You must have definitely heard of vitamin D deficiency, which means the lack of the essential vitamin, vitamin D in the body; but have you ever come across the term vitamin D toxicity? For those who consume vitamin D supplements regularly, a basic knowledge of vitamin D toxicity is extremely important to avoid the health risks associated with it.
How severe is vitamin D toxicity?
A study published in October 2024, on the Clinical and Biochemical Profiles of Hospitalized Patients with Hypercalcaemia from a Tertiary Care Centre in North India found vitamin D toxicity to be one of the reasons for increase in hypercalcemia cases. “Apparently, there is a changing profile of hypercalcaemia in India, especially in hospital settings, because of increasing reports of vitamin D toxicity and the early detection of PHPT, necessitating clinicians to be aware of such changes for effective diagnosis and treatment,” the report said.
Another study published in the Journal of the Endocrine Society talked about a patient treated at Michigan State University Endocrinology specialty clinic. “He started taking 5000 IU daily Vitamin D supplements and on subsequent follow up his levels corrected to 88 ng/ml. His supplements were held.On a routine repeat lab check, his 25-hydroxy vitamin D level is reported to be higher than 200 ng/ml. Which meets the biochemical diagnosis of Vitamin D toxicity,” the report said.
What is Vitamin D toxicity?
Vitamin D toxicity, also known as hypervitaminosis D, occurs when the levels of vitamin D in the body are excessively high, leading to an accumulation of calcium in the blood (hypercalcemia). This condition is not caused by prolonged sun exposure or a diet rich in vitamin D; instead, it typically results from taking high doses of vitamin D supplements over time. While vitamin D is fat-soluble and stored in the body, excessive amounts can disrupt normal physiological processes, posing serious health risks.
The recommended dietary allowance (RDA) of vitamin D varies in terms of age, gender, and health conditions. While the RDA for most adults would be 600 to 800 IU/day, a tolerable upper intake level is set at 4,000 IU/day. However, this is the amount that individuals often use, which often comes from misguided advice or assumptions of the benefits of taking vitamin D. It has been observed that taking supplements above 10,000 IU per day for weeks or months leads to toxicity.
It is also important to note that the risk is enhanced when vitamin D supplements are combined with high-calcium diets or calcium supplements. This can push calcium levels in the blood to dangerous levels, triggering health complications.
Common symptoms of Vitamin D toxicity
Vitamin D toxicity presents with a spectrum of manifestations that are primarily caused by hypercalcemia. Initial signs include nausea, vomiting, anorexia, polydipsia, polyuria, and weakness. The more severe manifestations occur in advanced stages of toxicity:
- High calcium levels can result in the development of kidney stones, impair kidney functions, or cause calcification of kidney tissues.
- Elevated calcium levels can lead to arterial calcification, which may increase the risk of heart attack and stroke.
- Ironically, excessive vitamin D can weaken bones by interfering with calcium regulation, thereby increasing the risk of fractures.
- Hypercalcemia can cause confusion, irritability, and, in extreme cases, seizures because of its impact on the nervous system.
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