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Calcium may be the bestresearched of all theminerals. It has the dis-tinction of being theonly one with an FDA-approved health claim(more on this later), andis by far the most preva-

lent mineral in the human body with 99percent of it found in bones and teeth,and the remaining one percent found inblood and soft tissue.1 As with otherminerals, issues have been raised aboutwhich forms of calcium are bestabsorbed, and whether calcium supple-mentation may be associated with riskfactors in certain population groups.

Functions of Calcium in the BodyFirst and foremost, calcium is a major structural ele-ment in bones and teeth along with phosphate.Together, these two minerals form hydroxyapatitecrystals, a major component of bone.2 Inadequate

calcium intake and/or resorption of bone calcium intothe blood (to be used for other purposes) may resultin osteoporosis over a long period of time.3 In addi-tion, calcium is necessary for nerve impulse transmis-sion, muscle contraction, relaxation and constrictionof blood vessels, and secretion of hormones (e.g.,insulin).4,5 Calcium is also needed to stabilize a num-ber of proteins and enzymes, including vitamin K-dependent clotting factors that stops bleedingthrough clot formation.6

OsteoporosisCalcium’s role in the prevention and treatment ofosteoporosis is also well established.7 Furthermore, cal-cium supplementation has been shown to effectivelyslow bone loss.88--1111 Research overwhelmingly supportsthe use of calcium supplementation, alone or in com-bination with other therapies, for slowing or stoppingthe progression of osteoporosis.12 As a matter of fact,FDA-approved therapy for the treatment of post-menopausal osteoporosis includes calcium supplemen-tation.13 In addition, osteoporosis can lead to anincreased incidence of fractures. Research has clearlyshown that calcium supplementation can help toreduce the risk of, and even prevent fractures in osteo-porosis.14-17 In fact, the data on calcium and osteoporo-sis is so compelling that the FDA has approved eitherof these healthy claims: “Adequate calcium throughoutlife, as part of a well-balanced diet, may reduce therisk of osteoporosis,” or “Adequate calcium as part ofa healthful diet, along with physical activity, mayreduce the risk of osteoporosis in later life.”

Colorectal CancerAnalysis of 10 prospective cohort studies whichinvolved 534,536 men and women, showed that thoseconsuming the highest calcium intake (1,051 mg) fromfood had a 14 percent lower risk of colorectal cancercompared to those consuming the least calcium (674mg).18 In addition, other human clinical research foundmodest decreases in the recurrence of colorectal ade-nomas (precancerous polyps) when calcium was sup-

CALCIUM:

FORM&FUNCTION

By Gene Bruno, MS, MHS

SupplementScience

AUGUST 2012 � WWW.VITAMINRETAILER.COM VITAMIN RETAILER 41

plemented at 1,200-2,000 mg daily.19,20

Other large prospective studies indicat-ed that calcium intakes are only weaklyassociated with a decreased risk of col-orectal cancer; this may be due to thefact that the people in the studies hadlower circulating levels of IGF-1.21

Hypertension Twenty-three large observational stud-ies showed significant reductions insystolic and diastolic blood pressure.22

A systematic review of 42 randomizedcontrolled studies found that calciumsupplementation ranging between500-2,000 mg daily reduced bloodpressure more effectively than a place-bo.23 Furthermore, research on peopleconsuming a diet providing a total ofabout 1,200 mg of calcium daily foundsignificant decreases in bloodpressure.24,25 This research suggeststhat a daily intake of about 1,000-1,200 mg calcium may be helpful inpreventing and treating moderatehypertension.26 In addition, a review ofplacebo-controlled studies demonstrat-ed that that calcium supplementationreduced the incidence of high bloodpressure in pregnant women at highrisk for pregnancy-induced hyperten-sion and in pregnant women with lowdietary calcium intake.27

Premenstrual Syndrome (PMS)Double-blind, placebo-controlled, clini-

cal research has demonstrated that1,200 mg of calcium daily reduced totalsymptom scores in PMS by 48 percent;although supplementation had to takeplace over the course of three menstru-al cycles to achieve results.28 Other clini-cal research using 1,000 mg of calciumdaily, showed similar positive bene-fits.29,30 Research in which womenobtained about 1,283 mg daily of calci-um from food showed a 30 percentlower risk of developing PMS.31

Weight LossPlacebo-controlled research has shownthat 1,200 mg of calcium supplement-ed daily in elderly women resulted insignificantly greater weight loss com-pared to a control group.32 Secondaryanalysis of data from a double-blind,placebo-controlled, randomized trialon 870 postmenopausal women foundthat 1,400 or 1,500 mg of calcium daily(with or without vitamin D3) was associ-ated with lower trunk fat gain andhigher lean trunk mass.33 Likewise,research on young women obtaining1,300-1,400 mg of calcium daily fromdairy products experienced a slightreduction in body fat mass.34

Increase in Prostate Cancer RiskEpidemiological research suggest thatmen who consume 2,000 mg or more ofcalcium daily had an increased risk ofprostate cancer; although this risk was

not seen at lower levels of intake.35 Aprospective study also found anincrease in prostate cancer risk amongmale smokers consuming more than1,000 mg of calcium daily.36 However,other epidemiological and prospectivestudies have not found an associationbetween calcium intake and prostatecancer.37,38 In fact, one Serbian case-con-trol study found increased calciumintake to be associated with adecreased risk of prostate cancer.39

Perhaps the best advise on calcium sup-plementation in men came from theLinus Pauling Institute: “Until the rela-tionship between calcium and prostatecancer is clarified, it is reasonable formen to consume a total of 1,000-1,200mg/day of calcium (diet and supple-ments combined), which is recommend-ed by the Food and Nutrition Board ofthe Institute of Medicine.”40

Elemental CalciumCalcium doesn’t naturally exist by itself.Rather it is attached to some type oforganic or inorganic acid. Mineralsattached to acids are called mineralsalts. All forms of calcium used indietary supplements provide one ormore calcium salts. For example, if youattached citric acid to calcium, youwould have a calcium salt called calciumcitrate. The issue with different calciumsalts is that they all provide differentpercentages of actual, or elemental, cal-

DOES CAFFEINE DECREASECALCIUM RETENTION?Some data suggests that low calcium intake together with drinking

two to three cups of coffee daily accelerated bone loss in post-menopausal women,* while other research showed no association

between caffeine intake and bone loss.** Most likely, a cup of cof-fee (8-oz.) will decrease calcium retention by about 2-3 mg,***so there does not appear to be any real basis for concernthat drinking coffee will reduce calcium levels.

*Harris SS, Dawson-Hughes B. Am J Clin Nutr. 1994;60(4):573-578.**Lloyd T, Johnson-Rollings N, Eggli DF, et al. J Am Coll Nutr.2000;19(2):256-261.***Weaver CM, Heaney RP. Calcium. In: Shils M, Olson JA,Shike M, Ross AC, eds. Modern Nutrition in Health andDisease. 9th ed. Baltimore: Lippincott Williams & Wilkins;1999:141-155.

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cium by weight. Sticking with the exam-ple of calcium citrate, it provides about22 percent elemental calcium.

By comparison, calcium carbonate isabout 38-40 percent elemental calciumamuch higher elemental potency, andclearly a good source of calcium. Thatmeans to obtain 500 mg of elementalcalcium, one would have to consumeabout 2,273 mg of calcium citrate or1,282 mg of calcium carbonate. That’sroughly double the amount of calciumcitrate tablets you’d have to take com-pared to calcium carbonate tablets.

Often when reading the labels of calci-um products, the issue of elemental cal-cium potency can be confusing or mis-leading. Here’s a quick primer on how totell whether the dosage listed is beingexpressed as elemental calcium or thetotal amount of the calcium salt. If thelisting on the label appears in one ofthese ways, the amount being expressedis elemental (the use of calcium carbon-ate is just an example):

Calcium 1,000 mg

Calcium 1,000 mg(as calcium carbonate)

Calcium 1,000 mg– elemental

If, on the other hand, the listing onthe label appears as follows, theamount is being expressed as the totalamount of the mineral salt, not theelemental amount:

Calcium carbonate 1,000 mg

Calcium AbsorptionSome research has found that approxi-mately the same level of absorptionoccurs with various forms of calcium(including calcium citrate, calcium car-bonate, hydroxyapatite, calcium glu-conolactate and calcium pidolate)41,while other research has shown thatcertain forms of calcium (such as calci-um citrate) are better absorbed overother forms (such as calcium glucono-lactate and carbonate).42-44 Still otherresearch shows that calcium carbonateis fairly well absorbed when taken witha meal.45 In any case, all of the researchshows that these forms of calcium areabsorbed.

Now, let’s consider the practicalaspects of calcium source and calciumabsorption by comparing apples toapples: If one used the same amount ofcalcium citrate and calcium carbonate,say 1,282 mg of each, the total ele-mental calcium you’d receive would be282 mg from citrate and 500 from car-

bonate. Even with 13 percent greatercalcium absorption from citrate, onewould still end up with far more calciumfrom the carbonate source. So the bot-tom line is that while some calcium saltsare better absorbed than others, what ismost important is to get the correct ele-mental amount of the mineral, and tomake sure to take the mineral supple-ment with a meal so that the hydrochlo-ric acid in your stomach will break itdown efficiently for absorption. VR

For a complete list of references, visitwww.vitaminretailer.com.

SupplementScience

Gene Bruno, MS, MHS, the dean ofacademics for Huntington Collegeof Health Sciences, is a nutritionist,herbalist, writer and educator. Formore than 30 years he has educat-ed and trained natural productretailers and health care profession-als, has researched and formulatednatural products for dozens ofdietary supplement companies, andhas written articles on nutrition,herbal medicine, nutraceuticals andintegrative health issues for trade,consumer magazines and peer-reviewed publications.

“Often whenreading the

labels of calcium

products,the issue of elemental calcium

potency canbe confusing or

misleading”