Vitamin B₁₂, also known as the anti-pernicious anemia factor, is an essential micronutrient totally dependent on dietary sources that is commonly integrated with food supplements. Four vitamin B₁₂ forms—cyanocobalamin, hydroxocobalamin, 5′-deoxyadenosylcobalamin, and methylcobalamin—are currently used for supplementation and, here, we provide an overview of their biochemical role, bioavailability, and efficacy in different dosage forms. Since the effective quantity of vitamin B₁₂ depends on the stability of the different forms, we further provide a review of their main reactivity and stability under exposure to various environmental factors (e.g., temperature, pH, light) and the presence of some typical interacting compounds (oxidants, reductants, and other water-soluble vitamins). Further, we explore how the manufacturing process and storage affect B₁₂ stability in foods, food supplements, and medicines and provide a summary of the data published to date on the content-related quality of vitamin B₁₂ products on the market. We also provide an overview of the approaches toward their stabilization, including minimization of the destabilizing factors, addition of proper stabilizers, or application of some (innovative) technological processes that could be implemented and contribute to the production of high-quality vitamin B₁₂ products.

A simple and fast high-performance liquid chromatography method with UV detection for determination of vitamin D₃ in stability studies as well as in solutions, nutritional supplements and pharmaceuticals was developed. Successful separation of vitamin D₃ from its degradation products was achieved on a Gemini C18 100 × 3.0 mm column using a mixture of acetonitrile and water (99:1, v/v) as а mobile phase. The method was successfully validated according to the ICH guidelines. The described reversed-phase HPLC method is favorable compared with other published HPLC–UV methods because of its stability-indicating nature, short run time (3.3 min) and wide analytical range with outstanding linearity, accuracy and precision. The method was further applied for quantification of vitamin D₃ in selected liquid and solid nutritional supplements and prescription medicines, confirming its suitability for routine analysis. Degradation products, formed under stress conditions (hydrolysis, oxidation, photolysis and thermal degradation), were additionally elucidated by suitable equipment (LC–DAD–MS) to confirm the stability-indicating nature of the developed method.

Vitamin D3 has numerous beneficial effects, such as musculoskeletal, immunomodulatory, and neuroprotective. However, its instability is the main obstacle to formulating quality products. Despite increased attention and growing use, data on vitamin D3 stability is scarce because data from individual studies is inconclusive and mostly qualitative. Therefore, we have systematically investigated the influence of various factors (temperature, light, oxygen, pH, concentration, and metal ions) on its stability in aqueous media using a stability-indicating HPLC-UV method. First-order kinetics fitted its degradation under all tested conditions except light and oxygen. In both cases, the established models in chemical kinetics were inappropriate and upgraded with the Weibull model. Metal ions and acidic conditions had the main destabilizing effect on vitamin D3 in aqueous media, but these solutions were successfully stabilized after the addition of ethylenediaminetetraacetic acid (EDTA), ascorbic acid, and citric acid, individually and in combination. EDTA showed the most significant stabilizing effect. Synergism among antioxidants was not observed. Our findings on vitamin D3 instability in aqueous media also correlated with its instability in commercial products. Vitamin D3 aqueous products require proper stabilization, thereby signifying the importance and contribution of the obtained results to the formulation of stable and quality products.