12 January - 20 June 2016

Could red raspberries be the next “super fruit”?

A number of animal model studies, published in the FASEB journal, and presented at 2016 Experimental Biology, have indicated that red raspberry consumption can reduce cardiovascular disease risk, help normal blood glucose levels, and have an anti-inflammatory effect related to bone health. A review published in Advances in Nutrition, published earlier this year, notes that red raspberries (Rubus idaeus L.) possess several essential micronutrients, dietary fibres, and polyphenolic components, especially ellagitannins and anthocyanins.

A number of animal model studies, published in the FASEB journal, and presented at 2016 Experimental Biology, have indicated that red raspberry consumption can reduce cardiovascular disease risk, help normal blood glucose levels, and have an anti-inflammatory effect related to bone health.  A review published in Advances in Nutrition, published earlier this year, notes that red raspberries (Rubus idaeus L.) possess several essential micronutrients, dietary fibres, and polyphenolic components, especially ellagitannins and anthocyanins.  

A study by Kirakosvan et al. has investigated the cardioprotective effects of red raspberries in obesity prone rats.  The scientists fed obesity prone rats a high fat diet (45% of kcals) containing 2% (wt/wt) freeze-dried whole raspberry power or added sugars to equal the calorific and micronutrient content for 8 weeks.  They report that the raspberry power reduced fasting triglycerides and fasting glucose, however it did not affect fasting insulin, low density lipoprotein or body weight gain.  Kirakosvan et al.  state that although there were no significant changes in blood pressure compared to the benchmark diet, the raspberry power did significantly reduce heart rate, and reduce left ventricular enlargement (a risk factor/precursor to heart failure), and wall thickening. 

Zhu et al. and Shay et al. both investigated the effect of raspberries on metabolic syndrome.  Shay et al. studied the effect of red raspberries in mice fed a high fat (45% kcal fat), high sugar diet.  Groups of mice (which were susceptible to diet-induced obesity, type 2 diabetes, and atherosclerosis) were fed ad libitum, for 10 weeks, either a low fat diet (10% kcal fat), a high fat diet or a high fat diet supplemented with either raspberry juice concentrate, raspberry puree concentrate, raspberry freeze-dried powered, ellagic acid raspberry ketone or ellagic acid and raspberry ketone.  Fruit products provided 10% of total energy and phytochemicals ~0.2% w/w of diets.  Mice weekly intake, and body weight were recorded and glucose intolerance measured at week 9.  At 10 weeks the mice were sacrificed and liver tissue and serum collected.  The diets supplemented with raspberry juice concentrate, puree concentrate, and both ellagic acids and raspberry ketone, were found to significantly reduce weight gain compared to the mice who were just fed a high fat diet.  On analysis of the expression of 87 genes related to metabolic factors, the scientists found that intake of either raspberry concentrate or puree, ellagic acid or raspberry ketone, showed a positive effect on gene expression in the liver and altered relative mRNA levels so they closely resembled the mice on the low fat diet. Zhu et al. also fed mice a high fat diet or a control diet supplement with or without 5% freeze dried raspberry for 12 week.  The high fat diet was found to increase body weight and blood glucose, which by the end of the study was alleviated by the raspberry supplementation.  The supplementation also improved glucose intolerance and insulin sensitivity. Zhu et al. report dietary raspberry reduced lipid droplets in the liver and decreased serum triglyceride level. 

Noratto et al. examined the effect of raspberry dietary supplementation on obese diabetic mice fed either a control diet or a diet supplemented with 9.75% freeze dried raspberries (equivalent to 208g freeze dried raspberry/day for 60kg adult).  The raspberry dietary supplement protected against appetite loss, weight loss and cachexia seen in the control group.  Fasting glucose was found to be lower in the raspberry supplemented group, but there was no different in blood insulin concentrations, indicating that “higher concentrations of plasma resistin in the raspberry group is correlated with higher body weight and is consistent with it delaying cachexia“.  Most heart tissue disease biomarkers were similar between experimental groups, although plasminogen activator inhibitor (elevated PAI-1 is a risk factor for thrombosis and atherosclerosis) was lower in the raspberry group compared to the control. 

Using mouse macrophage cells Thomas et al. studied the anti-inflammatory effect of polyphenols in red raspberries in the production of osteoclasts, the cells associated with the breakdown of bone.  Red raspberry polyphenols were found to reduce interleukin - 1β and IL-6 which the scientists state demonstrate its anti-inflammatory role in bone cells.  The polyphenols also reduced inducible nitric oxide, synthase protein and bone morphogenetic protein-2, which according to the study means the polyphenols act to retain RANKL mediated osteoclastogenesis.   The study in conclusion notes that “these findings suggest that polyphenols associated with red raspberry would inhibit the negative effect of osteoclasts on bone health. “

This year’s Experimental Biology was held in San Diego.  The annual, multidisciplinary, scientific meeting covered anatomy, biochemistry and molecular biology, investigative pathology, nutrition, pharmacology, and physiology.

RSSL can determine physiologically active compounds, including flavanols, other polyphenols and other phytochemicals in a range of fruits, vegetables, herbals and dietary supplements.  For more information please contact Customer Services on +44 (0) 118 918 4076 or email enquiries@rssl.com 

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