Calcium supplementation has been a hot topic these days for all age groups: Calcium is essential for healthy bones and skeletons during the growth period of children, teens want to top up their reserves before it starts to go downhill, pregnancy mom is well aware of the increased calcium demand during pregnancy and lactation, and the fear of osteoporosis start to hit middle-aged population so on and so forth. Do you want to know how effective are your means of supplementing – either food or supplements? And if are getting too much or too little?

1% vs. 99% Calcium in our Body

Calcium comprises about 2% of a person’s total body weight. In other words, you have 1kg of calcium if you weigh 50kg. 99% of that 1kg is in our bones (and teeth), the remaining 1% are supporting nerve conduction, energy production, hormone production, enzymatic activity, regulation of heartbeat and normal muscle functioning. As you can see, this 1% is critical in maintaining our chemistry and biological balance, your parathyroid gland is responsible for monitoring and maintaining this small range of calcium in blood and cells. When depleted, calcium will be leached from the bones to maintain the stability of this small yet vital function of calcium. And when the body detects an oversupply, calcium will be excreted in urine and can become a cause of kidney stone or hypercalcemia when the kidney is overloaded.

Differentiating Too Much from Too Little

Homeostasis ensured that serum calcium is maintained within a narrow range; hence, most calcium deficiency won’t be detectable in serum. Bone density measurement at hip joint has been the more informative test. There is still one thing missing though – when bones are not replenished at times, it became aged and fragile, or we call it “brittle bones”. Bone metabolic function may have slowed down (osteoblastogenesis) especially when you age implying the bones may have expired their elasticity of age and become brittle and is more susceptible to fractures irrespective of the bone density.

Bones can become weak or porous when you are deficient in calcium, which can lead to bone deformities. Other symptoms of calcium depletion include muscle spasms, leg cramps, restless leg syndrome. Insomnia, depression and hyperactivity and dirt craving can all be signs of calcium deficiency.

Calcium toxicity, on the other hand, may lead to irregular heartbeat, muscle pain, itchy skin, high blood pressure, and increased urination.

Maximizing Calcium Absorption

Nutrient uptake, not intake, is the most important when it comes to nutrition and calcium is no exception! Calcium absorption requires a lot of co-factors including vitamin D (D3 is synthesized through body processes upon exposure to sunlight), Magnesium, Potassium, Vitamin K, Boron, and Silica. Osteoblasts require the right balance of calcium and phosphorus. All these co-factors are needed in a particular ratio, and it can be damaging if it’s too high or too low. Apart from these nutritional co-factors, there are two other main factors that influence the absorption of calcium:

  1. Adequate HCL (hydrochloric acid): Calcium is best absorbed in an acidic environment. If your HCL runs low or you are on antacids, your digestive environment makes it hard for calcium absorption and can be overloading your other systems when supplementing high amounts. If you have a lot of gas, bloating, intestinal rumbling, you are likely to be running low on HCL. Low HCL also happens as you age. Hence, you can imagine that most of the calcium supplements taken by the elderly are wasted (at best) or burdening their systems. Getting a healthy digestion (with adequate HCL) is the #1 task in calcium absorption
  2. Sugar (especially all forms of refined sugar): Sugar depletes mineral in multiple ways. It can degrade Vitamin D and suppress the expression of an enzyme that supports the Vit D3 which in turn leads to calcium malabsorption. It also increases urine excretion which also leaches calcium. Hence, sugar is very nutrient depleting. Soft drinks are one of the top depleting drinks for calcium absorption. In fact, there are more hidden killers in packaged drinks or food, such as some of the “High Calcium” drinks like High Calcium Chocolate milk – Check out the ingredients on their packaging, and you will know what I’m talking about here. Caffeine is also another potential source of calcium leaching as it increases urination.


Supplementing Calcium

The rule of thumb here is Whole Food – vegetables, meat or herbs. Whole foods have the best gift in balancing and supporting digestion. Here are some suggested foods that are rich in calcium:

  • Dark leafy green vegetables, especially kale, broccoli, spinach, mustard greens, water spinach, etc.
  • Raw almonds – you can also make your DIY nutritious almond milk with sprouted raw almonds
  • Sprouted Non-GMO Soybeans
  • Black sesame, best if kept in its raw form
  • Tofu
  • Sardines, Wild Caught Salmon
  • Eggshell is rich source of calcium, and there have been clinical studies in human for eggshell in apple cider vinegar preventing and treating osteoporosis

nettle leaf

Herbs that are rich in calcium include:

  • Nettle leaf
  • Oatstraw
  • Red Clover Blossom
  • Red Raspberry leaf, etc.

A future article will look into all the mineral-rich herbs.

When choosing supplements, there are various forms of calcium and their bioavailability differs. For example, calcium carbonate contains more calcium than calcium citrate. However, its bioavailability is lower than that from calcium citrate, particularly when HCL is low. A high calcium content may not always translate to high calcium absorption. Read all the ingredients label carefully (don’t rely on just the nutrition label) and you can avoid falling into “advertising” traps of high calcium!

Again, the best way is your wholefood with good digestion system!


  • Eggshell calcium in the prevention and treatment of osteoporosis,Int J Clin Pharmacol Res. 2003;23(2-3):83-92
  • The Healing Power of Minerals by Paul Bergner, 1997
  • Evidence that glucose ingestion inhibits net renal tubular reabsorption of calcium and magnesium in man, The Journal of Laboratory and Clinical Medicine, 1970