Where is 99 of the body calcium

Accessed October 10, In the typical American diet, calcium is obtained mostly from dairy products, primarily cheese. A slice of cheddar or Swiss cheese contains just over milligrams of calcium. One cup of nonfat milk contains approximately milligrams of calcium, which is about a third of the RDA for calcium for most adults. Foods fortified with calcium such as cereals, soy milk, and orange juice also provide one third or greater of the calcium RDA.

Although the typical American diet relies mostly on dairy products for obtaining calcium, there are other good non-dairy sources of calcium. If you need to increase calcium intake, are a vegan, or have a food allergy to dairy products, it is helpful to know that there are some plant-based foods that are high in calcium. Tofu made with calcium sulfate , turnip greens, mustard greens, and chinese cabbage are good sources.

When obtaining your calcium from a vegan diet, it is important to know that some plant-based foods significantly impair the absorption of calcium.

These include spinach, Swiss chard, rhubarb, beets, cashews, and peanuts. With careful planning and good selections, you can ensure that you are getting enough calcium in your diet even if you do not drink milk or consume other dairy products.

Fact Sheet for Health Professionals: Calcium. Updated November 17, Accessed November 12, In the small intestine, calcium absorption primarily takes place in the duodenum first section of the small intestine when intakes are low, but calcium is also absorbed passively in the jejunum and ileum second and third sections of the small intestine , especially when intakes are higher. Interestingly, the calcium in some vegetables such as kale, brussel sprouts, and bok choy is better absorbed by the body than are dairy products.

About 30 percent of calcium is absorbed from milk and other dairy products. The greatest positive influence on calcium absorption comes from having an adequate intake of vitamin D. People deficient in vitamin D absorb less than 15 percent of calcium from the foods they eat. The hormone estrogen is another factor that enhances calcium bioavailability.

Thus, as a woman ages and goes through menopause, during which estrogen levels fall, the amount of calcium absorbed decreases and the risk for bone disease increases.

Some fibers, such as inulin, found in jicama, onions, and garlic, also promote calcium intestinal uptake. Chemicals that bind to calcium decrease its bioavailability. These negative effectors of calcium absorption include the oxalates in certain plants, the tannins in tea, phytates in nuts, seeds, and grains, and some fibers. Oxalates are found in high concentrations in spinach, parsley, cocoa, and beets. In general, the calcium bioavailability is inversely correlated to the oxalate content in foods.

High-fiber, low-fat diets also decrease the amount of calcium absorbed, an effect likely related to how fiber and fat influence the amount of time food stays in the gut. Anything that causes diarrhea, including sickness, medications, and certain symptoms related to old age, decreases the transit time of calcium in the gut and therefore decreases calcium absorption.

As we get older, stomach acidity sometimes decreases, diarrhea occurs more often, kidney function is impaired, and vitamin D absorption and activation is compromised, all of which contribute to a decrease in calcium bioavailability. Skip to content Chapter Major Minerals.

Tools for Change If you need to increase calcium intake, are a vegan, or have a food allergy to dairy products, it is helpful to know that there are some plant-based foods that are high in calcium. Birkett NJ. Am J Epidemiol. Accessed November 22, Ann Intern Med. J Sci Med Sport. Although cases of preeclampsia are at high risk of developing eclampsia, one-quarter of women with eclampsia do not initially exhibit preeclamptic symptoms. Risk factors for preeclampsia include genetic predisposition, advanced maternal age, first pregnancies, multiple pregnancies e.

While the pathogenesis of preeclampsia is not entirely understood, nutrition and especially calcium metabolism appear to play a role. Data from epidemiological studies have suggested an inverse relationship between calcium intake during pregnancy and the incidence of preeclampsia reviewed in Secondary hyperparathyroidism high PTH level due to vitamin D deficiency in young pregnant women has been associated with high maternal blood pressure and increased risk of preeclampsia In addition, vitamin D deficiency may trigger hypertension through the inappropriate activation of the renin-angiotensin system see the article on Vitamin D.

Potential beneficial effects of calcium in the prevention of preeclampsia have been investigated in several randomized , placebo -controlled studies. Greater risk reductions were reported among pregnant women at high risk of preeclampsia 5 trials; women or with low dietary calcium intake 8 trials; 10, women.

Yet, based on the systematic review of high-quality randomized controlled trials, which used mostly high-dose calcium supplements, the World Health Organization WHO recently recommended that all pregnant women in areas of low-calcium intake i. Finally, the lack of effect of supplemental calcium on proteinuria reported in two trials only suggested that calcium supplementation from mid-pregnancy might be too late to oppose the genesis of preeclampsia 67, Colorectal cancer CRC is the most common gastrointestinal cancer and the second leading cause of cancer death in the US CRC is caused by a combination of genetic and environmental factors, but the degree to which these two types of factors influence CRC risk in individuals varies widely.

In individuals with familial adenomatous polyposis FAP or hereditary nonpolyposis colorectal cancer HNPCC , the cause of CRC is almost entirely genetic, while modifiable lifestyle factors, including dietary habits, tobacco use, and physical activities, greatly influence the risk of sporadic non-hereditary CRC. Prospective cohort studies have consistently reported an inverse association between dairy food consumption and CRC risk. Experimental studies in cell culture and animal models have suggested plausible mechanisms underlying a role for calcium, a major nutrient in dairy products, in preventing CRC Intakes of milk, cheese, and yogurt, were inversely associated with CRC risk.

Total daily intake of calcium ranged from to 2, mg in the examined studies. At present, it is not clear whether calcium supplementation is beneficial in CRC prevention. Children who are chronically exposed to lead, even in small amounts, are more likely to develop learning disabilities, behavioral problems, and to have low IQs. Deficits in growth and neurological development may occur in the infants of women exposed to lead during pregnancy and lactation.

In adults, lead toxicity may result in kidney damage and high blood pressure. Although the use of lead in paint products, gasoline, and food cans has been discontinued in the US, lead toxicity continues to be a significant health problem, especially in children living in urban areas Adequate calcium intake could be protective against lead toxicity in at least two ways.

Increased dietary intake of calcium is known to decrease the gastrointestinal absorption of lead. Once lead enters the body it tends to accumulate in the skeleton, where it may remain for more than 20 years. Adequate calcium intake also prevents lead mobilization from the skeleton during bone demineralization. A study of circulating concentrations of lead during pregnancy found that women with inadequate calcium intake during the second half of pregnancy were more likely to have elevated blood lead levels, probably because of increased bone demineralization, leading to the release of accumulated lead into the blood Lead in the blood of a pregnant woman is readily transported across the placenta resulting in fetal lead exposure at a time when the developing nervous system is highly vulnerable.

Similar reductions in maternal lead concentrations in the blood and breast milk of lactating mothers supplemented with calcium were reported in earlier trials 84, In postmenopausal women, factors known to decrease bone demineralization, including estrogen replacement therapy and physical activity, have been inversely associated with blood lead levels High dietary calcium intake, usually associated with dairy product consumption, has been inversely related to body weight and central obesity in a number of cross-sectional studies reviewed in Cross-sectional baseline data analyses of a number of prospective cohort studies that were not designed and powered to examine the effect of calcium intake or dairy consumption on obesity or body fat have given inconsistent results Yet, a meta-analysis of 18 cross-sectional and prospective studies predicted a reduction in body mass index a relative measure of body weight; BMI of 1.

Energy-restricted diets resulted in significant body weight and fat loss in all three groups. Yet, body weight and fat loss were significantly more reduced with the high-calcium diet compared to the standard diet, and further reductions were measured with the high-dairy diet compared to both high-calcium and low-calcium diets. These results suggested that while calcium intake may play a role in body weight regulation, additional benefits might be attributable to other bioactive components of dairy products, such as proteins , fatty acids , and branched chain amino acids.

Yet, several mechanisms have been proposed to explain the potential impact of calcium on body weight reviewed in The most-cited mechanism is based on studies in the agouti mouse model showing that low-calcium intakes, through increasing circulating parathyroid hormone PTH and vitamin D , could stimulate the accumulation of fat lipogenesis in adipocytes fat cells Conversely, higher intakes of calcium may reduce fat storage, stimulate the breakdown of lipids lipolysis , and drive fat oxidation.

Moreover, while the model suggests a role for vitamin D in lipogenesis fat storage , human studies have shown that vitamin D deficiency — rather than sufficiency — is often associated with obesity, and supplemental vitamin D might be effective in lowering body weight when caloric restriction is imposed 92, Another mechanism suggests that high-calcium diets may limit dietary fat absorption in the intestine and increase fecal fat excretion.

Indeed, in the gastrointestinal tract, calcium may trap dietary fat into insoluble calcium soaps of fatty acids that are then excreted In addition, despite very limited evidence, it has also been proposed that calcium might be involved in regulating appetite and energy intake To date, there is no consensus regarding the effect of calcium on body weight changes.

A meta-analysis of 29 randomized controlled trials in 2, participants median age, Yet, further subgroup analyses showed weight reductions in children and adolescents mean, At present, additional research is warranted to examine the effect of calcium intake on fat metabolism, as well as its potential benefits in the management of body weight with or without caloric restriction PMDD interferes with normal functioning, affecting daily activities and relationships Low dietary calcium intakes have been linked to PMS in early reports, and supplemental calcium has been shown to decrease symptom severity Similar positive effects were reported in earlier double-blind, placebo-controlled, cross-over trials that administered 1, mg of calcium daily , The relationship between calcium intake and blood pressure has been investigated extensively over the past decades.

A meta-analysis of 23 large observational studies conducted in different populations worldwide found a reduction in systolic blood pressure of 0. Among participants diagnosed with hypertension , the combination diet reduced systolic blood pressure by Yet, two large systematic reviews and meta-analyses of randomized controlled trials have examined the effect of calcium supplementation on blood pressure compared to placebo in either normotensive or hypertensive individuals , Neither of the analyses reported any significant effect of supplemental calcium on blood pressure in normotensive subjects.

A small but significant reduction in systolic blood pressure, but not in diastolic blood pressure, was reported in participants with hypertension. A more recent meta-analysis of 13 randomized controlled studies in individuals with elevated blood pressure found a significant reduction of 2. The modest effect of calcium on blood pressure needs to be confirmed in larger, high-quality, well-controlled trials before any recommendation is made regarding the management of hypertension.

Finally, a review of the literature on the effect of high-calcium intake dietary and supplemental in postmenopausal women found either no reduction or mild and transient reductions in blood pressure However, it is typically during the most critical period for peak bone mass development that adolescents tend to replace milk with soft drinks Dairy products represent rich and absorbable sources of calcium, but certain vegetables and grains also provide calcium.

However, the bioavailability of the calcium must be taken into consideration. The calcium content in calcium-rich plants in the kale family broccoli, bok choy, cabbage, mustard, and turnip greens is as bioavailable as that in milk; however, other plant-based foods contain components that inhibit the absorption of calcium. Oxalic acid, also known as oxalate, is the most potent inhibitor of calcium absorption and is found at high concentrations in spinach and rhubarb and somewhat lower concentrations in sweet potatoes and dried beans.

Phytic acid phytate is a less potent inhibitor of calcium absorption than oxalate. Yeast possess an enzyme phytase that breaks down phytate in grains during fermentation , lowering the phytate content of breads and other fermented foods.

Only concentrated sources of phytate, such as wheat bran or dried beans, substantially reduce calcium absorption Additional dietary constituents may affect calcium absorption see Nutrient interactions.

Table 2 lists a number of calcium-rich foods, along with their calcium content. Most experts recommend obtaining as much calcium as possible from food because calcium in food is accompanied by other important nutrients that assist the body in utilizing calcium.

However, calcium supplements may be necessary for those who have difficulty consuming enough calcium from food The "Supplement Facts" label, required on all supplements marketed in the US, lists the calcium content of the supplement as elemental calcium. Calcium preparations used as supplements include calcium carbonate, calcium citrate, calcium citrate malate, calcium lactate, and calcium gluconate. To determine which calcium preparation is in your supplement, you may have to look at the ingredient list.

Calcium carbonate is generally the most economical calcium supplement. To maximize absorption, take no more than mg of elemental calcium at one time. Most calcium supplements should be taken with meals, although calcium citrate and calcium citrate malate can be taken anytime. Calcium citrate is the preferred calcium formulation for individuals who lack stomach acids achlorhydria or those treated with drugs that limit stomach acid production H 2 blockers and proton-pump inhibitors reviewed in Several decades ago, concern was raised regarding lead concentrations in calcium supplements obtained from natural sources oyster shell, bone meal, dolomite In , investigators found measurable quantities of lead in most of the 70 different preparations they tested Since then, manufacturers have reduced the amount of lead in calcium supplements to less than 0.

Because lead is so widespread and long lasting, no one can guarantee entirely lead-free food or supplements. Calcium inhibits intestinal absorption of lead, and adequate calcium intake is protective against lead toxicity, so trace amounts of lead in calcium supplementation may pose less of a risk of excessive lead exposure than inadequate calcium consumption. While most calcium sources today are relatively safe, look for supplements approved or certified by independent testing e.

Malignancy and primary hyperparathyroidism are the most common causes of elevated calcium concentrations in the blood hypercalcemia Hypercalcemia has not been associated with the over consumption of calcium occurring naturally in food. Hypercalcemia has been initially reported with the consumption of large quantities of calcium supplements in combination with antacids, particularly in the days when peptic ulcers were treated with large quantities of milk, calcium carbonate antacid , and sodium bicarbonate absorbable alkali.

This condition is termed calcium-alkali syndrome formerly known as milk-alkali syndrome and has been associated with calcium supplement levels from 1. Since the treatment for peptic ulcers has evolved and because of the widespread use of over-the-counter calcium supplements, the demographic of this syndrome has changed in that those at greater risk are now postmenopausal women, pregnant women, transplant recipients, patients with bulimia, and patients on dialysis , rather than men with peptic ulcers reviewed in Supplementation with calcium 0.

Mild hypercalcemia may be without symptoms or may result in loss of appetite, nausea, vomiting, constipation, abdominal pain, fatigue, frequent urination polyuria , and hypertension More severe hypercalcemia may result in confusion, delirium, coma, and if not treated, death 1. The UL is listed in Table 3 by age group. Although the risk of forming kidney stones is increased in individuals with abnormally elevated urinary calcium hypercalciuria , this condition is not usually related to calcium intake, but rather to increased absorption of calcium in the intestine or increased excretion by the kidneys 9.

Overall, increased dietary calcium intake has been associated with a decreased risk of kidney stones see Kidney stones. Concerns have also been raised regarding the risks of prostate cancer and vascular disease with high intakes of calcium. Prostate cancer is the second most common cancer in men worldwide Several observational studies have raised concern that high-dairy intakes are associated with increased risk of prostate cancer The analysis of a prospective cohort study 2, men followed for nearly 25 years conducted in Iceland, a country with a high incidence of prostate cancer, found a positive association between the consumption of milk at least once daily during adolescence and developing prostate cancer later in life Another large prospective cohort study in the US followed 21, male physicians for 28 years and found that men with daily skim or low-fat milk intake of at least mL 8 oz had a higher risk of developing prostate cancer compared to occasional consumers The risk of low-grade, early-stage prostate cancer was associated with higher intake of skim milk, and the risk of developing fatal prostate cancer was linked to the regular consumption of whole milk In a cohort of 3, male health professionals diagnosed with prostate cancer, men died of prostate cancer and 69 developed metastasized prostate cancer during a median follow-up of 7.

Yet, no increase in risk of prostate cancer-related mortality was associated with consumption of skim and low-fat milk, total milk, low-fat dairy products, full-fat dairy products, or total dairy products A recent meta-analysis of 32 prospective cohort studies found high versus low intakes of total dairy product 15 studies , total milk 15 studies , whole milk 6 studies , low-fat milk 5 studies , cheese 11 studies , and dairy calcium 7 studies to be associated with modest, yet significant, increases in the risk of developing prostate cancer However, there was no increase in prostate cancer risk with nondairy calcium 4 studies and calcium from supplements 8 studies.

Moreover, high dairy intakes were not linked to fatal prostate cancer There is some evidence to suggest that milk consumption may result in higher circulating concentrations of insulin-like growth factor-I IGF-I , a protein known to regulate cell proliferation Circulating IGF-I concentrations have been positively correlated to the risk of developing prostate cancer in a recent meta-analysis of observational studies In the large EPIC study, which examined the consumption of dairy products in relation to cancer in , men, the risk of prostate cancer was found to be significantly higher in those in the top versusbottom quintile of both protein and calcium intakes from dairy foods Another mechanism underlying the potential relationship between calcium intake and prostate cancer proposed that high levels of dietary calcium may lower circulating concentrations of 1,dihydroxyvitamin D, the active form of vitamin D , thereby suppressing vitamin D-mediated cell differentiation However, studies to date have provided little evidence to suggest that vitamin D status can modify the association between dairy calcium and risk of prostate cancer development and progression In a multicenter, double-blind , placebo -controlled trial, healthy men mean age of While no increase in the risk for prostate cancer has been reported during a In a review of the literature published in , the US Agency for Healthcare Research and Quality indicated that not all epidemiological studies found an association between calcium intake and prostate cancer The review reported that 6 out of 11 observational studies failed to find statistically significant positive associations between prostate cancer and calcium intake.

Inconsistencies among studies suggest complex interactions between the risk factors for prostate cancer, as well as reflect the difficulties of assessing the effect of calcium intake in free-living individuals. Several observational studies and randomized controlled trials have raised concerns regarding the potential adverse effects of calcium supplements on cardiovascular risk.

The prospective study of 23, participants years old of the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition cohort EPIC-Heidelberg observed that supplemental calcium intake was positively associated with the risk of myocardial infarction heart attack but not with the risk of stroke or cardiovascular disease CVD -related mortality after a mean follow-up of 11 years In addition, the secondary analyses of two randomized placebo-controlled trials initially designed to assess the effect of calcium on bone health outcomes also suggested an increased risk of CVD in participants daily supplemented with 1, mg of calcium for five to seven years , A re-analysis was performed with data from 16, women who did not take personal calcium supplements outside protocol during the five-year study Also, after an additional follow-up of 4.

No evidence of an association was observed between dietary calcium intake, supplemental calcium intake, or total calcium intake and cardiovascular mortality in either men or women A few prospective studies have reported positive correlations between high calcium concentrations in the blood and increased rates of cardiovascular events , Because supplemental calcium may have a greater effect than dietary calcium on circulating calcium concentrations see Toxicity , it has been speculated that the use of calcium supplements might promote vascular calcification — a surrogate marker of the burden of atherosclerosis and a major risk factor for cardiovascular events — by raising calcium serum concentrations.

In 1, older women from the Auckland Calcium Study and healthy older men from another randomized, placebo-controlled trial of daily calcium supplementation mg or 1, mg for two years, serum calcium concentrations were found to be positively correlated with abdominal aortic calcification or coronary artery calcification However, there was no effect of calcium supplementation on measures of vascular calcification scores in men or women. Data from 1, participants of the Framingham Offspring study were also used to assess the relationship between calcium intake and vascular calcification.

Again, no association was found between coronary calcium scores and total, dietary, or supplemental calcium intake in men or women Finally, an assessment of atherosclerotic lesions in the carotid artery wall of 1, participants in the CAIFOS trial was also conducted after three years of supplementation When compared with placebo, calcium supplementation showed no effect on carotid artery intimal medial thickness CIMT and carotid atherosclerosis.

Because these clinical trial data are limited to analyses of secondary endpoints, meta-analyses should be interpreted with caution. There is a need for studies designed to examine the effect of calcium supplements on CVD risk as a primary outcome before definite conclusions can be drawn.

Based on an updated review of the literature that included four randomized controlled trials, one nested case-control study, and 26 prospective cohort studies , the National Osteoporosis Foundation NOF and the American Society for Preventive Cardiology ASPC concluded that the use of supplemental calcium for generally healthy individuals was safe from a cardiovascular health standpoint when total calcium intakes did not exceed the UL NOF and ASPC support the use of calcium supplements to correct shortfalls in dietary calcium intake and meet current recommendations Taking calcium supplements in combination with thiazide diuretics e.

High doses of supplemental calcium could increase the likelihood of abnormal heart rhythms in people taking digoxin Lanoxin for heart failure Calcium, when provided intravenously , may decrease the efficacy of calcium channel blockers However, dietary and oral supplemental calcium do not appear to affect the action of calcium channel blockers Supplemental calcium can decrease the concentration of dolutegravir Tivicay , elvitegravir Vitekta , and raltegravir Isentress , three antiretroviral medications, in blood such that patients are advised to take them two hours before or after calcium supplements Intravenous calcium should not be administrated within 48 hours following intravenous ceftriaxone rocephine , a cephalosporin antibiotic, since a ceftriaxone-calcium salt precipitate can form in the lungs and kidneys and be a cause of death Use of H 2 blockers e.

The topical use of calcipotriene, a vitamin D analog, in the treatment of psoriasis places patients at risk of hypercalcemia if they take calcium supplements. The presence of calcium decreases iron absorption from nonheme sources i. However, calcium supplementation up to 12 weeks has not been found to change iron nutritional status, probably due to a compensatory increase in iron absorption 1.

Individuals taking iron supplements should take them two hours apart from calcium-rich food or supplements to maximize iron absorption. Although high calcium intakes have not been associated with reduced zinc absorption or zinc nutritional status, an early study in 10 men and women found that mg of calcium consumed with a meal halved the absorption of zinc from that meal see the article on Zinc Supplemental calcium mg calcium carbonate has been found to prevent the absorption of lycopene a nonprovitamin A carotenoid from tomato paste in 10 healthy adults randomized into a cross-over study Following these recommendations should provide adequate calcium to promote skeletal health and may also decrease the risks of some chronic diseases.

After adult height has been reached, the skeleton continues to accumulate bone until the third decade of life when peak bone mass is attained. Originally written in by: Jane Higdon, Ph. Updated in April by: Jane Higdon, Ph. Updated in October by: Victoria J. Drake, Ph. Updated in August by: Barbara Delage, Ph. Updated in May by: Barbara Delage, Ph. Reviewed in September by: Connie M. Weaver, Ph. The update of this article was supported by a grant from Pfizer Inc.

Weaver CM. Present Knowledge in Nutrition. J Clin Endocrinol Metab. Clapham DE. Calcium signaling. Racial differences in calcium retention in response to dietary salt in adolescent girls.

Am J Clin Nutr. Adverse effects of sodium chloride on bone in the aging human population resulting from habitual consumption of typical American diets.

J Nutr. A longitudinal study of the effect of sodium and calcium intakes on regional bone density in postmenopausal women. Effects of a low sodium diet on bone metabolism. J Bone Miner Metab. Potassium citrate prevents increased urine calcium excretion and bone resorption induced by a high sodium chloride diet. Food and Nutrition Board, Institute of Medicine.

Washington, D. The National Academies Press. Fulgoni VL, 3 rd. Lowering dietary protein to U. Recommended dietary allowance levels reduces urinary calcium excretion and bone resorption in young women.

Protein intake, calcium balance and health consequences. Eur J Clin Nutr. The impact of dietary protein on calcium absorption and kinetic measures of bone turnover in women. Dietary protein and bone health: a systematic review and meta-analysis. High phosphorus intake only slightly affects serum minerals, urinary pyridinium crosslinks and renal function in young women. Low calcium:phosphorus ratio in habitual diets affects serum parathyroid hormone concentration and calcium metabolism in healthy women with adequate calcium intake.

It plays a role in numerous vital functions of the body, including blood coagulation, muscular contraction, nerve conduction, hormone release, and cellular division.

Over the long term, calcium in the diet also reduces the risk of certain diseases, including osteoporosis , colorectal cancer, arterial hypertension, and overweight. However, its positive effects are often associated with the presence of other nutrients like vitamin D, proteins, phosphorus, and fluorine. Foods that provide the most calcium are milk and other dairy products cheese, yogurt, etc. This means that a diet without dairy products makes it fairly complicated to cover our daily value in calcium, though it is not impossible.

The final third of our daily value is covered by certain green, leafy vegetables, dried vegetables and fruits, and a few mineral water sources. They need to be enriched in calcium to provide an equivalent amount as a glass of milk. Carefully read the labels! Some calcium-rich mineral waters are very useful for covering your calcium needs.

They contain a considerable amount of calcium that can be absorbed as easily as calcium in dairy products. Once again, carefully read the labels! Another preconceived notion is that it is easy to replace dairy products with vegetables or fruits that are particularly rich in calcium. Yes, that is true. But the reality is somewhat more complicated. Calcium in dairy products is much easier to absorb , which means that to take in an equivalent amount of calcium, you need to eat larger quantities of those fruits and vegetables on a daily basis.

An example is sometimes the best way to illustrate a point: do you regularly eat large quantities of parsley? Even if calcium intake plays an important role in reducing the risk of osteoporosis, you also need to use other proven means of prevention: vitamin D intake, which promotes intestinal absorption of calcium, and physical activity. Intake of magnesium and proteins also plays a major role in calcium absorption.