Introduction
The need for adequate calcium intake has been the focus of numerous studies. Calcium is an essential nutrient needed for biological functions such as muscular contractions, miosis, blood coagulation, nervous or synaptic impulse transmission, intracellular signalling, hormone and enzyme secretions, though less than 1% of total body calcium is needed to support these critical metabolic functions. The remaining 99% is essential for structural support of the skeleton.1 The human body cannot produce calcium and therefore it has to be absorbed from food. Most individuals can easily receive at least half their calcium requirement per day through their diet.2 Many studies have demonstrated that calcium intake prevents diseases such as osteoporosis.3 Calcium supplementation is indicated for patients who are unable to obtain enough calcium on a daily basis through their diet. The scope of this article is not to discuss all the benefits of calcium, but to provide the pharmacist with a better understanding of the absorption of the different calcium supplements available, and how to assist their patients in obtaining the optimal calcium required. It is often a daunting task for patients to understand their daily requirements and how to achieve the goals set for them. This is further complicated by the availability of multiple supplements, each with different dosing regimens, compounds, and the lack of product standardisation.
The physiological function of calcium in the
human body
Calcium accounts for one to two per cent of adult human body weight and is one of the major mineral components of the skeletal system. Calcium is present in the skeletal system in the form of hydroxyapatite, which is an inorganic crystalline structure made
up of calcium and phosphorus [Ca10(PO4)6(OH)2] which provide rigidity.4 Calcium is also essential for nerve conductivity, muscle contraction, hormone and enzyme secretion and blood clotting.
Metabolism of calcium
Absorption, bioavailability and excretion of dietary calcium
Calcium requirement is dependent on the state of calcium metabolism, which is regulated by three main mechanisms: intestinal absorption, renal absorption and bone turnover. These in turn are regulated by a set of interacting hormones, including parathyroid hormone (PTH), 1,25-dihydroxyvitamin D [1,25 (OH)2D], ionised calcium itself, and their corresponding receptors in the gut, kidney and bone.5 Control is mediated through the calciotropic hormones: parathyroid hormone (PTH), calcitriol and calcitonin.4 Parathyroid hormone secreted by the parathyroid gland and calcitonin secreted by the thyroid gland maintain calcium levels at a range of 8.5–10.5 mg/dL. The PTH affects renal function to retain more calcium. The kidneys filter as much as 10,000 mg of calcium daily, with ~ 98% being reabsorbed. Serum calcium is very tightly regulated and does not fluctuate with changes in dietary intakes.4
Calcium is absorbed by the gastrointestinal tract through active transport, which occurs predominantly in the duodenum and the proximal jejunum. In the distal jejunum and the ileum calcium is absorbed via passive diffusion. The active compound is saturable, stimulated by 1.25(OH)D3 (calcitriol) and influences the active transport, increasing the permeability of the membrane, regulating the calcium migration through the intestinal cells, increasing the levels of caldindin (calcium transporting protein-CaBP).6 Caldindin transfers the calcium ion directly into the
Calcium supplements – an overview
Christel Hanson, BPharm, BScHons, MSc(Med) Pharmacy Correspondence to: [email protected]
Keywords: calcium, calcium carbonate, calcium citrate, absorption, supplement
Abstract
Calcium is an essential nutrient required for numerous biological functions. Considering the important role that calcium plays in bone health, it is necessary to take special care to reach the daily recommended calcium intake. This overview describes the factors that can influence calcium absorption, the methodologies used to evaluate calcium absorption, bioavailability, pharmacokinetics and pharmacodynamics, different calcium salts as well as the best approach to optimise the intake of calcium.
epithelial cell. Calcitriol is a cholesterol derivative. Under the influence of PTH, the kidneys convert cholecalciferol into the active hormone, 1.25 dihydrocholecalciferol, which acts on the epithelial cells lining the small intestine, to increase the rate of absorption of calcium. At low intakes, calcium is mainly absorbed by active transport, but as intakes increase, this mechanism becomes saturated and additional calcium is absorbed by carrier-mediated (non-saturable) diffusion. The net result is an increase in the absolute amount of absorbed calcium with increasing intakes, but a decrease in fractional absorption. Fractional absorption of calcium from foods and supplements is inversely related to the amount of calcium consumed over a range of 150–500 mg calcium. Calcium uptake, through active transport, is controlled by the circulating concentration of ionised calcium in the blood. Should this fall below 1.1 mmol/L, the amount of calcium absorbed is increased; conversely, should concentrations rise above 1.3 mmol/L, absorption is reduced.4 Low levels of PTH in the blood inhibit calcium absorption from the gut.
Vitamin D is essential for the absorption of calcium in the intestines. Calcitriol, the active form of vitamin D, increases the absorption of calcium. The PTH stimulates calcitriol synthesis from cholesterol. Vitamin D3 (cholecalciferol) is produced from sun exposure while vitamin D2 (ergocalciferol) is acquired by food intake.6 The absorbed vitamin D reaches the lymphatic system through the cholymicrons entering the bloodstream and is transported to the liver, bonded to the vitamin D transporter protein (DBP). In the liver it is hydroxylated to 25-hydroxyvitamin D [25(OH)D] where it is stored. Once the calcium concentration falls, 25(OH)D bonds to the DBP, is transported to the kidneys and released in the tubular renal cell and again hydroxylated, forming 1.25- dihydroxyvitamin D [1.25(OH)2D], the biological active form. Vitamin D is stored in the liver and becomes available through hydroxylation in the renal tubules to its active form 1,25(OH)2D3.⁷
Factors that influence calcium absorption, bioavailability and excretion of calcium
Amount consumed: The efficiency of absorption increases as calcium intake decreases.1 As calcium intake increases (> 500 mg/ day), passive diffusion presents a greater absorption of calcium.⁶
Age and life stage: Calcium absorption is as high as 60% in infants and young children. Growth hormone (GH) can promote calcium absorption indirectly activating the renal 1α hydroxylase and elevating the serum concentration of 1,25 (OH)2D3.⁶ Absorption decreases to 15–20% in adulthood, increases in pregnancy and continues to decrease in women and men older than 50 years.1
Pregnancy and lactation: Fractional calcium absorption is increased from 20–30% and up to 60% during the last trimester. This increase is associated with an increased plasma concentration of calcitriol, suggesting vitamin D plays a role. In addition, the hormones oestrogen, lactogen and prolactin may stimulate increased active calcium absorption. Increased bone mineral resorption from the mother’s skeleton liberates calcium, making it available for the foetus. During lactation, approximately
250 mg of calcium is secreted in breast milk. Maternal urinary calcium excretion is reduced and bone resorption increased. Following the resumption of menstruation, calcium absorption increases, due to increased oestrogen concentration, stimulating calcitriol production, and bone mineral density begins to increase.4
Postmenopausal women: Decreased oestrogen production increases bone resorption and decreases calcium absorption, resulting in bone loss. A decrease in oestrogen levels is associated with decreased calcitriol production and thus reduced calcium absorption. Annual decreases in bone mass of 3–5% per year frequently occur in the first years of osteoporosis.1
Vitamin D intake: Calcium absorption is dependent on an adequate level of the active form of Vitamin D, calcitriol.1 The inactive form of vitamin D3 (colecalciferol) is produced through cutaneous synthesis and solar exposition is responsible for 80–90% of the stocks of vitamin D. Vitamin D2 (ergocolecalciferol) is the dietary form of the vitamin, which is found in egg yolk, cheese and beef liver.6 Persons who are not exposed to sunlight should use Vitamin D supplements. Pharmacological dosing of vitamin D supplementation, 25-hydroxyvitamin D3, should be done under medical supervision.4
Vitamin K2: Vitamin K2 (menaquinone) facilitates the action of osteoblasts in the ossification of new skeletal material. Osteoblasts produce the protein osteoblastin, which binds calcium to the bone matrix. Vitamin K2 activates osteocalcin. Studies have shown levels of vitamin K2 were low in patients with osteoporotic fractures. In nature vitamin K2 is synthesised by bacteria and small amounts are available from fermented foods, milk products, especially cheese, and meat. Changes in diets and food-processing techniques have reduced the levels of vitamin K2 ingested in food. The daily value (DV) recommended supplementation of vitamin K2 is 180 mcg per day for adult males and 90 mcg for adult females.8,9,10
Other components of food: Phytic acid and oxalic acid, found naturally in green vegetables (e.g. cabbage, spinach, broccoli and beans), bind to calcium, forming insoluble complexes, and inhibit calcium absorption. Wheat products (except wheat bran) do not appear to inhibit calcium absorption.1 Dietary milk proteins and lactose increase calcium solubility and the osmolarity of calcium in the ileum, stimulating passive diffusion.6
Bioactive compounds: Bioactive compounds such as indigestible oligosaccharides (inulin, fructans) are resistant to hydrolysis of food enzymes. Once they are not hydrolysed and absorbed in the stomach and small intestines, these compounds undergo partial or total fermentation when entering into the large intestine. Fermentation leads to the production of short chain fatty acids, which results in the acidification of the intestines and consequently stimulation of calcium absorption.6
Protein intake: High protein intake was previously thought to increase calcium excretion and was therefore thought to negatively affect calcium status. However, more recent research suggests that high protein intake also increases intestinal calcium absorption. Diets low in protein may increase concentrations of PTH and calcitriol in the short term, and may be detrimental to skeletal health in the long term.11
Caffeine intake: The effect of caffeine in tea and coffee can affect calcium excretion moderately. One cup of regular brewed coffee causes loss of 2–3 mg of calcium. Massey (2005) found that moderate caffeine consumption of one cup of coffee and two cups of tea per day, has no harmful effect on bone status in individuals who ingest the recommended daily allowance of calcium.12
Alcohol intake: Alcohol can reduce the absorption of calcium. Alcohol also inhibits liver enzymes converting vitamin D to its active form. Cortisol levels increase with excessive alcohol consumption resulting in less osteoblast activity and increased osteoclast activity in the bone, resulting in bone resorption. Chronic alcohol consumption increases PTH which leaches calcium from bone. In men, testosterone levels decrease resulting in an increase in osteoclast activity and bone resorption. A detrimental effect of alcohol consumption on bone may occur only when in excess of three glasses of wine per day is consumed. Alcoholics have a 2.8-fold increased risk for bone fractures and a 23% prevalence of osteoporosis.13
Disease conditions: Disorders that influence calcium absorption include hyperparathyroidism, diseases of the kidney, achlorhydria and liver cirrhosis.13
Recommended intakes
Dietary Reference Intake (DRI) is the general term for the set of reference values used for planning and assessing the nutrient intakes of healthy people. These values vary by age and gender. Recommended Dietary Allowances (RDA) represent the average daily level of intake sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals. Table I lists the RDA for calcium as published by The National Osteoporosis Foundation of South Africa (NOFSA).2
Table I: Recommended Daily Allowance of calcium (National Osteoporosis
Foundation of South Africa)
Age group Elemental calcium per day (mg)
Infants 1000
Children and adolescents 1500
Young adults 1000
Pregnant and lactating females 1500
Post-menopausal women
• On hormone replacement therapy • No hormonal replacement therapy
1000 1500
Vitamin D
Recommended RDAs for vitamin D are as follows: men and women aged 19 to 70 years, 600 international units (IU); and men
and women older than 70 years, 800 IU. For maximal benefit to bone, cognition, and neuromuscular health, 25(OH)D levels in the blood should be at least 30 ng/mL (75 nmol/L). When 25(OH)D levels are below 20 ng/mL, the patient has vitamin D insufficiency, and when they are below 20 ng/mL (50 nmol/L), the patient has vitamin D deficiency.14
Calcium supplements (combinations, salts and
absorption)
Although obtaining calcium from dietary sources is preferable, calcium supplementation may be warranted in some patients, such as older adults with osteoporosis. Calcium supplements are derivatives of natural products, such as oyster shell or bone. Several different calcium compounds are used in supplements, including calcium carbonate, calcium gluconate, calcium phosphate and calcium citrate. Calcium carbonate is the most common supplement but is less soluble in water. Calcium citrate has an acidic base. This acidity requires less production of natural stomach acids, allowing this type of calcium to be better absorbed than the carbonate form. It does, however, have less elemental calcium concentration (20%) and low bioavailability.15
These compounds contain different amounts of elemental calcium. Table II indicates the elemental calcium in the different calcium compounds in calcium supplements available in South Africa.2
If 500 mg elemental calcium is required, 1 250 mg of calcium carbonate should be administered (40% of 1 250 = 500), 2 000 mg of calcium citrate compound will provide 500 mg elemental calcium (24% of 2 000 = 500) etc.2
Calcium supplements are best absorbed when taken several times per day in amounts of 500 mg or less. Initiating calcium supplementation, the dose should be gradually increased, starting with 500 mg per day for the first week and increased slowly. Calcium carbonate is the most concentrated form of calcium, allowing for smaller quantities to be used.2 Calcium citrate is better absorbed than calcium carbonate, but is more expensive and more of the supplement needs to be taken because the elemental calcium content is half that of calcium carbonate. Calcium is best absorbed in an acidic environment, thus should be taken with food. Food stimulates secretion of gastric acid and slow gastric emptying allowing better dispersion, dissolution and absorption of less soluble preparations. A light meal increases the absorption of calcium carbonate with 20–25%. Calcium carbonate and calcium citrate present a similar absorption when taken with food.6 Most branded products are absorbed easily in the body.2 Intestinal absorption of calcium does not necessarily reflect bioavailability of calcium.6
add the calcium product to some vinegar. If it has not dissolved after 30 minutes, it will probably not dissolve in the stomach.2 Methods to test the bioavailability of nutrient balance include balance serum concentrations, urinary excretion, serum (or body) tracer concentrations, biomarkers, and in vitro testing (dissolution and disintegration). Hanzlik (2005) compared the oral bioavailability of calcium formate, calcium carbonate and calcium citrate using the calcium blood serum and serum intact parathyroid hormone (iPTH) methods, with immunoradiometric assay, to test bioavailability.16 Changes in serum calcium are often mirrored by opposite but amplified changes in serum iPTH concentration. These changes are a pharmacodynamic indicator or biomarker of changes in serum calcium. For example, a 5% increase in serum calcium can elicit a 40% to 50% decrease in serum iPTH. In this study, serum calcium carbonate concentration increased with 4% and a fall in serum iPTH of 20–40%. Calcium citrate showed a modest change in serum calcium of 9%, while calcium formate had a 15% increase in serum calcium and 70% decrease in iPTH. In a randomised trial by Kressel et al, different organic calcium salts, calcium lactate malate and calcium lactate citrate, had almost the same bioavailability as calcium carbonate and calcium gluconate.17 The total serum calcium as calcium lactate citrate 7.6%, calcium lactate malate7.4%, calcium carbonate 5.5% and calcium gluconate 5.8%, two hours after ingestion. Intact parathyroid hormone concentration showed the expected depression for the calcium salts. In a similar study, Heller et al reported calcium citrate to be more bioavailable than calcium carbonate, when given with a meal.18
More important than the solubility, absorption and bioavailability of calcium salts is the quality of the supplements’ formulation. Badly formulated pharmaceutical compounds do not disintegrate when in contact with gastric secretions, diminishing their absorption.6
Analysis done by an independent laboratory, Labdoor laboratories (USA), on 30 calcium supplements available in the USA, found that the average product nearly matched its label for calcium, exceeding its claims by 3.8%. All 30 products contained no traces of heavy metal while the nutritional value scored an average of 9.6 out of 10. The projected efficacy tested indicated the average product contained 701.0 mg of calcium and 820.8 IU of vitamin D3 per serving. Products were scored and ranked. Of the products available in South Africa, the scores were as follows (ranking in brackets and scores A–-F): Solgar® calcium magnesium with Vitamin D3 (2nd; A); GNC® calcium citrate (4th; A-); Caltrate® calcium and vitamin D3 (29th; C-).19
Dosage forms and combination products
Oral calcium supplements are available in different delivery vehicles: chewable tablets, powder base, water dispersible and conventional tablets. In a 2013 study, patients preferred conventional tablets to chewable tablets and liked powder-based calcium supplements the least.21 Many supplements contain combinations of vitamin D, vitamin K2, zinc, magnesium and boron. These supplements are formulated to contain the recommended RDA per tablet, with a dosing interval of two to three times per day. Refer to Table II for calcium and vitamin D content of some of the calcium supplements available in South Africa.
Table II: Elemental calcium salts and vitamin D concentration in calcium products Calcium salt % Elemental
calcium Available product in South Africa Elemental calciumper dosage form Vitamin D
Calcium carbonate 40 Calcium (Revite) 875 100
Caltrate 600+D (Pfizer) 600 400
Sandoz Calcium Optimum+® (Sandoz) 600 400
Osteochoice® (Sanofi) 600 400
B-Cal-DM (iNOVA) 500 400
B-Cal-Ultra (Georen) 500 400
Calsuba® powder (GSK) 500 200
Emvit® Cal-D3 500 200
Menacal 7 (Ascendis Health) 500 400
Chewable calcium wafer (Solgar) 500
-Vital calcium (-Vital) 400 1.25
Caltrate D (Pfizer) 300 100
Calcium phosphate 30-40 Osteoscript® (Calcium-s-amino ethanol phosphate calcium biglycinate) (Medford®)
200 50
Calcium citrate 24 Chelated calcium® (calcium glycinate amino acid chelated, calcium carbonate) (Solgar)
1000
-Calcium citrate (GNC) 1000
-Calcium citrate malate 24 Advanced calcium complex®
(Calcium as dicalcium malate, citrate glycinate aminoacid chelate) (Solgar)
Adverse effects
Adverse effects occur most frequently with calcium carbonate. The most common adverse effects of calcium supplementation are constipation, bloating and excessive gas. Excessive gas and bloating are due to the chemical reaction between calcium carbonate and the hydrochloric acid in the stomach. CaCO3(s) + 2 HCl(aq) = H2O(l) + CO2(g) + CaCl2(aq).22
Calcium and medication interaction
Calcium supplements have the potential to interact with several prescription drugs and over-the-counter medications.
Decrease in calcium absorption
• Iron supplementation: An insoluble calcium-iron complex is formed when taken together orally. They should be taken two hours apart.23
• Tetracycline and fluoroquinolones: They form an insoluble complex with calcium which is not absorbed. They should be taken two hours apart.23
• Bisphosphonate: The calcium supplement should not be taken in the morning as it will interfere with absorption of bisphosphonates. The calcium supplement should be taken at noon and night.2
• Glucocorticosteroids: Glucocorticoids reduce bone remodelling by directly modulating osteoclast, osteoblast, and osteocyte
function. They increase renal calcium excretion and decrease gastrointestinal calcium absorption, resulting in reduced serum calcium. Reduced serum calcium causes increased secretion of PTH, and glucocorticoids increase PTH sensitivity. PTH action in turn stimulates osteoclast activity.24 Glucocorticoids also decrease intestinal calcium absorption, in part by opposing the action of vitamin D, and by decreasing the expression of calcium channels in the duodenum. In addition, glucocorticoids increase renal calcium excretion by decreasing calcium reabsorption.25 • Thiazide diuretics: This can interact with calcium carbonate and
vitamin D-supplements, increasing the risk of hypercalcaemia and hypercalcuria.1
• Aluminium and magnesium-containing antacids: Urinary calcium excretion is increased.2
• Proton pump inhibitors: Inhibition of the proton pump reduces the fraction of calcium absorbed from calcium carbonate in postmenopausal women. Long-term treatment with PPI, especially at high doses, is associated with increased risk of hip fractures.7
Increase in calcium absorption
Magnesium: Low magnesium levels stimulate calcium excretion in the urine. Supplementation with magnesium should only be undertaken when blood results confirm hypomagnesium.23
Vitamin D3: The RDA for Vitamin D is 800 UI per day in persons younger than 70 years and 1 200 IU in persons older than
Table III. A comparison between the different calcium salts
Calcium salt Absorption and bioavailability
Calcium carbonate • Alkaline-based compound found in nature in shells, rocks, limestone • Highest concentration of elemental calcium (35–40%)
• Bioavailability in humans 15–40%20
• Needs stomach acid to be absorbed, to be taken with food
Calcium citrate • Acidic base
• Less elemental calcium than calcium carbonate (20%) • Better absorbed than calcium carbonate (22–27%) • Bioavailability (21%)6
• Requires less stomach acid to be absorbed. Can be taken any time of day
• Suitable for aging patients with impaired gastric function, inflammatory bowel disease or achlorhydria • Preferable for patients using acid blockers (PPI)
Calcium citrate malate • Formed from calcium salt of citric acid and malic acid • Contains 26% elemental calcium
• Bioavailability 42%
• Absorption rate of 36–37%, due to its water-solubility and method of dissolution • Can be taken with or without food
• Suitable for aging patients with impaired gastric function, inflammatory bowel disease or achlorhydria • Preferable for patients using acid blockers (PPI)
• Vegetarian calcium source
Calcium lactate • Present in foods such as aged cheese and baking powder
• Low amount of elemental calcium (9–13%). Bioavailability is acceptable • Can be absorbed at various pH’s in body20
Calcium gluconate • Low amounts of elemental calcium (9–13%)20
Calcium phosphate • Absorption level similar to calcium carbonate • Elemental calcium of 31–38%20
70 years. Persons who are not exposed to sunlight should use Vitamin D supplements. Pharmacological doses of vitamin D supplementation, 25-hydroxyvitamin D3, should be done under medical supervision.2
Calcium affecting drug serum levels
Digoxin serum levels may decrease when calcium is used together with digoxin.23
Fluoroquinolones, levothyroxine, tetracycline, phenytoin: These drugs decrease the absorption of calcium supplements and dosing should be spread two hours apart.25
Iron supplements: Calcium salts chelate the iron in supplements and prevent the absorption of iron.23
Calcium supplementation risk/benefit ratio
Cardiovascular disease: Meta-analysis of randomised controlled trials by Bolland et al, first published in 2008, raised the risk of possible increase in risk of adverse cardiovascular events in women and men associated with the use of calcium or calcium plus vitamin D supplements.25 Similar results in some aspects were reported by Li et al.23 These published articles were reviewed by Heaney et al, after a number of issues were raised, such as inadequate compliance with intervention and use of nontribal calcium supplements.3 They concluded that “the authors do not believe that the evidence presented to date (2012) regarding the hypothesised relationship between calcium supplement use and increased cardiovascular disease risk is sufficient to warrant change in the Institute of Medicine recommendations, which advocate use of (calcium) supplements to promote optimal bone health in individuals who do not obtain recommended intakes of calcium through dietary sources”.3 Adverse effects of calcium supplementation on the cardiovascular system could be mediated through hypercalcaemia. These adverse effects occur when excessively high calcium intakes (more than 1 400 mg/day) override normal homeostatic control of serum calcium levels. Hypercalcaemia has been associated with an increased risk of death from cardiovascular disease and ischaemic heart disease, but not from stroke.26 Concern has recently arisen about the potential adverse effects of excessive calcium intake, i.e. calcium loading from supplements, on arterial calcification and risks of cardiovascular diseases (CVD) in older adults. Healthy kidneys have limited capability of eliminating excessive calcium in the diet; the likelihood of soft-tissue calcification may increase in older adults who take calcium supplements, particularly in those with age or disease-related reduction in renal function. Current studies are inconclusive on the increased risk of vascular calcification, and further studies are needed.27
Reid et al noted a 7% increase in HDL cholesterol and a 16% increase in HDL to LDL cholesterol ratio following consumption of 1 000 mg calcium per day over a period of a year in postmenopausal women. This may be associated with a 20–30% reduction in cardiovascular events.28
Gastritis: Calcium carbonate may cause gastritis if taken between meals as this can stimulate rebound acid production in the stomach.2
Kidney stones: No scientific evidence exists that calcium causes kidney stones. In hypercalcuria, it is advised to limit calcium intake to 1 000 mg per day. In normal urinary calcium levels in the presence of kidney stones, it is not necessary to limit calcium intake, but vitamin D supplementation should be used with caution.2
Post menopause: The Women’s Health Initiative (WHI) found a relative risk reduction of 29% in hip fractures in those women on treatment of 1 000 mg calcium carbonate and 400 UI of vitamin D.⁷
Cancer: Evidence from prospective cohort trials support the protective effect of calcium against colorectal cancer. A high calcium intake (> 1 000 mg/day) may reduce the risk of colorectal cancer between 15–40%.⁴ Any calcium that is not absorbed and passes into the colon is capable of forming insoluble calcium “soaps” with phosphate, free fatty acids and free bile acids, thus reducing the concentrations and toxicity of free fatty acids and free bile acids.⁴ Case-control studies suggest inverse association between calcium consumption and the risk of breast cancer. Women who consume more total calcium (from diet and supplements) are, on average, 20% less likely to develop breast cancer than women who consume less.⁴
Weight management: Evidence for a possible anti-obesity effect of calcium comes from a small number of studies conducted in overweight adults. A higher intake of calcium was associated with a greater reduction of body fat (4.4%) compared to the control group and a significant reduction in waist circumference was observed.29 Further research is required in this area to determine whether or not calcium plays a role in weight management. It is too early to promote weight-loss benefits of additional calcium supplements.4
Pre-eclampsia: Calcium supplements during pregnancy may reduce the risk of pre-eclampsia, but the benefits may apply only to patients with inadequate calcium intakes. The American College of Obstetrics and Gynecology recommends 1 500–2 000 mg calcium supplement, to reduce the severity of pre-eclampsia in pregnant women who have dietary calcium intakes of less than 600 mg per day.1
Conclusion
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