What is the most abundant mineral in the body? Though it may be marketed as “it does a body good” or included in fortified orange juice, many people still struggle to obtain adequate amounts of calcium that are essential to strong bones and various metabolic functions.
With so many calcium supplements on the market, consumers often feel clueless on what form is best. Even more complicated, is the fact that calcium cannot work alone. It requires other essential minerals (vitamin D and magnesium) to assimilate properly in the body.
Calcium’s benefits are vital to a strong skeletal system, as 99% of the body’s calcium is found in the bones and teeth. The remaining 1% is also important to healthy muscle contractions, weight management, balanced blood pressure, hormone and enzyme production, and so much more.
Calcium deficiencies are common in aging adults, especially postmenopausal women, where the breakdown of bone occurs more often than bone formation. Bones undergo a process of resorption (formation) and deposition (breakdown). When deposition exceeds resorption, bone density weakens, leading to osteoporosis.
What type of calcium should I take?
Calcium absorption is dependent upon several factors including the acidic condition in the small intestines, adequate levels of vitamin D and magnesium, and the form of calcium being ingested. Calcium is more soluble or easily dissolves when high levels of stomach acid are present, whereas alkaline conditions in the intestine prevent calcium assimilation. As we age hydrochloric acid levels (HCL) decline, leading to minimal absorption of certain types of calcium.
The two most common forms of calcium supplements are calcium carbonate and calcium citrate. While calcium carbonate is more commonly used, it is not readily assimilated. Calcium citrate has greater absorption potential, especially among individuals with low stomach acid.
Calcium carbonate, a popular form found in inexpensive calcium supplements and antacids, is only 4% assimilated when HCL levels are low and 22% absorbed in people with normal HCL levels. Calcium carbonate has been compared to cow’s milk, finding absorption is similar.
One study compared the consumption of calcium carbonate (1,000 mg/day), calcium carbonate/vitamin D (200 IU/day), cow’s milk (1 L added to average daily intake), or a placebo, among healthy women (28 to 59 years old). Researchers found that calcium carbonate and milk consumption had similar levels of absorption that significantly increased urinary calcium excretion, when compared to the placebo. Although calcium carbonate and milk have similar levels of calcium excretion, the addition of vitamin D to calcium carbonate intake had a higher urinary calcium excretion than milk. It was concluded that calcium carbonate absorption is at least as good as cow’s milk and calcium carbonate/vitamin D absorption increased urinary calcium excretion after an increase in calcium absorption.
With the presence of citrate, calcium citrate-malate (CCM) is able to create an acidic environment in the intestines making calcium more absorbable in the body. This is especially valuable for individuals that do not create enough stomach acid. CCM contains 20% of elemental calcium, which requires more pills throughout the day for a proper dose. Even so, the absorption rate has been shown to be more superior to calcium carbonate.
CCM’s absorption has beneficial effects on bone mass among adolescents, postmenopausal women, and older men. Additionally, the effects of CCM on increasing bone density and reducing fracture risks are improved when vitamin D and trace minerals are taken with CCM.
CCM (500 mg/day) or a placebo was given to 112 adolescent girls for two years, finding CCM had a significant increase in bone mineral density, when compared to the placebo group. Another study gave CCM (500 mg/day), calcium carbonate (500 mg/day), or a placebo to 301 postmenopausal women with a low calcium intake. Researchers found that CCM was most effective in maintaining bone density in postmenopausal women, when compared to subjects taking calcium carbonate or a placebo.
Calcium citrate and calcium carbonate were compared to understand the effects of bone resorption in postmenopausal women. Forty women were given 1000 mg/day of calcium citrate or calcium carbonate for 12-weeks followed by a two-week washout and another 12-week treatment with the alternate calcium supplement. Subjects also received 900 IU/day of vitamin D. The study found that calcium citrate significantly increased bone resorption when compared to calcium carbonate in postmenopausal women.
Unlike calcium carbonate, CCM can be taken without food. The absorption of CCM was compared to calcium carbonate in women taking calcium on an empty stomach, finding CCM had significant levels of assimilation that were not observed among women taking calcium carbonate. In studies that compare calcium citrate studies and calcium carbonate, researchers have found calcium citrate continues to have greater absorption potential. Consistent results have been observed with calcium citrate taken on an empty stomach or with meals.
Other Types of Calcium
Some calcium supplements may include calcium lactate or calcium gluconate; yet, these forms contain very low levels of elemental calcium requiring more pills. Coral calcium is another marketed form of calcium. It is calcium carbonate that is obtained from coral in the sea; therefore, its assimilation is similar to calcium carbonate obtained from other sources.
Calcium is absorbed more readily in smaller doses. As the amount consumed at one time increases, absorption decreases. When you take calcium supplements, split the doses into 500 mg at a time. For example, if you take 1,000 mg/day of calcium, divide the dose into twice a day, instead of all at once. Consuming 500 mg at a time has an ideal rate of absorption.
The recommended calcium dosage can depend on your age. With an increase in osteoporosis risks, older women are counseled to take more than young adults.
Recommended Daily Allowance
Birth to 6 months – 210 mg/day
7 – 12 months – 270 mg/day
1 – 3 years – 500 mg/day
4 – 8 years – 800 mg/day
9 – 13 years – 1,300 mg/day
14 – 18 years – 1,300 mg/day
19 – 50 years – 1,000 mg/day
50+ – 1,200 mg/day
What nutrients aid calcium absorption?
Calcium cannot work alone, but requires other minerals to aid proper assimilation. Most importantly magnesium and vitamin D3 should be included in your calcium supplement. Other valuable minerals include zinc, copper, manganese, boron, silica and vitamin K. Supplementing with probiotics also increases absorption in the intestines.
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