From the Guidelines
Magnesium supplementation does not significantly lower calcium levels when taken at normal recommended doses, though they do interact at absorption sites. Magnesium and calcium compete for the same absorption pathways in the intestine, but this competition is generally not clinically significant at standard supplementation doses (typically 200-400mg of magnesium daily) 1. In fact, magnesium is necessary for proper calcium metabolism and utilization in the body, helping to regulate calcium transport and contributing to bone formation. The body maintains tight control over calcium levels through various hormonal mechanisms, such as calcitonin and parathyroid hormone, regardless of acute calcium intake 1.
Some key points to consider:
- The recommended dietary allowance (RDA) for calcium is 1000 mg/day (North America) or 700 mg/day (UK) for adults, and 1300 mg/day (North America) or 1000 mg/day (UK) for adolescents 1.
- Magnesium plays a crucial role in energy production, muscle function, bone health, immune function, and pain modulation, and recent research has highlighted its importance in athletes, with 22% of athletes found to be deficient in one study 1.
- If you're taking both supplements, it's best to space them a few hours apart for optimal absorption.
- People with kidney disease should be cautious with magnesium supplementation as impaired kidney function can lead to magnesium retention.
- For most healthy individuals, the relationship between magnesium and calcium is complementary rather than antagonistic, with both minerals working together to support bone health, muscle function, and nerve transmission.
From the Research
Magnesium and Calcium Interaction
- Magnesium and calcium are essential nutrients that interact with each other in the body, and their optimal ratio is crucial for maintaining good health 2, 3.
- A high dietary calcium to magnesium intake ratio (>3.0) may be detrimental, and optimal ratios may be around 2.0 2.
- Increasing calcium to magnesium intake ratios, coupled with calcium and vitamin D supplementation coincident with suboptimal magnesium intakes, may have unknown health implications 2.
Effect of Magnesium Supplementation on Calcium Levels
- Magnesium supplementation may not directly lower calcium levels, but it can affect the body's calcium status by altering the calcium to magnesium ratio 3, 4.
- Studies have shown that magnesium supplementation does not significantly affect intestinal calcium absorption in humans 5, 4.
- However, a high intake of magnesium may be necessary to establish a more favorable dietary calcium to magnesium ratio, especially in individuals with high calcium intakes from diet and/or supplements 3.
Importance of Magnesium for Vitamin D Activation and Function
- Magnesium is essential for the activation of vitamin D, which helps regulate calcium and phosphate homeostasis to influence the growth and maintenance of bones 6.
- All of the enzymes that metabolize vitamin D seem to require magnesium, which acts as a cofactor in the enzymatic reactions in the liver and kidneys 6.
- Deficiency in either magnesium or vitamin D is reported to be associated with various disorders, such as skeletal deformities, cardiovascular diseases, and metabolic syndrome 6.