 2, and apolipoprotein E.

Mice fed with red raspberries experienced altered nicotinamide phosphoribosyltransferase mRNA, a protein associated with obesity and type 2 diabetes. The team said that more research is needed to determine if compounds in red raspberries play a role in human cardiometabolic pathways.

Reduce Inflammation

Ulcerative colitis causes mucosal injuries of the intestinal epithelium, increasing the risk of colorectal cancer. Red raspberries are rich sources of phytochemicals that have beneficial effects on colitis by reducing inflammation

A study conducted on mice found that supplementation of 5% dried red raspberry suppressed inflammation, decreased body weight, improved the disease activity index, and colon epithelium repair and wound healing. Further studies are needed to determine if supplementation of red raspberry supports epithelial function in humans.

The results of the studies are promising and contribute to the understanding of the health benefits of red raspberries. The studies were presented at the 2017 Experimental Biology conference in Chicago.

Reference:

1. Xiao, D. Huang, Y. Park, E. Edirisinghe, I. and Burton-Freeman, B. Red Raspberries and Insulin Action: Understanding the Role of Red Raspberry Consumption on Postprandial Metabolic Indices. The FASEB Journal, April 2017, vol. 31 no. 1 Supplement 973.9.
2. Zhang, X. Sandhu, A. Schill, K. Edirisinghe, I. and Burton-Freeman, B. The Reciprocal Interactions between Red Raspberry Polyphenols and Gut Microbiome Composition: Preliminary Findings. The FASEB Journal, April 2017, vol. 31 no. 1 Supplement 965.29.
3. Noratto, G. Garcia-Mazcorro, J. Chew, B. and Mertens-Talcott, S. Dietary Supplementation with Raspberry Whole Fruit Modifies the Relative Abundance of Fecal Microbial Communities in Obese Diabetic (db/db) Mice. The FASEB Journal, April 2017, vol. 31 no. 1 Supplement 965.19.
4. Min Du, Tiande Zou, Bo Wang, Xingwei Liang, and Mei-Jun Zhu. Raspberry intake reduces skeletal muscle lipid accumulation and improves insulin sensitivity in mice fed high fat diet. The FASEB Journal, April 2017, vol. 31 no. 1 Supplement 972.19.
5. Kirakosyan, A. Seymour, EM. Gutierrez, E. and Bolling, S. Associations of Dietary Intakes of Red Raspberry Fruits with Risk of Type 2 Diabetes Mellitus. The FASEB Journal, April 2017, vol. 31 no. 1 Supplement 973.4.
6. Bibi, S. Du, M. Kang, Y. Sun, X. Xue, Y. Soussa Moraes, LF. and Zhu, M. Dietary Red Raspberry Enhances Intestinal Epithelium Repair in Chronic Colitis. The FASEB Journal, April 2017, vol. 31 no. 1 Supplement 972.19.

Source-Medindia