Vitamin D hypervitaminosis: Potential hazards and health consequences of excessive vitamin D supplementation in humans
Katarzyna Mazur
2026-03-24
3 min. read
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Cholecalciferol, commonly referred to as vitamin D, serves a pivotal function in maintaining the body’s mineral homeostasis, primarily through the regulation of calcium and phosphate metabolism, which is essential for proper mineralization of bone tissue and teeth. Furthermore, its active metabolites exert a significant influence on immune system function—modulating inflammatory responses and adaptive immunity—as well as neurotransmission processes and skeletal muscle contractility. Epidemiological evidence suggests an association between optimal serum concentrations of 25-hydroxyvitamin D and a reduced incidence of malignant neoplasms, particularly those with hormonal underpinnings, such as breast and ovarian cancers in women.
Is it possible to overdose on vitamin D?
Although vitamin D is present in many food products, its best source is synthesis in the skin under the influence of sunlight. It is impossible to sell vitamin D in these two cases. Most often it is due to improper use of dietary supplements. Many vitamin D preparations are available on the market without a prescription. This makes it easy to fill in the deficiencies in the winter months when we are most lacking. However, these and other preparations should also be used wisely according to their intended purpose.
Excessive vitamin D is a symptom
Vitamin D excess primarily disrupts the calcium economy. Therefore, most of the side effects associated with vitamin D overdose can be attributed to elevated calcium levels in the blood (hypercalcaemia) and increased calcium excretion in the urine (hipercalciuria). They can occur at levels of 88 ng/ml of vitamin D, which are not yet considered toxic. However, calcium in your bloodstream can lead to further disorders in other body systems: kidney stones, renal calcification and other tissues, heart failure, nausea and vomiting, polycystic ovary syndrome (PCOS), lack of fluid intake, lack of medication, and frequent medical advice.
