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Supplements for Blood Pressure: What Lowers It, by How Much, and What Raises It

For high blood pressure, swapping table salt for a potassium-enriched salt substitute has the strongest evidence (grade A): systolic pressure about 5 mmHg lower across 20 trials, and fewer strokes in a 20,995-person trial. Hibiscus tea, beetroot juice, magnesium, garlic, black seed and cocoa lowered it about 2 to 7 mmHg (grade B). Extra potassium can harm people with kidney disease or on some blood pressure drugs, so ask first and never change your medicine on your own.

Published How we grade evidenceEditorial policy

The short version

How much can supplements lower blood pressure?

A few millimeters of mercury (mmHg), mostly in the top number, systolic pressure. Food changes do as much. Across 34 trials, eating about 4.4 g less salt a day lowered systolic pressure 4.18 mmHg, and 5.39 mmHg in people with high blood pressure (He 2013), and the DASH eating plan (Dietary Approaches to Stop Hypertension) lowered it 3.2 mmHg across 30 trials of 5,545 people (Filippou 2020); grade A for both. All the graded findings are on our high blood pressure page and blood pressure protocol.

SupplementWhat trials foundSize of effect (systolic)Grade
Potassium-enriched salt substituteLower pressure; fewer strokes and deaths in one large trialAbout 5 mmHgA
Potassium pillsLower pressure in people with high blood pressure3 to 5 mmHgB
Hibiscus (roselle) tea or extractLower pressure in mild to moderate high blood pressureAbout 7 mmHgB
Black seedLower pressure; trials varied widelyAbout 3 mmHgB
MagnesiumLower pressure in high blood pressure or low magnesiumAbout 3 mmHgB
Beetroot juiceLower systolic, not diastolicAbout 5 mmHgB
Garlic, aged garlic extractLower pressure, more in high blood pressure2.5 to 9 mmHgB
Cocoa flavanolsSmall drop, clearest in high blood pressureAbout 2 mmHgB
Fish oil (omega-3)Small drop at 2 to 3 g a dayAbout 2.6 mmHgA
Coenzyme Q10No clear drop in high blood pressure aloneUncertainC
Vitamin DNo changeNoneA

Do salt substitutes and potassium lower blood pressure?

Grade A for salt substitutes. A Cochrane review found they lowered systolic pressure 4.76 mmHg in 20 trials (21,414 adults) and diastolic 2.43 mmHg (Brand 2022). In a trial of 20,995 people in rural China who had had a stroke or were aged 60 or more with high blood pressure, salt that was 25% potassium chloride cut strokes (rate ratio 0.86) and deaths (0.88) over 4.74 years; serious high-potassium events were about equal (3.35 vs 3.30 per 1,000 person-years) (Neal 2021). The catch: every trial in the Cochrane review left out people for whom extra potassium is known to be harmful.

Grade B for potassium pills. In 22 trials of higher potassium intake from diet or supplements (1,606 people), systolic pressure fell 3.49 mmHg, an effect seen only in people with high blood pressure (Aburto 2013). In untreated high blood pressure, 19 short trials (803 people) found 5.3 mmHg lower clinic pressure, but side effects were more common on potassium (12.8% vs 3.2%) (Ravichagua Ashiyama 2026). Our database grades potassium B; we give salt substitutes an A because of the Cochrane review and the stroke trial.

Does hibiscus tea lower blood pressure?

Grade B. In 13 trials (1,205 people) with mild to moderate high blood pressure, hibiscus lowered systolic pressure 6.67 mmHg and diastolic 4.35 mmHg against placebo, but not in people with metabolic syndrome; how it compares with blood pressure drugs is unresolved (Abdelmonem 2022). In one trial, 65 adults with slightly raised pressure drank three 240 mL cups of hibiscus tea a day for 6 weeks; systolic pressure fell 7.2 mmHg against 1.3 on a placebo drink (McKay 2010). Why not A: a Cochrane review accepted only one trial (60 people with diabetes) and called the evidence insufficient (Pattanittum 2021). Our supplement kits page lists a blood pressure kit with hibiscus and black seed.

Does black seed lower blood pressure?

Grade B. Black seed (Nigella sativa) lowered systolic pressure 3.26 mmHg and diastolic 2.80 mmHg in 11 trials (860 people), over about 8 weeks; ground seed powder did better than the oil (Sahebkar 2016). A 2023 update found a similar 3.06 mmHg systolic drop, with results that varied a great deal between trials (Kavyani 2023). More on our black seed page.

Does magnesium lower blood pressure?

Grade B. Across 38 trials (2,709 people), magnesium lowered systolic pressure 2.81 mmHg; the drop reached 7.68 mmHg in people taking blood pressure drugs and 5.97 in people with low magnesium, with no clear effect at normal pressure. Trials varied a lot; the median amount was 365 mg a day for 12 weeks (Argeros 2025). Upper limit for adults: 350 mg a day from supplements; take more only with blood tests or your clinician's advice (NIH ODS; upper-limit calculator). On a blood pressure drug? Read can I take magnesium with blood pressure medicine? and ask your prescriber or pharmacist.

Does beetroot juice lower blood pressure?

Grade B for juice. In 7 trials (218 people with high blood pressure), 70 to 250 mL of beetroot juice a day lowered systolic pressure 4.95 mmHg but not diastolic (Benjamim 2022). In one 4-week trial of 68 people with high blood pressure, 250 mL a day lowered 24-hour systolic pressure 7.7 mmHg (Kapil 2015), yet a week of juice did nothing in 27 people already on treatment (Bondonno 2015). Nitrate pills (sodium nitrate) showed no clear drop in 6 trials (Forster 2026). See nitrate.

Does garlic lower blood pressure?

Grade B. Garlic supplements lowered systolic pressure 5.1 mmHg in 20 trials (970 people), and 8.7 mmHg in the 10 trials of people with high blood pressure (Ried 2016). For aged garlic extract, a 2025 analysis of 19 trials found a smaller 2.49 mmHg systolic drop and no change in diastolic (Bashiri 2025); in 88 people with uncontrolled pressure, 1.2 g daily for 12 weeks lowered it 5.0 mmHg (Ried 2016, trial). Our aged garlic page grades the systolic drop A; we grade B because the newest pooled estimate is smaller.

Does dark chocolate or cocoa lower blood pressure?

Grade B, for a small drop. In a Cochrane review of 35 trials (1,804 mostly healthy people) using 30 to 1,218 mg of flavanols a day, cocoa lowered systolic and diastolic pressure 1.76 mmHg each, and systolic about 4 mmHg in people with high blood pressure (Ried 2017). A 2026 update of 25 studies found a 2.73 mmHg systolic drop, with moderate certainty (Sakuda 2026). Our protocol page shows cocoa extract at grade D, for a different outcome; for blood pressure these reviews support B. See flavanols.

What about fish oil, CoQ10 and other supplements?

Most lower pressure a little, on weaker or mixed evidence.

  • Fish oil: Grade A for a small effect. In 71 trials (4,973 people), 2 to 3 g a day of EPA plus DHA lowered systolic pressure 2.61 mmHg (Zhang 2022). In large trials, fish oil made atrial fibrillation (an irregular heartbeat) about a quarter more likely (hazard ratio 1.25), and about half more likely above 1 g a day (hazard ratio 1.49) (Gencer 2021).
  • Coenzyme Q10: Grade C. A Cochrane review of 2 trials (50 people) in high blood pressure found no significant change (Ho 2016); in 26 trials of people with heart and metabolic disease, systolic pressure fell 4.77 mmHg (Zhao 2022).
  • Psyllium and flaxseed: Grade B, small. Psyllium lowered systolic pressure 2.04 mmHg in 11 trials (Clark 2020); flaxseed 3.19 mmHg in 33 trials, with very mixed results (Li 2023).
  • Arginine and grape seed extract: Grade B. L-arginine lowered systolic pressure 6.40 mmHg in 22 trials (Shiraseb 2022); grape seed extract 6.08 mmHg in 16 trials (810 people) (Zhang 2016).
  • Quercetin: Grade B, small. Systolic pressure fell 2.38 mmHg in 10 trials (841 people) (Popiolek-Kalisz 2022); our high blood pressure page shows D for no effect, from a single study.
  • Vitamin C: Grade C. About 3.7 mmHg systolic in 17 trials, on low-certainty evidence (Kosari 2026).

What we'd skip

  • Vitamin D for blood pressure. No change in 46 trials (4,541 people) (Beveridge 2015).
  • Resveratrol. No significant drop across 17 trials (Fogacci 2019).
  • Nitrate pills instead of beetroot juice. No clear effect in 6 placebo trials (Forster 2026).
  • Potassium pills without your doctor's OK. Side effects were four times as common as on placebo in short trials (Ravichagua Ashiyama 2026), and the risks below apply.

Which supplements raise blood pressure?

  • Licorice with glycyrrhizin: in 18 studies (337 people), it raised systolic pressure 5.45 mmHg and lowered blood potassium (Penninkilampi 2017). NCCIH warns that glycyrrhizin can cause an irregular heartbeat, and that even small amounts have been linked to severe effects in people with high blood pressure (NCCIH).
  • Bitter orange (synephrine): systolic pressure rose 6.37 mmHg with longer use in pooled placebo trials (Koncz 2022).
  • Ephedrine (ephedra): in a review of 140 reports to the FDA, high blood pressure was the most common single problem among related cases, and there were 10 strokes and 10 deaths (Haller 2000).
  • Yohimbine: a single oral dose raised blood pressure 5 mmHg within an hour in 25 people with untreated high blood pressure (Grossman 1993).
  • Caffeine pills: about 2 mmHg higher systolic and diastolic pressure in 8 trials; diastolic pressure rose more above 400 mg a day (Abbas-Hashemi 2023).

Safety and interactions

  • Potassium and salt substitutes: with kidney disease, an ACE inhibitor (lisinopril and others), an ARB (losartan and others) or spironolactone, extra potassium can build up to dangerous levels (NIH ODS; losartan label). Two people on ACE inhibitors developed severe high potassium from a salt substitute (Ray 1999). Ask your prescriber or pharmacist first.
  • Supplements plus your medicine: anything that lowers pressure can add to amlodipine, losartan, lisinopril or another drug and cause dizziness, so check your readings (magnesium and blood pressure medicine).
  • St John's wort: in 8 healthy men, it cut the amount of verapamil (a heart and blood pressure drug) reaching the blood by about 80% (Tannergren 2004); NCCIH lists it as weakening many medicines (NCCIH).
  • Grapefruit juice raises blood levels of some calcium channel blockers, most of all felodipine (Sica 2006). Ask your pharmacist.
  • Garlic may raise bleeding risk with blood thinners or before surgery (NCCIH). Black seed lowered HbA1c 1.52% in people on diabetes medicines, so watch for low blood sugar (Bamosa 2010), and a possible bleed was reported with antiplatelet drugs (case report) (Arab 2026).
  • Hibiscus: no interaction studies in people were found.
  • Stacks: taking several of these? Check your stack against the upper limits.

When to see a doctor

  • Call 911 if your pressure is above 180/120 on a second reading 5 minutes later and you have a sudden severe headache, chest, back or belly pain, trouble breathing, numbness or weakness, vision changes or trouble speaking (NHLBI).
  • Call your doctor if it stays above 180/120 without symptoms (NHLBI), or if your readings are consistently 130/80 or higher (NHLBI).
  • Measure at home with a validated, calibrated cuff; home readings help find high pressure that clinic checks miss (Muntner 2019).
  • Don't stop or change a blood pressure medicine on your own; ask the prescriber or pharmacist. If you are pregnant, breastfeeding or under 18, ask a clinician (your doctor or midwife) first.

FAQ

What supplement lowers blood pressure the most? In pooled trials, hibiscus tea (about 7 mmHg systolic), L-arginine and grape seed extract (about 6) had the biggest average drops, all grade B. A potassium-enriched salt substitute has the strongest evidence, about 5 mmHg and fewer strokes (grade A).

Can I take supplements with blood pressure medicine? Often, but ask your prescriber or pharmacist first. Potassium and salt substitutes can be dangerous with ACE inhibitors, ARBs, spironolactone or kidney disease.

Does magnesium lower blood pressure? A little: about 2.8 mmHg systolic across 38 trials, more in people on blood pressure medicine or low in magnesium (grade B).

Does beetroot juice lower blood pressure? Juice lowered systolic pressure about 5 mmHg in people with high blood pressure (grade B); nitrate pills showed no clear effect.

Which supplements raise blood pressure? Licorice, bitter orange, ephedra, yohimbine and high doses of caffeine.

Sources

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