Although these medications are both vitamin D supplements, they are available in different strengths and have different indications, as well as different potencies and absorption. The most common strength is the source of confusion though: both vitamin D2 and vitamin D3 come in a 50,000 unit capsule.
So why the confusion?
The trouble with vitamin D2 vs D3 comes up when your doctor does not specify on your prescription which type of vitamin D he or she wants you to have.
Many doctors will write vitamin D 50,000 units and leave it at that. The pharmacist will then have to call your doctor to find out their preference—D2 (ergocalciferol) or D3 (cholecalciferol).
At one time these two forms of vitamin D were thought to be equivalent, however, that is not the case! Vitamin D2 or ergocalciferol is actually less potent and has a shorter duration of action than its counterpart Vitamin D3 or cholecalciferol.
However, although Vitamin D3 50,000 units does not require a prescription, it is still usually purchased from behind the pharmacy counter and may need to be ordered in.
What are vitamin D2 and vitamin D3 prescribed for?
Vitamin D2 is indicated for rickets, hypoparathyroidism, and familial hypophosphatemia. In contrast, vitamin D3 is indicated for dietary supplementation (use as a vitamin).
What else can you do to get more vitamin D?
Vitamin D can be obtained from various sources including food, drink, and even sunlight. Some foods (such as tuna, salmon, sardines, egg yolks, mushrooms, and fortified cereal) and drinks (like milk, soy drinks, and orange juice) have up to 100 units of Vitamin D per serving.
What is the recommended daily intake amount of vitamin D in general?
The Institute of Medicine (IOM) recommends 600 units of Vitamin D per day for people 1 to 70 years of age, and 800 units of Vitamin D per day for those 71 years of age and older.