One of my favourite herbs is grape seed – usually the part of the fruit that we don’t eat. Modern research has identified some amazing health benefits for the seed of this ancient fruit. I particularly use grape seed as an extract standardised for OPCs (oligomeric procyanidins). These are large molecules that have flavonoid-like bioactivity and chemistry, although they are quite different to ‘bioflavonoids’. However, that similarity to flavonoids means that OPCs are particularly beneficial for maintaining the health of the micro-circulation (small blood vessels and capillaries) and this is a key focus of my use of this herb.
The micro-circulation is perhaps a neglected part of modern therapy. We tend to focus on treatments that benefit the heart or the arteries or the veins, ignoring the fact that the micro-circulation is the largest part of our circulatory system and is crucial for delivering adequate nutrition to our tissues. As well as poor tissue nutrition, unhealthy micro-circulation is implicated in easy bruising, excessive inflammation and poor healing. It is also relevant to problems affecting those parts of the body rich in small blood vessels, namely the retina of the eye, the glomerulus of the kidney and the circulation supplying the long nerves of the body, such as to the legs. It’s no coincidence that these are the sites attacked by long-term diabetes (retinopathy, nephropathy and neuropathy), a disorder that particularly affects the health of the micro-circulation.
The benefits of grape seed extract on the micro-circulation are supported by clinical research. In early uncontrolled and controlled trials, grape seed extract (100mg to 150mg/day of grape seed OPCs) increased capillary resistance in a range of conditions where capillary fragility, low capillary resistance or functional vein problems were present.1,2,3,4,5,6,7 In addition to capillary fragility and venous insufficiency, some patients had varicose veins and leg ulcers. Diabetic and hypertensive patients were assessed in one trial. In patients with venous insufficiency, symptoms such as swelling, itching, pain, heaviness in the legs were alleviated or resolved.5,7 Grape seed extract benefits vein disorders mainly because congested veins cause problems with the microcirculation that flows into them.
Patients with retinopathy experienced a reduction in oedema and an improvement in capillary resistance (uncontrolled trials, 100mg to 200mg/day of grape seed OPCs).8,9 Retinal damage was stabilised in 80 per cent of patients taking grape seed extract (150mg/day of grape seed OPCs) compared with 46 per cent of patients taking a placebo.10
More recent (and very high quality) research suggests that grape seed extract benefits the circulation as a whole. A team of Dutch scientists recently evaluated the effects of a grape seed extract (200mg once a day) on a variety of circulatory measures in relatively healthy smokers.11 The eight-week trial was a double-blind, randomised, placebo-controlled design involving 28 men who had smoked at least 10 cigarettes a day for at least five years. The scientists measured micro- and macro-vascular (circulatory) function and a cluster of systemic biomarkers for major pathological processes occurring in the circulation, including disturbances in metabolism and cellular oxidative balance and activation of inflammatory cells and platelets. Patients with a history or presence of any metabolic or cardiovascular disease or cancer were excluded, as were heavy drinkers.
Despite the small nature of this trial, with only 15 men in the active (grape seed extract) group and 13 in the placebo group, a number of significant findings were seen at eight weeks. Specifically, while LDL (low-density lipoprotein) cholesterol was not changed in the whole group, a significant reduction was seen by 7 per cent in the nine participants with elevated baseline levels. Additionally, there was a 22 per cent increase in the ratio of reduced (active) to oxidised (inactive) glutathione in red blood cells in the herbal group, indicating an important rise in antioxidant protection in the body. The vascular inflammatory response, assessed by the release of the inflammatory marker tumour necrosis factor (TNF)-alpha from stimulated blood, decreased substantially and significantly from baseline in the active group (by 14 per cent, p < 0.05) after eight weeks of treatment. This reduction was also significant compared with the placebo group (p < 0.05).
On the other hand, alterations in macro- and micro-vascular function were either not present or did not reach statistical significance. There were also no significant changes in systolic and diastolic blood pressure readings. However, when all the above measures (excluding blood pressure) were constructed into an algorithm that the authors called the vascular health index (VHI), a remarkable and intriguing outcome was revealed. The average VHI in the patients receiving grape seed extract rose by 123 ± 47 units (p < 0.05 versus baseline and the placebo group), whereas it fell by 66 ± 79 units in the placebo group. This indicated an overall improvement in vascular health in the active group. Notably, while many of the individual cardiovascular health measures did not show a significant change, a significant improvement was clearly evident when they were integrated into the global VHI. As the authors highlighted, their integrative biomarker approach has unveiled the pleiotropic (production of multiple effects) health benefit of a regular intake of grape seed extract on the circulation.
Despite the fact that this particular study found no effect of grape seed extract on blood pressure, an analysis of all the published clinical trials (known as a meta-analysis) found that it did. In this study, US authors located nine clinical trials on various grape seed extracts that met their inclusion criteria, involving 390 patients. Meta-analysis was possible for the following measures, systolic blood pressure (six trials), diastolic blood pressure (six trials), heart rate (five trials), blood lipids (seven to nine trials) and C-reactive protein (three trials). While the data indicated that clinical use of grape seed extract shifted all these parameters towards a lower cardiovascular risk profile (for example, C-reactive protein and total cholesterol were lowered and high-density lipoprotein (HDL) cholesterol was raised), only the results for systolic blood pressure and heart rate achieved statistical significance (p = 0.02 and p = 0.01, respectively).
In next month’s column I will review further interesting and novel clinical benefits from taking grape seed extract.
To your better health,
Nutrition & Healing
Volume 6, Issue 8 – August 2012
Full references and citations for this article are available in the downloadable PDF version of the monthly Nutrition and Healing issue in which this article appears.