Review

Authors: Blerina Shkembi, Thom Huppertz

This article reviews physicochemical aspects of calcium absorption from foods. Notable differences are observed between different food products in relation to calcium absorption, which range from <10% to >50% of calcium in the foods. These differences can be related to the interactions of calcium with other food components in the food matrix, which are affected by various factors, including fermentation, and how these are affected by the conditions encountered in the gastrointestinal tract. Calcium absorption in the intestine requires calcium to be in an ionized form. The low pH in the stomach is critical for solubilization and ionization of calcium salts present in foods, although calcium oxalate complexes remain insoluble and thus poorly absorbable. In addition, the rate of gastric transit can strongly affect fractional absorption of calcium and a phased release of calcium into the intestine, resulting in higher absorption levels. Dairy products are the main natural sources of dietary calcium in many diets worldwide, which is attributable to their ability to provide high levels of absorbable calcium in a single serving. For calcium from other food products, lower levels of absorbable calcium can limit contributions to bodily calcium requirements.

Topics: Calcium; Calcium, Dietary; Eating; Food; Food Analysis; Gastric Acid; Gastrointestinal Tract; Hydrogen-Ion Concentration; Intestinal Absorption; Ions; Nutritional Physiological Phenomena; Nutritional Requirements; Solubility

PubMed: 35011055
DOI: 10.3390/nu14010180

Review

Authors: Aurel T Tankeu, Valirie Ndip Agbor, Jean Jacques Noubiap...

Over the past decade, the number of individuals taking calcium supplementation worldwide has been on the rise, especially with the emergence of new pharmaceutical companies specialized in the marketing of dietary supplements; with calcium supplementation being their main business axis. This is mostly because of the established role of calcium in the prevention and treatment of osteoporosis and, to a lesser extent, its role in the prevention of fractures. Recently, a rising body of evidence on the adverse effect of calcium supplementation on nonskeletal, especially cardiovascular, health has been a cause for concern. In fact, a significant number of studies have reported an association between calcium supplementation and adverse cardiovascular events, even though high dietary calcium intake was shown to have a protective effect. The mechanism by which calcium supplementation could cause a cardiovascular event was still unclear until a recent study published in the Journal of the American Heart Association. Combining this recent finding with available data associating calcium supplementation with cardiovascular mortality and all-cause mortality, we call on the need for an evidence-based approach to calcium supplementation, while stressing on the safety of dietary calcium intake over the former on cardiovascular health.

Topics: Aged; Blood Pressure; Calcium; Calcium, Dietary; Cardiovascular Diseases; Dietary Supplements; Female; Fractures, Bone; Humans; Hypertension; Male; Middle Aged; Osteoporosis; Randomized Controlled Trials as Topic; Risk Factors

PubMed: 28466573
DOI: 10.1111/jch.13010

Meta-Analysis Review

Authors: Mark J Bolland, William Leung, Vicky Tai...

OBJECTIVE

To examine the evidence underpinning recommendations to increase calcium intake through dietary sources or calcium supplements to prevent fractures.

DESIGN

Systematic review of randomised controlled trials and observational studies of calcium intake with fracture as an endpoint. Results from trials were pooled with random effects meta-analyses.

DATA SOURCES

Ovid Medline, Embase, PubMed, and references from relevant systematic reviews. Initial searches undertaken in July 2013 and updated in September 2014.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials or cohort studies of dietary calcium, milk or dairy intake, or calcium supplements (with or without vitamin D) with fracture as an outcome and participants aged >50.

RESULTS

There were only two eligible randomised controlled trials of dietary sources of calcium (n=262), but 50 reports from 44 cohort studies of relations between dietary calcium (n=37), milk (n=14), or dairy intake (n=8) and fracture outcomes. For dietary calcium, most studies reported no association between calcium intake and fracture (14/22 for total, 17/21 for hip, 7/8 for vertebral, and 5/7 for forearm fracture). For milk (25/28) and dairy intake (11/13), most studies also reported no associations. In 26 randomised controlled trials, calcium supplements reduced the risk of total fracture (20 studies, n=58,573; relative risk 0.89, 95% confidence interval 0.81 to 0.96) and vertebral fracture (12 studies, n=48,967. 0.86, 0.74 to 1.00) but not hip (13 studies, n=56,648; 0.95, 0.76 to 1.18) or forearm fracture (eight studies, n=51,775; 0.96, 0.85 to 1.09). Funnel plot inspection and Egger's regression suggested bias toward calcium supplements in the published data. In randomised controlled trials at lowest risk of bias (four studies, n=44,505), there was no effect on risk of fracture at any site. Results were similar for trials of calcium monotherapy and co-administered calcium and vitamin D. Only one trial in frail elderly women in residential care with low dietary calcium intake and vitamin D concentrations showed significant reductions in risk of fracture.

CONCLUSIONS

Dietary calcium intake is not associated with risk of fracture, and there is no clinical trial evidence that increasing calcium intake from dietary sources prevents fractures. Evidence that calcium supplements prevent fractures is weak and inconsistent.

Topics: Aged; Bone Density; Calcium, Dietary; Dietary Supplements; Fractures, Bone; Frail Elderly; Humans; Middle Aged; Randomized Controlled Trials as Topic

PubMed: 26420387
DOI: 10.1136/bmj.h4580

Review

Authors: Kelvin Li, Xia-Fang Wang, Ding-You Li...

Calcium is an important integrative component of the human body and critical for human health. It has been well established that calcium intake is helpful in the prevention and treatment of osteoporosis, which has become one of the most serious public health problems across the world. However, community-dwelling adults with and without osteoporosis are rarely concerned or even not aware of the potential side effects of high or inappropriate doses of calcium intake. Some recent studies have revealed that excessive calcium intake might increase the risks of cardiovascular diseases. The purpose of this article was to review the health benefits, costs, and consequences of calcium supplementation on osteoporosis/osteoporotic fractures, cardiovascular events, kidney stones, gastrointestinal diseases, and other important diseases. In the end, we suggest that calcium supplementation should be prescribed and taken cautiously, accounting for individual patients' risks and benefits. Clearly, further studies are needed to examine the health effects of calcium supplementation to make any solid recommendations for people of different genders, ages, and ethnicities.

Topics: Calcium; Calcium, Dietary; Cardiovascular Diseases; Dietary Supplements; Gastrointestinal Diseases; Humans; Kidney Calculi; Osteoporosis; Osteoporotic Fractures

PubMed: 30568435
DOI: 10.2147/CIA.S157523

Meta-Analysis

Authors: Dan Han, Xuexian Fang, Danting Su...

Growing evidence has suggested a possible relationship between dietary calcium intake and metabolic syndrome (MetS) risk. However, the findings of these observational studies are inconclusive, and the dose-response association between calcium intake and risk of MetS remains to be determined. Here, we identified relevant studies by searching PubMed and Web of Science databases up to December 2018, and selected observational studies reporting relative risk (RR) with 95% confidence interval (CI) for MetS based on calcium intake and estimated the summary RRs using random-effects models. Eight cross-sectional and two prospective cohort studies totaling 63,017 participants with 14,906 MetS cases were identified. A significantly reduced risk of MetS was associated with the highest levels of dietary calcium intake (RR: 0.89; 95% CI: 0.80-0.99; I = 75.3%), with stronger association and less heterogeneity among women (RR: 0.74, 95% CI: 0.66-0.83; I = 0.0%) than among men (RR: 1.06, 95% CI: 0.82-1.37; I = 72.6%). Our dose-response analysis revealed that for each 300 mg/day increase in calcium intake, the risk of MetS decreased by 7% (RR: 0.93; 95% CI: 0.87-0.99; I = 77.7%). In conclusion, our findings suggest that dietary calcium intake may be inversely associated with the risk of MetS. These findings may have important public health implications with respect to preventing the disease. Further studies, in particular longitudinal cohort studies and randomized clinical trials, will be necessary to determine whether calcium supplementation is effective to prevent MetS.

Topics: Adult; Aged; Calcium, Dietary; Cross-Sectional Studies; Feeding Behavior; Female; Humans; Male; Metabolic Syndrome; Middle Aged; Risk Factors; Young Adult

PubMed: 31836761
DOI: 10.1038/s41598-019-55507-x

Meta-Analysis Review

Authors: Lixiao Cheng, Danqing Hu, Wenjie Jiang...

OBJECTIVE

Epidemiological investigations evaluating the association of dietary Ca intake with metabolic syndrome (MetS) risk have yielded controversial results. Therefore, a meta-analysis was conducted to quantitatively summarize the association between dietary Ca intake and the risk of MetS.

DESIGN

PubMed, Embase and Web of Science were searched for relevant articles published up to October 2018. The pooled OR and 95 % CI were calculated with a random-effects model.

SETTING

Meta-analysis.ParticipantsNine cross-sectional studies.

RESULTS

A total of nine articles with fifteen studies for dietary Ca intake were finally included in the meta-analysis. The combined OR with 95 % CI of MetS for the highest v. lowest category of dietary Ca intake was 0·80 (95 % CI 0·70, 0·91). For dose-response analysis, a non-linear relationship was found between dietary intake of Ca and risk of MetS (P non-linearity<0·001). The threshold for dietary Ca intake was 280 mg/d (OR=0·87; 95 % CI 0·82, 0·93), reducing the risk of MetS by 13 %.

CONCLUSIONS

The present meta-analysis suggests that dietary Ca intake might reduce the risk of MetS, which needs to be further confirmed by larger prospective cohort studies.

Topics: Adult; Aged; Aged, 80 and over; Calcium, Dietary; Diet; Female; Humans; Male; Metabolic Syndrome; Middle Aged; Observational Studies as Topic; Young Adult

PubMed: 30846011
DOI: 10.1017/S1368980019000247

Meta-Analysis

Authors: G Cormick, A P Betrán, I B Romero...

BACKGROUND

Evidence shows that adequate calcium intake during pregnancy reduces the risk of hypertensive disorders of pregnancy. In most low- and middle-income countries (LMICs) the daily calcium intake is well below recommendations. Mapping calcium intake during pregnancy worldwide and identifying populations with low calcium intake will provide the evidence base for more targeted actions to improve calcium intake.

OBJECTIVE

To assess dietary calcium intake during pregnancy worldwide.

SEARCH STRATEGY

MEDLINE and EMBASE (from July 2004 to November 2017).

SELECTION CRITERIA

Cross-sectional, cohort, and intervention studies reporting calcium intake during pregnancy.

DATA COLLECTION AND ANALYSIS

Five reviewers working in pairs independently performed screening, extraction, and quality assessment. We reported summary measures of calcium intake and calculated the weighted arithmetic mean for high-income countries (HICs) and LMICs independently, and for geographic regions, among studies reporting country of recruitment, mean intake, and total number of participants. When available, inadequate intakes were reported.

MAIN RESULTS

From 1880 citations 105 works met the inclusion criteria, providing data for 73 958 women in 37 countries. The mean calcium intake was 948.3 mg/day (95% CI 872.1-1024.4 mg/day) for HICs and 647.6 mg/day (95% CI 568.7-726.5 mg/day) for LMICs. Calcium intakes below 800 mg/day were reported in five (29%) countries from HICs and in 14 (82%) countries from LMICs.

CONCLUSION

These results are consistent with a lack of improvement in calcium dietary intake during pregnancy and confirm the gap between HICs and LMICs, with alarmingly low intakes recorded for pregnant women in LMICs. From the public health perspective, in the absence of specific local data, calcium supplementation of pregnant women in these countries should be universal.

TWEETABLE ABSTRACT

Despite dietary recommendations, women in LMICs face pregnancy with diets low in calcium.

Topics: Calcium, Dietary; Developing Countries; Diet; Female; Health Status Disparities; Humans; Hypertension, Pregnancy-Induced; Pregnancy; Risk Factors

PubMed: 30347499
DOI: 10.1111/1471-0528.15512

Review

Authors: Sarina Schrager

Obesity is increasing in the United States in epidemic proportions. Epidemiologic data suggest that people with high calcium intake have a lower prevalence of overweight, obesity, and insulin resistance syndrome. Studies in transgenic mice have demonstrated that calcium influences adipocyte metabolism. High calcium intake depresses levels of parathyroid hormone and 1,25-hydroxy vitamin D. These decreased hormone levels cause decreases in intracellular calcium, thereby inhibiting lipogenesis and stimulating lipolysis. High dietary calcium intakes also increases excretion of fecal fat and may increase core body temperature. Calcium from dairy products seems to have more of an impact than calcium from dietary supplements. Primary care providers should include recommendations about adequate calcium intake in standard dietary counseling about weight management.

Topics: Adipose Tissue; Calcium; Calcium, Dietary; Evidence-Based Medicine; Humans; Obesity; Weight Loss

PubMed: 15879568
DOI: 10.3122/jabfm.18.3.205

Authors: Mara Carsote, Mihaela Popescu, Alice Elena Ghenea...

Topics: Parathyroid Hormone; Calcium; Parathyroidectomy; Calcium, Dietary

PubMed: 37188053
DOI: 10.3389/fendo.2023.1199056

Authors: J M K Murthy

Topics: Anticonvulsants; Bone Diseases, Metabolic; Calcium, Dietary; Confounding Factors, Epidemiologic; Epilepsy; Female; Humans; Male; Vitamin D

PubMed: 20508330
DOI: 10.4103/0028-3886.63773