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Nutrients Dec 2021This article reviews physicochemical aspects of calcium absorption from foods. Notable differences are observed between different food products in relation to calcium... (Review)
Review
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 -
Journal of Clinical Hypertension... Jun 2017Over the past decade, the number of individuals taking calcium supplementation worldwide has been on the rise, especially with the emergence of new pharmaceutical... (Review)
Review
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 -
BMJ (Clinical Research Ed.) Sep 2015To examine the evidence underpinning recommendations to increase calcium intake through dietary sources or calcium supplements to prevent fractures. (Meta-Analysis)
Meta-Analysis Review
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 -
Clinical Interventions in Aging 2018Calcium 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... (Review)
Review
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 -
British Medical Journal Oct 1977
Topics: Calcium; Calcium, Dietary; Feces; Humans
PubMed: 589013
DOI: No ID Found -
Cleveland Clinic Journal of Medicine Jul 2018Calcium, a key component of bone, is obtained through diet or supplements, or both, and vitamin D is necessary for normal calcium absorption. Controversy exists as to... (Review)
Review
Calcium, a key component of bone, is obtained through diet or supplements, or both, and vitamin D is necessary for normal calcium absorption. Controversy exists as to the efficacy and even the safety of calcium. Our opinion, backed by studies and guidelines, is that adequate amounts of calcium are a must for patients concerned about bone health, and cardiovascular safety is not a concern.
Topics: Bone Density; Calcium, Dietary; Diet; Dietary Supplements; Humans; Vitamin D
PubMed: 30004379
DOI: 10.3949/ccjm.85a.17106 -
The American Journal of Clinical... Apr 2017
Topics: Calcium; Calcium, Dietary; Dietary Supplements; Vitamin D
PubMed: 28330910
DOI: 10.3945/ajcn.117.154278 -
Nutrients Jun 2017Several epidemiological studies have evaluated the association between calcium intake and the risk of ovarian cancer. However, the results of these studies remain... (Meta-Analysis)
Meta-Analysis Review
Several epidemiological studies have evaluated the association between calcium intake and the risk of ovarian cancer. However, the results of these studies remain controversial. Thus, we performed a meta-analysis to explore the association between calcium intake and the risk of ovarian cancer. Pubmed, Embase and Web of Science were searched for eligible publications up to April 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using the random-effects model. Small-study effect was estimated using Egger's test and the funnel plot. Among 15 epidemiological studies involving 493,415 participants and 7453 cases eligible for this meta-analysis, 13 studies were about dietary calcium intake, 4 studies about dairy calcium intake and 7 studies about dietary plus supplemental calcium intake. When comparing the highest with the lowest intake, the pooled RRs of ovarian cancer were 0.80 (95% CI 0.72-0.89) for dietary calcium, 0.80 (95% CI 0.66-0.98) for dairy calcium and 0.90 (95% CI 0.65-1.24) for dietary plus supplemental calcium, respectively. Dietary calcium was significantly associated with a reduced risk of ovarian cancer among cohort studies (RR = 0.86, 95% CI 0.74-0.99) and among case-control studies ( = 0.75, 95% CI 0.64-0.89). In subgroup analysis by ovarian cancer subtypes, we found a statistically significant association between the dietary calcium ( = 0.78, 95% CI 0.69-0.88) and the risk of epithelial ovarian cancer (EOC). This meta-analysis indicated that increased calcium intake might be inversely associated with the risk of ovarian cancer; this still needs to be confirmed by larger prospective cohort studies.
Topics: Calcium; Calcium, Dietary; Female; Humans; Ovarian Neoplasms
PubMed: 28665326
DOI: 10.3390/nu9070679 -
Annals of Internal Medicine Dec 2016Conflicting evidence exists regarding potential cardiovascular risks associated with high levels of calcium intake. (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Conflicting evidence exists regarding potential cardiovascular risks associated with high levels of calcium intake.
PURPOSE
To update and reanalyze 2 systematic reviews to examine the effects of calcium intake on cardiovascular disease (CVD) among generally healthy adults.
DATA SOURCES
MEDLINE; Cochrane Central Register of Controlled Trials; Scopus, including EMBASE; and previous evidence reports from English-language publications from 1966 to July 2016.
STUDY SELECTION
Randomized trials and prospective cohort and nested case-control studies with data on dietary or supplemental intake of calcium, with or without vitamin D, and cardiovascular outcomes.
DATA EXTRACTION
Study characteristics and results extracted by 1 reviewer were confirmed by a second reviewer. Two raters independently assessed risk of bias.
DATA SYNTHESIS
Overall risk of bias was low for the 4 randomized trials (in 10 publications) and moderate for the 27 observational studies included. The trials did not find statistically significant differences in risk for CVD events or mortality between groups receiving supplements of calcium or calcium plus vitamin D and those receiving placebo. Cohort studies showed no consistent dose-response relationships between total, dietary, or supplemental calcium intake levels and cardiovascular mortality and highly inconsistent dose-response relationships between calcium intake and risks for total stroke or stroke mortality.
LIMITATIONS
CVD disease outcomes were secondary end points in all trials. Dose-response metaregression analysis of cohort studies was limited by potential confounding, ecological bias, and imprecise measures of calcium exposures. Data were scarce regarding very high calcium intake-that is, beyond recommended tolerable upper intake levels.
CONCLUSION
Calcium intake within tolerable upper intake levels (2000 to 2500 mg/d) is not associated with CVD risk in generally healthy adults.
PRIMARY FUNDING SOURCE
National Osteoporosis Foundation.
Topics: Calcium, Dietary; Cardiovascular Diseases; Dietary Supplements; Humans; Risk Factors; Stroke; Vitamin D
PubMed: 27776363
DOI: 10.7326/M16-1165 -
Public Health Nutrition Aug 2019Epidemiological investigations evaluating the association of dietary Ca intake with metabolic syndrome (MetS) risk have yielded controversial results. Therefore, a... (Meta-Analysis)
Meta-Analysis Review
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