Managing High Blood Pressure

28 Mar Managing High Blood Pressure

Primary hypertension (HTN) is one of the most prevalent and preventable diseases facing North America. The disorder is linked to premature mortality, disability and morbidity, often in the form of cardio- and cerebrovascular events, in addition to increased medication and disease burden for other chronic health conditions. Alongside rising incidence rates, recent estimates of prevalence remain high, with self-reported diagnosis ranging from 20-35% of the adult population and use of anti-hypertensive medications ranging from 52-74% in the United States. In Canada, an estimated 23% of the population has been diagnosed with HTN, while a further 17% of adults remains undiagnosed. A concerted public health strategy has identified targets to reduce the prevalence of HTN to 13% of adults, and to improve effective control to 78%, though the means of achieving this for various populations remain unclear. The recently released guidelines for effective diagnosis and treatment of HTN by the National Institute for Health and Care Excellence (NICE) and the Canadian Hypertension Education Program clearly outline approaches to diagnosis and management through lifestyle and pharmacologically-focused strategies. A clear outline of lifestyle (physical exercise, diet, sodium intake, alcohol consumption, stress management and weight reduction) and the corresponding evidence levels is also presented in these guidelines.

Recent studies have demonstrated naturopathic medicine as a whole to be very effective for prevention and treatment of cardiovascular disease and hypertension. The following evidence-based treatment options should be discussed with your naturopathic physician or health care provider to help provide you with guidance on achieving targets, effective dosing strategies, and reasonable clinical expectations in a cost-effective manner.

Olive Oil

The evidence to support the use of olive oil in hypertension comes from several small, open-label trials that utilized olive oil as the main fat source in the participants’ diet. Large reductions in blood pressure (up to ~10 mm Hg for both DBP and SBP) were seen in studies using hypertensive patients, with one study showing a very significant reduction in medication use. Studies involving normotensive individuals demonstrated smaller reductions. The most recent study which showed the greatest reduction used a dose of 60 grams (4 tbsp) daily. Larger studies, utilizing more precise dosing, randomization, and blinding are needed. A study investigating the mechanism of action found that oleic acid is the active constituent through its effect on cell membrane structure and adrenoreceptor signaling pathways.

DASH and Mediterranean Diets

The DASH diet (Dietary Approaches to Stop Hypertension) includes an abundance of vegetables and fruit, whole grains, low-fat dairy products, lean meat or fish, legumes, nuts and seeds, and healthy fats, with limited sweets, red meat, and saturated and trans fats. This diet most closely resembles a Mediterranean diet. In large, randomized, controlled studies (RCTs), the DASH diet produced reductions of approximately 11 mm Hg for SBP and 6 mm Hg for DBP in patients with hypertension.14 The benefits are further enhanced when the DASH diet is combined with reduced sodium intake or weight loss. The DASH diet studies have been criticized because the food was prepared for the participants; however, the diet is based on simple healthy eating strategies. A free guide to eating the DASH Diet is available at the National Institute of Health’s website: https://www.nhlbi.nih.gov/health/public/heart/hbp/dash/.

Garlic

Two large meta-analyses of high-quality randomized clinical trials have shown a significant benefit of garlic in patients with hypertension. While they included different studies, both found that when analyzing studies in which subjects had a mean baseline SBP of >140 mm Hg, a mean reduction of 8 and 16.3 mm Hg was observed. In contrast, studies involving pre-hypertension individuals observed small or non-significant benefits, suggesting that this may not be a highly effective intervention for pre-hypertension. A recent study used garlic supplementation in patients with medicated, uncontrolled systolic hypertension and reported significant reductions, suggesting a potential benefit for this population. Gastrointestinal discomfort was the most frequently reported side effect. Animal studies have observed garlic to have angiotensin I-converting enzyme (ACE) properties, as well as induction of endothelium arterial relaxation and vasodilation.

Coenzyme Q10

A Cochrane review from 2009 combined the data of 3 randomized clinical trials and showed a large hypotensive benefit of coenzyme Q10 (11/7 mm Hg reduction). The authors expressed concerns about the quality of blinding and the credibility of one of the studies’ lead authors, and thus felt that the data was insufficient to draw conclusions. A fourth randomized clinical trial that was excluded from the meta-analysis because of its short pre-intervention washout period (10 vs 14 days) also showed a very large hypotensive benefit (18 mm Hg).

Fish Oil

Fish oil supplementation and increased dietary fish intake have shown benefit in reducing blood pressure in both medicated and unmedicated hypertensive individuals. One study compared fish oil, weight loss, and a combination of the two. Both interventions showed statistically significant benefit (6/3 and 5.5/2 mm Hg reductions, respectively), and the combined effect exceeded the sum of their individual effects (13/9 mm Hg). One study comparing EPA and DHA found that only DHA achieved statistically significant results compared to placebo; however, the placebo used in this study was olive oil, which has its own effects on blood pressure. Another study observed continued improvement between week-8 and week-16 assessments, suggesting that the full benefits of supplementation may be seen only after extended use. The studies reviewed used approximately 4 grams of combined EPA and DHA daily and olive oil as the control.

Exercise

Two large meta-analyses of randomized clinical trials have shown beneficial effects of exercise on blood pressure. Aerobic exercise significantly reduces BP by 3/3 mm Hg in normotensive patients, and by 7/5 mm Hg in hypertensive patients. Among studies using resistance training, statistically significant reductions were seen in normotensive patients but not in hypertensive patients; however, this may be due to the small number of studies examined.

Hibiscus Sabdariffa

The use of Hibiscus sabdariffa in tea and extract forms have shown excellent benefit in reducing both systolic and diastolic blood pressure in both medicated and unmedicated populations, diabetics with hypertension and in varying hypertension stages. Some studies have compared its use to the common pharmaceutical ACE inhibitors, captopril and lisinopril, and have exhibited a comparable hypotensive effect. Generally, Hibiscus sabdariffa has a negligible impact on electrolyte balance, though urinary sodium and chlorine excretion have been shown to elevate with its consumption. Tolerability of this herb is very high, with no reported cases of adverse effects under 300 mg/kg/day. Proposed mechanisms include antioxidant effects of its anthocyanins to reduce LDL-C oxidation and atherosclerosis, diuretic effects from inhibition of acetylcholinesterase, and blood vessel dilatation effects from nitric oxide-cGMP and calcium inhibition in smooth muscle cells.

Vitamin D

The use of vitamin D for essential hypertension stems from observational data noting an association between low vitamin D status and risk of cardiovascular disease and hypertension. The exact physiological mechanism for its hypotensive effect is largely unknown, though theories implicating improved calcium absorption and metabolism are generally accepted. Current evidence shows a small but statistically significant effect of vitamin D on both systolic and diastolic blood pressure reduction. A recent systematic review and meta-analysis confirms the literature trend that increased doses are more protective, with the highest studied dose, 2000 IU of cholecalciferol, exhibiting the greatest reduction. A mean reduction of 3.6 mm Hg for systolic, and of 3.1 mm Hg for diastolic was exhibited when combining studies using various doses and durations of treatment. Interestingly, unactivated forms of vitamin D (vitamin D2, D3, and UVB radiation) significantly outweighed the activated calcitriol/1-alpha calcidiol forms for systolic reduction only, with a mean decrease of 6.2 mm Hg reported in the meta-analysis of 11 studies.

Magnesium

Magnesium is a commonly utilized supplement for the management of hypertension, theoretically due to its impact on smooth muscle relaxation via calcium ion antagonism, and associations between high dietary magnesium intake and cardiovascular protection. Studies generally report a mild hypotensive effect of magnesium. A recent meta-analysis outlines a systolic decrease of 3-4 mm Hg and a diastolic decrease of 1-2 mm Hg with oral supplementation of magnesium.

Crataegus Laevigata (Hawthorn)

Minimal evidence exists to support the use of Crataegus laevigata (hawthorn) for essential hypertension, although some hypotensive effects are exhibited, with a trend towards systolic and diastolic lowering. This research suggests that a dose of 500-1200 mg hawthorn extract daily may achieve blood pressure reductions of ~3-10 mm Hg systolic and ~2-13 mm Hg diastolic.

Suggested dosing of anti-HTN agents 

Conclusions

There are many interventions used within the naturopathic medical sphere for essential hypertension management that are well supported and documented in the scientific literature to date. In assessing the evidence closely, typical populations studied include patients with mild-to-moderate hypertension, pre-hypertension, and hypertension with diabetes, all of whom commonly seek naturopathic care.

Some trends exist when assessing the literature on naturopathic approaches to hypertension management. The evidence suggests that typically, naturopathic interventions exhibit decreased efficacy as blood pressure approaches the normal range, which may be protective against hypotension. All supportive interventions discussed are generally well tolerated, with the exception of very minor gastrointestinal effects.

Naturopathic interventions fare quite well at reducing blood pressure, achieving comparable results to first-line anti-hypertensive medications within 2-3-month timeframes. Recent Cochrane review data show a blood pressure-lowering effect of about 8/4 mm Hg using thiazides, ACE inhibitors, angiotensin receptor blockers, and renin inhibitors, and many of the naturopathic interventions discussed above achieved similar or larger reductions. While some interventions yielded only small changes in blood pressure, it is important to note that these changes can have protective effects. It has been observed that reductions in resting systolic BP and diastolic BP of 3 mm  Hg can decrease coronary heart disease risk by 5%, stroke by 8%, and all-cause mortality by 4%.30 Given the widespread tolerability of the interventions discussed here, it is worthy to consider implementation of these strategies to prevent and treat hypertension, especially in the well-studied pre-, mild and moderate stages.