Boron (B) is a trace element with distinctive coordination chemistry that enables the formation of reversible esters with cis-diol-containing ligands, particularly carbohydrates and polyols. Among naturally occurring B–carbohydrate complexes, calcium fructoborate (CaFB) is the most extensively studied and clinically evaluated and is widely used as a nutraceutical ingredient. Initially identified in fruits and vegetables and subsequently developed as a stable Ca salt, CaFB provides a practical model for understanding how B’s biological effects may depend on chemical form in addition to elemental intake. Chemically, CaFB comprises mono- and di-ester fructoborates stabilized by Ca, supporting aqueous handling and storage stability. After ingestion, CaFB contributes primarily to systemic B exposure (predominantly as boric acid following gastrointestinal hydrolysis), while any distal-gut availability of intact B–carbohydrate species remains a plausible but currently unconfirmed possibility in humans and requires direct, speciation-aware assessment. Biologically, preclinical and clinical data indicate that CaFB may influence inflammatory tone, oxidative stress pathways, and aspects of bone and cardiovascular physiology, with a favorable safety profile within studied dose ranges at commonly used doses. In contrast, other naturally occurring B–carbohydrate species (e.g., polyol–borates) underscore the breadth of B chemistry in foods but remain less characterized and less clinically validated. Overall, CaFB stands out as supported by preliminary clinical evidence for nutritional B delivery, with documented tolerability and evidence of biological activity across multiple systems.