L-Arginine (Free Form / AAKG)

Performance & heart health

Function & benefits

A semi-essential amino acid that is the direct substrate of the NOS enzyme for making nitric oxide, which relaxes the smooth muscle in artery walls and so helps widen blood vessels and support oxygen-rich blood flow.

Dosage & how to use

Recommended dose	3–6 g daily
Best time to take	30–60 minutes before training on an empty stomach, or split with meals
Frequency	Once daily or in split doses

Best forms to choose

Arginine alpha-ketoglutarate (AAKG) for training; citrulline supplements raise blood arginine more efficiently because they bypass first-pass metabolism in the liver.

Important warnings

The herpes simplex virus needs arginine to multiply; the supplement may trigger cold sores or genital outbreaks in carriers

Large doses may cause intestinal cramps and diarrhoea

Drug interactions

Low blood pressure warning: it interacts strongly with blood pressure medication, heart nitrates and PDE-5 inhibitors (sildenafil, tadalafil) and can cause a dangerous drop in blood pressure.

View in the supplements guide

Related supplements

Scientific references

Dong JY et al. Am Heart J 2011 (meta-analysis, L-arginine and blood pressure) — PMID: 22137067
NIH National Library of Medicine (MedlinePlus): L-arginine

📚 Published sources and research: European Food Safety Authority (EFSA) • National Institutes of Health (NIH - ODS) • PubMed / Cochrane databases

Content last updated: 17 October 2026 · Based on published sources and research (EFSA / NIH / PubMed)

⚖️ Medical disclaimer: The information and data provided here are for health education and nutritional guidance only. They are not a medical diagnosis and never replace a direct consultation with your doctor or pharmacist. Always consult your doctor before starting any supplement, especially during pregnancy or breastfeeding or when taking long-term medication.