The Effect of Calcium Consumption on Iron Absorption and Iron Status
TL;DR: In this article, the authors show no effect of increased calcium intake on dietary iron absorption, at least in short, highly controlled, experimental studies, and experimental studies of calcium and iron status measures such as serum ferritin.
Abstract: Recent increases in recommended calcium intakes recognize the important role of calcium in skeletal health, but many Americans, especially women, consume far less than recommended amounts. A potential drawback to encouraging increased calcium intake is suggested by the extensive literature showing an adverse effect of high calcium intake on dietary iron absorption, at least in short, highly controlled, experimental studies. However, the applicability of short-term studies involving test meals to long-term iron absorption and iron status is limited given the variety of foods and food combinations in self-selected diets and the ability of individuals to adapt to reduced iron intake. In general, studies of whole diets and studies conducted over several weeks tend to show no effect of increased calcium intake on iron absorption. In addition, experimental studies of calcium and iron status measures such as serum ferritin show no long-term effect of calcium supplementation on iron status. Prevention and treatment of iron deficiency should emphasize adequate consumption of iron-rich foods and, when indicated, the use of iron supplements. Recommended calcium intakes are important for skeletal health and do not appear to increase the risk for iron deficiency in healthy people.
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TL;DR: Consumption of milk and other animal-source foods by undernourished children improves anthropometric indices and cognitive function and reduces the prevalence of biochemical and functional nutritional deficiencies, reducing morbidity and mortality.
Abstract: BACKGROUND: Milk and other animal-source foods are concentrated dietary sources of macro- and micronutrients. Despite a global increase in milk production and consumption over the past decades milk and other animal-source foods are often lacking in the diets of children in developing countries. OBJECTIVE: To evaluate the importance of milk and other animal-source food intake in promoting the growth development and health of children in low-income countries. METHODS: Original research articles describing observational and intervention studies with unfortified milk fortified milk and other animal-source foods in children were identified by searching the PubMed database. RESULTS: Consumption of milk and other animal-source foods by undernourished children improves anthropometric indices and cognitive function and reduces the prevalence of biochemical and functional nutritional deficiencies reducing morbidity and mortality. Unfortified and fortified milk used in supplementation trials has been well tolerated and widely accepted by parents and children. CONCLUSIONS: To improve the dietary quality of children in low-income countries and further the effort to eradicate extreme poverty and hunger in accordance with the United Nations Millennium Development Goals additional research is necessary to identify and implement programs and policy supporting increased intake of milk and other animal-source foods.
217 citations
Cites background from "The Effect of Calcium Consumption o..."
...However, more recent multiple-meal and longerterm absorption studies show no significant effect of calcium intake on iron absorption or iron nutritional status in children or adults [35, 36]....
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TL;DR: At the population level, an increase of around 400–500 mg/day could reduce the differences in calcium intake between high- and middle-low-income countries and the fortification of food and water seems a possible strategy to reach this goal.
Abstract: There are striking inequities in calcium intake between rich and poor populations. Appropriate calcium intake has shown many health benefits, such as reduction of hypertensive disorders of pregnancy, lower blood pressure particularly among young people, prevention of osteoporosis and colorectal adenomas, lower cholesterol values, and lower blood pressure in the progeny of mothers taking sufficient calcium during pregnancy. Studies have refuted some calcium supplementation side effects like damage to the iron status, formation of renal stones and myocardial infarction in older people. Attention should be given to bone resorption in post-partum women after calcium supplementation withdrawal. Mechanisms linking low calcium intake and blood pressure are mediated by parathyroid hormone raise that increases intracellular calcium in vascular smooth muscle cells leading to vasoconstriction. At the population level, an increase of around 400–500 mg/day could reduce the differences in calcium intake between high- and middle-low-income countries. The fortification of food and water seems a possible strategy to reach this goal.
154 citations
TL;DR: The efficacy and safety of calcium supplementation versus placebo or control for reducing blood pressure in normotensive people is assessed and the effect is consistent in both genders regardless of baseline calcium intake.
Abstract: Background Hypertension is a major public health problem that increases the risk of cardiovascular and kidney diseases Several studies have shown an inverse association between calcium intake and blood pressure, as small reductions in blood pressure have been shown to produce rapid reductions in vascular disease risk even in individuals with normal blood pressure ranges This is the first update of the review to evaluate the effect of calcium supplementation in normotensive individuals as a preventive health measure Objectives To assess the efficacy and safety of calcium supplementation versus placebo or control for reducing blood pressure in normotensive people and for the prevention of primary hypertension Search methods The Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to September 2020: the Cochrane Hypertension Specialised Register, CENTRAL (2020, Issue 9), Ovid MEDLINE, Ovid Embase, the WHO International Clinical Trials Registry Platform, and the US National Institutes of Health Ongoing Trials Register, ClinicalTrialsgov We also contacted authors of relevant papers regarding further published and unpublished work The searches had no language restrictions Selection criteria We selected trials that randomised normotensive people to dietary calcium interventions such as supplementation or food fortification versus placebo or control We excluded quasi-random designs The primary outcomes were hypertension (defined as blood pressure ≥ 140/90 mmHg) and blood pressure measures Data collection and analysis Two review authors independently selected trials for inclusion, abstracted the data and assessed the risks of bias We used the GRADE approach to assess the certainty of evidence Main results The 2020 updated search identified four new trials We included a total of 20 trials with 3512 participants, however we only included 18 for the meta-analysis with 3140 participants None of the studies reported hypertension as a dichotomous outcome The effect on systolic and diastolic blood pressure was: mean difference (MD) -137 mmHg, 95% confidence interval (CI) -208, -066; 3140 participants; 18 studies; I2 = 0%, high-certainty evidence; and MD -145, 95% CI -223, -067; 3039 participants; 17 studies; I2 = 45%, high-certainty evidence, respectively The effect on systolic and diastolic blood pressure for those younger than 35 years was: MD -186, 95% CI -345, -027; 452 participants; eight studies; I2 = 19%, moderate-certainty evidence; MD -250, 95% CI -422, -079; 351 participants; seven studies ; I2 = 54%, moderate-certainty evidence, respectively The effect on systolic and diastolic blood pressure for those 35 years or older was: MD -097, 95% CI -183, -010; 2688 participants; 10 studies; I2 = 0%, high-certainty evidence; MD -059, 95% CI -113, -006; 2688 participants; 10 studies; I2 = 0%, high-certainty evidence, respectively The effect on systolic and diastolic blood pressure for women was: MD -125, 95% CI -253, 003; 1915 participants; eight studies; I2 = 0%, high-certainty evidence; MD -104, 95% CI -186, -022; 1915 participants; eight studies; I2 = 4%, high-certainty evidence, respectively The effect on systolic and diastolic blood pressure for men was MD -214, 95% CI -371, -059; 507 participants; five studies; I2 = 8%, moderate-certainty evidence; MD -199, 95% CI -325, -074; 507 participants; five studies; I2 = 41%, moderate-certainty evidence, respectively The effect was consistent in both genders regardless of baseline calcium intake The effect on systolic blood pressure was: MD -002, 95% CI -223, 220; 302 participants; 3 studies; I2 = 0%, moderate-certainty evidence with doses less than 1000 mg; MD -105, 95% CI -191, -019; 2488 participants; 9 studies; I2 = 0%, high-certainty evidence with doses 1000 to 1500 mg; and MD -279, 95% CI -471, 086; 350 participants; 7 studies = 8; I2 = 0%, moderate-certainty evidence with doses more than 1500 mg The effect on diastolic blood pressure was: MD -041, 95% CI -207, 125; 201 participants; 2 studies; I2 = 0, moderate-certainty evidence; MD -203, 95% CI -344, -062 ; 1017 participants; 8 studies; and MD -135, 95% CI -275, -005; 1821 participants; 8 studies; I2 = 51%, high-certainty evidence, respectively None of the studies reported adverse events Authors' conclusions An increase in calcium intake slightly reduces both systolic and diastolic blood pressure in normotensive people, particularly in young people, suggesting a role in the prevention of hypertension The effect across multiple prespecified subgroups and a possible dose response effect reinforce this conclusion Even small reductions in blood pressure could have important health implications for reducing vascular disease A 2 mmHg lower systolic blood pressure is predicted to produce about 10% lower stroke mortality and about 7% lower mortality from ischaemic heart disease There is a great need for adequately-powered clinical trials randomising young people Subgroup analysis should involve basal calcium intake, age, sex, basal blood pressure, and body mass index We also require assessment of side effects, optimal doses and the best strategy to improve calcium intake
90 citations
Cites background from "The Effect of Calcium Consumption o..."
...Calcium has been shown to interfere with iron absorption in the short term; however, research has also shown that prolonged calcium supplementation has no effect on iron absorption over time (Harris 2002; Ilich-Ernst 1998; Kalkwarf 1998; Sokoll 1992)....
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...As there have been some concerns about adverse events of calcium supplementation (Bolland 2008; Curhan 2004; Harris 2002), there is a need to assess adverse events such as renal tract stone formation, impaired absorption of other minerals and increased cardiovascular events....
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TL;DR: Calcium fortification should follow regulations, implemented in an intersectorial way, and be informed by the right to health and equity, and may help guide and plan this public health strategy.
Abstract: Low calcium intake is common worldwide and can result in nutritional rickets in children and osteomalacia in adults. Calcium-fortified foods could improve calcium intake. However, there is limited calcium fortification experience, with technical and practical issues that may hamper its adoption. The objective of this landscape review is to summarize these issues to help policymakers guide the planning and design of calcium fortification as a public health strategy. One challenge is the low bioavailability of calcium salts (∼20-40%); thus, large amounts need to be added to food to have a meaningful impact. Solubility is important when fortifying liquids and acidic foods. Calcium salts could change the flavor, color, and appearance of the food and may account for 70-90% of the total fortification cost. Safety is key to avoid exceeding the recommended intake; so the amount of added calcium should be based on the target calcium intake and the gap between inadequate and adequate levels. Monitoring includes the quality of the fortified food and population calcium intake using dietary assessment methods. Calcium fortification should follow regulations, implemented in an intersectorial way, and be informed by the right to health and equity. This information may help guide and plan this public health strategy.
30 citations
TL;DR: The strategy to include calcium in the fortification mix in fortified staple foods seems promising in these countries, however, potential undesired changes on the organoleptic characteristics of fortified foods and products thereof, and operational feasibility at the manufacturing site should be evaluated by the stakeholders during the planning stage.
Abstract: Daily calcium intake is well below current recommendations in most low- and middle-income countries (LMICs). Calcium intake is usually related to bone health, however an adequate calcium intake has also been shown to reduce hypertensive disorders of pregnancy, lower blood pressure and cholesterol values, and to prevent recurrent colorectal adenomas. Food fortification of foods has been identified as a cost-effective strategy to overcome micronutrient gaps in public health. This review summarizes regulatory aspects of fortification of commonly consumed foods with micronutrients, with an emphasis on calcium. We selected a convenient sample of 15 countries from different WHO regions and described the regulatory framework related to calcium fortification of staple foods. We assessed the relevant policies in electronic databases including the WHO Global database on the Implementation of Nutrition Action (GINA) for fortification policies and the Global Fortification Data Exchange Database, a fortification database developed and maintained by Food Fortification Initiative (FFI), Global Alliance for Improved Nutrition (GAIN), Iodine Global Network (IGN), and Micronutrient Forum. Food fortification with micronutrients is widely used in many of the selected countries. Most countries had national legislation for the addition of micronutrients to staple foods, especially wheat flour. These national legislations, that includes regulations and standards, can provide the framework to consider the implementation of adding calcium to the fortification strategies, including the selection of the adequate food vehicle to reach the targeted population at risk safely. The strategy to include calcium in the fortification mix in fortified staple foods seems promising in these countries. However, potential undesired changes on the organoleptic characteristics of fortified foods and products thereof, and operational feasibility at the manufacturing site should be evaluated by the stakeholders during the planning stage. Codex Alimentarius standards should be considered by regulators in order to assure adherence to international standards. While the selected countries already have established national regulations and/or standards for fortification of key staple food vehicles, and there are experiences in the implementation of fortification of some staple foods, national food intake surveys can help plan, design, and modify existing fortification programs as well as monitor food and nutrient consumption to assess risk and benefits.
16 citations
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TL;DR: Iron deficiency and iron deficiency anemia are still relatively common in toddlers, adolescent girls, and women of childbearing age and were more likely in those who are minority, low income, and multiparous.
Abstract: Objective. —To determine the prevalence of iron deficiency and iron deficiency anemia in the US population. Design. —Nationally representative cross-sectional health examination survey that included venous blood measurements of iron status. Main Outcome Measures. —lron deficiency, defined as having an abnormal value for at least 2 of 3 laboratory tests of iron status (erythrocyte protoporphyrin, transferrin saturation, or serum ferritin); and iron deficiency anemia, defined as iron deficiency plus low hemoglobin. Participants. —A total of 24 894 persons aged 1 year and older examined in the third National Health and Nutrition Examination Survey (1988-1994). Results. —Nine percent of toddlers aged 1 to 2 years and 9% to 11% of adolescent girls and women of childbearing age were iron deficient; of these, iron deficiency anemia was found in 3% and 2% to 5%, respectively. These prevalences correspond to approximately 700000 toddlers and 7.8 million women with iron deficiency; of these, approximately 240 000 toddlers and 3.3 million women have iron deficiency anemia. Iron deficiency occurred in no more than 7% of older children or those older than 50 years, and in no more than 1% of teenage boys and young men. Among women of childbearing age, iron deficiency was more likely in those who are minority, low income, and multiparous. Conclusion. —lron deficiency and iron deficiency anemia are still relatively common in toddlers, adolescent girls, and women of childbearing age.
1,200 citations
TL;DR: Addition of calcium chloride to wheat rolls significantly reduced iron absorption, suggesting that the effect of calcium is related to the mucosal transfer of iron.
459 citations
TL;DR: The heart-healthy diets of women and men born in Mexico should be encouraged among all Mexican Americans living in the United States, especially given the increasing levels of obesity and diabetes among this rapidly growing group of Americans.
Abstract: As Mexican-American women and men migrate to the United States and/or become more acculturated, their diets may become less healthy, increasing their risk of cardiovascular disease. Data from the Third National Health and Nutrition Examination Survey (1988-1994) were used to compare whether energy, nutrient, and food intakes differed among three groups of Mexican-American women (n = 1,449) and men (n = 1,404) aged 25-64 years: those born in Mexico, those born in the United States whose primary language was Spanish, and those born in the United States whose primary language was English. Percentages of persons who met the national dietary guidelines for fat, fiber, and potassium and the recommended intakes of vitamins and minerals associated with cardiovascular disease were also compared. In general, Mexican Americans born in Mexico consumed significantly less fat and significantly more fiber; vitamins A, C, E, and B6; and folate, calcium, potassium, and magnesium than did those born in the United States, regardless of language spoken. More women and men born in Mexico met the dietary guidelines or recommended nutrient intakes than those born in the United States. The heart-healthy diets of women and men born in Mexico should be encouraged among all Mexican Americans living in the United States, especially given the increasing levels of obesity and diabetes among this rapidly growing group of Americans.
279 citations
TL;DR: It is suggested that taking regular calcium supplements with meals makes it more difficult for women to meet their daily iron requirement.
267 citations
TL;DR: The results indicate that in the context of a varied Western diet, nonheme-iron bioavailability is less important than absorption studies with single meals would suggest.
263 citations