This is a fact sheet intended for health professionals. For a general overview of Calcium, see our consumer fact sheet on Calcium.
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Introduction
Calcium, the most abundant mineral in the body, is found in some foods, added lớn others, present in some medicines (such as antacids), và available as a dietary supplement.
Calcium makes up much of the structure of bones and teeth and allows normal bodily movement by keeping tissue rigid, strong, and flexible <1>. The small ionized pool of calcium in the circulatory system, extracellular fluid, và various tissues mediates blood vessel contraction and dilation, muscle function, blood clotting, nerve transmission, & hormonal secretion <1,2>.
Calcium from foods & dietary supplements is absorbed by both active transport và by passive diffusion across the intestinal mucosa <1,3>. Active transport is responsible for most absorption when calcium intakes are lower, và passive diffusion accounts for an increasing proportion of calcium absorption as intakes rise. Vi-ta-min D is required for calcium khổng lồ be absorbed in the gut by active transport and to maintain adequate calcium levels in blood <1>.
Almost all (98%) calcium in the body is stored in the bones, & the toàn thân uses the bones as a reservoir for, và source of, calcium to maintain calcium homeostasis <1>. More than 99% of calcium in the body toàn thân is in the size of calcium hydroxyapatite, an inorganic matrix of calcium và phosphate that is stored in the bones và teeth <1,4,5>. Unlike teeth, bone undergoes continuous remodeling, with constant resorption and deposition of calcium into new bone <4>. Bone remodeling is required khổng lồ change bone kích thước during growth, repair damage, maintain serum calcium levels, and provide a source of other minerals <4>.
At birth, the body contains about 26 lớn 30 g calcium. This amount rises quickly after birth, reaching about 1,200 g in women và 1,400 g in men by adulthood <1>. These levels remain constant in men, but they start to drop in women as a result of increases in bone remodeling due khổng lồ decreased estrogen production at the start of menopause <1>.
An inverse relationship exists between calcium intake và absorption. Absorption of calcium from food is about 45% at intakes of 200 mg/day but only 15% when intakes are higher than 2,000 mg/day <6>. Age can also affect absorption of dietary calcium <1,4>. Net absorption of dietary calcium is as high as 60% in infants & young children, who need substantial amounts lớn build bone, but it decreases to lớn about 25% in adulthood & continues to lớn decline with age <1>.
Total calcium levels can be measured in serum or plasma; serum levels are typically 8.8 to lớn 10.4 mg/d
L (2. 2 khổng lồ 2.6 mmol/L) in healthy people <1,7>. However, serum levels bởi not reflect nutritional status because of their tight homeostatic control <4>. Levels of ionized (or free) calcium, the biologically active form, in serum are also used khổng lồ measure calcium status. The normal range of ionized calcium in healthy people is 4.6 to lớn 5.3 mg/d
L (1.15 to lớn 1.33 mmol/L) <7>. Dual x-ray absorptiometry testing of bone mineral mật độ trùng lặp từ khóa can be used to lớn assess cumulative calcium status over the lifetime because the skeleton stores almost all calcium in the body toàn thân <3>.
Recommended Intakes
Intake recommendations for calcium và other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food & Nutrition Board (FNB) at the National Academies of Sciences, Engineering, và Medicine <1>. DRIs is the general term for a mix of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age & sex, include:
Recommended Dietary Allowance (RDA): Average daily màn chơi of intake sufficient lớn meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.Adequate Intake (AI): Intake at this level is assumed to lớn ensure nutritional adequacy; established when evidence is insufficient lớn develop an RDA.Estimated Average Requirement (EAR): Average daily màn chơi of intake estimated khổng lồ meet the requirements of 50% of healthy individuals; usually used to assess the nutrient intakes of groups of people & to plan nutritionally adequate diets for them; can also be used to assess the nutrient intakes of individuals.Tolerable Upper Intake cấp độ (UL): Maximum daily intake unlikely to lớn cause adverse health effects.Table 1 lists the current RDAs for calcium <1>. For adults, the main criterion that the FNB used to lớn establish the RDAs was the amount needed khổng lồ promote bone maintenance and neutral calcium balance. For infants aged 0 to lớn 12 months, the FNB established an AI that is equivalent lớn the mean intake of calcium in healthy, breastfed infants. For children và adolescents, the RDAs are based on intakes associated with bone accumulation and positive calcium balance.
| 0-6 months* | 200 mg | 200 mg | ||
| 7–12 months* | 260 mg | 260 mg | ||
| 1–3 years | 700 mg | 700 mg | ||
| 4–8 years | 1,000 mg | 1,000 mg | ||
| 9–13 years | 1,300 mg | 1,300 mg | ||
| 14–18 years | 1,300 mg | 1,300 mg | 1,300 mg | 1,300 mg |
| 19–50 years | 1,000 mg | 1,000 mg | 1,000 mg | 1,000 mg |
| 51–70 years | 1,000 mg | 1,200 mg | ||
| >70+ years | 1,200 mg | 1,200 mg |
Sources of Calcium
FoodMilk, yogurt, & cheese are rich natural sources of calcium <1>. In the United States, approximately 72% of calcium intakes come from dairy products & foods with added dairy ingredients <1>. Nondairy sources include canned sardines và salmon with bones as well as certain vegetables, such as kale, broccoli, and Chinese cabbage (bok choi). Most grains vị not have high amounts of calcium unless they are fortified. However, they contribute to lớn calcium intakes, even though they contain small amounts of calcium, because people consume them frequently <1>. Foods fortified with calcium in the United States include many fruit juices and drinks, tofu, & ready-to-eat cereals <1,8>. Calcium citrate malate is a well-absorbed form of calcium used in some fortified juices <3>.
Calcium absorption varies by type of food. The absorption of calcium from dairy products và fortified foods is about 30% <1>. Certain compounds in plants (e.g., oxalic acid, phytic acid) can decrease calcium absorption by forming indigestible salts with calcium, decreasing its absorption <3>. As a result, absorption of calcium is only 5% for spinach, whereas it is much higher, at 27%, for milk <3>. In addition khổng lồ spinach, foods with high levels of oxalic acid include collard greens, sweet potatoes, rhubarb, và beans <1>. The bioavailability of calcium from other plants that bởi not contain these compounds—including broccoli, kale, and cabbage—is similar khổng lồ that of milk, although the amount of calcium per serving is much lower <3>. When people eat many different types of foods, these interactions with oxalic or phytic acid probably have little or no nutritional consequence. Net absorption of dietary calcium is also reduced to a small extent by intakes of caffeine và phosphorus & to a greater extent by low status of vitamin D <9-11>.
A variety of foods and their calcium nội dung are listed in Table 2.
| Yogurt, plain, low fat, 8 ounces | 415 | 32 |
| Orange juice, calcium fortified, 1 cup | 349 | 27 |
| Yogurt, fruit, low fat, 8 ounces | 344 | 27 |
| Mozzarella, part skim, 1.5 ounces | 333 | 26 |
| Sardines, canned in oil, with bones, 3 ounces | 325 | 25 |
| Milk, nonfat, 1 cup** | 299 | 23 |
| Soymilk, calcium fortified, 1 cup | 299 | 23 |
| Milk, whole (3.25% milk fat), 1 cup** | 276 | 21 |
| Tofu, firm, made with calcium sulfate, ½ cup*** | 253 | 19 |
| Salmon, pink, canned, solids with bones, 3 ounces | 181 | 14 |
| Cottage cheese, 1% milk fat, 1 cup | 138 | 11 |
| Tofu, soft, made with calcium sulfate, ½ cup*** | 138 | 11 |
| Soybeans, cooked, ½ cup | 131 | 10 |
| Breakfast cereals, fortified with 10% of the DV for calcium, 1 serving | 130 | 10 |
| Spinach, boiled, drained, ½ cup | 123 | 9 |
| Frozen yogurt, vanilla, soft serve, ½ cup | 103 | 8 |
| Turnip greens, fresh, boiled, ½ cup | 99 | 8 |
| Kale, fresh, cooked, 1 cup | 94 | 7 |
| Chia seeds, 1 tablespoon | 76 | 6 |
| Chinese cabbage (bok choi), raw, shredded, 1 cup | 74 | 6 |
| Beans, pinto, canned, drained, ½ cup | 54 | 4 |
| Tortilla, corn, one, 6” diameter | 46 | 4 |
| Sour cream, reduced fat, 2 tablespoons | 31 | 2 |
| Bread, whole-wheat, 1 slice | 30 | 2 |
| Kale, raw, chopped, 1 cup | 24 | 2 |
| Broccoli, raw, ½ cup | 21 | 2 |
| Apple, golden delicious, with skin, 1 medium | 10 | 0 |
The U.S. Department of Agriculture’s (USDA’s) Food
Data Central lists the nutrient content of many foods và provides a comprehensive các mục of foods containing calcium arranged by nutrient nội dung and by food name.
Dietary supplementsCalcium is available in many dietary supplements, including multivitamin/mineral products và supplements containing calcium only or calcium plus vitamin D <14>. Amounts of calcium in supplements vary widely; multivitamin/mineral supplements commonly contain about 200 khổng lồ 300 mg, & common amounts in calcium or calcium plus vi-ta-min D supplements are 500 or 600 mg <14>.
The two most common forms of calcium in supplements are calcium carbonate & calcium citrate <1>. In people with low levels of stomach acid, the solubility rate of calcium carbonate is lower, which could reduce the absorption of calcium from calcium carbonate supplements unless they are taken with a meal <3>. Calcium citrate is less dependent on stomach acid for absorption than calcium carbonate, so it can be taken without food <1>. In general, however, absorption of calcium supplements is greater when they are taken with food, regardless of whether the user’s gastric acid is low <3>. Other calcium forms in supplements include calcium sulfate, ascorbate, microcrystalline hydroxyapatite, gluconate, lactate, & phosphate <14>.
The forms of calcium in supplements contain varying amounts of elemental calcium. For example, calcium carbonate is 40% calcium by weight, whereas calcium citrate is 21% calcium <1>. Elemental calcium is listed in the Supplement Facts panel, so consumers bởi vì not need khổng lồ calculate the amount of calcium supplied by various forms of calcium in supplements.
The percentage of calcium absorbed from supplements, as with that from foods, depends not only on the source of calcium but also on the total amount of elemental calcium consumed at one time; as the amount increases, the percentage absorbed decreases. Absorption from supplements is highest with doses of 500 mg or less <15>. For example, the body absorbs about 36% of a 300 mg calcium dose và 28% of a 1,000 mg dose <16>.
Some individuals who take calcium supplements might experience gastrointestinal side effects, including gas, bloating, constipation, or a combination of these symptoms. Calcium carbonate appears to cause more of these side effects than calcium citrate, especially in older adults who have lower levels of stomach acid <1>. Symptoms can be alleviated by switching to a supplement containing a different size of calcium, taking smaller calcium doses more often during the day, or taking the supplement with meals.
MedicinesBecause of its ability to neutralize stomach acid, calcium carbonate is contained in some over-the-counter antacid products, such as Tums & Rolaids. Depending on its strength, each chewable pill or soft chew provides about 270 to 400 mg of calcium <14>.
Calcium Intakes & Status
A substantial proportion of people in the United States consume less than recommended amounts of calcium. An analysis of 2007–2010 data from the National Health & Nutrition Examination Survey (NHANES) found that 49% of children aged 4–18 years và 39% of all individuals aged 4 & older consume less than the EAR for calcium from foods và supplements <17>.
Average daily intakes of calcium from foods and beverages are 1,083 mg for men aged 20 and older & 842 mg for women <18>. For children aged 2–19, mean daily intakes of calcium from foods và beverages range from 965 to 1,015 mg <18>. Approximately 22% of men, 32% of women, and 4 to lớn 8% of children take a dietary supplement containing calcium <18>. Average daily calcium intakes from both foods và supplements are 1,156 mg for men, 1,009 mg for women, và 968 khổng lồ 1,020 mg for children <18>.
According khổng lồ 2009–2012 NHANES data, rates of calcium inadequacy (intakes below the EAR) are higher among non-Hispanic Blacks và non-Hispanic Asians (47–48%) than among Hispanics (30%) và non-Hispanic Whites (24%) in the United States <19>. Poverty is also associated with a higher risk of inadequacy. NHANES data from 2007 to 2014 show that the risk of inadequate calcium intakes (less than 800 to 1,100 mg) is 11.6% higher among adults aged 50 and older in households earning less than $20,000 per year than other households <20>.
Calcium Deficiency
Calcium deficiency can reduce bone strength and lead to lớn osteoporosis, which is characterized by fragile bones và an increased risk of falling <1>. Calcium deficiency can also cause rickets in children and other bone disorders in adults, although these disorders are more commonly caused by vi-ta-min D deficiency. In children with rickets, the growth cartilage does not mineralize normally, which can lead to lớn irreversible changes in the skeletal structure <1>. Another effect of chronic calcium deficiency is osteomalacia, or defective bone mineralization và bone softening, which can occur in adults and children <1>. For rickets & osteomalacia, the requirements for calcium & vitamin D appear lớn be interrelated in that the lower the serum vitamin D cấp độ (measured as 25-hydroxyvitamin D <25(OH)D>), the more calcium is needed to lớn prevent these diseases <21>.
Hypocalcemia (serum calcium màn chơi less than 8.5 mg/d
L <2.12 mmol/L> or an ionized calcium cấp độ below 4.61 mg/d
L <1.15 mmol/L>) is usually a result of a vi-ta-min D or magnesium deficiency, impaired parathyroid hormone (PTH) production leading to lớn hypoparathyroidism, impaired bone resorption of calcium, critical illness, or use of certain medications (e.g., bisphosphonates, cisplatin, or proton pump inhibitors) <22,23>. Hypocalcemia can be asymptomatic, especially when it is mild or chronic <23>. When signs & symptoms bởi vì occur, they can range widely because low serum calcium levels can affect most organs và symptoms <24>. The most common symptom is increased neuromuscular irritability, including perioral numbness, tingling in the hands và feet, & muscle spasms <23>. More severe signs and symptoms can include renal calcification or injury, brain calcification, neurologic symptoms (e.g., depression and bipolar disorder), cataracts, congestive heart failure, paresthesia, seizures, and, in rare cases, coma <22,24>.
Groups at Risk of Calcium Inadequacy
The following groups are among those most likely to lớn need extra calcium.
Postmenopausal womenMenopause leads to bone loss because decreases in estrogen production reduce calcium absorption and increase urinary calcium loss & calcium resorption from bone <1>. On average, women đại bại approximately 1% of their bone mineral density (BMD) per year after menopause <25>. Over time, these changes lead to lớn decreased bone mass và fragile bones <1>. About 30% of postmenopausal women in the United States & Europe have osteoporosis, and at least 40% of those with this condition develop at least one fragility fracture (a fracture that occurs after minor trauma, such as a fall from standing height or lower) <26>. The calcium RDA is 1,200 mg for women older than 50 years (vs. 1,000 mg for younger women) to lớn lessen bone loss after menopause <1>.
Individuals who avoid dairy productsPeople with lactose intolerance, those with an allergy to milk, và those who avoid eating dairy products (including vegans) have a higher risk of inadequate calcium intakes because dairy products are rich sources of calcium <1,27>. Options for increasing calcium intakes in individuals with lactose intolerance include consuming lactose-free or reduced-lactose dairy products, which contain the same amounts of calcium as regular dairy products <1,3>. Those who avoid dairy products because of allergies or for other reasons can obtain calcium from non-dairy sources, such as some vegetables (e.g., kale, broccoli, và Chinese cabbage
Calcium and Health
This section focuses on six health conditions & diseases in which calcium might play a role: bone health in older adults, cancer, cardiovascular disease (CVD), preeclampsia, weight management, và metabolic syndrome.
Bone health in older adultsBone is constantly being remodeled. Declining levels of estrogen in women during menopause và for approximately 5 years afterward lead lớn rates of bone resorption that are higher than rates of bone formation, resulting in a rapid decrease in bone mass <7>. Over time, postmenopausal women can develop osteoporosis, in which bone strength is compromised because of lower BMD and bone chất lượng <1>. Age-related bone loss can also occur in men & lead to osteoporosis, but fracture risk tends khổng lồ increase in older men about 5 lớn 10 years later than in older women <1>. Osteoporosis increases the risk of fractures, especially of the hip, vertebrae, & forearms <1,7>.
FDA has approved a health claim for the use of supplements containing calcium and vitamin D lớn reduce the risk of osteoporosis <29>. However, not all research supports this claim.
BMD. In spite of the importance of calcium in bone health, observational evidence is mixed on the link between calcium intakes & measures of bone strength in older adults. Tư vấn for such a link comes from an analysis of 2001–2006 NHANES cross-sectional data on 2,904 adults aged 60 & older (54.6% women) showing an association between higher dietary calcium intakes and greater lumbar spine BMD, but only in women <30>. In contrast, an analysis of baseline data from a randomized trial in australia in 1,994 women older than 65 years whose average dietary calcium intake was 886 mg/day found no association between quintile of calcium intake & BMD at any site, even after adjustment for such factors as age, physical activity, height, và weight <31>. Results were similar in 698 of the women who were followed for 6 years, even though mean daily intakes of calcium dropped by an average of 40 mg during this period.
Some but not all clinical trials have found that calcium supplementation can improve bone health in older adults. A post-hoc analysis of data from a double-blind, randomized controlled trial (RCT) of 1,000 mg elemental calcium in the khung of calcium carbonate và 400 International Units (IU) (10 microgram
Several recent systematic đánh giá and meta-analyses have found that supplementation with calcium alone or a combination of calcium and vitamin D increases BMD in older adults. For example, a systematic review and meta-analysis included 15 RCTs in postmenopausal women (but did not include the two studies described in the previous paragraph) in 78,206 women, of which 37,412 were in the intervention group & 40,794 were in the control group <34>. Supplementation with both calcium and vitamin D or consumption of dairy products fortified with both nutrients increased total BMD as well as BMD at the lumbar spine, arms, and femoral neck. However, in subgroup analyses, calcium had no effect on femoral neck BMD. Earlier systematic nhận xét and meta-analyses found a positive relationship between calcium & vitamin D supplementation and increased BMD in older males <35> và between higher calcium intakes from dietary sources or supplements in adults over 50 and higher BMD <25>. However, whether these BMD increases were clinically significant is not clear.
Fractures. As with the evidence on the link between increased calcium intakes and reductions in BMD loss, the findings of research on the use of calcium supplementation lớn prevent fractures in older adults are mixed.
For the most part, the observational evidence does not show that increasing calcium intakes reduces the risk of fractures và falls in older adults. For example, a longitudinal cohort study of 1,490 women aged 42 to lớn 52 years at baseline who were followed for 10–12 years found that fracture risk was not significantly different in calcium supplement users (some of whom also took vi-ta-min D supplements) and nonusers, even though supplement use was associated with less BMD loss throughout the study period <36>.
Some clinical trial evidence shows that supplements containing a combination of calcium and vitamin D can reduce the risk of fractures in older adults. For example, a meta-analysis of 8 RCTs in 30,970 adults older than 50 years found that 500 to lớn 1,200 mg/day calcium và 400 to 800 IU/day (10 to trăng tròn mcg/day) vitamin D supplementation for 1 khổng lồ 7 years reduced the risk of total fractures by 15% and hip fractures by 30% <37>. However, findings were negative in another systematic reviews and meta-analysis that included 14 RCTs of calcium supplementation & 13 trials comparing calcium và vitamin D supplements with hormone therapy, placebo, or no treatment in participants older than 50 years <38>. The results showed that calcium supplementation alone had no effect on risk of hip fracture, và supplementation with both calcium & vitamin D had no effect on risk of hip fracture, nonvertebral fracture, vertebral fracture, or total fracture. Similarly, a systematic nhận xét of 11 RCTs in 51,419 adults aged 50 và older found that supplementation with vi-ta-min D and calcium for 2 to 7 years had no impact on risk of total fractures or of hip fractures <39>.
The U.S. Preventive Services Task Force (USPSTF) concluded with moderate certainty that daily doses of less than 1,000 mg calcium & less than 400 IU (10 mcg) vitamin D bởi vì not prevent fractures in postmenopausal women & that the evidence on larger doses of this combination is inadequate to lớn assess the benefits in this population <40>. The USPSTF also determined the evidence on the benefits of calcium supplementation alone or with vitamin D to be inadequate to assess its effect on preventing fractures in men & premenopausal women.
Additional research is needed before conclusions can be drawn about the use of calcium supplements to lớn improve bone health và prevent fractures in older adults.
CancerCalcium might help reduce the risk of cancer, especially in the colon & rectum <1>. However, evidence on the relationship between calcium intakes from foods or supplements & different forms of cancer is inconsistent <4>.
All-cancer incidence & mortality. Most clinical trial evidence does not tư vấn a beneficial effect of calcium supplements on cancer incidence. A 4-year study of 1,500 mg calcium và 2,000 IU (50 mcg) vi-ta-min D or placebo daily for 4 years in 2,303 healthy women aged 55 years & older showed that supplementation did not reduce the risk of all types of cancer <41>. The large WHI study described above also found no benefit of supplemental calcium & vitamin D on cancer incidence <42>. In addition, a meta-analysis of 10 RCTs that included 10,496 individuals who took supplements containing 500 mg calcium or more (without vi-ta-min D) for a mean of 3.9 years found that calcium supplementation did not change the total cancer risk <43>. But one large clinical trial did find that calcium supplements reduce cancer risk. In this 4-year trial, by the same investigators as the 4-year trial above, 1,179 women aged 55 years or older in Nebraska took 1,400 lớn 1,500 mg calcium alone, 1,400 lớn 1,500 mg calcium plus 1,100 IU (27.5 mcg) vitamin D3, or placebo daily. Cancer incidence from all causes was 60% lower in women who took the combination & 47% lower in those who took calcium-only supplements than in the placebo group <44>. Some scientists have questioned these findings because of the lack of statistical power (the studies were designed to detect differences in bone health measures, not cancer incidence), details from the investigators on the study sample & randomization procedures <45,46>.
Observational evidence does not support an association between higher calcium intakes và a lower risk of cancer mortality. An analysis of data on 132,823 participants in the Cancer Prevention Study II Nutrition Cohort, who were followed for an average of 17.5 years, found no association between total dietary and supplemental calcium intakes & risk of cancer-related death or death from lung, colorectal, breast, or prostate cancer in men or women <47>. A systematic reviews and meta-analysis of 22 observational studies in 2,346,368 participants aged 8 and older followed for 4.6 lớn 28 years also found no association between total dietary & supplemental calcium intake và cancer mortality <48>.
Clinical trials have also not shown that supplemental calcium alone or combined with vi-ta-min D has an impact on risk of mortality from all cancers. An RCT in 5,292 adults aged 70 years or older (85% women) in the United Kingdom compared the effects of 1,000 mg calcium, 8,000 IU (200 mcg) vi-ta-min D3, both, or placebo for 24 lớn 62 months <49>. Rates of cancer incidence và cancer mortality did not differ between those who did và those who did not receive calcium supplements. In the WHI trial, 36,282 postmenopausal women were randomly assigned to lớn daily supplementation with a combination of 1,000 mg calcium & 400 IU (10 mcg) vitamin D3 or placebo <42>. After an average of 7 years, risk of cancer mortality did not differ between groups. The meta-analysis of 10 RCTs that included 10,496 individuals described above found no impact of calcium supplementation on cancer mortality rates <43>.
Colorectal Cancer. A substantial body toàn thân of evidence has addressed the role of calcium in preventing colorectal cancer or its precursor, adenomas.
Much but not all of the observational evidence supports a liên kết between higher calcium intakes & lower risk of colorectal cancer. A cohort study in 77,712 adults found that over a mean of 7.8 years, the highest total intake of dietary & supplemental calcium (median of 1,999 mg/day) was associated with a 26% lower risk of colon cancer than the lowest quintile (587 mg/day) but had no association with risk of rectal cancer <50>. In a dose-response meta-analysis of 15 prospective cohort studies in 1,415,597 participants (mean total dietary và supplemental calcium intake 250 khổng lồ 1,900 mg/day) followed for 3.3 lớn 16 years, risk of colorectal cancer dropped by 8% with each 300 mg/day increase in total calcium intake <51>. Findings were similar for dietary intakes of calcium in two other meta-analyses <52,53>.In spite of the observational evidence supporting an association between higher calcium intakes và lower colorectal cancer risk, clinical trials investigating calcium supplements for prevention of colorectal cancer or adenomas have had mixed results. A 2013 follow-up study by Cauley and colleagues evaluated outcomes 4.9 years after completion of the 7-year WHI trial of 1,000 mg/day calcium plus 400 IU (10 mcg)/day vi-ta-min D3 or placebo in 36,282 postmenopausal women <54>. Colorectal cancer rates did not differ between groups. Similarly, in a follow-up study an average of 55 months after administration of 1,200 mg/day calcium, 1,000 IU (25 mcg)/day vi-ta-min D3, or both for 3 lớn 5 years in 1,121 participants, supplements had no effect on risk of recurrent adenomas <55>. However, a systematic đánh giá and meta-analysis of four RCTs (not including the 2013 study by Cauley và colleagues) found that daily supplementation with 1,200 to lớn 2,000 mg elemental calcium for 36 to 60 months reduced the likelihood of recurrent adenomas by 11%, although the supplements had no effect on risk of advanced adenomas <56>.
Other Cancers. Xem thêm: Bệnh Van Tim: Nguyên Nhân, Triệu Chứng Và Phương Pháp Điều Trị
A meta-analysis included 15 epidemiological studies of calcium intake & ovarian cancer risk in 493,415 women who developed 7,453 cases of ovarian cancer <59>. In this meta-analysis, ovarian cancer risk was 20% lower in participants in the highest category of dietary calcium intakes (more than 820–1,500 mg/day, depending on the study) than the lowest intake category (less than 362–800 mg/day, depending on the study). However, the difference in risk was not statistically significant when both dietary and supplemental calcium intakes were considered.
For breast cancer, observational studies have had mixed findings on whether higher calcium intakes are associated with a lower risk. A meta-analysis of 11 prospective cohort studies in 872,895 women who developed 26,606 cases of breast cancer over 7 khổng lồ 25 years found that women with the highest calcium intakes had an 8% lower risk of breast cancer <60>. However, the WHI (described above) found similar incidence rates of invasive breast cancer in the supplement and placebo groups <61>.
Conclusion. Additional well-designed randomized trials are needed to lớn determine whether dietary or supplemental calcium intakes increase, decrease, or have no effect on risk of cancer in general or of specific types of cancer, or on cancer mortality.
Cardiovascular diseaseCalcium binds fatty acids, so it can reduce lipid absorption & might therefore lower CVD risk <1,4>. However, the findings from research on the role of dietary calcium & calcium supplements in reducing CVD have been mixed, and some evidence indicates that calcium supplements might even increase CVD risk.
Several large observational studies have shown an association between lower calcium intakes and higher risk of hypertension, stroke, & atherosclerosis. For example, an analysis of 1999–2010 NHANES data from 14,408 adults (mean age 54 years) with obesity found that calcium intakes were 10% lower in adults with obesity và hypertension than in those without hypertension <62>. This association was strongest in women, adults aged 20–44 years, those who did not have diabetes, and, especially, women aged 20–44 years. A prospective cohort study that followed 41,514 adults aged 40 to lớn 69 years in australia for 13 years found a 25% lower rate of stroke in adults in the highest calcium intake quartile (mean of 1,076 mg/day) than in the lowest quartile (mean of 641 mg/day) <63>. However, the study found no association between calcium intakes and risk of CVD mortality or myocardial infarction. The risk of atherosclerosis over 10 years in a study of 5,448 adults aged 45–84 years was 27% lower in the highest quintile of calcium intake (mean of 2,157 mg/day) than in the lowest quintile (mean of 313 mg/day) <64>. Furthermore, a systematic reviews and meta-analysis that included 27 observational studies found no consistent dose-response relationships between total, dietary, or supplemental calcium intakes và CVD mortality <65>. Evidence on dose-response relationships between calcium intakes và risk of stroke or stroke mortality was inconsistent.
A diet containing more calcium than the typical U.S. Diet because of added low-fat or non-fat dairy products lowered systolic blood pressure by an average of 5.5 mm
Hg và diastolic blood pressure by 3.0 mm
Hg <66>. However, this Dietary Approaches to lớn Stop Hypertension (DASH) diet also increases intakes of other nutrients, such as potassium và magnesium, that are associated with reductions in blood pressure, so any independent contribution of calcium cannot be determined.
Some clinical trials have shown that calcium supplements are associated with decreased hypertension risk or decreased cholesterol levels, but others have had more mixed findings. A Cochrane đánh giá of 16 trials in 3,048 adults with a median follow-up period of 3.5 months found that calcium supplementation (typically 1,000 to 2,000 mg/day) reduced systolic blood pressure by 1.43 mm
Hg and diastolic blood pressure by 0.98 mm
Hg <67>. Effects were greatest in adults younger than 35 years & with doses higher than 1,500 mg/day calcium. A meta-analysis of 23 RCTs in 4,071 participants showed that calcium supplements providing 162 khổng lồ 2,000 mg/day (combined with vi-ta-min D in 10 RCTs) for 2 weeks to lớn 5 years was associated with low-density lipoprotein cholesterol levels that were 4.6 mg/d
L lower & high-density lipoprotein cholesterol levels that were 1.9 mg/d
L higher <68>.
Findings were mixed in two analyses of data from the WHI. One analysis of results from 35,983 women aged 50 khổng lồ 79 years randomly assigned to lớn 1,000 mg/day calcium & 400 IU (10 mcg)/day vitamin D supplements or placebo for 10 years found no reduction in risk of heart failure <69>. However, the calcium & vitamin D supplements were associated with 5% lower heart failure risk in participants who had no preexisting heart failure risk factors (coronary heart disease, diabetes, or hypertension). In another secondary analysis of data on 16,801 WHI participants, the supplements had no association with atrial fibrillation risk <70>. Similarly, an evidence report & systematic reviews conducted for the USPSTF that included 11 RCTs of vi-ta-min D, calcium, or both for 2 khổng lồ 7 years in 51,419 adults aged 50 years và older found that supplementation with vi-ta-min D alone or combined with calcium had no effect on CVD incidence <39>.
In contrast, several prospective cohort studies và RCTs have shown that calcium supplements increase the risk of CVD. A meta-analysis of 14 RCTs (including 1 study that administered supplements providing 20 mcg <800 IU> vi-ta-min D per day) in 28,935 healthy postmenopausal women found that calcium supplements providing 500 to 2,000 mg/day calcium for 1 khổng lồ 7 years increased CVD risk by 15% & coronary heart disease risk by 16% <71>. In addition, when 132,823 adults (mean age 63 years) were followed for an average of 17.5 years, the risk of CVD mortality was 22% higher in men with calcium supplement intakes of 1,000 mg/day or more than in those not taking calcium supplements <47>. However, in women, the CVD mortality rate was 16% lower with supplemental calcium intakes of 1,000 mg/day than with no supplemental calcium intakes.
Other studies have found no association between calcium supplements and CVD risk or CVD outcomes. After 24 years of follow-up of 74,245 women aged 30 khổng lồ 55 years at baseline who participated in the Nurses’ Health Study, women taking more than 1,000 mg/day calcium supplements did not have a higher risk of CVD than those taking no supplemental calcium <72>.
An expert panel convened by the National Osteoporosis Foundation và American Society for Preventive Cardiology determined, on the basis of moderate-quality evidence, that calcium intakes with or without vitamin D from foods or supplements neither increase nor decrease the risk of CVD or CVD mortality <73>. The societies therefore concluded that calcium intakes that do not exceed the UL are safe "from a cardiovascular standpoint."
PreeclampsiaPreeclampsia is defined as hypertension and proteinuria or thrombocytopenia during pregnancy, usually after 20 weeks’ gestation <74>. It is a leading cause of maternal & neonatal morbidity and mortality that affects about 4% of pregnancies in the United States <75>.
Calcium supplementation during pregnancy might reduce the risk of preeclampsia, but the benefits might apply only khổng lồ women with inadequate calcium intakes, and much of this evidence comes from studies with methodological weaknesses <76,77>.
A Cochrane đánh giá included 27 RCTs of calcium supplements during pregnancy in 18,064 women khổng lồ prevent hypertensive disorders & related problems <78>. In the 13 studies—none of which administered vitamin D supplements—that evaluated high doses (at least 1,000 mg/day calcium) in 15,730 women, supplementation reduced the risk of high blood pressure by 35% and, in women with low dietary calcium intakes (less than 1,000 mg/day; 10 trials in 10,678 women), the risk of preeclampsia by 55%. However, the unique of this evidence was low. In 12 trials in 2,334 women, doses of less than 1,000 mg/day (usually 500 mg/day) reduced the risk of high blood pressure by 47% và of preeclampsia by 62%. However, most of these studies recruited women at high risk of preeclampsia and had a high risk of bias. An earlier systematic review and meta-analysis of 10 RCTs in 24,787 women also found that calcium supplementation (1,500 to 2,000 mg/day) reduced the risk of preeclampsia by 38% and, in women at increased risk of any hypertensive disorder of pregnancy, by 58% <79>. But when the analysis was restricted to trials with 4,000 or more women, the effect was no longer statistically significant. An RCT in 1,355 women in Argentina, South Africa, and Zimbabwe also found that 500 mg/day calcium supplementation starting before conception made no difference in the risk of preeclampsia <80,81>.
Several professional organizations recommend calcium supplements during pregnancy for women with low calcium intakes lớn reduce the risk of preeclampsia. For example, the American College of Obstetrics & Gynecology states that daily supplementation with 1,500–2,000 mg calcium might reduce the severity of preeclampsia in pregnant women who have calcium intakes of less than 600 mg/day <76>. The World Health Organization recommends 1,500–2,000 mg/day calcium for pregnant women with low dietary calcium intakes lớn reduce preeclampsia risk <82>. The Canadian Hypertensive Disorders of Pregnancy Working Group <83>, the International Society for the Study of Hypertension in Pregnancy <84>, và the Society of Obstetric Medicine of nước australia and New Zealand <85> have similar recommendations.
Weight managementObservational and clinical trial evidence linking higher calcium intakes from dairy products or supplements lớn lower body toàn thân weight or less weight gain over time is mixed.
An observational study found an association between higher calcium intakes & lower prevalence of overweight or obesity in 6,696 children (51% male, mean age 6 years) in eight European countries, of whom 2,744 were re-examined 6 years later <86>. The prevalence of overweight or obesity at 6-year follow-up was lower in boys (16%) and girls (18%) in the highest tertile of calcium intake (664 mg/1,000 kcal for boys & 667 mg/1,000 kcal for girls) than in boys (26%) & girls (25%) in the lowest tertile (249 mg/1,000 kcal for both boys and girls). In contrast, a longitudinal study in 2,159 participants in Portugal evaluated at ages 13 và 21 years found no association between total dietary và supplemental calcium intake at age 13 and body mass index (BMI) at age 21 after the analysis was adjusted for energy intake <87>. The study also found no associations between consumption of dairy foods (milk, yogurt, và cheese) at age 13 & BMI at age 21.
Clinical trials and meta-analyses of RCTs assessing the impact of calcium supplements or increased intakes of calcium from dairy products on prevention of weight gain or promotion of fat loss or weight loss have had mixed results <88-92>. For example, postmenopausal women who took 1,000 mg calcium và 400 IU (10 mcg) vi-ta-min D daily for 3 years in the WHI whose daily intakes were less than 1,200 mg calcium at baseline were 11% less likely khổng lồ gain 1 kilogam of weight or more than those who took placebo during this period <90>. A systematic review and meta-analysis of 41 RCTs that examined the effect of dairy foods or calcium supplements (at least 300 mg/day) in 4,802 adults found that higher calcium intakes from dairy foods had no impact on toàn thân weight or body toàn thân fat, although they did reduce body toàn thân fat when combined with an energy-restricted diet <91>. In addition, calcium supplements had no effect on body toàn thân weight or body toàn thân fat.
For additional information on calcium and weight management, see the health professional fact sheet on weight loss.
Metabolic syndromeMetabolic syndrome is a set of at least three risk factors for heart disease, stroke, & diabetes—large waistline, high triglyceride level, low high-density lipoprotein cholesterol level, high blood pressure, & high fasting blood sugar level. Some observational evidence liên kết higher calcium intakes with lower risk of metabolic syndrome.
An analysis of 2001–2010 NHANES data on 9,148 adults found that women in the highest quintile (at least 1,172 mg/day) of calcium intake, based on 24-hour recall, had a 27% lower risk of metabolic syndrome than those in the lowest quintile (less than 547 mg/day) <93>. Furthermore, women who met the RDA for calcium for adults (1,000 to lớn 1,200 mg/day, depending on age) had an 18% lower risk of metabolic syndrome, but the association was not statistically significant in men who met the RDA for calcium. In a meta-analysis of eight cross-sectional studies and two prospective cohort studies in 63,017 participants aged đôi mươi years and older, 14,906 participants developed metabolic syndrome <94>. For each 300 mg/day increase in dietary calcium intake, risk of metabolic syndrome dropped by 7%. Subgroup analyses suggested that the inverse association between dietary calcium intakes & metabolic syndrome risk was stronger in women than men.
Clinical trial evidence on the links between calcium và metabolic syndrome is very limited. In one placebo-controlled clinical trial in Iran in 66 adults who were overweight và had type 2 diabetes và coronary heart disease, supplements of 5 mcg (200 IU) vitamin D, 90 mcg vitamin K, and 500 mg calcium for 12 weeks significantly reduced maximum levels of left carotid intima media thickness and improved metabolic status (including improvements in insulin resistance, insulin concentrations, beta-cell function, & quantitative insulin sensitivity kiểm tra index) <95>.
More evidence, including from well-designed clinical trials, is needed to lớn determine whether higher intakes of calcium can reduce the risk of metabolic syndrome.
Health Risks from Excessive Calcium
Hypercalcemia (serum levels greater than 10.5 mg/d
L <2.63 mmol/L>) & hypercalciuria (urinary calcium levels higher than 250 mg/day in women & 275 mg/day in men) are rare in healthy people and usually result from cancer, primary hyperparathyroidism, and other conditions <1,4>. Hypercalcemia & hypercalciuria can cause poor muscle tone, renal insufficiency, hypophosphatemia, constipation, nausea, weight loss, fatigue, polyuria, heart arrhythmias, và a higher risk of CVD mortality <1,4,48>.
High calcium intakes might also increase the risk of CVD (see section on CVD in "Calcium và Health" section above) <39,62,67,69,70> & prostate cancer (see "Other Cancers" in "Calcium & Health" section above for more details) <57,58>, although not all studies confirm these findings.
The ULs for calcium established by the Food and Nutrition Board are listed in Table 3. They are based on observational evidence from the WHI showing a links between higher intakes of supplemental calcium (1,000 mg/day for 7 years) & a greater risk of kidney stones <96,97>. However, two subsequent systematic review of the evidence from 10 studies in more than 8,000 adults with osteoporosis who took 120 lớn 1,500 mg supplemental calcium daily for 3 days khổng lồ 3 years <98> & 11 RCTs in 51,419 adults 50 years & older who took 1,000 khổng lồ 1,600 mg calcium with or without vi-ta-min D for 2 to 7 years <39> found no such association.
| 0-6 months | 1,000 mg | 1,000 mg | ||
| 7–12 months | 1,500 mg | 1,500 mg | ||
| 1–8 years | 2,500 mg | 2,500 mg | ||
| 9–18 years | 3,000 mg | 3,000 mg | 3,000 mg | 3,000 mg |
| 19–50 years | 2,500 mg | 2,500 mg | 2,500 mg | 2,500 mg |
| 51+ years | 2,000 mg | 2,000 mg |
Interactions with Medications
Calcium has the potential khổng lồ interact with certain medications, and several types of medications might adversely affect calcium levels. A few examples are provided below. Individuals taking these and other medications on a regular basis should discuss their calcium status with their health care providers.
DolutegravirDolutegravir (Dovato, Tivicay) is an HIV integrase inhibitor used in adults và children. Concomitant use of calcium supplements & dolutegravir can reduce blood levels of dolutegravir substantially, apparently through chelation <99,100>. The labels approved by the FDA for dolutegravir advise patients to take dolutegravir 2 hours before or 6 hours after taking calcium supplements <101,102>.
LevothyroxineCalcium carbonate supplements can interfere with the absorption of levothyroxine (Synthroid, Levoxyl, & others), a thyroid hooc môn used to lớn treat hypothyroidism và thyroid cancer <103-105>. The FDA-approved label for this medication instructs patients taking calcium carbonate supplements khổng lồ avoid taking levothyroxine within 4 hours of taking the supplement <106>.
LithiumLong-term use of lithium (Eskalith, Lithobid), a treatment for bipolar disorder, can lead lớn hypercalcemia, and use of both lithium và calcium supplements could increase this risk <107>.
Quinolone antibioticsSimultaneous use of calcium supplements & quinolone antibiotics—such as ciprofloxacin (Cipro), gemifloxacin (Factive), & moxifloxacin (Avelox)—can reduce the absorption of quinolones <108,109>. Taking the antibiotic 2 hours before or 2 hours after calcium supplements prevents this effect <108>.
Calcium và Healthful Diets
The federal government’s 2020-2025 Dietary Guidelines for Americans notes that "Because foods provide an array of nutrients và other components that have benefits for health, nutritional needs should be met primarily through foods. ... In some cases, fortified foods và dietary supplements are useful when it is not possible otherwise khổng lồ meet needs for one or more nutrients (e.g., during specific life stages such as pregnancy)."For more information about building a healthy dietary pattern, refer to lớn the Dietary Guidelines for Americans và the U.S. Department of Agriculture’s My
Plate.
The Dietary Guidelines for Americans describes a healthy eating pattern as one that:
Includes a variety of vegetables, fruits, whole grains, fat-free or low-fat milk & milk products, and oils.Many dairy products, such as milk, cheese, & yogurt, are rich sources of calcium. Some vegetables provide significant amounts of calcium, as bởi vì some fortified cereals và juices.Includes a variety of protein foods, including seafood, lean meats & poultry, eggs, legumes (beans and peas), nuts, seeds, & soy products.Tofu made with calcium salts is a good source of calcium (check the label), as are canned sardines & canned salmon with edible bones.Limits foods và beverages higher in added sugars, saturated fat, và sodium.Limits alcoholic beverages.Stays within your daily calorie needs.References
Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: The National Academies Press; 2011.Heaney RP. Calcium. In: Coates PM, Betz JM, Blackman MR, et al., eds. Encyclopedia of Dietary Supplements. 2nd ed. London and New York: Informa Healthcare; 2010:101-6.Weaver CM, Heaney RP. Calcium. In: Ross AC, Caballero B, Cousins RJ, Tucker KL, Ziegler TR, eds. Modern Nutrition in Health and Disease. 11th ed. Baltimore, MD: Lippincott Williams và Wilkins; 2014:133-49.Weaver CM. Calcium. In: Marriott BP, Birt DF, Stallings VA, Yates AA, eds. Present Knowledge in Nutrition. 11th ed. Cambridge, Massachusetts: Wiley-Blackwell; 2020:321-48.Institute of Medicine SCotSEo
DR, Intakes,. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, vi-ta-min D, & Fluoride. Washington, DC: National Academies Press; 1997.
Disclaimer
This fact sheet by the National Institutes of Health (NIH) Office of Dietary Supplements (ODS) provides information that should not take the place of medical advice. We encourage you to talk khổng lồ your health care providers (doctor, registered dietitian, pharmacist, etc.) about your interest in, questions about, or use of dietary supplements và what may be best for your overall health. Any mention in this publication of a specific sản phẩm or service, or recommendation from an organization or professional society, does not represent an endorsement by ODS of that product, service, or expert advice.
Calcium is an important nutrient that your body needs for many basic functions. Read on khổng lồ learn more about this mineral and how much you should be getting.Calcium plays a role in many of your body’s basic functions. Your body needs calcium in order lớn circulate blood, move muscles, & release hormones. Calcium also helps carry messages from your brain to lớn other parts of your body.
Calcium is a major part of tooth & bone health as well. It makes your bones strong and dense. You can think of your bones as your body’s calcium reservoir. If you don’t get enough calcium in your diet, your toàn thân will take it from your bones.
Your body doesn’t produce calcium, so you have to rely on your diet lớn get the calcium you need. Foods that are high in calcium include:
dairy products such as milk, cheese, & yogurtdark green vegetables such as a kale, spinach, và broccoliwhite beanssardinescalcium-fortified breads, cereals, soy products, và orange juicesYour toàn thân needs vitamin D in order to absorb calcium. That means you won’t fully benefit from a calcium-rich diet if you’re low on vi-ta-min D.
You can get vi-ta-min D from certain foods, such as salmon, eggs yolks, và some mushrooms. Like calcium, some food products have vitamin D added lớn them. For example, milk often has added vi-ta-min D.
Sunshine is your best source of vi-ta-min D. Your skin naturally produces vitamin D when exposed to the sun. Those with darker skin don’t produce vitamin D as well, so supplements may be necessary lớn avoid deficiency.
4. Calcium is even more important for women
Several studies show that calcium may ease symptoms of premenstrual syndrome (PMS). This study concluded that women with PMS have lower intakes of calcium and magnesium, and lower serum levels.
5. The recommended amount depends on your age
How bởi you know if you’re getting enough calcium? The National Institutes of Health (NIH) say that adults should get 1,000 mg every day. For women over 50 and during pregnancy and breast-feeding, NIH recommends 1,200 mg daily.
One cup of skim, low-fat, or whole milk contains about 300 mg of calcium. Kiểm tra the UCSF’s helpful guide khổng lồ see how much calcium is in many common foods.
6. Lack of calcium can lead khổng lồ other health issues
A lack of calcium could lead to lớn other health issues. For adults, too little calcium can increase your risk of developing osteoporosis, or frail and porous bones that easily fracture. Osteoporosis is especially common in older women, which is why the NIH recommends they consume more calcium than their male counterparts.
Calcium is essential for children as they grow & develop. Children who don’t get enough calcium may not grow to their full potential height, or develop other health issues.
7. Calcium supplements can help you get the right amount
Not everyone gets the calcium they need from diet alone. If you’re lactose intolerant, vegan, or just not a fan of dairy products, you may find it difficult to get enough calcium in your diet.
A calcium supplement can help địa chỉ cửa hàng calcium khổng lồ your diet. Calcium carbonate và calcium citrate are the two most recommended forms of calcium supplements.
Calcium carbonate is cheaper và more common. It can be found in most antacid medicines. It needs to lớn be taken with food in order for it to work well.
Calcium citrate doesn’t need khổng lồ be taken with food and may be better absorbed by older people with lower levels of stomach acid.
Take note that calcium supplements vì have side effects. You may experience constipation, gas, và bloating. The supplements may also interfere with your body’s ability khổng lồ absorb other nutrients or medications. Check with your doctor before starting any supplements.
8. Too much calcium can have negative effects
With any mineral or nutrient, it’s important to get the right amount. Too much calcium can have negative side effects.
Symptoms such as constipation, gas, và bloating may indicate that you’re getting too much calcium.
Extra calcium may also increase your risk of kidney stones. In rare cases, too much calcium can cause deposits of calcium in your blood. This is called hypercalcemia.
Some doctors think that taking calcium supplements can increase your risk of heart disease, but others disagree. At the moment, more research is needed khổng lồ understand how calcium supplements affect heart health.
The takeaway
Calcium is essential khổng lồ your overall health. You can get the calcium you need from many different foods, and if necessary, from supplements. Calcium works together with other nutrients such as vitamin D, so it is important keep up a balanced diet. As with any mineral or nutrient, you should monitor your calcium intake so that you aren’t getting too much or too little.
Last medically reviewed on May 16, 2016
How we reviewed this article:
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bachnghehcm.edu.vn has strict sourcing guidelines và relies on peer-reviewed studies, academic research institutions, & medical associations. We avoid using tertiary references. You can learn more about how we ensure our nội dung is accurate & current by reading our editorial policy.
Saeedian, K. A., Amani, R., và Cheraghian, B. (2015, October 25). The Association between the Risk of Premenstrual Syndrome và Vitamin D, Calcium, & Magnesium Status among University Students: A Case Control Study. Health Promotion Perspectives, 5(3), 225-30What you need lớn know about calcium. (2003, April)
Our experts continually monitor the health và wellness space, và we update our articles when new information becomes available.
Current Version
Aug 14, 2018
Edited By
Katrina Chernoff
May 16, 2016
Medically Reviewed By
Natalie Butler, RD, LD
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Medically reviewed by Natalie Butler, R.D., L.D. — By Summer Fanous — Updated on August 14, 2018
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