Vitamin D intoxication occurs when blood levels rise above 150 ng/ml (375 nmol/l). However, taking extremely high doses of vitamin D3 for long periods may lead to excessive buildup in your body. Studies have shown that each additional 100 IU of vitamin D3 you consume per day will raise your blood vitamin D levels by 1 ng/ml (2.5 nmol/l), on average ( 2, 3). Vitamin D3 has been found to increase blood levels significantly more than D2.
Vitamin D3 is produced in response to sun exposure and is found in animal products, whereas vitamin D2 occurs in plants. Supplements are very common, and both vitamin D2 and vitamin D3 can be taken in supplement form. In fact, it’s estimated that about 1 billion people worldwide don’t get enough of this vitamin ( 1). What’s more, most people don’t get enough sun exposure to produce adequate vitamin D. Yet, aside from fatty fish, there are few foods rich in vitamin D. It occurs naturally in food and can also be produced by your body when your skin is exposed to sunlight. Vitamin D is involved in calcium absorption, immune function, and protecting bone, muscle, and heart health.
