Recommendations Summary
HTN: Garlic 2008
Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.
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Recommendation(s)
Garlic
Consumption of garlic may or may not be beneficial for the reduction of blood pressure, since the current evidence is inconclusive regarding its effect on blood pressure.
Rating: Weak
Imperative
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Risks/Harms of Implementing This Recommendation
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Conditions of Application
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Potential Costs Associated with Application
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Recommendation Narrative
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Two randomized controlled trials on healthy subjects report no significant differences in total blood pressure between groups consuming dried garlic powder (~3 cloves per day) for 12 weeks or garlic oil (12.3mg per day) for 16 weeks (Zhang et al, 2001; Turner et al, 2004).
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Two non-randomized clinical trials with both hypertensive and normotensive subjects consuming either garlic pearls (250mg per day) for eight weeks or garlic extract (~10g garlic per day) report significant declines in both systolic and diastolic blood pressures in subjects with hypertension, but not in normotensive controls (Dhawan et al, 2004; Durak et al, 2004).
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One cross-sectional study reports that lower systolic blood pressures were associated with increased garlic consumption (Qidwai et al, 2000).
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Recommendation Strength Rationale
- Conclusion Statement is Grade III
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Minority Opinions
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Supporting Evidence
The recommendations were created from the evidence analysis on the following questions. To see detail of the evidence analysis, click the blue hyperlinks below (recommendations rated consensus will not have supporting evidence linked).
What is the relationship between garlic intake and blood pressure in healthy and hypertensive adults?
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References
Dhawan V, Jain S. Effect of garlic supplementation on oxidized low density lipoproteins and lipid peroxidation in patients of essential hypertension. Mol Cell Biochem. 2004; 266 (1-2): 109-115.
Durak I, Kavutcu M, Aytac B, Avci A, Devrim E, Ozbek H, Ozturk HS. Effects of garlic extract consumption on blood lipid and oxidant/antioxidant parameters in humans with high blood cholesterol. J Nutr Biochem. 2004; 15 (6): 373-377.
Qidwai W, Qureshi R, Hasan SN, Azam SI. Effect of dietary garlic (Allium sativum) on the blood pressure in humans - a pilot study. J Pak Med Assoc. 2000; 50 (6): 204-207.
Turner B, Molgaard C, Marckmann P. Effect of garlic (Allium sativum) powder tablets on serum lipids, blood pressure and arterial stiffness in normo-lipidaemic volunteers: a randomised, double-blind, placebo-controlled trial. Br J Nutr. 2004; 92 (4): 701-706.
Zhang XH, Lowe D, Giles P, Fell S, Board AR, Baughan JA, Connock MJ, Maslin DJ. A randomized trial of the effects of garlic oil upon coronary heart disease risk factors in trained male runners. Blood Coagul Fibrinolysis. 2001; 12 (1): 67-74.
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References not graded in Academy of Nutrition and Dietetics Evidence Analysis Process