Citrulline silicate

Amino-acidCitrullineBest in the morningBest taken with food

What is it

Citrulline silicate is a bonded form of the amino acid L-citrulline with silicate (silica), used in some pre-workout supplements. It is marketed as providing both the nitric oxide precursor benefits of citrulline and the potential vascular benefits of silica.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Exercise performance / pump

Limited Evidence

Standard L-citrulline at 6–8 g has modest evidence for improving exercise endurance, reducing perceived exertion, and increasing 'pump' via nitric oxide. The specific citrulline silicate form has not been studied head-to-head against standard L-citrulline at equivalent doses; benefits are inferred from the citrulline literature.

How it works

Once dissociated, L-citrulline is converted in the kidneys to L-arginine, which is the substrate for nitric oxide synthase (NOS). Increased nitric oxide promotes vasodilation, potentially improving blood flow to working muscle and decreasing ammonia accumulation during exercise. The silicate portion is presumed to contribute trace silicon. L-citrulline itself has reasonable evidence for raising plasma arginine more effectively than oral L-arginine, with modest performance effects in some exercise studies. The silicate-bonded form lacks dedicated published human pharmacokinetic or efficacy data compared to standard L-citrulline or citrulline malate.

Dosage

Effective L-citrulline doses in trials are typically 6–8 g/day taken about an hour before exercise. Pre-workout products containing citrulline silicate often deliver 2–4 g citrulline per serving, which is likely sub-therapeutic for performance based on the citrulline literature. There is no specific UL for citrulline or for the silicate-bonded form.

When and how to take it

If used for exercise performance, take 30–60 minutes before training. Splitting daily doses (one with breakfast, one pre-workout) is common in studies.

1 commercial form

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Citrulline silicate

Bonded form found in some pre-workout blends.

Pharmacokinetics versus standard L-citrulline are not well characterized.

Safety

L-citrulline is well tolerated in studies up to 10 g/day, with occasional mild GI upset. Silica/silicate is GRAS at typical supplement levels. Dedicated safety data on this specific bonded form is limited.

Who should be cautious

Avoid combination with nitrate medications. Pregnancy and breastfeeding safety not characterized. People with kidney disease should consult their clinician before high-dose amino acid supplementation.

Interactions

May potentiate the blood pressure-lowering effects of nitrates, PDE5 inhibitors (sildenafil, tadalafil), and antihypertensive medications. Caution in anyone on these drugs.

Food sources

Watermelon (for L-citrulline)

Amount
~1.6 g/kg fresh weight in rind/flesh
%DV
—

Frequently asked questions

Is citrulline silicate better than regular L-citrulline?⌄

There is no published head-to-head evidence showing it is superior. The performance literature is largely based on standard L-citrulline at 6–8 g.

What dose should I take?⌄

Studies use 6–8 g of L-citrulline. Check the actual citrulline content per serving on the label, which may be lower in bonded forms.

References

Citrulline silicate on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Citrulline silicate (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.