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NCCIH Clinical Digest

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Complementary Health Approaches for Hypertension : What the Science Says

February 2018

Clinical Guidelines, Scientific Literature, Info for Patients: 
Complementary Health Approaches for Hypertension

hypertension blood pressure

Mind and Body Approaches

Relaxation Techniques

Relaxation techniques have shown modest, short-term reductions in blood pressure; however, many of these studies were of poor quality.

What Does the Research Show?

  • A 2010 systematic review of 36 randomized controlled trials found no convincing evidence that consistently demonstrates the effectiveness of any biofeedback intervention in the control of hypertension when compared with pharmacotherapy, placebo, or no treatment.
  • A 2009 Cochrane systematic review(link is external) of 25 randomized controlled trials involving 1,198 participants found that overall, relaxation techniques resulted in small average reductions in blood pressure, but many trials were not well designed and had inconsistent results. The reviewers concluded that the evidence of causal association between relaxation and the reduction of blood pressure is weak.

Safety

  • Mind and body practices, including relaxation techniques, are generally safe for healthy people if properly performed by a qualified practitioner or taught by a well-trained instructor.

Meditation

A 2013 review and scientific statement on alternative approaches to lowering blood pressure from the American Heart Association provides the following statement regarding meditation for high blood pressure: “The overall evidence supports that Transcendental Meditation (TM) modestly lowers blood pressure.” However, the review indicates that it is uncertain whether TM is truly superior to other meditation techniques in terms of blood pressure lowering because there are few head-to-head studies. TM is meditative technique used to achieve a relaxed state through regular periods of meditation during which a mantra is repeated.

What Does the Research Show?

  • A 2013 review and scientific statement on alternative approaches to lowering blood pressure, from the American Heart Association suggests that the overall evidence supports that TM modestly lowers blood pressure. However, the review indicates that it is uncertain whether TM is truly superior to other meditation techniques in terms of blood pressure lowering because there are few head-to-head studies. Because of the paucity of data, no recommendation could be made on a specific method of practice when TM is used for the treatment of high blood pressure. Further, the mechanism whereby meditation techniques lower blood pressure when it occurs remains unclear.
  • Results of a 2009 randomized controlled trial involving 298 college students that assessed the effects of Transcendental Meditation (TM) versus wait-list control on blood pressure, psychological distress, and coping suggest that meditation may lower the blood pressure of people at increased risk of developing hypertension. The findings also suggested that practicing meditation can help with psychological distress, anxiety, depression, anger/hostility, and coping ability.

Safety

  • Meditation is considered to be safe for healthy people.
  • There have been rare reports that meditation could cause or worsen symptoms in people who have certain psychiatric problems, but this question has not been fully researched.

Yoga

There is some low-quality evidence that yoga may be a useful adjunct intervention for the management of hypertension.

What Does the Research Show?

  • A 2014 systematic review and meta-analysis of seven randomized controlled trials involving a total of 452 patients found very low-quality evidence, compared with usual care, of beneficial effects of yoga on systolic and diastolic blood pressure. Compared with exercise, no evidence was found for effects of yoga on systolic or diastolic blood pressure.
  • A 2013 systematic review of 6 studies involving a total of 386 patients found some encouraging evidence of yoga for lowering systolic and diastolic blood pressure; however, the trials included in the review were of low methodological quality, so definitive conclusions about the efficacy and safety of yoga for essential hypertension could not be drawn.

Safety

  • Mind and body practices, including yoga, are generally safe for healthy people if properly performed by a qualified practitioner or taught by a well-trained instructor. However, some practices may not be appropriate for people with health conditions. For example, people with high blood pressure may need to modify or avoid some yoga poses.

Natural Products

Research results suggest that certain foods and dietary supplements, including garlic, fish oil (omega-3 fatty acids), green or black tea, probiotics, and the herb roselle (Hibiscus sabdariffa), may help reduce blood pressure in people with hypertension. For some of these products, the evidence for an effect on blood pressure is limited and the benefit may be small.

Garlic

There is evidence that garlic preparations may lower blood pressure in people with hypertension, but most of the research consists of small, preliminary, or low-quality studies.

What Does the Research Show?

  • A 2015 systematic review and meta-analysis of nine double-blind trials involving 482 participants found some evidence suggesting that garlic preparations may lower blood pressure in hypertensive individuals, the evidence is not strong.
  • A 2012 Cochrane review of two randomized controlled trials found insufficient evidence to determine if garlic provides a therapeutic advantage compared to placebo in terms of reducing the risk of mortality and cardiovascular morbidity in patients diagnosed with hypertension. Although garlic appeared to reduce mean supine systolic and diastolic blood pressure compared with placebo, the reviewers noted that the difference in blood pressure reduction falls within the known variability in blood pressure measurements, making it difficult to determine the impact, if any, of garlic on lowering blood pressure.

Safety

  • Taking garlic supplements may increase the risk of bleeding in people taking anticoagulants.
  • Garlic has been found to interfere with the effectiveness of some drugs, including saquinavir.

Omega-3 Fatty Acids (Fish Oil)

Results from randomized controlled trials are mixed, but overall, data suggest some benefit of omega-3 fatty acids from fish oils in lowering blood pressure.

What Does the Research Show?

  • A 1993 meta-analysis of 11 controlled clinical trials involving 728 participants found that diet supplementation with a relatively high dose of omega-3 polyunsaturated fatty acids can lead to clinically relevant reductions in blood pressure in patients with untreated hypertension. However, omega-3 fatty acids as antihypertensive therapy requires more data on long-term efficacy and patient acceptability of lower doses.
  • A 2014 meta-analysis of 70 randomized controlled trials concluded that overall, available evidence suggests that EPA+DPA provision reduces systolic and diastolic blood pressure compared with placebo. The strongest effects were seen among untreated hypertensive participants.

Safety

  • Side effects of omega-3 supplements are usually mild. They include unpleasant taste, bad breath, bad-smelling sweat, headache, and gastrointestinal symptoms.
  • Several large studies have linked higher blood levels of long-chain omega-3s with higher risks of prostate cancer. However, other research has shown that men who frequently eat seafood have lower prostate cancer death rates and that dietary intakes of long-chain omega-3s aren’t associated with prostate cancer risk. The reason for these apparently conflicting findings is unclear.
  • Omega-3 supplements may interact with anticoagulant drugs.
  • It’s uncertain whether people with seafood allergies can safely take fish oil supplements.

References

  • Appel LJ, Miller ER 3rd, Seidler AJ, Whelton PK. Does supplementation of diet with ‘fish oil’ reduce blood pressure? A meta-analysis of controlled clinical trials. Arch Intern Med. 1993;153(12):1429-38.
  • Brook RD, Appel LJ, Rubenfire M, et al. Beyond medications and diet: alternative approaches to lowering blood pressure: a scientific statement from the American Heart Association. Hypertension. 2013;61(6):1360-83.
  • Cramer H, Haller H, Lauche R, et al. A systematic review and meta-analysis of yoga for hypertension. Am J Hypertens. 2014 Sep;27(9):1146-51.
  • Dickinson HO, Beyer FR, Ford GA, et al. Relaxation therapies for the management of primary hypertension in adults. Cochrane Database of Systematic Reviews. 2008;1:CD004935.
  • Greenhalgh J, Dickson R, Dundar Y. Biofeedback for hypertension: a systematic review. J Hypertens. 2010;28(4):644-52.
  • Miller PE, Van Elswyk M, Alexander DD. Long-chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid and blood pressure: a meta-analysis of randomized controlled trials. Am J Hypertens. 2014;27(7):885-96.
  • Nidich SI, Rainforth MV, Haaga DA, et al. A randomized controlled trial on effects of the Transcendental Meditation program on blood pressure, psychological distress, and coping in young adults. Am J Hypertens. 2009;22(12):1326-31.
  • Rohner A, Ried K, Sobenin IA, et al. A systematic review and metaanalysis on the effects of garlic preparations on blood pressure in individuals with hypertension. Am J Hypertens. 2015;28(3):414-23.
  • Stabler SN, Tejani AM, Huynh F, Fowkes C. Garlic for the prevention of cardiovascular morbidity and mortality in hypertensive patients. Cochrane Database Syst Rev. 2012;15;(8):CD007653.
  • Wang J, Xiong X, Liu W. Yoga for essential hypertension: a systematic review. PLoS One. 2013;4;8(10):e76357.

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