Mechanism of garlic (Allium sativum) induced reduction of hypertension in 2K-1C rats: a possible mediation of Na/H exchanger isoform-1

Evaluating the effects of dark chocolate formulated with micro-encapsulated fermented garlic extract on cardio-metabolic indices in hypertensive patients: A crossover, triple-blind placebo-controlled randomized clinical trial

This study aimed to investigate the health-related effects of microencapsulated fermented garlic extract (FGE) containing dark chocolate in hypertensive adults. For this purpose, 36 hypertensive adults (15 males vs. 21 females) were randomized to receive the FGE (5 g/day) dark chocolate containing 650 mg of FGE powder or the placebo. Intervention periods lasted for 6 weeks and were separated by a 3-week wash-out period. The response variables included blood pressure, anthropometric indices, lipid profile, and inflammatory and oxidative stress indices. Statistical analyses were performed using the Pkcross procedure, and Cohen's d was estimated for all response variables. There was no significant inter-period difference between the mean changes of body weight, waist circumference, and body mass index (BMI). Furthermore, no significant change was confirmed in participants' blood pressure, triglycerides, total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), very low-density lipoprotein (VLDL), serum homocysteine, high-sensitive c-reactive protein (hs-CRP), malondialdehyde (MDA), and total antioxidant capacity (TAC). It seems that the dose of FGE used in this study was not sufficient to cause any significant changes in the outcomes. Therefore, further studies with dose-response designs and longer durations are recommended.

K, P. UD. Spices and Hypertension: An Insight for Researchers

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Hypertension is a global public health concern since it can lead to complications like stroke, heart disease, and kidney failure. These complications can add to a disability, increase healthcare costs, and can even result in mortality. In spite of the availability of a large number of anti-hypertensive drugs, the control of blood pressure is suboptimal in many patients. Spices have been used as flavouring agents and in treating diseases in folk medicine since they are considered to be rich sources of phytochemicals, especially polyphenols. Hence, during recent years, there has been renewed interest among researchers in exploring natural sources, especially spices, in an attempt to find cheaper alternatives with fewer side effects. Our aim is to review the relevant preclinical and clinical studies focused on the potential use of spices in the management of hypertension. Studies conducted on the most common spices, such as celery, cinnamon, cardamom, garlic, ginger, saffron, and turmeric, have been elaborated in this review. These spices may lower blood pressure via several possible mechanisms, including antioxidant effect, increase in nitric oxide production, reduction in calcium ion concentration, modulation of the renin-angiotensin pathway, etc.

Pharmacotherapeutic Potential of Garlic in Age-Related Neurological Disorders

Age-related neurological disorders [ANDs] involve neurodegenerative diseases [NDDs] such as Alzheimer's disease [AD], the most frequent kind of dementia in elderly people, and Parkinson's disease [PD], and also other disorders like epilepsy and migraine. Although ANDs are multifactorial, Aging is a principal risk factor for them. The common and most main pathologic features among ANDs are inflammation, oxidative stress, and misfolded proteins accumulation. Since failing brains caused by ANDs impose a notable burden on public health and their incidence is increasing, a lot of works has been done to overcome them. Garlic, Allium sativum, has been used for different medical purposes globally and more than thousands of publications have reported its health benefits. Garlic and aged garlic extract are considered potent anti-inflammatory and antioxidants agents and can have remarkable neuroprotective effects. This review is aimed to summarize knowledge on the pharmacotherapeutic potential of garlic and its components in ANDs.

Antihypertensive phytocomplexes of proven efficacy and well-established use: Mode of action and individual characterization of the active constituents

Hypertension has become the leading risk factor for worldwide cardiovascular diseases. Conventional pharmacological treatment, after both dietary and lifestyle changes, is generally proposed. In this review, we present the antihypertensive properties of phytocomplexes from thirteen plants, long ago widely employed in ethnomedicines and, in recent years, increasingly evaluated for their activity in vitro and in vivo, also in humans, in comparison with synthetic drugs acting on the same systems. Here, we focus on the demonstrated or proposed mechanisms of action of such phytocomplexes and of their constituents proven to exert cardiovascular effects. Almost seventy phytochemicals are described and scientifically sound pertinent literature, published up to now, is summarized. The review emphasizes the therapeutic potential of these natural substances in the treatment of the 'high normal blood pressure' or 'stage 1 hypertension', so-named according to the most recent European and U.S. guidelines, and as a supplementation in more advanced stages of hypertension, however needing further validation by clinical trial intensification.

A mini review: garlic extract and vascular diseases

Vascular diseases refer to medical conditions that narrow blood vessels. Narrowed cardiac or cerebral arteries can lead to myocardial infarction or ischemic stroke. Risk factors including atherosclerosis, hypertension, and diabetes may induce either cardiovascular or cerebral complications. Based on current research, garlic favorably affects atherosclerosis, hypertension and diabetes, and helps decrease the risk of myocardial infarction and ischemic stroke. Garlic has been utilized for hundreds of years as a natural health remedy. New research is emerging regarding its effectiveness in treating common diseases, including atherosclerosis, hypertension, and diabetes. The underlying mechanisms by which garlic, and its byproducts, can alter pathophysiology have begun to be elucidated by these studies. Garlic is a prominent topic for future research regarding its potential as an adjuvant to conventional pharmacotherapy for these common health conditions. In this mini-review, we discuss the current state of the literature regarding garlic and its effects in patients with vascular disease. Specifically, we decided to briefly discuss the key points regarding the mechanisms underlying garlic's anti-hypertensive, anti-hyperlipidemic, and hypoglycemic effects. This allows the readers to understand each process while keeping the paper concise. These mechanisms can be further explored in the original articles, at the reader's discretion.

Garlic extract increases non-clipped kidney tubular natriuresis and diuresis in the 2-kidney, 1-clip rat model: Significance in hypertension

BACKGROUND

Angiotensin II (AngII) is a potent modulator of vascular tone and renal clearance function. Raw garlic aqueous extract (RGAE) inhibits angiotensin I converting enzyme (ACE) dipeptidase activity and therefore AngII generation in the 2-kidney, 1-clip rat model (2K-1Cr).

OBJECTIVE

This study investigated the effect of RGAE on the non-clipped kidney clearance function and blood pressure (BP) in the 2 K-1Cr.

METHOD

2K-1Cr were anesthetized, cannulated and instrumentalized and the acute effect during the first hour post-administration of a single intravenous dose of RGAE (30mg/100gb.wt/0.3ml) was tested on: 1- The ACE dipeptidase activity estimated from a reduction in the vasopressor action of angiotensin I [(AngI, 200ng/0.2ml): the precursor of AngII] in one group (n=5); 2- The non-clipped (left) kidney (LK) clearance function in a second group (n=6). Similar protocols were carried out on two groups of normal rats (Nr: n=5+n=6).

RESULTS

In the 2K-1Cr, RGAE partially, however significantly, decreased the vasopressor action of AngI. Furthermore, RGAE had no effect on systolic BP, mean BP, plasma osmolarity, LK cortical circulation or glomerular filtration rate. Alternatively, RGAE significantly increased LK urine volume, fractional excretion of water, sodium clearance and fractional excretion of sodium; while significantly decreasing heart rate and LK urine osmolarity.

CONCLUSIONS

Our findings suggest that a single i.v. dose of RGAE causes ACE dipeptidase inhibition, thus reducing AngII generation and bioavailability in the 2K-1Cr. This action of RGAE enhances the non-clipped kidney clearance of sodium and water by modulating the tubular handling mechanisms.

The acute effect of high-dose intravenous vitamin C and other nutrients on blood pressure: a cohort study

Background

Regular intake of vitamin C/ascorbate reduces blood pressure (BP) in hypertensives. High-dose intravenous vitamin C (IVC) achieves higher plasma levels; however, there is a paucity of research on acute BP effects. Our study is the first to investigate the effect of high-dose IVC, with or without concomitant i.v. nutrients, on BP during i.v. treatment.

Methods

A cohort of adult patients scheduled to receive IVC treatment for infection, cancer or fatigue, as prescribed by their treating doctor, participated at a Melbourne clinic, Australia. Ambulatory BP was assessed every 10 min over 90 min during i.v. treatment. Patients received 15–100 g of IVC alone or in addition to i.v. vitamin B, glutathione, magnesium or zinc. BP change over time adjusted for baseline BP, IVC dosage, i.v. treatment and BMI was analysed.

Results

A total of 77 mostly normotensive patients participated, with a third receiving IVC alone (42±20 g), and two-thirds also received other i.v. nutrients. IVC alone (>30 g) reduced the mean BP up to 8–9 mmHg in prehypertensive patients. In contrast, concomitant intravenous vitamin B12 (IVB12) significantly increased the mean BP by 11–13 mmHg. Comparison of BP change during IVC versus IVC+IVB12 indicated a highly significant difference [systolic blood pressure: mean difference (SD)=16.6 (17.8) mmHg, P<0.001; diastolic blood pressure: mean difference (SD)=12.5 (16.7) mmHg, P=0.003].

Conclusion

Our study suggests an acute BP-reducing effect of high-dose IVC, particularly with dosages above 30 g, and in patients with prehypertension and normal BMI. Furthermore, our study indicated a marked and clinically relevant hypertensive effect of IVB12, suggesting routine BP monitoring during i.v. therapy in clinical practice.

Inhibition of Angiotensin Converting Enzyme, Angiotensin II Receptor Blocking, and Blood Pressure Lowering Bioactivity across Plant Families

Hypertension is a major risk factor for coronary heart disease, kidney disease, and stroke. Interest in medicinal or nutraceutical plant bioactives to reduce hypertension has increased dramatically. The main biological regulation of mammalian blood pressure is via the renin-angiotensin-aldosterone system. The key enzyme is angiotensin converting enzyme (ACE) that converts angiotensin I into the powerful vasoconstrictor, angiotensin II. Angiotensin II binds to its receptors (AT1) on smooth muscle cells of the arteriole vasculature causing vasoconstriction and elevation of blood pressure. This review focuses on the in vitro and in vivo reports of plant-derived extracts that inhibit ACE activity, block angiotensin II receptor binding and demonstrate hypotensive activity in animal or human studies. We describe 74 families of plants that exhibited significant ACE inhibitory activity and 16 plant families with potential AT1 receptor blocking activity, according to in vitro studies. From 43 plant families including some of those with in vitro bioactivity, the extracts from 73 plant species lowered blood pressure in various normotensive or hypertensive in vivo models by the oral route. Of these, 19 species from 15 families lowered human BP when administered orally. Some of the active plant extracts, isolated bioactives and BP-lowering mechanisms are discussed.

Does Garlic Supplementation Control Blood Pressure in Patients with Severe Coronary Artery Disease? A Clinical Trial Study

Background

Hypertension is one of the major risk factors for cardiovascular morbidities, including coronary artery disease (CAD).

Objectives

With interest on the important role of hypertension in the progression of CAD, this study was designed to estimate the effect of garlic powder tablets on the blood pressure (BP) in patients with severe CAD.

Methods

A randomized, placebo-controlled, clinical trial was conducted on 56 CAD patients, aged 25 - 75 years old. The patients were randomly divided into two groups: Galois groups (n = 27), receiving garlic powder tablet (400 mg garlic) twice daily and the placebo groups (n = 29), receiving placebo for 3 months. The BP was assessed at baseline and at the end of the study.

Results

During the 3 months study, in the placebo group, systolic BP (SBP) increased with 6.3 mmHg and diastolic BP (DBP) increased with 4.6 mmHg, changes which were significant. After the 3 months, the effect of garlic on SBP, after adjusting for baseline value, was significant, and this effect was more significant in hypertensive patients. Plasma lipids and lipoproteins did not change significantly in either the garlic or placebo groups, during the study. Tolerability, compliance and acceptability were high in all patients.

Conclusions

These results demonstrate that treatment with garlic-based drugs can be an effective treatment for controlling BP in CAD patients and has no interaction with other drugs that CAD patients take. Therefore, it may be considered as a safe adjunct treatment for this group of patients.

Anti-diabetic and anti-oxidant potential of aged garlic extract (AGE) in streptozotocin-induced diabetic rats

Background

Although aged garlic extract (AGE) shares some active components with fresh garlic and in spite of its palatability and milder side effects, the anti-diabetic and related anti-oxidant properties of AGE have not been investigated extensively, and the reported findings are inconsistent.

This study investigated the anti-diabetic effects of 3 incremental doses of AGE in streptozotocin (STZ)-induced diabetic rats (fasting blood sugar > 20 mM).

Method

Diabetic rats were divided into a control diabetic group (CD) and AGE-treated diabetic group (AGE-D). The AGE-D was divided into 3 groups and accordingly treated with AGE i.p. at 100, 300 and 600 mg/kg daily for 8 weeks. A control normal group (CN) was also included for reference.

Results

Compared to the CN group, the CD group showed significant loss of body weight (over 50 %); and decreased serum insulin concentration (10 fold) and total anti-oxidant level and catalase activity (45–70 %) in serum, kidney and liver. Conversely, the CD rats had an elevated blood glucose (nearly 4 fold), serum cholesterol (nearly 2 fold) and triglycerides (>2 fold), erythrocyte glycated hemoglobin (GHb, 3 fold) and kidney and liver lipid peroxidation (MDA levels). Treatment with AGE positively reversed the diabetic changes in the targeted parameters to levels significantly lower than those measured in the CD group and the degrees of attenuation were almost dose dependent especially with the two higher doses.

Conclusion

AGE exhibits a dose-dependent ameliorative action on indicators of diabetes in STZ-induced diabetic rats.

Effect of garlic on blood pressure: a meta-analysis

Garlic supplements are thought to reduce blood pressure (BP). The authors performed a meta-analysis to investigate garlic's effect on BP. Ovid Medline, Cochrane Library, and PubMed (1946 to November 2013) were used to search for randomized controlled trials. Seventeen trials were included. Pooled analysis showed that garlic intake caused a 3.75-mm Hg reduction (95% confidence interval [CI], -5.04 to -2.45, I(2) =30.7%; P<.001) in systolic BP and a 3.39-mm Hg reduction (95% CI, -4.14 to -2.65, I(2) =67%; P<.001) in diastolic BP compared with controls. Meta-analysis of subgroups showed a significant reduction in systolic BP in hypertensive (-4.4 mm Hg; 95% CI, -7.37 to -1.42, I(2) =0.0%; P=.004) but not normotensive patients. No significant reduction in diastolic BP was seen. After sensitivity analysis, heterogeneity disappeared and significant diastolic BP reduction (-2.68 mm Hg, 95% CI, -4.93 to -0.42, I(2) =0.0%; P=.020) was shown in hypertensive patients. This meta-analysis suggests that garlic supplements are superior to controls (placebo in most trails) in reducing BP, especially in hypertensive patients.

Potential of garlic (Allium sativum) in lowering high blood pressure: mechanisms of action and clinical relevance

Garlic supplements have shown promise in the treatment of uncontrolled hypertension, lowering blood pressure (BP) by about 10 mmHg systolic and 8 mmHg diastolic, similar to standard BP medication. Aged garlic extract, which contains S-allylcysteine as the bioactive sulfur compound, in particular is standardizable and highly tolerable, with little or no known harmful interaction when taken with other BP-reducing or blood-thinning medication. Here we describe biologically plausible mechanisms of garlic's BP-lowering effect. Garlic-derived polysulfides stimulate the production of the vascular gasotransmitter hydrogen sulfide (H2S) and enhance the regulation of endothelial nitric oxide (NO), which induce smooth muscle cell relaxation, vasodilation, and BP reduction. Several dietary and genetic factors influence the efficiency of the H2S and NO signaling pathways and may contribute to the development of hypertension. Sulfur deficiency might play a part in the etiology of hypertension, and could be alleviated with supplementation of organosulfur compounds derived from garlic.

Mechanisms underlying the antihypertensive effects of garlic bioactives

Cardiovascular disease remains the leading cause of death worldwide with hypertension being a major contributing factor to cardiovascular disease-associated mortality. On a population level, non-pharmacological approaches, such as alternative/complementary medicine, including phytochemicals, have the potential to ameliorate cardiovascular risk factors, including high blood pressure. Several epidemiological studies suggest an antihypertensive effect of garlic (Allium sativum) and of many its bioactive components. The aim of this review is to present an in-depth discussion regarding the molecular, biochemical and cellular rationale underlying the antihypertensive properties of garlic and its bioactive constituents with a primary focus on S-allyl cysteine and allicin. Key studies, largely from PubMed, were selected and screened to develop a comprehensive understanding of the specific role of garlic and its bioactive constituents in the management of hypertension. We also reviewed recent advances focusing on the role of garlic bioactives, S-allyl cysteine and allicin, in modulating various parameters implicated in the pathogenesis of hypertension. These parameters include oxidative stress, nitric oxide bioavailability, hydrogen sulfide production, angiotensin converting enzyme activity, expression of nuclear factor-κB and the proliferation of vascular smooth muscle cells. This review suggests that garlic and garlic derived bioactives have significant medicinal properties with the potential for ameliorating hypertension and associated morbidity; however, further clinical and epidemiological studies are required to determine completely the specific physiological and biochemical mechanisms involved in disease prevention and management.

A role of intestine in hypertension: mechanism of suppression of intestinal Na-H exchanger isoform-3 in spontaneously hypertensive rats

The main objective of this study was to investigate the role and the underlying mechanism of Na-H exchanger-3 (NHE-3) expression in spontaneously hypertensive rat (SHR) intestine. Expression of colonic and ileal NHE-3 isoform, its regulatory factor-1 (NHERF-1) and cyclic GMP kinase II (cGKII) were examined using western blot analysis. Since NHE-3 activity is regulated by its abundance on the plasma membrane, its levels were also examined in lipid rafts-enriched membrane fractions. The lipid rafts fractions were characterized by examining the concentration of flotillin-1 and caveolin-1, total protein, and cholesterol. Twelve-weeks-old SHR used in this study developed significant hypertension, proteinuria, and renal and cardiac hypertrophy. These changes were significantly reversed by captopril treatment. There was a significant decrease in the levels of NHE-3 and NHERF-1 proteins, and sodium pump activity, but an increase in the cGKII levels in both tissues from SHR. Reduction in NHERF-1 levels was reversed by captopril but not of the other proteins. Cholesterol profile was significantly different in SHR colon as compared to normo-tensive Wistar Kyoto rats. These findings suggest that suppression of NHE-3 in intestine is a counteracting mechanism of hypertension and is regulated by NHERF-1 through cGKII activation in SHR. NHE-3 suppression together with decrease in the sodium pump activity would accumulate intracellular Na(+) and may contribute to the reported hypertension-induced tissue damage in the GI-tract.

Garlic increases antioxidant levels in diabetic and hypertensive rats determined by a modified peroxidase method

Oxidative damage by free radicals has been implicated in the pathogenesis of vascular disease in diabetes and hypertension. In the present study, the total antioxidant status in diabetic and hypertensive rats before and after treatment with garlic (Allium sativum) was determined. The total serum antioxidants were measured by a modified method reported earlier by Miller and coworkers. The reproducibility of the assay was confirmed by determining standard curves for the known antioxidants: trolox (a stable analog of vitamin E), glutathione and vitamin C with interassay correlation coefficients (R(2), n = 10 in triplicate) of 0.9984, 0.9768 and 0.987, respectively, confirming the reliability and reproducibility of the assay. This assay was then used to determine total serum antioxidant levels of streptozotocin-induced diabetic rats and two-kidney one-clip hypertensive rats both before and after 3 weeks of treatment with an aqueous extract of garlic (500 mg/kg IP daily). The serum antioxidant levels of rats after 3 weeks of treatment were significantly higher (P < .001) than the pretreatment levels in both diabetic and hypertensive rats. The increased serum antioxidant levels were paralleled by a decrease in serum glucose in the garlic-treated diabetic rats and lowered systolic blood pressure in the garlic-treated hypertensive rats. We conclude from our study that (i) total antioxidants can be measured by a simple, reproducible, reliable assay and (ii) the total antioxidant status can be significantly improved by treatment with garlic.

Effect of garlic on blood pressure: a systematic review and meta-analysis

Background

Non-pharmacological treatment options for hypertension have the potential to reduce the risk of cardiovascular disease at a population level. Animal studies have suggested that garlic reduces blood pressure, but primary studies in humans and non-systematic reviews have reported mixed results. With interest in complementary medicine for hypertension increasing, it is timely to update a systematic review and meta-analysis from 1994 of studies investigating the effect of garlic preparations on blood pressure.

Methods

We searched the Medline and Embase databases for studies published between 1955 and October 2007. Randomised controlled trials with true placebo groups, using garlic-only preparations, and reporting mean systolic and/or diastolic blood pressure (SBP/DBP) and standard deviations were included in the meta-analysis. We also conducted subgroup meta-analysis by baseline blood pressure (hypertensive/normotensive), for the first time. Meta-regression analysis was performed to test the associations between blood pressure outcomes and duration of treatment, dosage, and blood pressure at start of treatment.

Results

Eleven of 25 studies included in the systematic review were suitable for meta-analysis. Meta-analysis of all studies showed a mean decrease of 4.6 ± 2.8 mm Hg for SBP in the garlic group compared to placebo (n = 10; p = 0.001), while the mean decrease in the hypertensive subgroup was 8.4 ± 2.8 mm Hg for SBP (n = 4; p < 0.001), and 7.3 ± 1.5 mm Hg for DBP (n = 3; p < 0.001). Regression analysis revealed a significant association between blood pressure at the start of the intervention and the level of blood pressure reduction (SBP: R = 0.057; p = 0.03; DBP: R = -0.315; p = 0.02).

Conclusion

Our meta-analysis suggests that garlic preparations are superior to placebo in reducing blood pressure in individuals with hypertension.

Wine, diet, and arterial hypertension

Hypertension is one of the leading causes of death in developed countries, and the number of prehypertensive patients is increasing. The beneficial effects of moderate wine consumption on cardiovascular diseases have been demonstrated, along with the healthy influence of a Mediterranean dietary pattern. The association of these 2 factors on hypertension and its complications is considered here. As wine polyphenols exert a vasorelaxing action, they might positively influence the hemodynamic situation of these patients. These effects could be enhanced by dietary constituents, such as garlic, onions, and olive oil, which are widely employed in Mediterranean cooking. By evaluating many studies performed in animal models and in humans, the authors conclude that moderate wine consumption, if associated with a healthy dietary pattern, such as the Mediterranean one, could help hypertensive patients to ameliorate their arterial pressure and quality of life by reducing cardiovascular morbidity and mortality rates.

Nitric oxide mediates the blood-pressure lowering effect of garlic in the rat two-kidney, one-clip model of hypertension

Garlic reduces blood pressure (BP) in two-kidney, one-clip (2K-1C) rats, and enhances nitric oxide (NO) synthesis in in vivo and in vitro experiments. NO is an important modulator of BP in the 2K-1C model. This study investigated the role of NO in the BP-lowering effect of garlic in the 2K-1C model. BP readings (mm Hg) were obtained from 2K-1C rats in 4 groups treated intraperitoneally for 2 wk with either normal saline (NS), garlic, L-nitroarginine-methylester (L-NAME), or L-NAME+garlic (n=4x5). BP was determined using the tail-cuff method and compared with data of 4 similarly treated groups of normal (unclipped) rats (NRs). The BP readings of NR groups were 120+/-3 mm Hg for the NS-treated group, 120+/-2 mm Hg for the garlic-treated group, 167+/-3 mm Hg for the L-NAME treated group (higher than NS or garlic, P<0.001) and 128+/-5 mm Hg for the garlic+L-NAME-treated group (lower than L-NAME, P<0.001). The BP readings of 2K-1C rat groups were: for the NS group, 169+/-6 mm Hg (higher than NRs, P<0.001); for the garlic group, 116+/-7 mm Hg (lower than NS, P<0.001); for the L-NAME group: 184+/-8 mm Hg (higher than garlic, P<0.001), and for the L-NAME+garlic group: 130+/-6 mm Hg (lower than garlic or NS, P<0.001). The data show that L-NAME increases the BP of both NRs and 2K-1C rats, with the rise more evident in the NRs (39 vs. 9%, respectively). Garlic counteracts the hypertensive effect of L-NAME in NRs as well as 2K-1C rats. We conclude that the BP-lowering effect of garlic in the rat 2K-1C model may be partly mediated through the NO pathway.

What's Cooking with Garlic: Is This Complementary and Alternative Medicine for Hypertension?

PURPOSE

To define complementary and alternative medicine (CAM); describe one type of CAM, garlic (Allium sativum L); and discuss its effects on blood pressure as a treatment for hypertension.

DATA SOURCES

Literature review from professional journals, abstracts, natural therapy books, and the World Wide Web (Internet). Information from the following professional organizations and agencies: The World Health Organization, Agency of Healthcare Research and Quality, National Cancer Institute, National Center for Complementary and Alternative Medicine, American Botanical Council, and Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure.

CONCLUSION

Garlic is widely used throughout the world as a CAM. It is one of the most popular herbal products sold in the United States. However, while some studies have shown small positive effects in reducing blood pressure, there are insufficient scientific data to draw conclusions regarding its efficacy on clinical blood pressure outcomes. Thus, healthcare providers should be cautious in recommending this herbal product as an antihypertensive CAM.

IMPLICATIONS FOR PRACTICE

CAMs may be used by clients for a variety of conditions including hypertension. Healthcare providers must be cognizant of the use, efficacy, adverse affects, and scientific evidence concerning CAM in order to provide safe and effective practice as well as appropriate and accurate information to their clients.

Potential benefits of complementary medicine modalities in patients with chronic kidney disease

Use of complementary and alternative medicine (CAM) by the general population is common, and, although potential for harm exists, evidence is accumulating that several modalities, including acupuncture, massage, relaxation response/guided or integrative imagery, meditation, and herbal supplements, have actions that are beneficial for patients with chronic illness. Potential areas in which CAM might benefit patients with kidney disease include prolonging time of progression to kidney failure as well as treatment of concomitant problems, including arthritides, pruritus, cardiovascular risk factors, anxiety, depression, and fatigue, as well as hepatoprotection and treatment of uremic bruising. Although no systematic survey of prevalence of use has been performed in patients with chronic kidney disease and much research remains to be done so that safety and efficacy issues can be resolved, it is likely that many patients are using the services of CAM providers without the knowledge of their nephrologists. Thus, it behooves us to become conversant in these therapies so that we may hold open dialogues with our patients, discouraging potentially harmful treatments, suggesting potentially helpful ones, and monitoring them for effects, both beneficial and harmful.

Effects of Natural Health Products on Blood Pressure

OBJECTIVE:

To review the scientific literature to identify reports of the effects of natural health products (NHPs) on blood pressure. DATA SOURCES: Electronic databases (MEDLINE [1965–May 2004] via PubMed, the Cochrane Library [1995–May 2004], International Pharmaceutical Abstracts [1970–May 2004], Iowa Drug Information Services [1965–May 2004]) were searched using the key words medicine, herbal plants, medicinal plant preparations, phytotherapy, angiosperms/therapeutic use, gymnosperms/therapeutic use, ethnopharmacology, pharmacognosy, blood pressure, hypertension, hypotension, and diuretic. Searches were not limited by date, language, or publication type. Review articles and texts, as well as reference lists of relevant articles, were used to identify additional reports.

STUDY SELECTION AND DATA EXTRACTION:

Articles (English-language after 1980) were assigned to the following categories: human study, case report, animal study, in vitro study, or theoretical prediction based on chemical constituents. Discussions of mechanisms of action were noted.

DATA SYNTHESIS:

A comprehensive search of the scientific literature identified NHPs capable of affecting blood pressure. Case reports and clearly defined mechanisms of action provided strong evidence for the ability of ephedra and licorice to increase blood pressure. Coenzyme Q10 was reported to decrease systolic and diastolic blood pressure, although the mechanism is unclear. The clinical significance of the blood pressure effects of other NHPs is unclear due to lack of conclusive in vivo data, as well as substantial variability in the chemical content of preparations of NHPs.

CONCLUSIONS:

Among published information, there is little definitive evidence with regard to the impact of NHPs on blood pressure. Additionally, effects may vary in a given patient with the formulation and standardization of a particular product. Until research better characterizes the effect of NHPs on blood pressure, patients should be encouraged to talk with their healthcare provider before starting or stopping any herbal product.