Although many people worry about vitamin D deficiency, some suffer from too much vitamin D. Common symptoms of vitamin D toxicity include loss of appetite, vomiting, nausea, extreme thirst, excessive urination and itchy skin, according to the University of Maryland Medical Center. If you suspect you have excess vitamin D in your body, discuss your symptoms with your doctor and request a blood test. If your doctor discovers dangerously high levels, discuss strategies for adjusting your intake.
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Analyze your vitamin D levels with your doctor’s assistance. In the liver, sources of vitamin D convert to 25-hydroxyvitamin D, or 25 (OH) D, the most reliable indication of vitamin D levels, according to the Office of Dietary Supplements. High-serum 25 (OH) D concentrations over 150 nmol/L indicate potentially dangerous levels, while concentrations of 500 to 600 nmol/L indicate toxicity. A normal concentration, in contrast, hovers in the 50 nmol/L range.
Reduce or eliminate supplements of vitamin D if you have an abnormally high level. Although toxicity remains unlikely with intakes below 10,000 IU a day, the Harvard School of Public Health suggests an intake of 1,000 to 2,000 IU per day. Note the relatively low recommended dietary allowance intake for vitamin D: 600 IU for most children and adults and 800 IU for those over 70.
Consider your geographic location. If you have yearly sun exposure, you may not need as much vitamin D as someone living in a northern latitude and therefore can reduce your intake of supplements. Although too much sunbathing can cause skin cancer, exposure alone will not lead to toxic vitamin D levels.
Assess your food intake. A mere 1 tbsp. of cod liver oil contains a whopping 1,360 IU of vitamin D, while 3 oz. of salmon or tuna have 447 and 388 IUs, respectively. Fortified foods, such as 1 cup of fortified milk (124 IU) and orange juice (137 IU), also add to the daily intake. Note, however, that supplements, not food sources, provide most of the excess intake of vitamin D.
Evaluate the effects of your specific vitamin D supplement and your prescriptions. For example, vitamin D3 exceeds the potency of vitamin D2 by 300 percent to 400 percent. If you take a hormone replacement pill, the estrogen can raise vitamin D levels in the blood. Similarly, thiazide diuretics can elevate vitamin D. By evaluating reasons for your excess vitamin D, you and your doctor can eliminate unnecessary sources.