The common view is that our cardiovascular or circulatory system consists only of veins, arteries, and the heart. Any circulatory health problems are generally believed to arise from malfunctions of these key structures of the macro-circulation. But missing from this perspective is any consideration for what is actually the largest part of our circulatory system: the micro-circulation.
This micro-circulation blindness leads to neglect and ultimately health problems. One recent scientific review of the micro-circulation put it best:1
“The difficulty of accessing micro-circulation in view of the extremely small dimensions of these vessels has been by far the principal reason why this enormous anatomical entity has been essentially neglected for decades… With very few exceptions, pentoxifylline and the antidiabetic metformin, no specific treatments have been developed for treating disorders at the micro-circulatory level.”
In other words, there are few conventional drug treatments for this important part of our circulation.
So you’re probably wondering what exactly micro-circulation is. The micro-vascular bed is an anatomical entity which comprises myriads of small arterioles, capillaries and venules.1 Organ tissues such as the retina of the eye and the glomeruli (filtering apparatus) of the kidney are particularly rich in micro-circulation, because of their specific functions. Also the health of our micro-circulation determines the blood supply and nutrient flow to all our vital tissues, but especially to vulnerable structures such as the long nerves that flow out of our spinal column to our limbs. That’s why with diabetes, which damages the micro-circulation, these tissues are specifically affected, namely as retinopathy, nephropathy and neuropathy. All of these come under the general heading of diabetic micro-angiopathy, which is the best known expression of micro-circulatory disease.
Health problems linked to poor micro-circulation
Diabetic micro-angiopathy is directly linked to hyperglycaemia, and can be detected in people with only marginally raised blood glucose levels.1 A popular theory focuses on postprandial (post meal) hyperglycaemia: meals can interfere with normal blood vessel function even in healthy people. Inadequate eating (fat and/or sugar-rich meals) can, over time, damage the cells lining your micro-circulation.1
Poor micro-circulation has now been linked to a range of other health issues. These include metabolic syndrome, high blood pressure, sleep disorders, Alzheimer’s disease, vein problems, types of liver disease, polycystic ovary syndrome, gestational diabetes, heart attacks and strokes (especially relevant to recovery from these), and various autoimmune diseases.1 In addition, the health of your micro-circulation is important to avoid diseases of the retina (including macular degeneration), kidneys, and peripheral nervous system, even if you are not diabetic.
Herbs to help your micro-circulation
Obviously I wouldn’t be discussing the micro-circulation in a herbal column unless there was evidence that they can play a key role in maintaining micro-circulatory health. In fact, at present there is much more information about the benefits of plants in this context than for drugs. My key herbs to boost micro-circulatory health are bilberries, cocoa (yes, chocolate done properly can be therapeutic), garlic, ginkgo, gotu kola, and grape seed or pine bark extracts. I’ll briefly discuss each one in turn.
The bilberry (and here you could probably substitute the blueberry as a less active alternative) has a long-held reputation for benefiting vision, and a significant part of this comes from its support of the micro-circulation. For example, in open trials, bilberry extract improved symptoms caused by decreased capillary resistance (micro-vascular bleeding, bruising and faecal occult blood),2 reduced the micro-circulatory changes induced by cortisone therapy in patients with asthma and chronic bronchitis,3 and improved diabetic retinopathy with a marked reduction or even disappearance of haemorrhages.4 Post-operative complications from surgery of the nose were reduced in patients who received bilberry extract administered for seven days before and 10 days after surgery, probably because of its benefits for the micro-circulation.5 In placebo controlled trials, bilberry extract improved early phase diabetic retinopathy.6
Cocoa is beneficial too, but in my view only if consumed without too much sugar (and research supports this). I typically recommend the 85 or 90 per cent cocoa chocolate to my patients (about 20g or 2/3oz per day). There are several studies that suggest that cocoa has a positive effect on the micro-circulation. In a clinical trial, the impairment of endothelial function (the lining of blood vessels) caused by a glucose challenge was reduced by dark chocolate, but not white chocolate.7
I believe garlic (particularly as the fresh-crushed raw clove or as an allicin-releasing powder) is good for both the micro-circulation and micro-circulatory flow. For example, in a controlled clinical trial a single 900mg dose of garlic powder significantly increased capillary skin perfusion by 55 per cent.8 Another study found that garlic powder (600mg/day) administered for seven days increased calf blood flow by approximately 15 per cent.9
Clinical studies of ginkgo in retinal problems are the best illustration of its positive effect on micro-circulation. For example, improved retinal artery and capillary flow rates have been observed,10,11 which probably would explain its effect on improving vision in patients with glaucoma, since glaucoma12 results in poor blood flow to the retina.
Two controlled trials have investigated the activity of gotu kola actives in patients with micro-vascular damage due to diabetes. The largest trial involved 100 patients with or without neuropathy, and compared the extract with a placebo over 12 months and also 40 healthy controls.13 It was significantly more effective at improving micro-circulatory measures and oedema. A smaller trial in 50 patients compared a similar dose of gotu kola actives to a placebo or no treatment for six months.14 There was significant improvement in measures linked to microscopic vascular damage, including capillary permeability.
I have already described the benefits of grape seed extract on the micro-circulation in a previous column (see the August 2012 issue of N&H). Similar properties could also be expected for pine bark extract
A case history: Improved micro-circulation using herbs
A 61-year-old man came to see me with the main problem of declining kidney function. He had high blood pressure (controlled by multiple drugs) and type-2 diabetes, although this was well controlled with just diet.
Although his poor kidney function could have been caused by the diabetes, a medical specialist advised that some sort of autoimmune damage to the glomeruli might be at play as well. In addition, tests showed that the tissue around his glomeruli exhibited a high degree of fibrosis, leading to a main diagnosis of arterionephrosclerosis. His glomerular filtration rate (eGFR) was quite abnormal at 35 and his plasma creatinine was elevated.
It was recommended to the patient that he include garlic (raw crushed), blueberries, green tea (also probably good for micro-circulation) and chocolate (85 per cent cocoa) in his diet. In addition he was prescribed tablets containing high doses of echinacea root (for the autoimmune aspects), turmeric (anti-inflammatory and protective of the kidneys) and grape seed, gotu kola, and ginkgo for his micro-circulation. Finally, he was advised to take a high-dose fish oil supplement for its anti-inflammatory omega-3 fatty acids.
Five months later, the man had another blood test conducted by his medical specialist. To their surprise, his creatinine level had fallen by 33 per cent and his eGFR had risen to 51. The specialist commented that it was very rare for the eGFR to come back in this way, especially for his damaged kidneys. Normally it was a one-way decline. This treatment, focused on improving his micro-circulation, is on-going.
To your better health,
Nutrition & Healing
Volume 7, Issue 8 – August 2013
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.