From the Guidelines
Vitamin D plays a crucial role in maintaining calcium homeostasis by enhancing calcium absorption from the intestines, and its deficiency can lead to hypocalcemia, while excessive supplementation can cause hypercalcemia. The relationship between vitamin D and calcium is complex, with vitamin D helping to regulate calcium levels by stimulating the production of calcium transport proteins in the intestinal cells, promoting calcium reabsorption in the kidneys, and mobilizing calcium from bone when necessary [ 1 ]. According to the study published in the Annals of Internal Medicine in 2013 [ 1 ], vitamin D deficiency can lead to impaired dietary calcium absorption, resulting in the body using calcium from skeletal stores, which can weaken existing bones.
Key Points
- Vitamin D helps maintain proper calcium levels by promoting calcium reabsorption in the kidneys and mobilizing calcium from bone when necessary
- The recommended daily intake of vitamin D is 600-800 IU for most adults, with some individuals requiring higher doses of 1,000-2,000 IU daily, especially those with deficiency [ 1 ]
- Vitamin D deficiency can lead to hypocalcemia, which may cause muscle cramps, numbness, and in severe cases, tetany
- Excessive vitamin D supplementation can cause hypercalcemia, resulting in symptoms like nausea, confusion, and kidney stones
Calcium Metabolism
The study published in the Annals of Internal Medicine in 2016 [ 1 ] found that calcium intake from food and supplements that does not exceed the tolerable upper level of intake should be considered safe from a cardiovascular standpoint. Maintaining adequate vitamin D levels through a combination of sun exposure, diet, and supplements when needed is essential for optimal calcium metabolism. It is crucial to note that the relationship between vitamin D and calcium is complex, and both nutrients play a critical role in maintaining strong bones and overall health.
From the Research
Effect of Vitamin D on Calcium Levels
- Vitamin D plays a crucial role in maintaining calcium homeostasis, increasing the efficiency of intestinal absorption of dietary calcium, reducing calcium losses in urine, and mobilizing calcium stored in the skeleton 2, 3, 4, 5.
- A low calcium intake can aggravate the consequences of vitamin D deficiency, suggesting an interaction between vitamin D and calcium intake 6.
- The active vitamin D metabolite, 1,25-dihydroxyvitamin D, binds to the vitamin D receptor in the intestinal cell and stimulates the active calcium transport from the intestine to the circulation 6.
- Vitamin D deficiency can lead to insufficient calcium absorption, increased parathyroid hormone production, and mobilization of calcium from bones to maintain normal serum calcium levels, resulting in secondary hyperparathyroidism 3.
- Clinical consequences of low vitamin D levels include osteomalacia, osteoporosis, rickets, neuro-muscular dysfunction, and fractures, which can be prevented or reduced with vitamin D supplementation 3, 4, 6.
Interaction between Vitamin D and Calcium
- A high calcium intake can increase the half-life of 25-hydroxyvitamin D and decrease the secretion of parathyroid hormone 6.
- Clinical trials with vitamin D and/or calcium have shown that trials with both vitamin D and calcium had better results in decreasing fracture incidence than trials with calcium or vitamin D alone 6.
- The effects of these trials depend on baseline calcium intake, baseline vitamin D status, age, and residence, with trials in institutionalized persons having better results than in independently living elderly 6.