Research

Absorbability and Cost Effectiveness in Calcium Supplementation.
J Am Coll Nutr. 2001 Jun;20(3):239-46
Heaney RP, Dowell MS, Bierman J, Hale CA, Bendich A.
Creighton University, Osteoporosis Research Center, Omaha, Nebraska 68131, USA. rheaney@creighton.edu
Background:: Cost-effectiveness of calcium supplementation depends not only on the cost of the product but on the efficiency of its absorption. Published cost-benefit analyses assume equal bioavailability for all calcium sources. Some published studies have suggested that there are differences in both the bioavailability and cost of the major calcium supplements. DESIGN: Randomized four period, three-way cross-over comparing single doses of off-the-shelf commercial calcium supplements containing either calcium carbonate or calcium citrate compared with a no-load blank and with encapsulated calcium carbonate devoid of other ingredients; subjects rendered fully vitamin D-replete with 10 microg/day 25(OH)D by mouth, starting one week prior to the first test. SUBJECTS: 24 postmenopausal women METHODS: Pharmacokinetic analysis of the increment in serum total and ionized calcium and the decrement in serum iPTH induced by an oral calcium load, based upon multiple blood samples over a 24-hour period; measurement of the rise in urine calcium excretion. Data analyzed by repeated measures ANOVA. Cost calculations based on average retail prices of marketed products used in this study from April through October, 2000.
Results:: All three calcium sources (marketed calcium carbonate, encapsulated calcium carbonate and marketed calcium citrate) produced identical 24-hour time courses for the increment in total serum calcium. Thus, these 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. Serum iPTH showed the expected depression accompanying the rise in serum calcium, and there were no significant differences between products.
Conclusion:: Given the equivalent bioavailability of the two marketed products, the cost benefit analysis favors the less expensive carbonate product.

Surgery for Obesity and Related Diseases
Official Journal of the American Society for Metabolic and Bariatric Surgery, September/October 2008
American Association of Clinical Endocrinologists, The Obesity Society, and the American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice for the Perioperative Nutritional, Metabolic, and Nonsurgical Support of the Bariatric Patient: "Minimal nutritional supplementation includes 1–2 adult multivitamin-mineral supplements containing iron, 1200–1500mg of calcium, and a vitamin B-complex preparation." pS121
The Levels of Calcium and Zinc that Are Found Naturally in Foods or in Calcium-Fortified Foods Do Not Affect Iron Absorption
Drs. Penelope Nestel and Ritu Nalubola: "Iron and Calcium's inhibition of absorption however, has not been found in long-term (6 months or longer) intervention studies. [3,4] An adaptive response, possibly involving an up-regulation in the efficiency of iron absorption, may prevent prolonged inhibition of iron absorption or the development of inadequate iron status when supplemental doses of calcium are taken. [3,6] The inhibitory effect of calcium on iron absorption has not been observed with calcium fortification or naturally occurring calcium in foods."
Effect of calcium supplementation on daily nonheme-iron absorption and long-term iron status
Minihane AM, Fairweather-Tait SJ
Institute of Food Research, Norwich Research Park, Colney, United Kingdom: "The long-term effect of consuming calcium supplements with meals (1200 mg Ca/d) on body iron (functional and storage iron) was investigated in 11 iron-replete adults over a 6-mo period. An unsupplemented control group (n = 13) was also monitored to correct for any seasonal changes in the biochemical measurements. There were no changes in any of the hematologic indexes, including hemoglobin, hematocrit, zinc protoporphyrin, and plasma ferritin resulting from the calcium supplementation. The results clearly show that long-term supplementation with calcium did not reduce plasma ferritin concentrations in iron-replete adults consuming a Western-style diet containing moderate to high amounts of calcium in most meals."
Calcium absorption and achlorhydria (no stomach acid)
RR Recker: "Defective absorption of calcium has been thought to exist in patients with achlorhydria. I compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement."
Why do I need a chewable multi-vitamin?: Vitamin and mineral supplementation after gastric bypass surgery is critical in maintaining proper health and nutrition. Micro-nutrient deficiency is the most common side effect from this procedure do to the malabsorptive component of gastric bypass. This typically occurs in approximately 21% of patients. Some frequently seen deficiencies include: iron, B12, folate, and calcium. Side affects when lacking in these important nutrients include: easy bruising, loss of hair, and lack of energy. Taking a chewable multivitamin is the easiest and most effective way of reducing the risk of micro nutrient deficiencies in the body after gastric bypass surgery. A chewable vitamin ensures success of absorption by beginning the digestive process in the mouth . Chewing breaks down the multivitamin to its most biologically available form and gives your digestive tract a distinct advantage of absorbing all the vitamins and minerals possible. Taking a capsule delays the absorption of supplements being taken. The shell of the capsule must be broken down in the digestive tract before absorption can occur. When and where this takes place cannot be determined with 100% accuracy. You must find a vitamin and mineral formulation that is made specifically for patients who have had gastric bypass surgery. This formulation should have dramatically higher percentages of vitamins A-E, B12, Folic Acid and Calcium. It must also include iron and chelated forms of minerals which increase your chance of absorption. Those patients taking anti-coagulants such as warfarin and coumadin must be sure to avoid formulations containing Vitamin K. Patients who suffer from migranes should consider a product that is sweetened with sucralose (Splenda) rather then aspartame. Be sure that your surgeon or primary doctor routinely checks your blood-work for early detection of any underlying deficiencies.