The limitations of this work are that we included RCTs, non-RCTs, and observational studies, which may lower the overall quality of evidence of the included studies
This is usually mild and goes away within a day or so
There are concerns about adherence to oral treatment, for example, if the person: Is older, is or has recently been in hospital and has either multimorbidity or frailty
Fat reduction in the body might show up in 2 to 4 weeks when people stick to healthy eating and exercise
Clinical assessment and full blood count showing macrocytic anaemia are also important, though neurological symptoms can occur without haematological changes
That matters if you have trouble absorbing B12 from food or pills, which is more common than most people realize