People who take certain medications may also be at risk of vitamin B12 deficiency, including, but not limited to, estrogen, H2 receptor antagonists, PPIs (Proton Pump Inhibitors), Chloramphenicol, and Metformin
Tandon et al., 2022) the authors evaluated the quality of the clinical trial included in the qualitative synthesis, based on 5 items assessing the randomization process, blinding, and the dropout rate (i.e., the patients lost to follow-up)
Vitamin B12 is a nutrient that your body doesn't make, so you have to get it from animal products, such as meats, dairy, and eggs, or from supplements
Some practitioners theorize that local abdominal injection may enhance regional fat mobilization, though this has not been conclusively proven in research
References: Office of Dietary Supplements, NIH