Copper forms for supplement manufacturing

How the forms compare

Copper gluconate is the copper raw material covered on this page. It contains 14.0 % elemental copper on an anhydrous basis, so 714 mg of powder delivers 100 mg of copper. Copper label claims are small, so formulators usually work per milligram: 7.14 mg of copper gluconate carries 1 mg of copper.

Copper gluconate is the copper(II) salt of gluconic acid. As an organic salt, it carries a lower copper fraction per gram than inorganic copper salts such as cupric sulphate. In practice this rarely affects fill volume or tablet mass. A copper claim needs only a few milligrams of powder per serving, so a lower copper fraction makes almost no difference to fill volume or tablet mass.

The real constraint is distribution. A few milligrams spread through a 500 mg to 1,000 mg tablet or capsule fill is hard to blend uniformly from neat powder. Most manufacturers add copper gluconate through a premix or trituration on a carrier such as dicalcium phosphate, or as part of a multi-mineral premix. Validate content uniformity on the finished batch.

The 14.0 % figure is calculated from the anhydrous formula. SoleChem sends the specification sheet and the certificate of analysis with its quote, and these state the assay and water content of the delivered lot. Use those figures, not the theoretical value, in the batch record. The elemental content calculator does the conversion for any label claim.

Choosing a copper form

There is no single best form of copper for every product. The choice follows the format, the other actives in the formula and the name you want in the ingredient list. These are the decision points for copper gluconate:

• Label claim per serving. At 7.14 mg of powder per 1 mg of copper, a 2 mg claim needs 14.3 mg of copper gluconate before any overage. Mass is never the problem; blend uniformity is.
• Format. In tablets and capsules, copper gluconate behaves like any minor mineral ingredient once it is premixed. Its water solubility suits effervescent tablets and drink powders, where it dissolves with the base.
• Compatibility. Dissolved cupric ions catalyse the oxidation of ascorbic acid and other oxidation-sensitive actives. In multivitamin-mineral formulas, keep moisture low, consider coated or encapsulated vitamin forms and confirm stability in the finished pack.
• Taste. Copper salts taste metallic and astringent in solution. The low inclusion level limits this in drinks and effervescent products, but confirm it in sensory trials.
• Colour. The powder is blue. Poor dispersion in a white tablet or powder can show as blue specks, which a good premix avoids.
• Cost per milligram of copper. Gluconate needs more powder per milligram of copper than higher-content inorganic salts. At the inclusion levels involved, the copper source is a small part of total formula cost.
• Regulatory status. The form must appear in the EU list of permitted mineral substances. Copper gluconate does, as described below.

Copper is often declared in multi-mineral products alongside zinc and iron. If you are building such a formula, the zinc forms guide and the iron forms guide cover the companion ingredients, and the Minerals & Mineral Salts category lists the full range. State the grade your specification requires when you use the quote form.

EU regulatory status

Annex I of Directive 2002/46/EC lists copper among the minerals that may be used in food supplements. Annex II of the same directive lists cupric gluconate among the permitted mineral substances. Substances in Annex II must also meet the applicable purity criteria. The directive’s Annex II contains other copper compounds as well. Check the current consolidated text before switching to another form. The guide to permitted forms explains how the lists work.

Cupric gluconate also appears in Annex II of Regulation (EC) No 1925/2006, which governs the addition of minerals to ordinary foods. This matters if the same raw material goes into fortified foods as well as supplements.

The EU has not adopted harmonised maximum amounts of copper in food supplements. Member states apply their own maximum levels or national practice, and these differ. The maximum levels guide explains how to find the figure for each market. Member states may also require notification when a food supplement is placed on their market, by forwarding a model of the label to the competent authority; check the rules in each market.

On the label, Directive 2002/46/EC requires the amount of copper per recommended daily portion in numerical form. It also requires the amount as a percentage of the reference value, which Regulation (EU) No 1169/2011 sets in Annex XIII. The labelling guide covers layout and naming. For authorised claim wording, consult the EU Register of nutrition and health claims and the health-claims guide.