February 8, 2011
Calcium is the key mineral in bone health, and consumers are well aware of it. The 2009 International Food Information Council (IFIC) Functional Foods/Food for Health Consumer Trending Survey found 93 percent of them know calcium promotes bone health, and 93 percent said they are already eating or want to eat foods with calcium to promote bone health. However, that survey was taken before calciums bad press year of 2010. In July, a meta-analysis was published showing a positive correlation between calcium supplementation (without vitamin D) and the risk of heart attack.1 Of the 15 trials, five had patient-level data (8,151 participants) and 11 had trial-level data (11,921 participants). In the patient-level data studies, 143 people allocated to calcium had a myocardial infarction compared with 111 allocated to placebo. The meta-analysis of trial level data showed similar results: 296 people had a myocardial infarction (166 allocated to calcium, 130 to placebo), with an increased incidence of myocardial infarction in those allocated to calcium. The Council for Responsible Nutrition (CRN), among other industry members, reacted to the meta-analysis publication by reminding consumers that calcium supplementation has a long history of positive results in osteoporosis, and the organization called the researchers conclusion dramatically overstated.
Then, in November, the Institute of Medicine (IOM) said calcium and vitamin D intakes are mostly adequate and supplementation is largely unnecessary. Calcium needs range from 700 mg/d to 1,300 mg/d, depending on age, claimed the report. USDAs Agricultural Research Service (ARS) also suggested 741 mg/d is the average amount of dietary calcium needed to maintain a neutral calcium balancewhen the amount of calcium consumed equals the amount of calcium lost through elimination, but noted calcium intake of 1,035 mg/d would cover the needs of 95 percent of the American adult population.
Still, many Americansparticularly men, ethnic minorities and the socially disadvantagedare not meeting the current recommendations for adequate calcium of 1,200 mg/d through diet or supplements.2 Those who dont get enough may look to fortified foods and supplements, especially as research shows the bone benefits of calcium. A 2006 study found supplementation with calcium carbonate tablets supplying 1,200 mg/d was effective in preventing clinical fractures in the elderly population, as long as those patients were compliant.3 Even in younger subjects, calcium supplementation reduced the risk of all fractures and minimal trauma fractures.4 The benefit appeared to dissipate after treatment stopped.
Supplements and fortified foods may be better at addressing calcium deficiency, as other Boston researchers found no evidence higher intakes of milk or calcium from food sources reduce fracture incidence in a 12-year prospective study among 77,761 women, aged 34 through 59, who had never used calcium supplements.5 And ARS collaborative research found young girls who think they are lactose intolerant have curtailed their milk intake, resulting in decreased calcium intake and significantly decreased bone mineral density (BMD), compared to their peers who drank a steady amount of fortified milk.6
Children who dont get enough calcium may be robbing future bone health, as researchers presented findings at Experimental Biology 2010 meeting that showed bone health may be programmed as early as infancy.
Calcium also increases mens BMD, according to a University of Auckland, New Zealand, study that found 1,200 mg/d of calcium has effects on BMD in men comparable with those found in postmenopausal women, but a dosage of 600 mg/d is ineffective for treating BMD.7
Manufacturers can decide among various forms of calcium for their products. The most popular are calcium citrate, which is acidic based, and calcium carbonate, which is alkaline based. Popular knowledge has it that since calcium is best absorbed in an acidic environment, calcium citrate can still be absorbed even on an empty stomach. Calcium carbonate, on the other hand, requires extra stomach acid for better absorption and it is best taken right after meals, according to the theory.
Researchers from the Osteoporosis Research Center, Omaha, NE, tested this notion by comparing single doses of off-the-shelf commercial calcium supplements containing either calcium carbonate or calcium citrate compared with a placebo and with encapsulated calcium carbonate devoid of other ingredients in 24 postmenopausal women.8 They found all three calcium sources produced identical 24-hour total serum calcium levels, showing they were equally absorbed and had equivalent bioavailability. Urine calcium rose slightly more with the citrate than with the carbonate preparations, but the difference was not significant. Because calcium carbonate is less expensive, they concluded their cost-benefit analysis favors calcium carbonate.
However, calcium carbonate contains less elemental calcium than calcium citrate (40 percent vs. 21 percent), which usually requires a larger pill. Fortunately for consumers, elemental calcium is listed in the Supplement Facts panel, so they do not need to calculate the amount of calcium supplied by various forms of calcium supplements.
Other sources of calcium contain higher levels of elemental calcium and are becoming more popular among those looking for natural options. For instance, ESM Technologies offers ESC® (eggshell calcium), which the company says has a minimum of 35 percent elemental calcium. Perhaps this was the extra element that empowered eggshell calcium to show a positive effect bone density in a review from Slovakia.9 Researchers found eggshell calcium from chickens increased bone density in animal models of postmenopausal osteoporosis; reduced pain and osteoresorption, and increased mobility and bone density in postmenopausal women and women with senile osteoporosis; and showed similar or better absorption than food-grade purified calcium carbonate in piglets.
In another comparison to conventional calcium, researchers from the Harvard Medical School, Boston, and University of Connecticut, Storrs, discovered a calcium supplement derived from marine algae was more effective at bone formation.10 Their report detailed head-to-head comparisons of calcium carbonate or calcium citrate with the algae-sourced calcium (as AlgaeCal®, from Algaecal Inc.) on proliferation, mineralization and oxidative stress in cultured human osteoblast cells. The algae calcium increased alkaline phosphatase activity (a measure of mineralization) two- to 2.5-times more effectively than calcium carbonate and calcium citrate, respectively. The algae calcium was also three- to four-times more effective, respectively, on DNA synthesis, which leads to new bone-building cells, in addition to depositing one- to four-times more calcium than either top calcium form, respectively.
References are on the next page...
1. Bolland MJ, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010 Jul 29;341:c3691. doi: 10.1136/bmj.c3691.
2. Ma J, Johns RA, Stafford RS. Americans are not meeting current calcium recommendations. Am J Clin Nutr. 2007 May;85(5):1361-6.
3. Prince RL, et al. Effects of calcium supplementation on clinical fracture and bone structure: results of a 5-year, double-blind, placebo-controlled trial in elderly women. Arch Intern Med. 2006 Apr 24;166(8):869-75.
4. Bischoff-Ferrari HA, et al. Effect of calcium supplementation on fracture risk: a double-blind randomized controlled trial. Am J Clin Nutr. 2008 Jun;87(6):1945-51.
5. Feskanich D, et al. Milk, dietary calcium, and bone fractures in women: a 12-year prospective study. Am J Public Health. 1997 Jun;87(6):992-7.
6. Leann Matlik, et al. Perceived Milk Intolerance Is Related to Bone Mineral Content in 10- to 13-Year-Old Female Adolescents. Pediatrics. 2007 Sep;120:e669 - e677.
7. Reid IR, et al. Randomized controlled trial of calcium supplementation in healthy, nonosteoporotic, older men. Arch Intern Med. 2008 Nov 10;168(20):2276-82.
8. Heaney RP, et al. Absorbability and cost effectiveness in calcium supplementation. J Am Coll Nutr. 2001 Jun;20(3):239-46.
9. Rovenský J, et al. Eggshell calcium in the prevention and treatment of osteoporosis. Int J Clin Pharmacol Res. 2003;23(2-3):83-92.
10. Adluri RS, et al. Comparative effects of a novel plant-based calcium supplement with two common calcium salts on proliferation and mineralization in human osteoblast cells. Mol Cell Biochem. 2010 Jul;340(1-2):73-80. Epub 2010 Mar 7.
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