How much you need: 2.4 mcg is RDA for women over 50. Best sources: Vitamin B12 is found naturally in foods of animal origins, ...

GI symptoms, including nausea and diarrhea. Having low levels of B12 can cause fewer red blood cells to reach your digestive ...

This may help reduce the burning associated with dry eye. There isn’t a recommended vitamin B12 dosage for dry eye symptoms. How much you should take depends on your ability to absorb the vitamin.