What is supplement substantiation?

Substantiation is the process of gathering and documenting scientific evidence that supports the health claims you make on your supplement labels and marketing materials. The FDA requires that all structure–function claims be truthful, non-misleading, and substantiated by competent and reliable scientific evidence — typically clinical trials on healthy human subjects.

How does Nutra Comp's AI analysis work?

Nutra Comp searches PubMed for clinical trials relevant to your ingredient, filters for studies on healthy human subjects with oral administration, and uses AI to extract key data: p-values, effect sizes, study design, population details, and conclusions. It distinguishes between across-group and within-group significance and ranks evidence strength with a confidence scoring system.

What data sources does Nutra Comp use?

Nutra Comp primarily searches PubMed/MEDLINE, the world's largest biomedical literature database maintained by the U.S. National Library of Medicine. We focus on peer-reviewed clinical trials, randomised controlled trials (RCTs), meta-analyses, and systematic reviews.

Are the generated claims FDA-compliant?

Yes. Nutra Comp generates structure–function claims in strict accordance with the FDA Small Entity Compliance Guide. All claims avoid explicit and implicit disease references. However, we recommend having your legal/regulatory team review the final output before use, as Nutra Comp is a tool to assist — not replace — professional compliance review.

How long does a typical ingredient search take?

Most ingredient searches complete within 5–15 minutes, depending on the volume of clinical literature available. Compare this to the typical manual process which can take 40–100+ hours per ingredient when done by a human compliance expert.

Can I export my reports?

Absolutely. All clinical evidence reports, structure–function claims, and substantiation memos can be exported as professional PDF documents. These are formatted for easy sharing with your legal team, regulatory reviewers, or business partners.

What does 'ingredient searches per month' mean?

Each search is one ingredient analysis — for example, searching 'Ashwagandha' or 'Vitamin D3'. The search generates a complete evidence report, claims, and substantiation memo for that ingredient. Your monthly allowance resets on your billing date.

When will Nutra Comp be available?

We're currently in private beta. Join the waitlist to get early access and be notified when we launch. Early waitlist members will receive priority access and special launch pricing.

L-Citrulline: Clinical Evidence & Substantiation Summary

Clinical Trials

Strongest Evidence

Exercise Performance

Typical Dosage

3–8 g/day (L-citrulline) or 6–8 g/day (citrulline malate)

Common Forms

L-Citrulline

What Is L-Citrulline?

L-Citrulline is a non-essential amino acid that serves as a precursor to L-arginine and nitric oxide. It is more effective than direct L-arginine supplementation at raising plasma arginine levels due to superior oral bioavailability and bypassing first-pass hepatic metabolism.

Mechanism of action: L-Citrulline is converted to L-arginine in the kidneys, which is then converted to nitric oxide (NO) by endothelial nitric oxide synthase (eNOS). NO is a vasodilator that improves blood flow, nutrient delivery, and waste product removal. Citrulline also participates in the urea cycle, aiding ammonia clearance during exercise.

Clinical Evidence Summary

Below are 5 key clinical studies on L-Citrulline. Nutra Comp analyses 29+ studies in its full clinical evidence report.

Systematic review and meta-analysis2020PMID: 32182294

Citrulline supplementation and exercise performance: a systematic review

Population: 12 RCTs

Key finding: Citrulline supplementation significantly improved high-intensity exercise performance (p=0.01) and reduced perceived exertion.

Meta-analysis2017PMID: 29099763

L-Citrulline supplementation and blood pressure

Population: 11 RCTs, 476 participants

Key finding: Citrulline supplementation significantly reduced systolic BP by 4.1 mmHg (p<0.01) and diastolic BP by 2.1 mmHg (p=0.02).

RCT, double-blind2017PMID: 28768407

Citrulline malate and resistance exercise

Population: 41 resistance-trained men

Key finding: 8 g citrulline malate pre-exercise significantly increased repetitions to failure (9.4% increase, p<0.05) across multiple sets.

Systematic review2019PMID: 31305906

L-Citrulline and endothelial function

Population: 8 RCTs

Key finding: Citrulline supplementation improved flow-mediated dilation (FMD), a marker of endothelial function, in adults with cardiovascular risk factors.

RCT2018PMID: 30163680

Citrulline and amino acid metabolism in exercise

Population: 24 cyclists

Key finding: 6 g/day L-citrulline for 7 days significantly increased plasma arginine (+30%) and reduced blood lactate during intense cycling.

Evidence-Based Structure–Function Claims

Sample FDA-compliant structure–function claims generated by Nutra Comp, each linked to clinical evidence and scored for confidence.

“Supports healthy nitric oxide production and blood flow”

Category: Cardiovascular · Confidence: 9/10

“Supports exercise performance and muscular endurance”

Category: Performance · Confidence: 8/10

“Supports healthy blood pressure already within the normal range”

Category: Cardiovascular · Confidence: 7/10

Get the full substantiation report for L-Citrulline

Includes all 29+ clinical studies analysed, complete claims library, and a ready-to-file substantiation memo.

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Related Ingredients

Creatine Monohydrate

186 studies · Muscle Strength & Power

Beta-Alanine

35 studies · Exercise Performance

Key Terms

Randomised Controlled Trial (RCT)Bioavailability Dose-Response Relationship

Frequently Asked Questions

Is L-citrulline FDA approved?

L-Citrulline is sold as a dietary supplement and does not require FDA approval. It is a naturally occurring amino acid found in watermelon and other foods.

What are the most studied benefits of citrulline?

The strongest evidence supports citrulline for nitric oxide production, exercise performance (particularly resistance training volume), and blood pressure support.

What dosage is used in clinical studies?

Pure L-citrulline: 3–6 g/day. Citrulline malate: 6–8 g/day (providing ~3.5–5 g citrulline). For acute exercise benefits, take 30–60 minutes before training.

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