However, this self-supplementation raises concerns. Some specialists favor ultra-high-dose medications (50,000 to 100,000 IU ampoules) available by prescription. Yet, research indicates that more moderate, but regular, intake may be more effective in preventing falls and fractures.
For comparison, a 2017 study analyzed the effects of a level of 300 nmol/L, corresponding to a daily intake of 15,000 IU. It concluded that these levels, although very rare, did not present any significant danger.
True cases of vitamin D toxicity are exceptional and generally occur at blood concentrations above 375 nmol/L. This threshold corresponds to a daily intake of approximately 50,000 IU for several months. When this toxicity is reached, it can cause severe hypercalcemia, leading to nausea, vomiting, weight loss, polyuria (increased urine production), and kidney failure.
What is the safe dose?
The researchers behind the study believe that supplementation between 400 and 4,000 IU per day is safe for the majority of the population. Risks would only arise in cases of prolonged, massive intake, as illustrated by an extreme case in the United Kingdom, where a man reportedly consumed up to 150,000 IU daily , in combination with other supplements.
In France, the Esteban study conducted in 2015 revealed that a third of the adult population had a vitamin D deficiency, with levels below 50 nmol/L . However, a vitamin D deficiency is associated with an increased risk of cancer, cardiovascular disease, diabetes, autoimmune diseases, and depression .
Therefore, while supplementation is often beneficial, it should ideally be tailored to each individual’s specific needs. A preliminary blood test would allow for adjusting intake and avoiding any risk of unnecessary excess.
← The main risk is related to increased levels of calcium and phosphate in the blood. Since vitamin D promotes their absorption, an overdose can cause kidney overload and excessive accumulation of these minerals in the blood vessels. This calcification leads to stiffening of the arteries, thus increasing the risk of atherosclerosis and cardiovascular disease.Health
It is precisely to assess these risks that German researchers conducted a large-scale study on the effects of high levels of vitamin D in the blood.
A reassuring study on the effects of high supplementation
