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Vitamin D Overdose Effects

author image Sandi Busch
Sandi Busch received a Bachelor of Arts in psychology, then pursued training in nursing and nutrition. She taught families to plan and prepare special diets, worked as a therapeutic support specialist, and now writes about her favorite topics – nutrition, food, families and parenting – for hospitals and trade magazines.
Vitamin D Overdose Effects
High doses of vitamin D supplements can become toxic. Photo Credit diego_cervo/iStock/Getty Images

If you take vitamin D supplements, watch the dose to be sure you don’t consume too much. Your body eliminates water-soluble vitamins when you get more than you need, but fat-soluble vitamins accumulate in your system. Since it’s fat-soluble, vitamin D may build to toxic levels. When that happens, it causes bone loss, kidney stones and calcification of your heart or other soft tissues.

Causes of Toxicity

Vitamin D Overdose Effects
Be sure you're not over consuming vitamin D supplements. Photo Credit bert_phantana/iStock/Getty Images

Your skin produces vitamin D from exposure to sunlight, but toxicity from this source has never occurred, according to the Linus Pauling Institute. Foods that are fortified with vitamin D, such as milk, are the primary source for most people because very few foods contain vitamin D naturally. However, you're not likely to consume enough from food to reach toxic levels, notes the Office of Dietary Supplements. The primary cause of vitamin D toxicity, which is called hypervitaminosis D, is taking large doses of supplements on a regular basis.

Effects of High Levels

Vitamin D Overdose Effects
High levels of vitamin D cause an increase in calcium. Photo Credit AndreyPopov/iStock/Getty Images

Vitamin D regulates the amount of calcium absorbed during digestion, as well as how much calcium circulates in your bloodstream. High levels of vitamin D cause an increase in calcium. Symptoms of high calcium, or hypercalcemia, can appear in less than four weeks if you take high doses of vitamin D daily. Early symptoms include fatigue, irritability, vomiting, dehydration and constipation. You may also experience a loss of appetite or muscle weakness. As hypercalcemia gets worse, your heart may beat irregularly. If the condition remains untreated, high levels of calcium can cause kidney stones and calcification of soft tissues, including your blood vessels and heart.

Recommended Intakes

Vitamin D Overdose Effects
Never consume more than 100 micrograms of vitamin D daily. Photo Credit Spectral-Design/iStock/Getty Images

The Food and Nutrition Board of the Institute of Medicine determined the recommended dietary allowance, or RDA, for vitamin D based on the amount you need to maintain strong, healthy bones. Men and women need 600 international units, or 15 micrograms, of vitamin D daily. The precise amount of vitamin D it takes to reach toxic levels is not known, according to “Dietary Reference Intakes for Calcium and Vitamin D.” To ensure your safety, you should never consume more than 4,000 international units, or 100 micrograms, of vitamin D daily.

Interactions and Warnings

Vitamin D Overdose Effects
The metabolism of many medications is affected by vitamin D. Photo Credit Fuse/Fuse/Getty Images

Your risk of developing high levels of calcium from hypervitaminosis D increases if you have kidney disease, hyperparathyroidism, sarcoidosis, tuberculosis or lymphoma, according to the Linus Pauling Institute. Vitamin D supplements may make hardening of the arteries worse. The metabolism of many medications is affected by vitamin D, from over-the-counter antacids to prescription medications such as digitalis, Lipitor and water pills. If you have any of these conditions or you take medications, talk to your doctor before adding vitamin D supplements to your daily regimen.

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