Coral Calcium Hype VS. Fact Part 2

Coral Calcium Hype vs. Fact, Part 2...

The Challenges of Dissolution (Breaking Down) and Heavy Metal Contamination in Calcium Supplements
Curently, there is a large discussion in the medical community regarding the challenges of traditional calcium supplements. Simply put, doctors are concerned because these products are not breaking down in the body and their patients are not seeing benefit.

In addition, physicians are worried about contamination with high amount of heavy metals like lead in calcium supplements. So much that several medical journals have printed articles in relation to this.

01. In Vitro Dissolution of Calcium Carbonate Preparations
02. Calcium in the Diet: Food Sources, Recommended Intakes, and Nutritional Bioavailability
03. Contribution of Lead from Calcium Supplements to Blood Lead
04. Lead Content of Calcium Supplements
05. Lead Content in 70 Brands of Dietary Calcium Supplements
06. Meta-Analysis of Calcium Bioavailability: A Comparison of Calcium Citrate with Calcium Carbonate
07. Lead in Calcium Supplements

01. In Vitro Dissolution of Calcium Carbonate Preparations
Calcif Tissue Int 1991 Nov;49(5):308-12
Comment in: Calcif Tissue Int. 1992 Feb;50(2):197

Brennan MJ, Duncan WE, Wartofsky L, Butler VM, Wray HL

Department of Medicine, Walter Reed Army Medical Center, Washington, DC 20307-5001

Calcium supplements are widely used for the treatment of osteoporosis. The bioavailability of these preparations is unknown. Because poor tablet dissolution accounts for a majority of drug bioavailability problems, we determined the in vitro dissolution at 30, 60, and 90 minutes of 27 commercially available calcium carbonate supplements using the method of the U.S. Pharmacopoiea. At 30 minutes, five preparations (18%) were more than 75% dissolved, four (15%) between between 33 and 74%, and the remaining 18 (67%) were less than 33% dissolved. After 90 minutes, 17 (63%) of the preparations were less than 50% dissolved. Dissolution correlated negatively with the weight of filler (noncalcium carbonate material in the tablet) (rs= -0.51, P less than 0.01) but not with tablet hardness or cost. Similar to previous studies, we also found no correlation of dissolution with the stated calcium content, chemical source of calcium carbonate (oyster shell or chemical precipitate), or retail source. We conclude that there is a wide range of in vitro dissolution among the calcium carbonate preparations tested, and that the filler is an important determinant of the dissolution of these tablets. These results raise concern about the bioavailability of the calcium in these preparations and may have important implications for the therapeutic use of the various calcium carbonate supplements.

**This study demonstrated the fact that under stomach conditions, even after 1 1/2 hours of sitting in stomach like conditions in the laboratory, the majority of supplements were not even 50% dissolved of broken down.

02. Calcium in the Diet: Food Sources, Recommended Intakes, and Nutritional Bioavailability
Adv Food Nutr Res 1989;33:103-56

Miller DD

Institute of Food Science, Cornell University, Ithaca, New York 14853

Calcium nutritional status among some groups in the United States is suboptimal when judged by calcium intakes and the high prevalence of osteoporosis. Unfortunately, however, it is not clear that increases in calcium intake will have a significant impact on osteoporosis or other chronic diseases that have been linked to calcium nutriture. There is still considerable controversy surrounding the issue of calcium RDAs. The body's ability to adapt to varying levels of calcium intakes, the lack of sensitive indicators of calcium status, and the complexity and slow progression of chronic diseases such as osteoporosis make it very difficult to establish the role of diet in this regard. Great progress has been made in the study of calcium absorption. Much is know about the mechanisms involved in calcium absorption and its regulation. Thus, a rapidly advancing field and further developments will be invaluable to our understanding of the role of diet in calcium nutrition. Calcium bioavailability is affected by diet composition and the chemical form of calcium in foods. The calcium in dairy products is readily absorbed in the intestine. Lactose enhances calcium absorption efficiency under some conditions. Components of plants such as fiber, phytate, and oxalic acid may depress calcium absorption. High intakes of protein increase urinary losses of calcium but this effect may be partially offset by the phosphate association with most high-protein foods. Calcium absorption from salts used in supplement tablets is generally good. Absorption from salts such as calcium carbonate, which require acid for dissolution, may be poor in persons with achlorhydria (low or no stomach acid) unless the tablets are consumed with a meal. The practical significance of factors that may alter calcium bioavailability in normal mixed diets is difficult to assess. It may be a significant factor when calcium intakes are marginal or when absorption by the active transport, vitamin dependent process is impaired or not fully developed, i.e., it may be significant when vitamin D status is poor, in the elderly, and in young infants.

03. Contribution of Lead from Calcium Supplements to Blood Lead
Environ Health Perspect 2001 Mar;109(3):283-8

Gulson BL, Mizon KJ, Palmer JM, Korsch MJ, Taylor AJ

Graduate School of the Environment, Macquarie University, Sydney NSW 2109, Australia, bgulson@gse.mq.edu.au

We conducted a case-control study to determine the contribution of lead to blood from consumption of calcium supplements approximating the recommended daily intakes over a 6-month period. Subjects were males and females ages 21 to 47 years (geometric mean 32 years) with a geometric mean blood lead concentration of 2.5 microg/dL. They were subdivided into three groups. One treatment group (n=8) was administered a complex calcium supplement (carbonate/phosphate/citrate) and the other treatment group (n=7) calcium carbonate. The control group (n=6) received no supplement. The lead isotopic compositions of the supplements were completely different from those of the blood of the subjects, allowing us easily to estimate contributrion from the supplements. The daily lead dose from the supplements at 100% compliance was about 3 microg Pb. Three blood samples were taken at 2-month intervals before treatment to provide background values, and three were taken during treatment. Subjects in the treatment group were thus their own controls. Lead isotopic compositions for the complex supplement showed minimal change during treatment compared with pretreatment. Lead isotopic compositions in blood for the calcium carbonate supplement showed increases of up to 0.5% in the (206)Pb/(204)Pb ratio, and for all isotope ratios there was a statistically significant difference between baseline and treatment (p<0.005). The change from baseline to treatment for the calcium carbonate supplement differed from that for both the control group and the group administered the complex supplement. Blood lead concentrations, however, showed minimal changes. Variations in blood lead levels over time did not differ significantly between groups. Our results are consistent with earlier investigations using radioactive and stable lead tracers, which showed minimal gastrointestinal absorption of lead in the presence of calcium (+/- phosphorus) in adults. Even though there is no discernible increase in blood lead concentration during treatment, there are significant changes in the isotopic compositions of lead in blood arising from the calcium carbonate supplement, indicating a limited input of lead from diet into the blood. Because calcium carbonate is overwhelmingly the most popular calcium supplement, the chanes we have observed merit further investigation. In addition, this type of study, combined with a duplicate diet, needs to be repeated for children, whose fractional absorption of lead is considerably higher than that of adults.

04. Lead Content of Calcium Supplements
JAMA 2000 Sep 20;284(11):1425-9
Comments in: JAMA 2000 Dec 27;284(24):3126-7, JAMA 2000 Dec 27;284(24):13126;discussion 3126-7, JAMA 2000 Sep 20;284(11):1432-3

Ross EA, Szabo NJ, Tebbett IR

EnStage Renal Disease Program, Division of Nephrology, Hypertension, and Transplantation, University of Florida, Box 100224, Gainesville, FL. 32610-0224, USA, Rossea@medicine.ufl.edu

CONTEXT: Substantial quantities of lead have been reported in some over-the-couner calcium supplement preparations, including not only bone-meal and dolomite, but also over-the-counter natural and refined calcium carbonate formulations. Examination of this issue is warranted given recent increases in physician recommendations for calcium supplements for prevention and treatment of osteoporosis. OBJECTIVES: To determine the lead content of calcium supplements and to quantify the lead exposure from popular brands of calcium in dosages used for childhood recommended daily allowance, osteoporosis, and phosphate binding in dialysis patients. DESIGN AND SETTING: Analysis of lead content in 21 formulations of nonprescription calcium carbonate (including 7 natural [i.e. oyster shell] and 14 refined), 1 brand of prescription-only calcium acetate, and 1 noncalcium synthetic phosphate binder conducted in March 2000. MAIN OUTCOME MEASURES: Lead content, assayed using electrothermal atomic absorption, expressed as micrograms of lead per 800 mg/d of elemental calcium, per 1500 mt/d of calcium, and for a range of dosages for patients with renal failure. Six microg/d of lead was considered the absolute dietary limit, with no more than 1 microg/d being the goal for supplements. RESULTS: Four of 7 natural products had measurable lead content, amounting to approximately 1 microg/d for 800 mg/d of calcium, between 1 and 2 microg/d for 1500 mg/d of calcium, and up to 10 microg/d for renal dosages. Four of the 14 refined products had similar lead content, including up to 3 microg/d of lead in osteoporosis calcium dosages and up to 20 microg/d in high renal dosages. No lead was detected in the calcium acetate or polymer products. Lead was present even in some brand name products from major pharmaceutical companies not of natural oyster shell derivation. CONCLUSIONS: Despite increasingly stringent limits of lead exposure, many calcium supplement formulations contain lead and thereby may pose an easily avoidable public health concern.

05. Lead Content in 70 Brands of Dietary Calcium Supplements
Am J Public Health 1993 Aug;83(8):1155-60
PMID: 8342726 [PubMed - indexed for MEDLINE]

Bourgoin BP, Evans DR, Cornett JR, Lingard SM, Quattrone AJ

Environmental and Resource Studies Program, Trent University, Peterborough, Ontario, Canada

OBJECTIVES: Elevated lead levels in calcium supplements may pose a health risk, particularly to children with milk intolerance who rely on these products to meet their calcium requirement. Earlier reports chiefly focused on the lead content in supplements derived from bonemeal and dolomite. This study undertook to determine the lead levels in the major forms of calcium supplements curently available. METHODS: The lead content was measured in 70 brands of calcium supplemnets grouped in the following five categories: dolomite, bonemeal, refined and natural source calcium carbonate, and calcium chelates. RESULTS: The lead level measured in the supplements ranged from 0.03 microgram/g to 8.83 micrograms/g. Daily lead ingestion rates revealed that about about 24% of the products exceeded the US Food and Drug Administration's "provisional" total tolerable daily intake of lead for children aged 6 years and under. Less than 20% of the supplements had "normalized" lead level comparable to or lower than that reported for cow's milk. CONCLUSIONS: Children are the most sensitive to the low-level effects of lead. If calcium supplements are to provide an alternate source of calcium to some of these individuals, they should also deliver concomitant lead dosages no greater than those obtained from milk products themselves.

06. Meta-Analysis of Calcium Bioavailability: A Comparison of Calcium Citrate with Calcium Carbonate
Am J Ther 1999 Nov;6(6):313-21
Comments in: Am J Ther 2001 Jan-Feb;8(1):73-4, Am J Ther 2001 Jan-Feb;8(1):74-7

Sakhaee K, Bhuket T, Adams-Huet B, Rao DS

University of Texas Southwestern Medical School, Center for Mineral Metabolism and Clinical Research, Dallas, TX 75235-8891

OBJECTIVE: To perform a meta-analysis of data from available published trials comparing the bioavailability of calcium carbonate with that of calcium citrate. DATA SOURCES: The whole set was comprised of 15 studies involving 184 subjects who underwent measurement of calcium absorption from calcium carbonate and calcium citrate. Category A excluded four studies for lack of physiological relevance, use of a mixed prepration with low content of calcium carbonate, or wide variability in results. Category B was comprised of five studies (from Category A) involving 71 subjects who took calcium supplements on an empty stomach. Category C was comprised of six studies (from Category A) involving 65 subjects who took calcium preparations with meals. METHOD: The meta-analysis of calcium absorption data from calcium carbonate and calcium citrate, with calculation of effect size and 95% confidence intervals. RESULTS: Calcium absorption from calcium citrate was consistently significantly higher than that from calcium carbonate by 20.0% in the whole set, by 24.0% in Category A, by 27.2% on an empty stomach, and by 21.6% with meals. CONCLUSION: Calcium citrate is better absorbed than calcium carbonate by approximately 22% to 27%, either on an empty stomach or co-administered with meals.

07. Lead in Calcium Supplements
Environ Health Perspect 2000 Apr;108(4):309-19

Scelfo GM, Flegal AR

Environmental Toxicology, University of California, Santa Cruz, CA. 95064, USA, gscelfo@es.ucsc.edu

Intercalibrated measurements of lead in calcium supplements indicate the importance of rigorous analytical techniques to accurately quantify contaminant exposures in complex matrices. Without such techniques, measurements of lead concentrations in calcium supplements may be either erroneously low, by as much as 50%, or below the detection limit needed for new public health criteria. In this study, we determined the lead content of 135 brands of supplements that were purchased in 1996. The calcium in the products was derived from natural sources (bonemeal, dolomite, or oyster shell) or was synthesized and/or refined (chelated and nonchelated calcium). The dried products were acid digested and analyzed for lead by high resolution-inductively coupled plasma-mass spectrometry. The method's limit is quantitation averaged 0.06 microg/g, with a coefficient of variation of 1.7% and a 90-100% lead recovery of a bonemeal standard reference material. Two-thirds of those calcium supplements failed to meet the 1999 California criteria for acceptable lead levels (1.5 microg/daily dose of calcium) in consumer products. The nonchelate synthesized and/or refined calcium products, specifically antacids and infant formulas, had the lowest lead concentrations, ranging from nondetectable to 2.9 microg Pb/g calcium, and had the largest proportion of brands meeting the new criteria (85% of the antacids and 100% of the infant formulas).

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CORAL CALCIUM: HYPE VS. FACT PT. 2