Journal·Ingredient deep-dives

L-Citrulline at the level used in the published research — why pure free-form, not malate

The free-form vs malate question is the most-skipped distinction in supplement labelling. Here's what L-citrulline is, why we use the level used in the published research of the pure free-form amino, and the published research behind both forms.

By The Founders · Co-founder · Innately Halal·18 February 2026·7 min read

The molecule

L-citrulline is a non-essential amino acid, first isolated from watermelon (Citrullus lanatus) in 1914 — hence the name. It is found in modest concentrations in several fruits and vegetables, with the highest natural concentration in watermelon and notable amounts in dates, cucumber, and pumpkin.

In the body, L-citrulline is converted to L-arginine, which in turn is involved in the urea cycle and the body's natural nitric-oxide (NO) production pathway. NO is what mediates vascular dilation — the same biological mechanism that, at the pharmacological level, sildenafil acts on through a different upstream lever.

We use the level used in the published research of pure pharmaceutical-grade L-citrulline per daily serving. Not "the level used in the published research of L-citrulline malate." That distinction matters more than most labels admit.

L-citrulline vs L-citrulline malate

L-citrulline malate is a 2:1 mixture (by weight, typically) of L-citrulline bonded with malic acid. A label reading "L-citrulline malate 3,000 mg" is therefore providing approximately the level used in the published research of actual L-citrulline plus the level used in the published research of malate. The two are not interchangeable doses.

Why some brands use malate: - Malate is cheaper than pure L-citrulline - The 3,000 mg dose looks higher on the label than the level used in the published research of pure - Malate adds a separate compound (malic acid) that some research suggests has its own ergogenic role

Why we use pure free-form: - The dose on the label is the actual L-citrulline content. No conversion needed. - The published clinical research that informed our dose used pure free-form L-citrulline (Bailey et al. 2015; Suzuki et al. 2016) - Free-form has higher published bioavailability than malate (peak plasma L-citrulline arrives ~60 minutes after oral dose; arginine peak follows ~30 minutes later) - We don't include malic acid in a formulation we haven't specifically designed around it

Why the published clinical level

The published clinical research on L-citrulline supplementation uses doses ranging from a clinical-research range per day across different protocols. The most-cited intervention window for cardiovascular and exercise endurance markers is a clinical-research range over 2-8 weeks.

We chose the published clinical level because:

It is at the lower-but-clinically-relevant end of the published range — established efficacy in human trials, not pushing into the doses that might raise tolerability concerns

The Barakah Pill is a daily-ritual formulation, not a pre-workout SKU. Higher L-citrulline doses (3,000-6,000 mg) are appropriate in pre-workout context but unnecessary in a daily morning serving

The capsule load matters. At L-citrulline at the published clinical level, occupies two of the four daily capsules. Higher doses would push us toward six or eight capsules per serving — too much

The published research, briefly

The most-cited clinical studies on standardised L-citrulline supplementation:

- Bailey et al. 2015 (Journal of Applied Physiology) — 1,500-6,000 mg/day intervention, reported on plasma L-arginine and exercise efficiency - Suzuki et al. 2016 (Journal of the International Society of Sports Nutrition) — 1,200 mg pre-exercise intervention, reported on subjective measures of muscle fatigue - Schwedhelm et al. 2008 (British Journal of Clinical Pharmacology) — pharmacokinetic study establishing L-citrulline → L-arginine conversion timeline - Cormio et al. 2011 (Urology) — the published clinical level/day intervention in adult men, reported on vascular markers

None of these studies result in a GB NHC-authorised health claim. What you read above is a description of what the research investigates, not a claim about what the supplement will do. The Barakah Pill is a food supplement, not a medicine.

The form, the purity, the source

The L-citrulline in The Barakah Pill is standardised to its principal active pharmaceutical-grade pure free-form, sourced through our UK manufacturing partner in our UK manufacturing centre. Each batch is HPLC-verified for purity and identity by our manufacturer's QC lab.

It is plant-derived (synthesised from L-glutamine in a fermentation process; no animal inputs). It is halal-declared by the supplier and covered in our HFA own-brand audit.

A daily-diet alternative (not a substitute)

You can hit substantial L-citrulline intake from diet alone. Watermelon contains approximately 250 mg per 100 g (the rind is even higher). Six dates contain roughly 50-100 mg L-citrulline depending on variety. A daily serving of either would provide a fraction of the supplement dose but is dietary practice we recommend regardless.

The Sunnah of breaking fast with dates is therefore both a religious tradition and a nutritionally-relevant practice — dates are one of the better natural L-citrulline sources, alongside their better-known potassium and magnesium content.

What you should know if you're taking L-citrulline

**Don't combine with sildenafil or other PDE5 inhibitors** without speaking to your GP. Both act on the NO pathway and combining them can produce hypotension.

**Don't take with blood-pressure medication** without consulting your GP. Hypotensive interaction is well-documented.

**Effects, where documented in research, are dose-dependent and time-dependent.** A daily the published clinical level over 4-8 weeks is the published intervention; expecting same-day effects from a one-off dose is not supported by the literature.

**Pure L-citrulline is largely tasteless** in capsule form. The bitter aftertaste sometimes associated with L-citrulline malate is the malate, not the citrulline.

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Sources: Bailey et al. 2015 (J Appl Physiol 119:385); Suzuki et al. 2016 (JISSN 13:6); Schwedhelm et al. 2008 (Br J Clin Pharmacol 65:51); Cormio et al. 2011 (Urology 77:119); GB Nutrition & Health Claims Register.

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