Traditional herbal thinking recognizes that chronic diseases are first created and then sustained by a variety of different factors. So the most logical way to address chronic diseases is to use a range of interventions to correct the various imbalances these multiple factors cause. Biomedical scientists have proposed an elegant concept that describes this concept of chronic diseases, calling them mosaic diseases. More than 60 years ago, Irvine Page (a pioneer in hypertension research who discovered angiotensin II) proposed the Mosaic Theory of Hypertension, saying that many factors – including genetic, environmental, adaptive, neural, mechanical and hormonal factors – interact to raise blood pressure.1 This concept was also revisited for autoimmune disease by the immunologist Yehuda Shoenfeld in 1989. He wrote:
“ The Shorter Oxford English Dictionary defines a mosaic as: ‘The process of producing pictures or patterns by cementing together small pieces of stone, glass etc.’ This definition carries the implication that by reassembling the pieces in a different order another pattern or picture will emerge. It is our contention that much the same process is evident with autoimmune diseases. Thus by rearranging much the same starting materials different patterns of disease develop.”
Harrison, reviewing the work of Page in developing the Mosaic Theory of Hypertension, writes:1
“ In the 1940s, as now, there was ongoing debate regarding the etiology of hypertension, with various investigators advocating renal, neural, and hormonal causes. Page had contributed to each of these fields, and ultimately concluded that it was overly simplistic to assign all hypertension to any one cause… He wrote. ‘Even the simplest hypertension is a mosaic in which many mechanisms are to a greater or lesser extent involved. Elevated blood pressure is the resultant of multiple forces acting on the variety of tissues which compose the circulatory apparatus. Is it then to be supposed that this is any simple problem the solution of which will be found in the elucidation of but one of these forces?”
So the mosaic theory of chronic disease argues for complex rather than simple interventions, acting on both known and unknown pieces in the person’s individual mosaic and across a range of mechanisms. In the case of hypertension, each intervention might only lower blood pressure (BP) by a small amount, but the cumulative effect might be a clinically relevant reduction. This means it doesn’t matter that any one herb is not a sufficient treatment for hypertension on its own, because a combination of several of them can deliver the desired outcome (as per the mosaic theory). This could add up to reductions in systolic BP of 20 mm Hg or more. A number of lifestyle changes are also relevant as key considerations in addressing the complete mosaic of hypertension.
What is hypertension and why treat it?
Hypertension is a significant risk factor for:4,5 strokes, Alzheimer’s disease, heart attacks and microangiopathy (damage to your fine blood vessels). High BP can be difficult to treat, and a range of drugs are used including thiazide, diuretics, beta blockers, angiotensin-converting enzyme inhibitors (ACE), angiotensin II receptor blockers (ARBs) and calcium channel blockers.
The most common form of hypertension is called primary or essential, where no clear cause of the raised BP can be identified. This is where the mosaic concept is most useful. In contrast, secondary hypertension will have a clear single cause, be it kidney disease, adrenal tumours, congenital malformations or drugs, either prescribed or illicit.
Research has identified a number of key risk factors for hypertension. These include age, race, family history, overweight or obese, physical inactivity, smoking, excessive dietary salt, deficient dietary potassium, excessive alcohol, stress, chronic disease, insulin resistance and sleep apnoea.3
Important herbs proven to lower BP
Widely (and mistakenly) regarded as an immune tonic, the real clinical value of olive leaf (Olea europaea) is for hypertension. In a 1996 open-label study, olive leaf decreased systolic BP (by 18 mm Hg) and diastolic BP (by 10 mm Hg) from baseline in two groups of patients with moderate essential hypertension.6 An eight-week double-blind clinical study was conducted to evaluate the antihypertensive effect of olive leaf extract in comparison with the drug captopril in patients with Stage 1 hypertension.7 The two treatments were comparable.
The clinical evidence for garlic (Allium sativum) in lowering blood pressure is controversial. Of particular relevance in hypertension is the meta-analysis (where the results of several trials are pooled and analysed) by Reinhart and team that found garlic reduced systolic BP by 16.3 mm Hg, and diastolic BP by 9.3 mm Hg, in patients with elevated systolic BP.8 However, garlic did not reduce BP in patients with normal systolic pressures. A recent single blind, controlled study from Saudi Arabia in 210 patients with Stage 1 essential hypertension found a dose-response effect for garlic over 24 weeks.9 The effect at 1,500 mg/day garlic was less than, but close to, the beta-blocker atenolol (100 mg/day).
Grape seed (Vitis vinifera) extract is a significant cardiovascular herb with a mild activity in terms of lowering BP. Hence, it fits in well using the mosaic approach for treating this disorder. A 2011 meta-analysis incorporating nine randomized, controlled trials found that grape seed extract significantly lowered BP (by an average of 1.5 mm Hg) and heart rate.10 In 2012, it was observed that grape polyphenols lowered BP in men with metabolic syndrome.11 Some of the components of hawthorn (Crataegus species) resemble those in grape seed extract, namely the oligomeric procyanidins (OPCs). Like the grape seed, clinical trials have demonstrated a modest effect of hawthorn in lowering BP.12
Although tea (Camellia sinensis) might be thought to increase BP because of its caffeine content, clinical studies have shown the opposite. A 2013 systematic review and meta-analysis from the Cochrane Collaboration identified 11 randomised controlled trials (RCTs) with a total of 821 participants.13 Seven trials examined green tea and four trials assessed black tea. Black tea was found to produce statistically significant reductions in low-density lipoprotein (LDL) cholesterol (mean difference (MD) -0.43 mmol/L), and BP (systolic BP: MD -1.85 mm Hg and diastolic BP: MD -1.27 mm Hg) over six months. Green tea was also found to produce statistically significant reductions in total cholesterol (MD -0.62 mmol/L), LDL cholesterol (MD -0.64 mmol/L), and blood pressure (systolic BP: MD -3.18 mm Hg; diastolic BP: MD -3.42 mm Hg). When both tea types were analysed together, they showed favourable effects on LDL cholesterol (MD -0.48 mmol/L) and blood pressure (systolic BP: MD -2.25 mm Hg; diastolic BP: MD -2.81 mm Hg).
To your better health,
Nutrition & Healing
Vol. 8, Issue 6 – June 2014
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.