What is so special about Calcium?

What is the big deal about calcium and what does the body do with calcium?

Calcium is a vital mineral and electrolyte. It not only provides the body with structural material, it mediates blood vessel dilation and contraction, it’s very important for muscle function, blood clotting, nerve impulse transmission and even hormone secretion.

Calcium is the most abundant mineral in the body. And is naturally present in whole foods such as dark leafy greens, kale, spinach, collard greens, amaranth, some kinds of beans, nuts and seeds. We can also find huge amounts of calcium in fortified and enriched foods as well as medicines and dietary supplements.

That famous saying has been drilled into our heads, to make sure we drank our milk so that we could get as much calcium as possible to build strong and healthy bones.  As a growing child, that saying may stand true. The amount of calcium required to build strong and healthy bones quickly rises after birth, then levels off as we reach adulthood.  A manʻs calcium level in the body remains fairly constant at about 1,400 g.  However, a womanʻs calcium level reaches about 1,200 g, but then begins to drop due to estrogen production at the beginning of menopause. (1)


The body balances calcium levels with hormones that regulate the movement of calcium in the kidneys, gut, and bone. The three main hormones are parathyriod hormone (PTH), vitamin D-3 and little known calcitonin.

PTH is released from the parathyroid gland in the neck.  PTH acts on two things, the kidneys and bones. The kidney responds to PTH to reabsorb calcium in the kidney during the urine making process. The kidney then secretes vitamin D-3, which stimulates calcium absorption through the gut. PHT also stimulates the osteoclasts in the bones, which are responsible for helping bones grow and develop, to reabsorb and release free calcium into the blood, which contributes to increasing calcium in the blood serum.(1)

If the body senses too much calcium in the blood, calcitonin is released by C-cells. Calcitonin then stimulates osteoblasts to deposit calcium into the bones. Calcitonin also stops kidney absorption of calcium, and increases the excretion of calcium through the urine.(2) The level of serum calcium is highly regulated by the parathyroid glands.

What does Calcium interact with?

Calcium absorption directly competes with iron, magnesium, and zinc and is a good idea to take calcium supplements between meals.

Will calcium supplements cause kidney stones?

Kidney stones are mineral deposits inside the kidney. The primary mineral dominant in kidney stones (80%) is calcium oxylate mixed with calcium phosphate. The formation of stones is common and has noticed consistent increases within the past 50 years and is expected to increase into the future because of dietary factors and changes in lifestyles.(3) The risk factors for stone formation are Obesity, diabetes, hypertension and metabolic syndrome. And if you have a history of stone formations studies show that you have higher risk of hypertension, chronic kidney disease (CKD) and end-stage renal disease (ESRD).(3)

Why calcium supplements are bad?

Within the past few decades, there has been mounting evidence that points to two strange trends in the calcium supplement scientific data. One, for both men and women ages 50+, taking calcium supplements or calcium and vitamin D supplements, did not indicate significant reduced risk of cardiovascular diseases. However, multiple research studies demonstrated, those that did not take any calcium supplements showed  significant reduction of cardiovascular related diseases.(4) Keeping in mind that the information surrounding excess use of calcium supplements and risk of cardiovascular and all-cause mortality events are contradictory. Additional studies found that there was no correlation between calcium supplementation and increased risk of cardiovascular mortality. (5,6,7) While another study among Swedish females suggests a possitive correlation between calcium supplementation and cardiovascular death. Interestingly. (7)

Who needs calcium supplements?

People who have poor diets. If you are not getting the daily recommended amounts of fruits and vegetables, you may not be getting enough calcium or magnesium in your diet. Foods with good amounts of calcium are:

  1. milk, skim milk
  2. cheese
  3. soybeans
  4. lentils
  5. millet
  6. cauliflower leaves
  7. moringa
  8. beans
  9. grains

Where do calcium supplements come from?

Calcium is available as carbonate, citrate, acetate, phosphate, lactate, and gluconate, with varying concentrations of ionic calcium contents.

Calcium carbonate is the least expensive, however, it can cause constipation and bloating and it is recommended to be taken with meals for adequate absorption. Calcium citrate is more expensive than calcium carbonate and requires more tablets to get the recommended dose. The absorption of calcium citrate is not dependent on gastric acid, and it is less likely to cause GI side effects. For optimal absorption of any calcium supplement, it is recommended that the dose of calcium should not exceed 500 mg per dose. Generally, for those that require >500 mg/day, the dose should be divided.


Recommended Calcium Supplements

  1. Calcium & Magnesium
  2. Organic 30+ Essential Vitamins & Minerals


  1. Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: The National Academies Press; 2011.
  2. Munoz F, Hu H. The Role of Store-operated Calcium Channels in Pain. Adv Pharmacol. 2016;75:139-51. doi: 10.1016/bs.apha.2015.12.005. Epub 2016 Jan 27. PMID: 26920011.
  3. Khan SR, Pearle MS, Robertson WG, Gambaro G, Canales BK, Doizi S, Traxer O, Tiselius HG. Kidney stones. Nat Rev Dis Primers. 2016 Feb 25;2:16008. doi: 10.1038/nrdp.2016.8. PMID: 27188687; PMCID: PMC5685519.
  4. Blancquaert L, Vervaet C, Derave W. Predicting and Testing Bioavailability of Magnesium Supplements. Nutrients. 2019 Jul 20;11(7):1663. doi: 10.3390/nu11071663. PMID: 31330811; PMCID: PMC6683096.
  5. Li K, Kaaks R, Linseisen J, Rohrmann S. Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition study (EPIC-Heidelberg). Heart. 2012 Jun;98(12):920-5. doi: 10.1136/heartjnl-2011-301345. PMID: 22626900.
  6. Bolland MJ, Grey A, Avenell A, Gamble GD, Reid IR. Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women’s Health Initiative limited access dataset and meta-analysis. BMJ. 2011 Apr 19;342:d2040. doi: 10.1136/bmj.d2040. PMID: 21505219; PMCID: PMC3079822.
  7. Michaëlsson K, Melhus H, Warensjö Lemming E, Wolk A, Byberg L. Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study. BMJ. 2013 Feb 12;346:f228. doi: 10.1136/bmj.f228. PMID: 23403980; PMCID: PMC3571949.

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