Unlocking Bone Health: The Dynamic Trio of Calcium, Magnesium, and Vitamin D

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Unlocking Bone Health: The Dynamic Trio of Calcium, Magnesium, and Vitamin D

Robust bone health doesn’t just happen, it’s cultivated. Understanding the complex interplay between calcium, magnesium, and vitamin D will aid you in keeping your frame strong and healthy for life. Calcium, the backbone of bone strength, builds a sturdy foundation until our thirties, after which we rely on our bone ‘savings.’ Enter magnesium, the unsung hero, orchestrating essential functions and supporting calcium and vitamin D in their roles. Vitamin D steps into the spotlight, activating calcium’s potential and influencing immune function. Together, this trio not only fortifies bones but also safeguards overall health. Read on to learn more about this synergistic relationship, how these nutrients affect pregnancy and a growing baby, and the secrets to lifelong bone vitality.


Calcium, the most abundant mineral in the body, gives bones their strength and structure and plays a role in muscle movement, nerve communication, blood flow, hormone secretion, cellular communication, and immune response. 99% of the total calcium in the body remains stockpiled away in bone. Up until about age 30, the body stows away more calcium in the bones than it breaks down or draws (3). But just like a retirement fund, once this age has come and gone, we must live off the calcium savings that have been built up during the first 30 years of life. If these calcium account deposits during this time were inadequate, osteoporosis develops, leading to an increased risk of bone fractures and chronic pain. Besides diet, one overall healthy way to positively impact bone density is to engage in exercise involving impact. Believe it or not, the force of impact during activity such as running, jumping, and weight-bearing exercise causes small strains in the bones, which provides the beneficial side effect of bone growth, thereby increasing bone density (2). Cool, right!?

During pregnancy, extra calcium is required to mineralize the skeleton of the growing baby. If dietary calcium intake is not sufficient, calcium is released from maternal bone stores, quickly depleting that long-term calcium savings. The good news is that by consuming a diet rich in calcium, maternal bone resorption (the breakdown of tissue in bones to release minerals) can be prevented and those much-needed calcium reserves can be saved for the future. Opportunely, pregnancy signals the intestines to absorb extra calcium which is transported through the placenta to the growing baby. (4). While it may seem reasonable to turn to supplements as a safeguard, recent research is calling into question the effectiveness of supplements on bone density, even when dietary intake is low. A growing body of evidence suggests calcium supplementation provides no health benefit, even during pregnancy or breastfeeding (4)(5). The importance of a diet rich in calcium cannot be overstated, particularly during pregnancy when calcium needs are high.

It’s important to note that calcium supplements should not be consumed at the same time as prescription medication, as there are 220 known medications that interact with calcium carbonate (8). Ask your pharmacist how far apart prescriptions and calcium intake should be spaced. Calcium also influences how the body absorbs iron, zinc, and magnesium. Supplementation should be taken separately from these nutrients and separate from meals high in iron as it blocks iron absorption (9). Calcium supplementation is safest at doses below 500mg, as the body cannot utilize more than that amount, and significant excess can be harmful (9). Certain health conditions affect calcium absorption as well.

Vitamin D

 While calcium may be considered the star of the bone health show, it’s essentially useless to the body without its partner, Vitamin D. This nutrient is necessary for the body to utilize calcium and is responsible for a wide range of other functions as well, but what exactly is it? Vitamin D is both a fat-soluble vitamin that we consume as well as a hormone our bodies create from exposure to ultraviolet B rays from the sun. To become usable by the body after sun exposure, vitamin D must first be activated by the liver and kidneys (10). This nutrient can be obtained from diet, direct sunlight, or supplementation. The two forms of this vitamin that can be found in supplements are D2 (ergocalciferol), a form produced in plants and fungi, and D3 (cholecalciferol), which is produced in animals, including humans. D3 is generally the preferred supplemental form due to better bioavailability. (6) Because it’s difficult to acquire adequate amounts through diet and, in some locations, through sunlight, supplementation is often recommended by medical professionals.

It’s easy to guess that vitamin D plays a role in a baby’s bone and teeth development during pregnancy, but maternal vitamin D levels also affect the baby’s immune function, with deficiency leading to a significant increase in the risk of RSV infection (10). Both past and recent epidemiologic and case-control studies highlight a correlation between vitamin D deficiency and preeclampsia (10).


Magnesium is the quiet overachiever and unsung hero of so many vital functions. And while calcium has co-dependency issues with Vitamin D, Vitamin D is overly enamored with magnesium and simply cannot function without it. Oh, the drama. The enzymes responsible for producing and breaking down vitamin D cannot complete the task without the help of magnesium. The activation of vitamin D after sun exposure that takes place in the liver and kidneys also requires magnesium to happen. So, while you may be consuming a high intake of calcium and vitamin D, a deficiency in magnesium renders them both essentially useless and can lead to high blood levels of calcium and even calcification of blood vessels (7). How’s that for an important supporting role?! Magnesium also assists no fewer than 300 enzymes in facilitating a wide range of necessary chemical reactions throughout the body. It plays a role in regulating blood sugar, blood pressure, muscle and nerve functions, and holds the job of the electrical conductor to the heart that keeps your heartbeat steady. Like most nutrients, a diet rich in magnesium remains the safest and most effective way to increase magnesium levels. While calcium requires magnesium to do its work, the two have a competitive relationship. They share a receptor and compete for absorption in the gastrointestinal tract. That’s right, although calcium needs magnesium to do any good it simply will not be caught entering the show at the same time as measly little magnesium. Although some could call it an unhealthy relationship, the two function to keep each other in check when both are consumed in adequate amounts.

During pregnancy, magnesium remains the hard-working supporting character. According to the National Institutes of Health, “magnesium deficiency during pregnancy is associated with a higher health risk for both mother and newborn, including restricted fetal growth, intrauterine growth restriction, gestational diabetes, preterm labor, and pre-eclampsia. Low magnesium intake during pregnancy may also have relevant consequences on the health status throughout life, such as the insurgence of metabolic syndrome later in life (11).”

Teamwork Makes the Dream Work

Nutrients rarely work alone and almost without exception rely on other nutrients to function or even simply to make it to their job site. Because of this, vitamins and minerals are most effective and potent when taken in the form of nutritious and delicious meals. Food contains all the supporting help that supplements lack, providing hundreds of carotenoids, flavonoids, minerals, and antioxidants that increase your body’s ability to make use of the nutrients you take in. Although supplements have their place and can be important, at times necessary, the benefit of a varied and nutritious diet has no match.

This blog is intended to be informational and should not be used as medical advice. As always, your doctor is the best source for health advice.


  1. https://www.hopkinsmedicine.org/health/wellness-and-prevention/vitamin-d-and-calcium
  2. Rogers, K. (2023, January 9). University of Notre Dame. Biomechanics in the Wild. https://sites.nd.edu/biomechanics-in-the-wild/2022/05/02/jumping-into-better-bone-health-impact-exercise-and-your-bones/
  3. Mayo Foundation for Medical Education and Research. (2024, February 24). Osteoporosis. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/osteoporosis/symptoms-causes/syc-20351968
  4. Calcium supplementation during pregnancy and maternal … (n.d.). https://nyaspubs.onlinelibrary.wiley.com/doi/full/10.1111/nyas.14705
  5. Calcium supplements: Should you take them?. Johns Hopkins Medicine. (2022, November 1). https://www.hopkinsmedicine.org/health/wellness-and-prevention/calcium-supplements-should-you-take-them
  6. Alayed Albarri, E. M., Sameer Alnuaimi, A., & Abdelghani, D. (2022a, August 4). Effectiveness of vitamin D2 compared with vitamin D3 replacement therapy in a primary healthcare setting: A retrospective cohort study. Qatar medical journal. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9372493/
  7. Magnesium. The Nutrition Source. (2023, March 7). https://www.hsph.harvard.edu/nutritionsource/magnesium/
  8. Calcium carbonate drug interactions. Drugs.com. (n.d.). https://www.drugs.com/drug-interactions/calcium-carbonate-index.html
  9. Katherine Zeratsky, R. D. (2023, May 20). The best time to take your calcium supplement. Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/calcium-supplements/faq-20058238
  10. Wagner, C. L., Taylor, S. N., Johnson, D. D., & Hollis, B. W. (2012, May). The role of vitamin D in pregnancy and lactation: Emerging concepts. Women’s health (London, England). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4365424/
  11. Fanni, D., Gerosa, C., Nurchi, V. M., Manchia, M., Saba, L., Coghe, F., Crisponi, G., Gibo, Y., Van Eyken, P., Fanos, V., & Faa, G. (2021, October). The role of magnesium in pregnancy and in fetal programming of adult diseases. Biological trace element research. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8360883/