The recommended dietary amount of vitamin B-12 is 2.4 micrograms daily for ages 14 and up, according to Mayo Clinic. Pregnant women need to consume at least 2.6 micrograms daily, while breast-feeding women should be consuming 2.8 micrograms per day.
The daily dosage of vitamin B-12 for children ranges from 0.5 micrograms to 1.8 micrograms. Elderly individuals should maintain their vitamin B-12 levels with a multivitamin or an enriched diet. Vitamin B-12 deficiencies are common worldwide, and those suffering from it should take a 125 to 2,000 micrograms dosage daily for up to three years to correct the condition, according to Mayo Clinic.