Ingesting too much vitamin D in supplements or fortified foods can cause bone pain, muscle aches, and other body symptoms. A loss of bone calcium causes the bone pain, and the resulting increase in blood calcium level and its effect on body tissues cause the other symptoms. With the current emphasis on the multiple roles of vitamin D and the risks of vitamin D deficiency, make sure you are not taking in more of the vitamin than recommended.
Vitamin D, Calcium, and Bone Pain
According to Advances in Experimental Medicine and Biology, vitamin D, along with calcium and phosphorous, is essential to normal bone formation and mineralization. A high vitamin D blood level leads to bone pain by causing increased resorption and remodeling of bone and calcium turnover. This can happen quickly from taking a massive doses of vitamin D, or slowly from prolonged ingestion of somewhat smaller doses. It depends on other individual health factors.
Loss of Bone Calcium and Pain
Bone remodeling is an ongoing dynamic process of breaking down (resorption) and releasing calcium, then rebuilding (mineralization) by reusing calcium. With high vitamin D levels, the process of resorption is greater than that of mineralization, and bone loses calcium to the blood circulation. This leeching of calcium causes bone aches and pains and in the extreme, it can lead to osteopenia and osteoporosis in adults and osteomalacia in children. The level of pain depends on how much your bones are affected. You may be at greater risk if you have kidney or liver problems or take a medicine, such as a diuretic or steroids.
Effect of High Vitamin D on Calcium Levels
Vitamin D and calcium metabolism are closely linked, and one of vitamin D's main role is to help tightly maintain normal calcium blood level by regulating bone calcium stores. In addition to the contribution from the increased bone resorption, high vitamin D intake causes an increase in blood calcium levels by:
- Increased absorption of calcium from the gut to the blood circulation
- Causing the kidneys take back more filtered calcium from the urine
The resulting high calcium blood level (hypercalcemia) from the three activities explains the multiple other symptoms seen in other organ systems when too much vitamin D is consumed.
Vitamin D Levels That Lead to Bone Pain and Hypercalcemia
Based on a 2008 review in the American Journal of Clinical Nutrition, hypercalcemia is seen when vitamin D blood levels rise above 375 to 500 nanomoles per liter (nmol/L). Bone pain can begin to occur even at the lower end of excess vitamin D levels when the exposure is prolonged.
According to the National Center for Biotechnology Information, researchers consider a normal vitamin D blood serum level to be between 30 to 50 nmol/L and 250 nmol/L a safe upper limit of normal. Toxic symptoms of vitamin D excess, or hypervitaminosis D, occur most often when the vitamin D level is 750 nmol/L or higher.
Other Symptoms of Vitamin D Excess
In addition to bone pain, muscles aches, and muscle weakness, you may have some level of the other symptoms caused by the hypercalcemia of vitamin D excess. Early or mild symptoms include fatigue, nausea, vomiting, abdominal pain, thirst, and constipation, which may be passed off as other illnesses
The higher and more prolonged the vitamin D intake and the higher the calcium level, the more severe the symptoms. According to a MedlinePlus and a Mayo Clinic review, symptoms of high vitamin D and hypercalcemia, based on organ systems, include:
- Renal: Frequent urination, thirst, dehydration, kidney stones, kidney failure
- Gastrointestinal: Nausea, vomiting, dry mouth, loss of appetite, abdominal pain, constipation, pancreatitis
- Cardiac: Irregular heart beat, low blood pressure and fainting; later high blood pressure can occur due to calcifications in blood vessels
- Neurologic: Lethargy, weakness, confusion, seizures, dementia, coma
- Psychological: Lack of motivation, irritability, depression, memory loss
The worst symptoms are seen in cases of vitamin D toxicity or overdose. Over time, calcium deposits can occur in tissues throughout the body, including the brain, heart, and blood vessels.
Other Causes of Bone Pain
If you have generalized bone pain, take a look at your vitamin D and calcium intake; however, there are other causes to consider. These include other metabolic abnormalities or disease that increase your calcium level, including:
- Hyperparathyroidism: Increased parathyroid hormone from the gland leads to increased vitamin D absorption and increased bone metabolism and calcium levels
- Hyperthyroidism: Increases metabolism and bone activity
- High phosphorous or magnesium: Which interlink with vitamin D and calcium metabolism
- Kidney disease: Which interferes with vitamin D, calcium, and bone metabolism
- Sarcoidosis and tuberculosis: Are associated with high serum calcium
- Cancers: Such as lymphoma and leukemia, bone and other malignancies cause bone pain and may interfere with vitamin D and calcium metabolism
Sources of High Vitamin D Ingestion
It is difficult, and likely impossible, to get too much vitamin D from regular food sources or from sun exposure, according to the National Institutes of Health (NIH) factsheet. Based on case reports, such as one in 1992 in the New England Journal of Medicine and another in 2001 in the same journal, high vitamin D ingestion or intoxication usually occurs from:
- Taking high doses of vitamin D supplements, especially combined with calcium
- Taking supplements mistakenly laced with too much vitamin D
- Drinking too much vitamin D-enriched milk
- Drinking milk, juices, or other foods over-fortified with vitamin D in error
- Excessive cod liver oil
- Pharmacist prescription-filling error
Because vitamin D is fat soluble, it is stored in fat and released when needed. Excess amounts from these sources can build up over time and, although uncommon, can lead to toxic symptoms.
Reduce Your Risk of Taking Too Much Vitamin D
To reduce your chance of getting too much vitamin D, don't be tempted take more than the recommended daily allowance (RDA) for the vitamin. According to the National Institutes of Health (NIH) factsheet referenced above, the RDAs for men and women are:
- Age 1-70: 600 IU (international units) or 15 micrograms
- Age 71 and over: 800 IU or 20 micrograms
For comparison, these are the vitamin D levels in selected foods using data from the United States Department of Agriculture National Nutrient Database:
- Cod liver oil: One tablespoon equals 1,360 IU
- Salmon: Three ounces equals 447 IU
- Fortified orange juice: One cup equals 137 IU
- Fortified milk: One cup equals 115-124 IU
- Egg yolk: One large egg equals 41 IU
- Fortified cereal: One cup equals 40 IU
Add up all your sources of vitamin D to keep on top of your daily intake. There is no need to take a supplement if you are getting enough from your diet unless your doctor advises it for health benefits.
Avoid High Dose Supplementation
Experts suggest toxic symptoms are more likely with a daily intake of vitamin D between 10,000 to 40,000 IU; however, prolonged intake below 10,000 IU may cause symptoms, according to the NIH factsheet. The experts advise that 4,000 IU of vitamin D a day is the "upper tolerable limit" but to avoid toxicity, don't take more than 1,000 IU daily. To avoid the risk of high doses of vitamin D:
- Try to increase natural food sources of vitamin D in your diet, such as salmon, sardines, and egg yolk.
- If you take supplements or drink or eat fortified foods, make sure you are buying them from reputable, familiar sources.
- Scrutinize your vitamin product labels so you understand how the dose stacks up against expert recommendations.
Check With Your Doctor
If you are taking high doses of vitamin D from supplements or other sources and develop bone pain, especially if associated with symptoms of high calcium, speak with your doctor. A simple blood test to measure your blood serum vitamin D and calcium levels will provide valuable information.