How Does Body Handle Too Much Calcium And Vitamin D?

Vitamin D is produced in the body when sunshine hits the skin. Calcium, which is the most abundant mineral in the body, cannot be created by the body, but is available from foods and supplements. Calcium can only be absorbed when vitamin D is present. Both nutrients serve similar purposes, such as maintaining bone health, as well as individual purposes. While getting too much vitamin D through supplementation can lead to vitamin D toxicity, it can also dangerously raise calcium levels in the blood.

Vitamin D Toxicity

The recommended daily intake of vitamin D, according to the Institute of Medicine, or IOM, is 600 international units, or IU, for adults and kids, and 800 IU for senior citizens over age 70. The body can make about 20,000 IU of vitamin D when a person goes outside in the sun for about 20 minutes while wearing a bathing suit. It takes about 40,000 IU of vitamin D through supplementation to cause toxicity. According to the Vitamin D Council, the body has a built-in mechanism for preventing toxicity from vitamin D produced in the skin from sunshine.

Symptoms of Toxicity

Hypervitaminosis D, also known as vitamin D toxicity, causes abnormally high blood levels of calcium. It can result in bone loss, kidney stones and organ calcification. Medications used to treat thyroid glands, certain types of cancer, sarcoidosis and tuberculosis have been known to increase blood levels of calcium in response to dietary and supplemental vitamin D, according to the Linus Pauling Institute.

Calcium Toxicity

Calcium toxicity, or hypercalcemia, is a rare condition that can occur when too much vitamin D and calcium are consumed at the same time, or if a person is receiving calcium through an IV or supplementation. This condition can also be triggered if parathyroid glands -- which regulate calcium -- become overactive.

Avoiding Toxicity

The best way to avoid dangerously high levels of vitamin D and calcium is by following the IOM's daily intake recommendations and not exceeding the threshold for supplements. The Office of Dietary Supplements recommends taking no more than 10,000 IU of vitamin D daily. The recommended upper limit for calcium, according to the National Kidney Foundation, is 2,000 mg per day from all combined sources. If you have a health condition that interferes with nutrient absorption, your doctor can prescribe vitamin D and calcium in amounts that suit your specific medical needs. Before starting a new supplemental protocol, you should first discuss it with your doctor.