L-Arginine

L-arginine is an amino acid, one of the building blocks your body uses to make protein. You produce some yourself and you take in the rest through food. Fish, chicken, dairy, soya, lentils, peanuts and pumpkin seeds are all rich in it, and a normal mixed diet supplies a few grams a day. That is why arginine is called semi-essential: usually your own production and your plate cover it. People who look for the supplement version are often training hard or eating mostly plant-based. You will find it here alongside our wider amino acid range.

Free-base, HCl and AAKG mean different amounts of arginine

The labels look alike, but the forms are not. Free-base L-arginine is pure arginine: one gram of powder is one gram of arginine. It has an alkaline taste and dissolves slowly. L-arginine HCl is arginine bound to hydrochloride. It mixes easily and costs less, but about one fifth of the weight is the hydrochloride part, so a 1000 mg capsule gives you roughly 800 mg of arginine. AAKG pairs arginine with alpha-ketoglutarate and turns up mostly in pre-workout blends. None of these is automatically better. What counts is the arginine per serving and whether the taste and mixing fit your day.

Powder makes sense above a few grams, capsules below it

Studies on arginine work with grams a day, not milligrams. That is the practical snag with capsules: at 500 to 1000 mg each, you need a handful to reach three grams. Powder costs less per gram and lets you weigh exactly what you want, although it needs a drink with a strong flavour. Capsules win on convenience and when you travel. One honest limit: oral arginine is not fully absorbed, because enzymes in your gut and liver break part of it down before it reaches the blood. Spreading the day's amount over two or three servings, taken with food, is easier on the stomach. If your stomach still objects, L-Citrulline is the usual alternative, because the body converts it into arginine.

How we choose the L-arginine we stock

We judge three things: the form, the amount per serving and the combination. We keep free-base powder for anyone who wants three grams or more without swallowing six capsules, and HCl capsules for people who prefer a fixed daily habit. We look at the arginine content per serving, not only the salt weight, so products can be compared fairly. A blend earns its place only when the extra ingredient has a reason to be there, such as citrulline or B vitamins. Every product passes our compliance team, we test batches ourselves and independent labs spot-check them. Read how we select our brands.

What we can and cannot say about arginine

Arginine is an ingredient where honesty costs us a sales line. The European food safety authority (EFSA) assessed arginine claims about the immune system, muscle mass, blood pressure, erectile function and physical performance, and none were authorised for use. So you will not read a benefit promise from us on this page. What you do get is the form, the dose per serving and our reasoning, so you can weigh a product up yourself. Most labels are written for adults. If you take blood pressure medication or you are prone to cold sores, speak to your GP or pharmacist first.