Outcome
    Moderate Evidence

    L-Citrulline for Blood Pressure Regulation

    Citrulline modestly lowers blood pressure in some populations, with effects in the low single digits.

    Overview

    Citrulline modestly lowers blood pressure in some populations, with effects in the low single digits.

    Verdict

    Mixed evidence

    How It Works

    Citrulline is converted to arginine in the kidney, raising substrate for endothelial nitric oxide synthase and promoting vasodilation.

    Dosing & Protocol

    Typical dose

    Recommended dose
    3-6 g/day of L-citrulline, or 8 g/day citrulline malate, on an empty stomach
    Expected timeframe
    4-8 weeks

    Protocol

    form
    L-citrulline, or watermelon extract, both used in the trials
    step 1
    Establish a proper baseline - two morning and two evening home readings daily for a week, since single clinic readings are too noisy to judge a 4 mmHg effect
    timing
    Away from large protein meals
    duration
    6-8 weeks
    titration
    6 g/day after two weeks if tolerated and readings have not moved
    honest note
    Meta-analyses report reductions of roughly 4 mmHg systolic and 2 mmHg diastolic, with larger effects in people who start hypertensive
    measurement
    Repeat the week of home readings at week 8 and compare weekly averages
    starting dose
    3 g/day L-citrulline on an empty stomach

    Evidence

    What the studies say

    Meta-analyses report reductions of roughly 4 mmHg systolic and 2 mmHg diastolic with L-citrulline or watermelon extract, with larger effects in hypertensive and older participants.

    Effect of L-Citrulline Supplementation on Blood Pressure: a Systematic Review and Meta-Analysis of Clinical Trials

    Score: 7/10
    2019
    meta_analysis
    n=300

    Barkhidarian B, Khorshidi M, Shab-Bidar S +1 more

    L-citrulline supplementation significantly reduced systolic blood pressure.

    View source

    Safety

    Caveats

    A 4 mmHg average is real but modest, and heterogeneous across trials - it will not control stage 2 hypertension. Contraindicated with nitrates and PDE5 inhibitors because of severe hypotension risk. Additive with antihypertensives - monitor for dizziness and involve your prescriber. Caution in kidney or liver disease given urea cycle loading. Mild gastrointestinal upset is common. Not established in pregnancy or breastfeeding; pregnancy hypertension needs obstetric care. Never stop prescribed blood pressure medication to trial a supplement.

    Less likely to help if

    People with normal baseline blood pressure, who show little change, and those with resistant or secondary hypertension.

    Medical Disclaimer

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    Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.