The 1,000 microgram (mcg) dose is standard for a B12 supplement ... Metformin or gastric acid inhibitors including omeprazole, lansoprazole, cimetidine, and ranitidine can reduce the absorption of B12 ...
Your doctor can also help decide the right dosage for you. For some people, taking a folic acid supplement might do more harm than good. Use caution if you belong to one of the following groups, and ...