Are there herbal remedies and supplements to treat high blood pressure? (2025)

Herbal remediesand dietary supplements have been used to treat hypertension and somehave been shown to be moderatelyeffectivein small trials.1–4But they are not regulated with the same standards of effectiveness and safety as pharmacological treatments and, as such, should be used with caution.

While prescription and over-the-counter medication manufacturers must provide high-quality evidence to the Food and Drug Administration (FDA) that their products are safe and effective before they can be sold, the FDA does not review herbal remedies or dietary supplements for safety and effectiveness before they aremarketed.^1,2For this reason, high-quality randomized controlled trials often do not exist for dietary supplements. In addition, although the FDA does provide guidance for good marketing practice to help ensure their identity, purity, strength, and composition, some supplements have been found to contain hidden prescription drugs or other compounds because the FDA has no regulatory oversight for the manufacturing process. There is no guarantee that the actual contents of any given bottle of herbs or supplements contains what it claims to contain. In addition, some supplements are known to interfere with the pharmacokinetics of other medication.

Whenevaluating the use ofcomplementary and alternative antihypertensive treatment, it is important to consider the quality and generalizability of the evidence supporting their efficacy,the lack of quality control in their production, limited information about side effects,their potential for harm, and the possible interactions between the alternative treatment and other medicines being taken.

It is not surprising that plant-based remedies might have therapeutic applications since many medicines on the market today had plants as a starting point in their development and plant-based treatments have been used throughout the history of medicine.5Herbs and supplements that are antioxidants may interrupt vascular cell damage. Othershave anti-inflammatory, diuretic, or vasorelaxant properties.^1,5,6

No herbs and supplements that claim to be effective in lowering blood pressure have actually been shown to be potentially effective as a treatment for hypertension in large high quality human clinical trials.^3,4These include coenzyme Q10, fish oil, vitamin C,and garlic. A summary of the evidence for their efficacy and safety is given below.

Coenzyme Q10

Coenzyme Q10 is present in all human cells, withthehighest concentrations in the heart, liver, kidney, and pancreas.1It acts as a potent antioxidant, a membrane stabilizer, and is a co-factor in the generation of adenosine triphosphate, a major cellular energy source.7Severalsmallstudies have demonstrated that supplementation with coenzyme Q10 lowersblood pressure in hypertensive patients.^8,9Some researchers believe that supplementation with coenzyme Q10 might reduce the need for treatment with multiple antihypertensive medications.10

Singh et al.conducted a randomized controlledtrialwith64 patients who had been on antihypertensive treatment forat least one year.8Half received coenzyme Q10 60 mg foreightweeks while the other half receivedavitaminB-complex.In the coenzyme Q10 group,meansystolic BP levels droppedfrom 168 ± 9.6 mm Hgat baselineto 152 ± 8.2 mm Hg after eight weeks. Diastolic BP levelsdroppedfrom 106 ± 4.6 mm Hg to 97 ± 4.1 mm Hg.In thevitamin-Bgroup,meansystolic BP levels droppedfrom 166±8.5mm Hgat baselineto 164± 8.2 mm Hg after eight weeks. Diastolic BP levelsdropped from 105± 4.8mm Hg to103± 4.6mm Hg.At the conclusion of the study,those taking coenzyme Q10 had significantly lower systolic and diastolic blood pressure than those onvitamin B(p<0.05).

Burke et al.studied 41 men and 35 women with isolated systolic hypertension (150 to 170 mm Hg).9Half received 60 mgofcoenzyme Q10 with vitamin E and half received just vitamin E for 12 weeks. At the conclusion of the study, those taking coenzyme Q10 had a mean drop in systolic blood pressure of 17.8 mm Hg (± 7.3 mm Hg), a statistically significant drop relative to baseline(p<0.01)and compared tothose taking vitamin E(p<0.01).

Langsjoenet al.studied the effect of adding coenzyme Q10 to a pre-existing antihypertensive regimen in a prospective observational studyof 109 patientsin a private cardiology practice.10The dosage of the coenzyme Q10 varied during the course of the study to achieve measured levels higher than 2.0 mcg/mL.The average daily dose was 225 mgperday. After a minimum follow-up period ofoneyear, the average drop in blood pressure was 12/9 mm Hg (p<0.01). Just over half of the participants were able to discontinue at least oneof their antihypertensive medications.

No large randomized controlled study has been conducted to assess the impact of coenzyme Q10 as an antihypertensive therapy or on specific clinical effects such as the incidence of stroke or heart attack.7Due to a lack of large high-quality trialsthat measure BP-lowering effects and cardiovascular outcomes, theNIH Center for Complementary and Integrative Health considers the evidence for the blood pressure-lowering effect of coenzyme Q10 insufficient to recommend it for this purpose.1Theyalsopoint outthat it may interact with blood thinners, insulin, and some cancer treatments. Side effects that have been reported include abdominal discomfort, nausea, vomiting, diarrhea, and anorexia, allergic rash and headache.7

Fish Oil

Fish oil ispresent in the tissues of cold-water fish like herring and salmon and is marketed commercially in capsules as a supplement. It contains long-chain omega-3 polyunsaturated fatty acids that havedemonstratedsome heart-healthy effectsincluding the lowering of serum triglycerides.^1,11There is some evidence that omega-3 fatty acids may also have antiarrhythmic, antithrombotic, and antihypertensive effects.4Healthy young people that have higher omega-3 levels in their blood have lower blood pressure generally.12However, in the Physicians Health Study of21,185male physicians,dietary intake of fishwasnotassociated with reduced cardiovascular mortality.13

Miller et al.conducted ameta-analysis of70randomized controlled trials(n=4,409)studying the effect ofeicosapentaenoicacid and docosahexaenoic acid (EPA+DHA), theomega-3 fatty acidspresent in fish oil,on blood pressure.14The meta-analysis included trials(of three weeks duration or longer)of adults not currently taking antihypertensive medications when the dosage of EPA+DHAwas availableand blood pressure readings were reported as outcome measures. Both food sources of fish oil and supplements were included in the analysis. The mean dosage of fish oil was 3.8 g per day.Compared with placebo, EPA+DHAreducedsystolic blood pressureby an average of1.52 mm Hg (95% confidence interval [CI][2.25–0.79]). Among hypertensive subjects, the blood pressure was loweredby an average of4.51/3.05 mmHg (95%CI[6.12–2.83/ 4.35–1.74]).This blood-pressure-lowering effect is comparable to the effect of some lifestyle changes including restriction of salt and alcohol.¹⁵However, unlike studies examining the effect of salt and alcohol on blood pressure, this meta-analysis included small and heterogeneous studies of generally short duration, which limits the certainty of its findings.

Campbell et al.conducted a systematic review of 17 randomized controlled studies and crossover trials of adults taking fish oil supplements for at leasteightweeks (total n=1,524).16In the eight studies of hypertensive patients (blood pressure 140/85 mm Hg or higher) taking fish oil supplements, blood pressure droppedby a mean of2.56/1.47mm Hg(95%CI[0.58–4.53/0.41–2.53]). Blood pressure also dropped in the nine studies of normotensive people taking fish oil supplements, but the drop was not statistically significant.

There have been no large randomized controlled studies that demonstratetheeffectivenessof fish oilin improvingimportantpatient outcomessuch as heart attacks or strokeor preventing cardiovascular diseasein patients with normal blood pressure.Fish oil supplements aregenerally well-tolerated, with mild side effects such as eructation and dyspepsia reported infrequently. In large doses,fish oilcanpotentially cause bleeding.11

VitaminC

Vitamin C (ascorbic acid) is an antioxidantthat can protect cells from oxidative damage that is known to be a major cause of cardiovascular disease.1However, it is not known if vitamin C specifically is cardio-protective or if it is helpful for people who already have heart disease. The US Preventive Services Task Force found insufficient evidence that vitamin C supplementation prevents cardiovascular disease.17

Duffy et al.demonstrated that taking 500 mg of vitamin C daily lowered systolic blood pressure(froma mean of155 ± 22 mg Hgat baselineto 142 ± 16 mm Hgat one month)among42hypertensive patients already taking antihypertensive medication.18Placebo had no effect on mean systolic blood pressure at one month.

Sato et al.administered 200 mg of ascorbic acid three times a day for six months to24patients with refractory hypertension.19Twelve patients over 65 who took the ascorbic acid had a meanreductionin ambulatory systolic blood pressure of 20 mm Hg (p<0.001). The statistically significant effect was not seen in younger patients.

Although these small studies showed promising effects,Jurascheket al.conducted a systematic review and meta-analysis of clinical trials that examined the effect of vitamin C supplements on blood pressureand saw a more modest effectthan the smaller studies.20In the 29 trials that met eligibility criteria, the median dose was 500 mgaday, the median duration waseightweeks.Among patients taking vitamin C, the blood pressurewas reduced byan average of 3.84/1.48 mm Hg(systolic 95% CI[2.38 –5.29], p<0.01;diastolic 95% CI[0.12 –2.86], p=0.04).

Although there is limited harm to taking vitamin C in moderation, taking too much vitamin C can cause diarrhea, nausea, andothergastrointestinal symptoms. The upper limit for vitamin C in adults is 2000 mgperday.1

Garlic

Garlic is a plant bulb that has been used to treat high cholesterol and high blood pressure, among other things.1It is also sold as a capsule or tablet for medicinal purposes.Garlic has antioxidant and vasodilating properties which may explain its effect on blood pressure.4A number of small studies have been done to evaluate its effectiveness.3Several reviews and meta-analysessuggest that garlic may be more effective than placebo in lowering blood pressure, butstudiesweresmall21orlimited bysignificant variation in outcomes and methods.^21,22

A meta-analysis byRohneret al.included studies published through 2014(n= 577).22Systolic and diastolic blood pressureswerereducedmore after treatment with garlic compared to placebo, but the heterogeneity among the nine studieswas high.Mean systolic blood pressure was reduced 9.1 mm Hg (95% CI [5.4 – 12.7]) and mean diastolic blood pressure was reduced 3.8 mm Hg (95% CI [1 – 6.7]).When only higher quality studies were analyzed, the effect of garlic on lowering blood pressure was less pronounced although still statistically significantcompared to placebo. The authors conclude that while encouraging, the evidence is not strong, and further well-controlled studies are needed to evaluate the effectiveness of garlic on blood pressure.

Garlic hasafew known harmful effectsincludingallergic reactions, upset stomach, heartburn, and a possible increased risk of bleeding.1It also can interfere with other medications including anticoagulants and medications used to treat HIV.

^References

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