prophylaxis: 10-100 mcg/day in the form of cyanocobalamin;
older people over 60 years old – 50-100 mcg / day with other B vitamins (B2, B6 and folic acid);
old age, memory impairment, dementia, Alzheimer’s disease: 500-1000 mcg/day with other B vitamins (B2, B6 and folic acid);
antacids: 50-500 mcg/day;
cardiovascular disease: 500-1000 mcg/day;
intestinal diseases: 1000 mcg / day for 3-4 months;
depression: 500-1000 mcg/day with other B vitamins (B2, B6 and folic acid);
elevated homocysteine: 100-1000 mcg/day with other B vitamins (B2, B6 and folic acid);
neuropathy: 500-1500 mcg / day, then 500-1000 mcg / day 1-3 times a week.

Synthetic cyanocobalamin, which is the most common form found in medications and supplements, is the inactive form of vitamin B12. Methylcobalamin, the active form of the coenzyme, is believed to be better metabolized and stored in the liver than cyanocobalamin.
Methylcobalamin has also been shown to be more effective in lowering homocysteine ​​and uremia (kidney damage) than cyanocobalamin. The latest form available on the market is hydroxocobalamin, such as a depot with complex action. There are reports that taking the vitamin in this form and at a dose of 100 mcg shows a longer effect than cyanocobalamin.
Vitamin B12 as well as is best taken with meals or between meals, it is best to divide the daily dose into several smaller ones and take it throughout the day.
For older people or people with gastric disorders, it is better to administer intramuscularly, this will provide a better bioavailability of this vitamin. In the case of vitamin B12 toxicity, no side effects associated with cyanocobalamin have been demonstrated, even with long-term use. It is because of its low toxicity that the Food and Nutrition Board has not set an upper tolerable intake level.