Chromium

Chromium is an essential trace mineral that exists primarily as the trivalent ion (Cr³⁺) in the human body. It is most widely recognized for its role in enhancing insulin action, thereby helping to regulate carbohydrate and lipid metabolism. In dietary supplements, chromium is typically supplied as chromium picolinate, chromium polynicotinate, or chromium chloride.

• Supplement Forms: Chromium in supplements is most often present as chromium(III) picolinate (C₁₁H₈CrN₃O₆) or chromium(III) polynicotinate (C₁ ₈H₁₈CrN₅O₁₁).
• Molecular Structure: The central atom is trivalent chromium (Cr³⁺) coordinated by two or three picolinate ligands that chelate the metal via nitrogen and oxygen donor atoms, forming a stable octahedral complex.
• Oxidation State and Coordination: The metallic ion has a +3 oxidation state, a high positive charge density, and a preference for octahedral coordination geometry.
• Picolinate Ligand: The picolinate ligand (pyridine‑2‑carboxylate) provides aromatic stability and enhances oral bio‑availability compared with inorganic salts.
• Atomic Properties: Chromium’s atomic number is 24, and its elemental molar mass is 51.996 g·mol⁻¹.
• Pure Form: In its pure metallic form, chromium is a hard, corrosion‑resistant transition metal with a melting point of 1 907 °C.

• Production Source: Commercial chromium supplements are primarily produced from chromium(III) oxide (Cr₂O₃) mined from chromite ore (FeCr₂O₄) in South Africa, Kazakhstan, and India.
• Processing: The oxide is reduced to Cr³⁺ solutions, then reacted with picolinic acid (or nicotinic acid) under controlled pH to form the chelated complex.
• Alternative Synthesis: A smaller proportion is synthesized from high‑purity laboratory‑grade chromium salts via aqueous or organic synthesis, ensuring low heavy‑metal contamination.
• Natural Sources: Natural dietary sources (e.g., broccoli, whole grains, nuts) contain only trace amounts (0.1‑5 µg per serving), so supplements rely on the consistent, high‑purity synthetic route.
• Quality Control: Good Manufacturing Practice (GMP) and third‑party testing (e.g., USP, NSF) are essential to confirm elemental chromium content, absence of heavy metals, and proper chelation, which directly influences bio‑availability and safety.