When you take a massive dose of Vitamin B12 (such as a 1000 mcg pill), that 1% absorption rate allows about 10 mcg to enter your bloodstream [6] [8]
Results vary depending on your starting point, metabolism, treatment plan, and adherence
A 2025 systematic review analyzing this data reported that 7 of 12 patients maintained symptom improvement beyond 6 months
Options may include oral supplements, dietary guidance, or B12 injections, all designed to restore healthy levels safely and effectively
Several technical reasons may explain our distinctive findings, including differences in the microbiome sampling site, the limited n per group, singly housing mice, or the use of highly similar lean, Western, and high-fat diets which systematically exchanged fat content with carbohydrate content
The British National Formulary (BNF), the British Society of Haematology Guidelines, NHS Clinical Knowledge guides, Integrated Care Board guidance notes such as this one from NHS Cambridgeshire and Peterborough, Vitamin B12 full guidance