Black raspberries (Rubus occidentalis) has been used for a long time in traditional alternative medicine in Korea because of its potential to improve vascular function.
According to data from new Korean study, an extract which is found in black raspberries can significantly lower arterial stiffness, a key measure of cardiovascular disease.
Some previous researches have shown that Black raspberries are effective in preventing colorectal tumors and esophageal cancer.
Recent findings have established a link between the consumption of this fruit and circulating endothelial progenitor cells (EPCs), which helps in repairing and regenerating damaged arteries.
Arterial stiffness is a key indicator of metabolic syndrome, a cluster of cardiovascular (CV) risk factors, especially in obese and insulin resistant patients.
A team of researchers from Korea University Anam Hospital and Gochang Black Raspberry Research Institute (Korea) carried out the trial.
The team took two groups of patients with metabolic syndrome to receive either 750 mg/day of black raspberry extract or a placebo for 12 weeks.
Scientists were recording blood pressure, degree of vascular stiffness, circulating number of EPCs and various markers of inflammation at the start of the study and at a 12-week follow-up.
The team found vascular stiffness values to significantly have decreased in the black raspberry group compared to the placebo group (–5% vs. 3%).EPCs at the 12-week follow-up were significantly higher in the black raspberry group compared to the placebo group (19 microlitres vs. –28micro-L).
Indicators of inflammation, such as interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF), were significantly bigger in the black raspberry group compared to the placebo group (–0.5 picogram per millilitre vs. –0.1 pg/ml, and –5.4 pg/ml vs. –0.8 pg/ml, respectively).
Adiponectin levels which is a hormone involved in regulating metabolic processes, were significantly higher in the black raspberry group when compared to the baseline (2.9 micro-g/ml vs.– 0.2 micro-g/ml).
“The use of black raspberry significantly lowered the augmentation index and increased circulating EPCs, thereby improving CV risks in patients with metabolic syndrome during the 12-week follow-up.”
Benefits of Black raspberry
The health benefits of anthocyanidins and its derivatives have been well-documented and added to an ever growing body of science to support the potential heart health benefits of black raspberries, with the bioactives proposed to be anthocyanins, flavonols, resveratrol, ellagitannin and tannins.
In particular, antioxidant compounds of black raspberry are effective in reducing blood pressure.
These components are already well-documented for their anti-inflammatory,a antioxidative and anti-atherosclerotic effects.
Studies have shown antioxidant compounds of black raspberry are especially effective in reducing blood pressure and improving arterial stiffness.
Some other studies have demonstrated black raspberries to improve blood pressure, lipid profiles and vascular function.
As the researchers have pointed, the fruit’s flavonoid content is primarily responsible for the improvement of vascular function in the subjects.
Flavonoids are effective in increasing bioavailability of nitric oxide (NO) and the enzyme endothelial nitric oxide synthase (eNOS). These are two known factors that contribute to the relaxation of coronary arteries.
Anthocyanins were also highlighted as factors which possess an anti-inflammatory and antioxidant capacity.
However, the researchers hypothesised that the degree of vascular stiffness was lessened due to the increased circulating number of EPCs, which are believed to home into the injury site in order to replicate endothelial cells and activate the endogenous repair system.
The study noted: “The number of circulating EPCs inversely correlates with CV risk factors, suggesting that the circulating number of EPCs is lower in patients with CV diseases.Increases in circulating EPCs during the 12-week follow-up in this study suggest rapid restoration to the damaged endothelium, thereby contributing to the improvement of arterial stiffness and the augmentation index.”