Vitamin D Supplement Side Effects and Toxic Levels

A relatively safe supplement to take, there are not many danger vitamin D side effects from taking a normal dose. Vitamin D is necessary for bone health, and there is some preliminary evidence that it might help reduce the risk of cancer and heart disease as well (although the jury is still out on that).

Toxic effects aren’t truly seen until you’ve been taking well over 50,000 IU per day for several months. A typical over-the-counter supplement might contain 400 or 1000 IU, so you’d have to swallow a bottle every day for a long time. Obviously, this is difficult. Toxic effects at that stage would include extreme thirst, frequent urination, unexplained weight loss, irritability, and constipation.

Such large amounts of vitamin D are difficult to acquire, which makes the vitamin one of the safer supplements to take. However, there can still be some health consequences at lower doses.

At daily doses above 4000 IU, calcification of the kidneys, heart, and blood vessels can occur. This can lead to secondary effects, like kidney stones, kidney failure, and hardening of the arteries. There is also some evidence that amounts over 4000 can lead to cancer (ironically, as vitamin D is popular as a potential cancer fighter), including pancreatic cancer. As a result, it probably best to keep your doses of D at a lower dose than 4000.

The recommended daily allowance in the US is 600 per day; some typical supplements are 1000 IU, which would probably be fine also.

In addition to the potential side effects from large doses, don't forget to check out the low vitamin D symptoms, which can include bone health problems, and possibly even cancer and heart disease.