Calcium: Safety Assessment

The European food safety authority (EFSA) last evaluated vitamins and minerals for safety in 2006 and set a so-called Tolerable Upper Intake Level (UL) for each micronutrient, provided sufficient data were available. This UL reflects the maximum safe level of a micronutrient that will not cause adverse effects when taken daily from all sources for a lifetime.

The maximum safe daily intake for calcium is 2,500 mg. The maximum safe daily intake for calcium is 3 times the EU recommended daily intake (Nutrient Reference Value, NRV).

This value applies to adults as well as pregnant and lactating women. The safe daily intake limit for calcium of 2,500 mg was reaffirmed by EFSA in 2012. The data of the NVS II (National Nutrition Survey II, 2008) on the daily intake of calcium from all sources (conventional diet and dietary supplements) indicate that an unintentional exceeding of such an amount is only conceivable at all in combination with an extraordinarily high intake via food and an additional high intake of calcium via dietary supplements. In view of the great importance of calcium for bone health, however, an undersupply weighs much more heavily than a high intake. A high intake of calcium, both conventionally via food and via dietary supplements, is corrected by reduced absorption in the intestine and by increased excretion in the urine and does not usually lead to an overload of the body. Only in special situations such as pathologically increased bone resorption (e.g. bone cancer or hyperthyroidism/hyperthyroidism), due to genetic causes or excessive vitamin D intake can an excessive intake of calcium lead to hypercalcemia (increased calcium concentrations in the blood). The NOAEL (No Observed Adverse Effect Level) – the highest dose of a substance that has no detectable and measurable adverse effects even with continued intake – has been set by EFSA at 2,500 mg and corresponds to the maximum safe daily intake. Adverse effects of excessive calcium intake include an increased risk of nephrolithiasis (kidney stones) in appropriately preloaded individuals (kidney stone patients with hypercalciuria) and disruption of the absorption of zinc and iron. Regarding the increased risk of nephrolithiasis (kidney stones), it should be noted that no calcium dose that promotes kidney stone formation can be deduced from the available data, either in healthy individuals or in preloaded individuals. In fact, two large prospective (prospective) studies indicate that calcium intakes slightly above the DGE intake recommendations reduce the risk of kidney stone formation. Excessive calcium intake alone is not the cause of kidney stones. Other factors, such as salt intake, play a crucial role in their formation. In 2012, EFSA reaffirmed, based on the current state of studies, that calcium intake from conventional foods and supplements of up to 3,000 mg per day does not contribute to the formation of kidney stones in healthy adults. With regard to the risk of impaired absorption of zinc and iron due to a high calcium intake, it should be noted that the simultaneous intake of calcium and the corresponding trace element in particular leads to reduced absorption via the intestine. Accordingly, the absorption of iron from food can be disturbed by simultaneous intake of calcium and iron. Long-term studies with calcium supplements showed no negative effect on the long-term supply of iron to the body. Similarly, the simultaneous intake of calcium and zinc can reduce zinc absorption in the intestine. However, there are also studies that have found no effect on zinc absorption with simultaneous calcium intake. In addition to the time of intake, the quantity also seems to be decisive for an influence. The discussed risk of cardiovascular diseases due to increased calcification (hardening) of the blood vessels was also evaluated. EFSA concludes that a sustained intake of up to 3,000 mg of calcium per day through conventional diet and supplements is not associated with an increased risk of cardiovascular disease.