Calcium supplements are a popular health product for many people, but did you know that if the ratio between calcium and magnesium is not carefully balanced, it can actually lead to health risks? Finding a balance is an important principle that applies to maintaining the well-being of all things in the world, including the human body. There are delicate relationships between nutrients that must be maintained in a certain balance in order to optimize bodily functions, especially when it comes to the two major minerals that affect physiological functions: calcium and magnesium! What kind of relationship exists between calcium and magnesium? Apart from daily dietary intake, how should calcium supplementation be approached in order to achieve a healthy balance within the body?
The Role, Distribution, and Homeostasis of Calcium in the Body
Distribution of Calcium
The majority of calcium in the body (>99%) is bound to collagen protein in the form of hydroxyapatite, which is present in bones and teeth. The remaining 1% or so of calcium may exist in the form of free ions, protein-bound complexes, or ion complexes, distributed in the extracellular fluid or soft tissues. [1]
Functions of Calcium
Calcium that exists in bones primarily serves two functions:
Calcium is an essential material for the construction and maintenance of bones and teeth. Adequate calcium supply is necessary to ensure bone growth and maintenance.
1.Calcium in bones also plays a role in maintaining the dynamic balance of calcium within and outside cells, preventing calcium deficiency in the extracellular fluid or soft tissues.
2.Although the amount of calcium distributed in body fluids or soft tissues is only about 1%, it is closely related to many important physiological functions, including muscle contraction (including cardiac muscles), nerve transmission, clotting assistance, enzyme activation, cell differentiation, immune response, and apoptosis. [2]
Regulation of Calcium Homeostasis
Calcium outside the bones is an indispensable mineral for basic physiological functions. Therefore, the body precisely regulates blood calcium levels through the small intestine, kidneys, and bones. The hormones most closely related to the control of blood calcium are parathyroid hormone (PTH), calcitonin, and active form of vitamin D3 (1,25-dihydroxyvitamin D3).
When blood calcium levels are low, calcium-sensing receptors in the parathyroid lose activity and stimulate the secretion of PTH. PTH acts on the kidneys, increasing calcium reabsorption in the renal tubules to reduce calcium loss. PTH also stimulates the kidneys to synthesize and release active vitamin D3 to enhance calcium absorption in the intestines.
PTH also acts on bones, enhancing the ability of osteoclasts to break down hard bone tissues into minerals, releasing calcium to replenish the deficient blood calcium. This process is called bone resorption. Conversely, when blood calcium levels are high, the body reduces calcium absorption in the intestines, decreases calcium reabsorption in the renal tubules, and weakens the ability of osteoclasts to break down hard bone tissues. Through these precise regulations, blood calcium levels are maintained in balance. [1]
The Role, Distribution, and Homeostasis of Magnesium in the Body
Distribution of Magnesium
The distribution of magnesium in the body is not as concentrated in bones as calcium is. Approximately 50-60% of magnesium is stored in bones, while 40-50% is stored in muscles and other soft tissues. The remaining 1% or so of magnesium can be found in the plasma and red blood cells. [3]
Functions of Magnesium
Magnesium is the second most abundant cation in cells, after potassium. Magnesium acts as a cofactor for more than 300 enzymes and is involved in various physiological functions, including protein synthesis, muscle contraction, nerve function, blood sugar regulation, blood pressure control, facilitation of other ion channels (such as calcium and potassium), as well as direct involvement in energy metabolism, ATP production, and synthesis of nucleic acids (DNA and RNA).
1.Improving bone density:
Adequate magnesium supplementation helps prevent bone degradation and improves bone density. However, both insufficient and excessive magnesium intake can have detrimental effects on bone health.
2.Preventing cramps:
Supplementing with 360 milligrams of magnesium daily helps alleviate cramps caused by magnesium deficiency, but it does not have a significant effect on cramps caused by calcium or potassium deficiency.
3.Preventing diabetes:
Observational studies have shown that populations with the highest magnesium intake have a 36% lower risk of developing type 2 diabetes compared to those with the lowest intake.
4.Assisting in mood regulation:
Magnesium also assists in the synthesis of hormones related to mood regulation, making it beneficial for combating anxiety and depressive symptoms. Studies have shown a negative correlation between magnesium intake and anxiety or depression. [3]
Magnesium Homeostasis
The body’s regulation of magnesium is similar to that of calcium, primarily involving the intestines, bones, and kidneys. However, the difference in magnesium homeostasis compared to calcium is the role of hormones. Estrogen can stimulate the gene expression of ion channels, enhancing magnesium absorption in the intestines and magnesium reabsorption in the kidneys.
Relationship Between Calcium and Magnesium
While calcium and magnesium are both divalent ions, they have differences in cellular distribution and function. Calcium primarily exists extracellularly, while magnesium is intracellular. Calcium provides hardness to bones, while magnesium imparts flexibility to bones through collagen. Calcium ions often cause nerve excitation, whereas magnesium acts to counteract calcium ion channels, preventing excessive nerve excitation. Calcium, along with potassium, aids in muscle contraction, while magnesium controls calcium and potassium ion channels to promote muscle relaxation.
Due to the high overlap in the absorption and functions of calcium and magnesium, French scientist Jean Durlach first suggested in 1989 that regardless of the source of calcium and magnesium intake (food, water, or supplements), the total amount should be controlled to achieve a 2:1 ratio of calcium to magnesium. An imbalanced calcium-magnesium ratio, either too high or too low, can increase the risk of cardiovascular diseases, metabolic syndrome, or certain cancers.
Current research suggests that maintaining a dietary calcium-magnesium ratio between 1.7 and 2.6 is most conducive to reducing the risk of diseases.
Harm of Excessive Calcium Supplementation
Excessive calcium supplementation from diet is rare, as according to the “National Nutrition and Health Condition Changes Survey” conducted from 2017 to 2020, calcium intake remains inadequate among the general population.[5]
The recommended daily intake for calcium in adults is 1000 milligrams, with an upper limit of 2500 milligrams per day, according to the “Dietary Nutrient Reference Intakes for Chinese.” Even if calcium intake is controlled at 2500 milligrams per day, there should be no issue of excessive intake, even with calcium from supplements.
Inadequate dietary choices, water consumption, or supplement usage leading to excessive calcium intake may result in adverse reactions such as hypercalcemia, hypercalciuria, kidney damage, vascular calcification, and increased risk of cardiovascular diseases.[6]
Choosing the Right Calcium Supplements
To achieve the recommended daily calcium intake, one can start by increasing the consumption of high-calcium foods such as milk, legumes, fish, and nuts. The remaining shortfall can be met with the right supplements, following these principles:
- Calcium Dosage: Begin by looking at the calcium content. The small intestine has an upper limit for calcium absorption of around 500 milligrams, so choosing supplements closer to 500 milligrams per dose is appropriate.
- Calcium Form: The type of calcium directly affects absorption and bioavailability. The most common forms are calcium carbonate and calcium citrate, with seaweed calcium being a newer source. Calcium citrate does not require stomach acid to aid absorption and has better solubility, absorption at different pH levels, and overall bioavailability compared to calcium carbonate. Additionally, it is less likely to cause gastrointestinal discomfort and increase the risk of kidney stones when supplemented.
- Calcium-Magnesium Ratio and Complex Components: Calcium should ideally be chosen in combination with other components that enhance its effectiveness, such as magnesium. The golden ratio is a 2:1 calcium-magnesium ratio, along with vitamin D to aid calcium absorption, vitamin C to improve calcium utilization, and vitamin K to assist bone calcification.
In light of government campaigns, the percentage of people who regularly supplement calcium is not low. However, many people often overlook the physiological functions of calcium and magnesium, which are often interconnected. To fully understand the importance of calcium supplementation, both calcium and magnesium should not be ignored.
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