Experts warn against excessive consumption of vitamin D supplements, despite its great importance to the body’s health, stressing that an excess of it may turn into a health risk no less serious than a deficiency.
Vitamin D is known as the "sunshine vitamin" because it is produced in the body when exposed to sunlight. It is essential for calcium absorption, maintaining bone health, supporting the immune system, and regulating muscle and nerve function. Sunlight exposure typically provides about 90% of the body's needs, while the remaining amount comes from foods such as fatty fish and fortified dairy products.
Despite its benefits, scientists do not agree that everyone should take vitamin D supplements, as using them without medical need or in high doses can, in rare cases, lead to poisoning.
The danger of excessive vitamin D intake lies in its ability to increase calcium absorption in the body, potentially leading to hypercalcemia, where calcium accumulates in the blood and tissues, and may even reach the arteries or kidneys. This results in an increased risk of kidney stones, bone health problems, and symptoms such as nausea, vomiting, constipation, fatigue, muscle weakness, and bone pain.
In severe cases, vitamin D poisoning can lead to serious complications including kidney failure requiring dialysis, or potentially life-threatening intestinal bleeding, although these cases remain rare.
Medical studies confirm that treatment for poisoning is often possible by stopping supplements and lowering calcium levels using intravenous fluids or appropriate medications, but delaying treatment may lead to serious complications.
Some research also suggests that higher vitamin D levels in older adults may be associated with an increased risk of falls, although scientific debate continues regarding these findings.
In a scientific review, researchers in the United States warned against complacency in dealing with high doses of vitamin D, noting that its widespread use, sometimes driven by inaccurate claims about its benefits, has contributed to an increase in cases of poisoning.
The optimal dose of vitamin D is still a matter of debate among scientists, but general recommendations suggest that adults taking supplements usually need no more than 600 to 800 IU per day (15 to 20 micrograms), and should not exceed 4,000 IU (100 micrograms) per day without medical supervision.
In cases of vitamin D deficiency, doctors advise starting to rely on fortified foods and natural sources, in addition to consulting a doctor before taking any supplements or adjusting doses, to avoid the risks of unintentional excess.
