Safety considerations Pregnancy and breastfeeding: Not recommended
in total, 9 genera (including the unclassified group) and 38 metabolites met these criteria (metabolites published in Sampson et al., 2021 13 )
The standard schedule is a starting point, not a strict rule The 2024 NICE guideline NG239 on B12 deficiency in over 16s makes an important point: the optimal route, dose and frequency of B12 replacement have never been firmly established, and have often followed custom and historical practice
The NHS confirms that taking up to 2mg (2000 micrograms) daily is unlikely to cause harm, with no established upper limit in the UK
For many busy adults, this is the real win: staying consistent long enough to see results without feeling drained
Food and Drug Administration (FDA) for fat loss, muscle growth, or performance enhancement unless specifically stated