Copper is a trace mineral that the body requires in small amounts to carry out numerous biological functions. It acts as a cofactor for several enzymes, supporting processes like energy production, iron metabolism, and the synthesis of connective tissue. However, copper in its simple, inorganic form is often difficult for the digestive system to absorb efficiently. This challenge is due to its high reactivity, which can lead to it binding with other dietary components in the gut, making it unavailable for the body to use. The development of chelated copper aims to solve this problem by chemically protecting the mineral.
The Chemistry of Chelation
Chelation is a chemical process that involves surrounding a metal ion with an organic molecule, known as a chelator. This term originates from the Greek word chēlē, meaning “claw,” which perfectly describes how the organic molecule fully encapsulates the mineral. For copper supplements, the chelator is typically an amino acid, such as glycine or aspartate.
The copper ion is bound to the amino acid through multiple points, creating a stable, ring-like structure. This structure is electrically neutral and chemically stable, a significant contrast to inorganic copper salts like copper sulfate. Inorganic salts are highly reactive and easily form unstable compounds in the harsh environment of the digestive tract.
Why Chelated Copper is Preferred
The primary advantage of the chelated structure is an increase in the mineral’s bioavailability and absorption. The protective organic “claw” shields the copper ion from reacting with antinutritional factors in the gut, such as phytates and phosphates. These compounds would otherwise bind to the copper, forming large, insoluble complexes that the body cannot absorb, leading to their excretion.
This stable, protected molecular structure allows the copper to pass through the stomach and small intestine without being neutralized. The body’s intestinal wall recognizes and readily absorbs the amino acid component of the chelate, effectively carrying the copper across the intestinal barrier. This mechanism ensures a more efficient delivery of the trace mineral into the bloodstream compared to non-chelated forms.
Common Chelated Forms and Their Uses
A variety of chelated copper forms are available in dietary supplements, each utilizing a different organic acid or amino acid as the chelator. Common examples include copper gluconate, which uses gluconic acid, and copper aspartate, which uses the amino acid aspartic acid. These differences relate to the specific compound used to bind and protect the mineral.
Copper bisglycinate is the most highly absorbed chelated form, as it involves the copper ion being bound to two molecules of the amino acid glycine. Supplementation with chelated copper is used to address copper deficiency or to support specific enzyme functions that rely on the mineral. These functions include the enzymes needed for collagen synthesis, antioxidant defense, and proper iron utilization.
Safe Intake and Potential Interactions
The Recommended Dietary Allowance (RDA) for copper in adult men and women is 0.9 milligrams (900 micrograms) per day. While copper deficiency is uncommon, excessive intake can lead to copper overload. The body has homeostatic mechanisms to regulate copper levels, but high doses from supplements can overwhelm this system.
A significant interaction exists between copper and the trace mineral zinc. High doses of zinc can interfere with copper absorption in the small intestine. Excess zinc stimulates the production of a protein called metallothionein, which binds to copper, sequestering it and preventing its entry into the bloodstream. To avoid this imbalance, experts recommend maintaining a copper-to-zinc ratio of approximately 1:8 to 1:15 in supplements. Anyone considering copper supplementation should consult a healthcare professional to determine the appropriate dosage.