Does coconut water lower blood pressure?

Nobody has shown it in a randomized trial. We found one randomized trial of coconut water, in 32 women with prehypertension, and its abstract reports plasma potassium and no blood pressure result. Two small non-randomized studies, in 30 and 28 people with hypertension, saw pressure fall over one to two weeks. The case for coconut water rests on its potassium, and potassium does lower blood pressure: a meta-analysis of supplement trials in people with hypertension found systolic pressure fell by 4.48 mmHg. Those trials used potassium supplements, and a glass of coconut water carries much less.

Unsettled. The idea is plausible and untested. Coconut water contains potassium, potassium lowers blood pressure in trials, and no trial has yet put the two together and measured the result. The studies that did measure pressure after coconut water were too small and too loosely controlled to separate the drink from chance or from the act of being studied.

What the trials found

Coconut water itself

The only randomized trial we found allocated 32 women aged 25 to 44 with prehypertension to 14 days of tender coconut water or plain water, 10 fl oz (300 mL) twice a day. After 14 days plasma potassium did not differ significantly between the groups. The abstract says nothing about blood pressure, and we could not get the full text, so whether pressure moved is unknown to us.

A 2024 study from Indonesia gave 5.1 fl oz (150 mL) of young coconut water each morning for 7 days to adults over 35 with stage 1 hypertension, 15 in each group. Pressure fell significantly within the coconut water group and did not change significantly in the controls. The study was not randomized, the coconut water group was all women while the controls were mostly men, and it compared each group with itself rather than the groups with each other. The abstract gives no figure in mmHg.

A 2005 study in Trinidad split 28 people with hypertension into four groups of seven for two weeks: bottled water, coconut water, mauby, or a mixture of the two. The mixture gave the largest falls in mean pressure, 24 mmHg systolic and 15 mmHg diastolic, about double the largest falls seen with either drink alone. Randomization is not described, and seven people per group is too few to lean on.

The potassium inside it

Fresh coconut water holds 250 mg of potassium per 3.5 oz (100 g) in the USDA records, and the ready-to-drink kind 165 mg. Potassium has a much deeper evidence base. In a meta-analysis of potassium supplement trials lasting at least four weeks in people with hypertension, systolic pressure fell by 4.48 mmHg and diastolic by 2.96 mmHg. The meta-analysis behind the WHO potassium guideline pooled 21 studies and found falls of 3.49 mmHg systolic and 3.02 mmHg diastolic, rated high quality. In people with normal blood pressure, a 2024 meta-analysis found 60 mmol a day or less lowered systolic pressure by 2.34 mmHg.

Two things keep these numbers from transferring to a glass of coconut water. The trials gave potassium supplements, at 30 to 140 mmol a day in the dose-response meta-analysis below. By the USDA figures above, a 10 fl oz (300 mL) glass of coconut water holds roughly 500 to 750 mg of potassium, about 13 to 19 mmol. And the evidence on potassium has its own dissent: a Cochrane review of the six highest-quality trials found reductions that did not reach significance.

A dose-response meta-analysis of 32 trials also found that more is not simply better. The fall in pressure weakened above about 30 mmol a day of extra potassium, and above about 80 mmol pressure rose again, a finding that came from few studies and only in people on blood pressure drugs.

Who should be careful

Not for everyone. The people most likely to try coconut water for blood pressure are the ones who most need to check first. According to the NIH Office of Dietary Supplements, people with chronic kidney disease, or taking ACE inhibitors or potassium-sparing diuretics, can develop high blood potassium even from dietary intakes below the adequate intake. The US label for losartan warns that combining it with other things that raise serum potassium may cause hyperkalemia.

One case report describes a 78-year-old man with kidney failure and diabetes, on losartan and spironolactone, who drank a lot of king coconut water for a week and reached a serum potassium of 7.02 mEq/L with paralysis and a dangerous heart rhythm. It is one person with several risk factors at once, and it shows what the drug labels mean. The NIH also notes that very high amounts of potassium from supplements or salt substitutes can cause acute hyperkalemia even in healthy people.

In healthy kidneys the drink itself looks well tolerated. In a double-blind trial of 95 people with ulcerative colitis, 14 fl oz (400 mL) of coconut water a day for 8 weeks caused no more adverse events than placebo and no case of hyperkalemia. Those were people with colitis, and the trial did not report blood pressure.

What expert bodies say

WHO strongly recommends increasing potassium intake from food to lower blood pressure and the risk of cardiovascular disease in adults. It does not name coconut water. The NIH fact sheet on potassium reports both sides: most trials lowered pressure, and the highest-quality six did not reach significance. We found no expert body that recommends coconut water for blood pressure.

How we searched

What would change this answer

• The blood pressure result of the existing randomized trial in 32 prehypertensive women. If the full text reports it, that single number would be the best direct evidence there is.
• A randomized trial of coconut water against plain water in people with stage 1 hypertension, long enough to matter, comparing the groups with each other and reporting the difference in mmHg.
• A trial that measures how much potassium a realistic daily amount of coconut water actually adds, so the potassium meta-analyses can be read against it rather than against supplement doses.
• A systematic review. None exists for coconut water and blood pressure, and with three small studies there is not yet enough to pool.

Sources

1. ev-cwbp-01 · Observational data · quasi-experimental controlled study, not randomized · n = 30 (15 per group)
   Systolic and diastolic blood pressure before and after the intervention showed significant difference in group A (p<0.05), while the difference in group B was not significant (p>0.05).
   
   Who: people aged over 35 years with stage I hypertension, Kuantan Singingi district, Riau, Indonesia
   Effect: significant within-group fall in systolic and diastolic BP in the coconut water group (p<0.05); no significant change in controls (p>0.05); mmHg difference not given in the abstract
   Certainty: Not randomized; the intervention group is women only, the control mostly men; 7 days; comparison within groups, not between groups. A signal, not evidence.
   J Pak Med Assoc, 2024, The Effect of Young Coconut Water on Blood Pressure in Hypertensive Patients (PMID 39221800) · checked 2026-10-07 · we read the abstract
2. ev-cwbp-02 · Observational data · non-randomized single-blind controlled trial · n = 28
   For the group receiving the mixture, the largest decreases in mean systolic and mean diastolic pressure were 24 mmHg and 15 mmHg respectively; these were approximately double the largest values seen with the single interventions.
   
   Who: 28 hypertensive subjects in four equal groups (bottled water, coconut water, mauby, mixture), 2 weeks
   Effect: largest falls in the mixture group: 24 mmHg systolic, 15 mmHg diastolic, about double the single interventions
   Certainty: Groups of 7, randomization not described, 2 weeks; the largest reduction in mean pressure in the mixture group is given, not the difference from the control group.
   West Indian Med J, 2005 · checked 2026-10-07 · we read the abstract
3. ev-cwbp-03 · Randomized controlled trial(s) · randomized parallel-group controlled trial · n = 32
   Thirthy-two female aged 25-44 years were randomly allocated to 14 days on TCW or water in a parallel randomized clinical trial.
   
   Who: 32 women aged 25-44 years with prehypertension, 10 fl oz (300 mL) tender coconut water or water twice daily, 14 days
   Effect: plasma potassium not significantly different between groups (p = 0.247); blood pressure result not reported in the abstract
   Certainty: No full text in PMC (no_pmc), so the blood pressure result is unknown; MeSH includes Blood Pressure. Dose 600 mL/day ≈ 1-1.5 g potassium.
   Curr Hypertens Rev, 2017 · checked 2026-10-07 · we read the abstract
4. ev-cwbp-04 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 25 RCTs, 1163 participants (per NIH ODS)
   Overall, potassium supplementation decreased systolic blood pressure of 4.48mmHg (95% CI 3.07-5.90) and diastolic blood pressure of 2.96mmHg (1.10-4.82).
   
   Who: hypertensive subjects in RCTs of potassium supplementation lasting at least 4 weeks
   Effect: SBP -4.48 mmHg (95% CI 3.07 to 5.90); DBP -2.96 mmHg (1.10 to 4.82)
   Certainty: About potassium supplements, not coconut water; 10 fl oz (300 mL) of coconut water per USDA (cwat-r2-01) gives ≈13-19 mmol potassium.
   Int J Cardiol, 2017 · checked 2026-10-07 · we read the abstract
5. ev-cwbp-05 · Meta-analysis or systematic review · systematic review and subgroup meta-analysis of RCTs · n = —
   Potassium at dosages of ≤60 mmol/day and durations greater than 1 month reduced SBP by -2.34 and -2.80 mm Hg, respectively.
   
   Who: general normotensive population in placebo-controlled RCTs of potassium supplementation
   Effect: SBP -2.34 mmHg at doses of 60 mmol/day or less; -2.80 mmHg with duration over 1 month
   Certainty: Number of studies not stated in the abstract; supplements, not food.
   Nutrients, 2024 · checked 2026-10-07 · we read the abstract
6. ev-cwbp-06 · Meta-analysis or systematic review · dose-response meta-analysis of RCTs · n = 32 trials
   We observed a U-shaped relationship between 24-hour active and control arm differences in potassium excretion and BP levels, with weakening of the BP reduction effect above differences of 30 mmol/d and a BP increase above differences ≈80 mmol/d.
   
   Who: mostly adults with hypertension in trials of potassium supplementation (30 to 140 mmol/day), at least 4 weeks
   Effect: U-shaped curve: benefit weakens above a 30 mmol/day difference in potassium excretion; BP increase above about 80 mmol/day, seen in drug-treated hypertension
   Certainty: A blood pressure rise at very high potassium is based on a small number of studies, only in those on medication.
   J Am Heart Assoc, 2020 · checked 2026-10-07 · we read the abstract
7. ev-cwbp-07 · Meta-analysis or systematic review · WHO-commissioned systematic review and meta-analysis · n = 21 studies
   The meta-analysis of 21 studies with 21 comparisons found that increased potassium resulted in a decrease in resting systolic blood pressure of 3.49 mmHg (95% confidence interval [CI]: 1.82, 5.15) (quality of evidence high1) and a decrease in resting diastolic blood pressure of 3.02 mmHg (95%CI: 1.17, 4.86) (quality of evidence high).
   
   Who: adults in trials of increased versus lower potassium intake (median difference 57 mmol/day)
   Effect: SBP -3.49 mmHg (95% CI 1.82 to 5.15); DBP -3.02 mmHg (1.17 to 4.86); quality high
   Certainty: The number from T2, under it the T1 card ev-cwbp-04 (meta-analysis of RCTs). WHO does not consider coconut water.
   WHO, 2012, Guideline: potassium intake for adults and children · checked 2026-10-07 · we read the section
8. ev-cwbp-08 · Position of an expert body · WHO guideline (NUGAG, GRADE) · n = —
   WHO recommends an increase in potassium intake from food for reduction of blood pressure and risk of cardiovascular disease, stroke and coronary heart disease in adults (strong recommendation1 ).
   
   Who: adults
   Effect: strong recommendation to increase potassium intake from food
   Certainty: Recommendation about dietary potassium in general; coconut water not named.
   WHO, 2012, Guideline: potassium intake for adults and children · checked 2026-10-07 · we read the section
9. ev-cwbp-09 · Position of an expert body · government fact sheet · n = 6 trials (Cochrane)
   However, a Cochrane Review of six of the highest-quality trials found nonsignificant reductions in systolic and diastolic blood pressure with potassium supplementation [47].
   
   Who: people in potassium supplementation trials, NIH potassium fact sheet
   Effect: nonsignificant reductions in systolic and diastolic BP in the highest quality trials
   Certainty: Discrepancy within the potassium evidence; ODS itself prints it.
   NIH Office of Dietary Supplements, Potassium Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
10. ev-cwbp-10 · Position of an expert body · government fact sheet · n = —
    However, in people with impaired urinary potassium excretion due to chronic kidney disease or the use of certain medications, such as angiotensin converting enzyme (ACE) inhibitors or potassium-sparing diuretics, even dietary potassium intakes below the AI can cause hyperkalemia [11].
    
    Who: people with impaired urinary potassium excretion
    Effect: no UL for potassium in healthy people; hyperkalemia risk with CKD, ACE inhibitors, potassium-sparing diuretics
    Certainty: Precisely those who treat blood pressure with ACE inhibitors/ARBs or spironolactone should be careful with coconut water as a "potassium" drink.
    NIH Office of Dietary Supplements, Potassium Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
11. ev-cwbp-11 · Position of an expert body · FDA-approved drug label · n = —
    Coadministration of losartan with other drugs that raise serum potassium levels may result in hyperkalemia.
    
    Who: patients taking losartan
    Effect: risk of hyperkalemia; monitor serum potassium
    Certainty: The label speaks of drugs and supplements; coconut water is not named. A known case of hyperkalemia on losartan after excess coconut water is already in the database (30002937).
    Losartan potassium tablets, FDA-approved label (DailyMed), effective 2026-08-27 · checked 2026-10-07 · we read the section
12. ev-cwbp-12 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial · n = 95
    Adverse events were comparable, and no patient developed hyperkalemia.
    
    Who: patients with mild to moderate ulcerative colitis, 14 fl oz (400 mL) coconut water or placebo daily plus standard therapy, 8 weeks
    Effect: adverse events comparable; no patient developed hyperkalemia
    Certainty: People with colitis, not with hypertension or CKD; 8 weeks. Blood pressure not reported.
    Clin Gastroenterol Hepatol, 2024 · checked 2026-10-07 · we read the abstract
13. cwat-r2-01 · Position of an expert body · USDA reference dataset · n = 2 records
    Nuts, coconut water (liquid from coconuts) (FDC 170174, SR Legacy, Nut and Seed Products): magnesium 25 mg per 100 g = 6% DV; potassium 250 mg = 5% DV; sodium 105 mg = 5% DV; across 2 records magnesium 6-25, potassium 165-250, sodium 26-105; Foundation samples 0, CoFID match none
    
    Who: USDA SR Legacy records for Nuts, coconut water (liquid from coconuts) and Beverages, Coconut water, ready-to-drink
    Effect: potassium 250 mg per 3.5 oz (100 g) (5% DV), sodium 105 mg (5% DV), magnesium 25 mg (6% DV); range across 2 records potassium 165 to 250, sodium 26 to 105, magnesium 6 to 25 mg
    Certainty: Two SR Legacy entries, no Foundation, no spread across samples; CoFID gives no second number.
    USDA FoodData Central, SR Legacy, FDC 170174 · checked 2026-09-29 · we read the dataset
14. cwat-r2-09 · Position of an expert body · fact sheet · n = —
    However, very high amounts of potassium supplements or salt substitutes that contain potassium could exceed the kidney’s capacity to excrete potassium, causing acute hyperkalemia even in healthy individuals.
    
    Who: General population, NIH potassium fact sheet
    Effect: acute hyperkalemia possible with very high potassium amounts
    Certainty: About supplements and salt substitutes, not coconut water; the threshold for food is not named.
    NIH Office of Dietary Supplements, Potassium Fact Sheet for Health Professionals · checked 2026-09-29 · we read the section
15. cwat-r2-10 · Laboratory or animal data · case report · n = 1
    We report the case of acute ascending flaccid paralysis secondary to hyperkalemia induced by multiple trigger factors-king coconut water, renal failure, diabetes, metabolic acidosis, and potassium sparing diuretics. CASE PRESENTATION: A 78-year-old man presented with acute ascending type flaccid paralysis over five-hour duration and subsequently developed preterminal cardiac arrhythmias secondary to severe hyperkalemia (serum potassium: 7.02 mEq/L). He was on Losartan and Spironolactone for ischemic heart disease. Dietary history revealed excessive intake of king coconut water (Cocos nucifera) over past one week.
    
    Who: One 78-year-old man with renal failure, diabetes and ischemic heart disease
    Effect: serum potassium 7.02 mEq/L, preterminal arrhythmia, full neurological recovery within 24 h
    Certainty: A single case, several triggers at once (renal failure, medications, acidosis).
    Case Rep Neurol Med, 2018 · checked 2026-09-29 · we read the abstract