Compare citrulline, arginine, AAKG and beetroot nitrate products on the amount of each ingredient per serving and the cost per serving. Research on these ingredients shows small or mixed effects, so we describe what's in them rather than what they promise.
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What are nitric oxide supplements?
"Nitric oxide supplements" is the name people search for products containing citrulline, arginine (including AAKG, arginine alpha-ketoglutarate) or dietary nitrate from beetroot. Nitric oxide is a molecule the body makes itself; these products contain ingredients involved in that process, but we don't claim any of them raises nitric oxide or improves your training.
None of these ingredients has an authorised health claim in Great Britain, and the government says only authorised claims in the GB register may be used. So we describe the ingredients and the research.
What does the research on citrulline, arginine and nitrate show?
The effects reported are small or mixed. A 2019 meta-analysis found a small benefit for citrulline over placebo on strength and power, and a 2020 meta-analysis of arginine reported possible positive effects on test results but found signs of publication bias in the endurance data (meaning studies with positive results may be more likely to be published), so its authors advised caution.
For dietary nitrate, a 2016 meta-analysis found a small positive effect on how long people could keep exercising, but less effect on time trials. An earlier review found effects were more often seen in inactive to recreationally active people than in trained athletes.
How do you compare these products?
Check which ingredient you're buying, how much is in each serving, and whether the product also contains caffeine. Citrulline malate contains less citrulline per gram than L-citrulline, so compare the citrulline content.
If a product contains caffeine, EFSA (the European Food Safety Authority) says healthy adults can have single doses up to 200mg and up to 400mg a day from all sources. If you take blood-pressure medication or any other medicine, or are pregnant or breastfeeding, speak to your GP or pharmacist first. More detail on our citrulline page.
We sell the products on this page. That's our commercial interest, and it's why we show the evidence alongside them. This page is general information for adults, not personalised medical advice. Food supplements should not replace a varied, balanced diet.
Written by Andy Arshad, SupplementHQ. Last reviewed 11 October 2026.