How Much Vitamin D Is Excessive?

The sun triggers the production of vitamin D in the skin.

The sun triggers the production of vitamin D in the skin.

Vitamin D plays a vital role in the absorption of calcium, making it an important vitamin for keeping your bones healthy and strong. Most people get the amount of vitamin D they need from sun exposure -- cells in your skin can produce vitamin D -- and fortified foods, but those who develop a deficiency can benefit from taking vitamin D supplements. Take care to follow the advice of your healthcare provider, because taking an excessive amount of vitamin D can cause adverse effects.

Recommended Intake

The Institute of Medicine recommends healthy children and adults ages 9 to 70 consume 15 micrograms of vitamin D per day. Elderly adults over the age of 70 should consume 20 micrograms per day due to reduced sun exposure and an increased need for calcium to keep bones healthy. These are the amounts deemed necessary to support normal calcium metabolism and maintain healthy bones. Although very few foods naturally contain vitamin D, including egg yolks, fish liver oil and fatty fish like salmon and tuna, many foods like milk, orange juice and breakfast cereals are fortified with vitamin D.

Tolerable Upper Level

In addition to determining the amount of vitamin D necessary to support your daily needs, the Institute of Medicine also sets the tolerable upper level intake. This is the highest amount likely to not cause any adverse effects. The Office of Dietary Supplements reports the tolerable upper level intake for ages 9 and up to be 100 micrograms per day. Taking more vitamin D than the listed tolerable upper intake level over a long period of time may lead to vitamin D toxicity.

Toxicity Symptoms

Vitamin D toxicity causes generalized symptoms including weight loss, excessive urination, irregular heartbeat and anorexia. The increase in vitamin D may also increase the amount of calcium in your blood which can damage the blood vessels, heart and kidneys. The increase in calcium can also promote the formation of kidney stones.

Excessive Intake

The amount of vitamin D considered excessive remains a matter of debate. Although the tolerable upper intake level is set at 100 micrograms per day, The Food and Nutrition Board recognizes that symptoms of toxicity are unlikely at intakes of less than 250 micrograms per day, a level significantly higher than the tolerable upper intake. However, the Office of Dietary Supplements reports that clinical trials involving vitamin D suggest that intakes lower than the 250 micrograms may increase the risk of long-term complications such as certain types of cancer, cardiovascular trouble and broken bones in the elderly. The tolerable upper intake level was set at its current value to avoid these possible complications.

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