Vitamin D Overdose: Causes, Signs, Diagnosis, and Remedies
Hypervitaminosis D is an uncommon but potentially serious condition that occurs when you consume too much vitamin D. The primary culprit is often high-dose vitamin D supplements.
When your body absorbs an excessive amount of vitamin D, it can cause elevated levels of calcium in the bloodstream. This can wreak havoc on bones, tissues, and other organs, leading to various health issues.
The Trouble with Too Much Vitamin D
It's unlikely that you'll get too much vitamin D from food or sun exposure. However, cases of hypervitaminosis D have been reported due to excessive supplementation, and there's been an increase in such cases in recent years [1][2].
Taking more than the recommended daily value of vitamin D is a common cause. If you're taking a multivitamin, check the amount of vitamin D it contains. You might not need additional calcium and vitamin D if your multivitamin provides enough vitamin D.
Some medications used for treating high blood pressure (thiazide diuretics) and heart diseases (digoxin) can cause an increase in blood vitamin D levels. Furthermore, estrogen therapy, long-term use of antacids, and isoniazide (an antituberculosis medication) can also lead to elevated vitamin D levels [1].
The Mayo Clinic recommends a daily intake of 600 international units (IU) of vitamin D for most adults [1]. Higher doses may be prescribed for short periods to treat medical conditions such as vitamin D deficiency, diabetes, or cardiovascular disease [1]. However, prolonged use of high-dose vitamin D supplements can lead to toxicity.
You're more likely to develop hypervitaminosis D if you have pre-existing health problems, such as kidney disease, liver disease, tuberculosis, hyperparathyroidism, sarcoidosis, or histoplasmosis [1].
Signs and Symptoms
Excessive vitamin D can cause calcium levels in the blood to rise, leading to a condition called hypercalcemia. This may manifest in symptoms such as:
- Fatigue
- Loss of appetite
- Weight loss
- Excessive thirst
- Frequent urination
- Dehydration
- Constipation
- Irritability and nervousness
- Tinnitus (ringing in the ears)
- Muscle weakness
- Nausea, vomiting
- Dizziness
- Confusion and disorientation
- High blood pressure
- Heart arrhythmias
Untreated hypervitaminosis D can lead to long-term complications, such as kidney stones, kidney damage, kidney failure, bone loss, arterial and soft tissue calcification, and increased risk of abnormal heart rhythms [1][3].
Diagnosis and Treatment
Your doctor will review your medical history, medications, and supplements and perform a physical examination to determine if you may have hypervitaminosis D. If suspected, they may order blood tests for vitamin D, calcium, and phosphorus levels and urine tests for excessive calcium. Additionally, bone X-rays may be taken to check for bone loss [1].
Treatment typically involves stopping vitamin D supplements and temporarily reducing calcium intake, with corticosteroids or bisphosphonates occasionally used to suppress the release of calcium from bones [1][3]. Your doctor will closely monitor your vitamin D levels until they return to normal.
Preventing hypervitaminosis D consists of discontinuing or lowering your intake of high-dose vitamin D supplements and ensuring you remain within the tolerable upper limit of 4,000 IUs per day [1]. Your doctor may also recommend reducing your calcium intake if necessary. To naturally obtain vitamin D, incorporate foods such as cod liver oil, fatty fish, beef liver, cheese, egg yolks, mushrooms, fortified foods, or moderate sunlight exposure [4].
Sources:[1] Mayo Clinic. (2022, June 7). Hypervitaminosis D: MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/article/000392.htm[2] Fawzi WW, Mitchell SL. (2013). Vitamin D. In: Gropper SS, Smith JL. Advanced nutrition and human metabolism. West Sussex, UK: Wiley-Blackwell.[3] Hollis BW. (2017). Vitamin D. In: Yarnell E. A Textbook of Integrative Medicine: From Basic Principles to Clinical Practice. World Scientific Publishing.[4] National Institutes of Health Office of Dietary Supplements. (2022, September 6). Vitamin D. https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
- An excessive intake of vitamin D, primarily from high-dose supplements, can lead to hypervitaminosis D, a potentially dangerous condition.
- The Mayo Clinic advises a daily intake of 600 IU of vitamin D for most adults, while higher doses may be prescribed for specific medical conditions.
- Kidney disease, liver disease, tuberculosis, hyperparathyroidism, sarcoidosis, or histoplasmosis can increase the risk of developing hypervitaminosis D.
- Excessive vitamin D can cause hypercalcemia, a condition marked by high levels of calcium in the bloodstream.
- Symptoms of hypercalcemia may include fatigue, loss of appetite, weight loss, excessive thirst, frequent urination, dehydration, constipation, irritability, tinnitus, muscle weakness, nausea, vomiting, dizziness, confusion, high blood pressure, heart arrhythmias, and kidney stones or damage.
- Prolonged use of high-dose vitamin D supplements can lead to tissue and organ damage, including bone loss, arterial and soft tissue calcification, and increased risk of abnormal heart rhythms.
- Treatment for hypervitaminosis D typically involves stopping vitamin D supplements, reducing calcium intake, and using corticosteroids or bisphosphonates in some cases.
- To avoid hypervitaminosis D, one should discontinue or lower the intake of high-dose vitamin D supplements and aim to stay within the tolerable upper limit of 4,000 IUs per day.
- Natural sources of vitamin D include cod liver oil, fatty fish, beef liver, cheese, egg yolks, mushrooms, fortified foods, and moderate sunlight exposure.
- Preventative measures may also include reducing calcium intake if necessary, as outlined by a healthcare professional.
- Science continues to explore the role of vitamin D in overall health, including its connection to mental health, diabetes types, dementia like Alzheimer's, obesity, and various therapies and treatments.
- It's essential to talk to a healthcare provider about any concerns regarding vitamin D intake and its potential interactions with medications, underlying health conditions, and the overall health-and-wellness approach, including mental-health considerations.
