Carnitine forms for supplement manufacturing

How the forms compare

Carnitine reaches supplement formulations in three forms: L-carnitine itself, L-carnitine L-tartrate and acetyl-L-carnitine hydrochloride. Calculated from their molar masses, the two salts carry 68.2 % and 67.3 % of their mass as L-carnitine equivalent. The choice between L-carnitine vs acetyl-L-carnitine, or the tartrate, therefore turns on handling, format and labelling more than on content.

The percentages use the supplied molar masses. For acetyl-L-carnitine HCl: 161.20 ÷ 239.69 = 67.3 %. For the tartrate, the molar mass of 472.5 describes a salt with two carnitine units per tartrate: (2 × 161.20) ÷ 472.5 = 68.2 %. The elemental content calculator applies the same arithmetic to other salts.

The practical difference is moisture. L-carnitine is strongly hygroscopic, so the powder picks up water, cakes and becomes hard to dose in humid rooms. L-carnitine L-tartrate is used largely because it is the easier solid to handle in tablets and capsules.

Acetyl-L-carnitine HCl is also hygroscopic and gives an acidic solution because it is a hydrochloride. It is an ester, so it can hydrolyse in water-containing formats. Stability in any liquid or high-moisture product should be confirmed by the finished-product manufacturer’s own testing.

L-carnitine vs acetyl-L-carnitine as raw materials

Acetyl-L-carnitine is the acetyl ester of L-carnitine, supplied here as its hydrochloride salt. For a formulator it is a distinct substance, not a different grade of the same one. It has its own CAS number and its own specification, and national lists of permitted substances may treat it as a separate entry.

This matters at the label. A product made with acetyl-L-carnitine HCl declares acetyl-L-carnitine, not L-carnitine, and the two cannot be swapped without changing the label and the regulatory file. The L-carnitine vs acetyl-L-carnitine comparison sets out the label-claim arithmetic and processing differences side by side.

Choosing a form

• Label claim per capsule. To declare 500 mg of L-carnitine per serving you need 500 mg of L-carnitine or about 733 mg of L-carnitine L-tartrate. Expressed as L-carnitine equivalent, the same figure needs about 743 mg of acetyl-L-carnitine HCl. Add overage separately with the overage calculator.
• Format. L-carnitine dissolves readily and suits liquids, drink powders and effervescent tablets, where moisture uptake during storage is controlled by the pack. L-carnitine L-tartrate is the usual choice for tablets and capsules.
• Moisture control. All three forms need sealed storage and low-humidity processing. A flow aid such as silicon dioxide is common in hygroscopic powder blends. With L-carnitine base, check the blend after each step for caking.
• Taste. The tartrate and the hydrochloride both bring acidity to a powder or liquid. Factor this into flavour systems for powders and sports nutrition.
• Cost per milligram of carnitine. Each salt carries roughly a third non-carnitine mass. Compare offers on the cost per milligram of L-carnitine equivalent, not the price per kilogram of powder.
• Regulatory status. National rules may list one form and not another, or set different conditions. Check each target market before fixing the form.

State the form and the basis of your label claim in the quote form; SoleChem sends the specification sheet and certificate of analysis with its quote.

EU regulatory status

Carnitine is not a vitamin or a mineral. None of the three forms appears in Annex II of Directive 2002/46/EC, which lists only vitamin and mineral substances. The directive’s definition of food supplements also covers other substances with a nutritional or physiological effect, and carnitine falls into that group.

There are no harmonised EU rules on the use of carnitine in food supplements. Member states regulate it nationally. Some keep lists of permitted substances and forms, some set maximum amounts per daily portion, and some require notification before sale. The maximum levels guide explains how these national systems work.

Regulation (EC) No 1925/2006 lets the Commission restrict or prohibit other substances through its Article 8 procedure. Whether any carnitine form has been placed under that procedure must be checked in Annex III before publication of a product.

Novel-food status must be confirmed form by form. Check each form against the Union list in Implementing Regulation (EU) 2017/2470 and the rules of Regulation (EU) 2015/2283. The novel food guide describes how to do this.

Directive 2002/46/EC requires the amount of substances with a nutritional or physiological effect to be declared in numerical form on the label. How the substance is named, and whether an L-carnitine equivalent may also be shown, depends on national guidance. The labelling guide covers the wider requirements of Regulation (EU) No 1169/2011.

Any claim on the label must follow Regulation (EC) No 1924/2006. Check the EU Register of nutrition and health claims and the health-claims guide before writing any claim wording.