In the study mentioned here, calcium supplements (specifically, calcium citrate) provided benefits at a dose of 1 g daily.
In a 12-month study of 223 postmenopausal women, calcium supplements (calcium citrate at a dose of 1 g daily) significantly improved the ratio of HDL ("good") cholesterol to LDL ("bad") cholesterol.155
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It appears that calcium supplements help increase levels of "good" (HDL) cholesterol. This improves the ratio of HDL to LDL ("bad") cholesterol, which is beneficial.
Some research suggests that calcium helps raise levels of HDL ("good") cholesterol, improving the ratio of HDL to LDL ("bad") cholesterol.
It appears that calcium supplements help increase levels of "good" (HDL) cholesterol. This improves the ratio of HDL to LDL ("bad") cholesterol, which is beneficial.
Calcium plays a number of roles in the body. For instance, calcium is involved in the contraction and dilation of blood vessels,28 both of which affect blood pressure.
In general, it's safe to take up to 2,500 mg of calcium daily, although this is more than you need. 1 Greatly excessive intake of calcium can cause numerous side effects, including dangerous or painful deposits of calcium within the body.
Note:If you have cancer, hyperparathyroidism, or sarcoidosis, you should take calcium only under a physician's supervision.
Some evidence hints that use of calcium supplements might slightly increase kidney stone risk. 2 However, increased intake of calcium from fooddoes not seem to have this effect and could even help prevent stones. 3 One study found that if calcium supplements are taken with food, there is no increased risk. 4 Calcium citrate supplements may be particularly safe regarding kidney stones because the citrate portion of this supplement is used to treatkidney stones. 5 There is preliminary evidence that calcium supplementation in healthy, post-menopausal women may slightly increase the risk of cardiovascular events, such as myocardial infarction. However, it remains far from clear whether this possible risk outweighs the benefits of calcium supplementation in this population. 6 Large observational studies have found that, in men, higher intakes of calcium are associated with an increased risk of prostate cancer. 7 This seems to be the case whether the calcium comes from milk or from calcium supplements.
Calcium supplements combined with high doses of vitamin D might interfere with some of the effects of drugs in the calcium channel blocker family. 8 It is very important that you consult your physician before trying this combination.
Concerns have been raised that the aluminum in some antacids may not be good for you. 9 There is some evidence that calcium citrate supplements might increase the absorption of aluminum; 10 11 12 13 for this reason, it might not be a good idea to take calcium citrate at the same time of day as aluminum-containing antacids. Another option is to use different forms of calcium, or to avoid antacids containing aluminum.
When taken over the long term, thiazide diuretics tend to increase levels of calcium in the body by decreasing the amount excreted by the body. 14 15 16 It's not likely that this will cause a problem. Nonetheless, if you are using thiazide diuretics, you should consult with your physician on the proper doses of calcium and vitamin D for you.
Finally, calcium may interfere with the absorption of antibiotics in the tetracycline and fluoroquinolone families as well as thyroid hormone. 17 18 19 20 21 22 If you are taking any of these drugs, you should take your calcium supplements at least 2 hours before or after your medication dose.
Many foods are calcium rich and/or fortified with extra calcium. When it comes to supplements, calcium comes in different forms, some of which may be more readily absorbed than others. For more information, see the Requirements/Sources and Therapeutic Doses section of the full article on calcium.
Although there are some variations between recommendations issued by different groups, the official US and Canadian recommendations for daily intake of calcium are as follows:
To absorb calcium, your body also needs an adequate level of vitamin D (for more information, see the article on Vitamin D ).
Various medications may impair calcium absorption or metabolism, either directly or through effects on vitamin D. People who use these may benefit by taking extra calcium and vitamin D. Implicated medications include corticosteroids , 1 2 heparin , 3 4 isoniazid , 5 6 and anticonvulsants . 7 8 9 10 11 12 Note:Calcium carbonate might interfere with the effects of anticonvulsant drugs, and for that reason should not be taken at the same time of day. 13 Milk, cheese, and other dairy products are excellent sources of calcium. Other good sources include orange juice or soy milk fortified with calcium, fish canned with its bones (such as sardines), dark green vegetables, nuts and seeds, and calcium-processed tofu.
Many forms of calcium supplements are available on the market, each with its own advantages and disadvantages.
Naturally Derived Forms of Calcium
These forms of calcium come from bone, shells, or the earth: bonemeal, oyster shell, and dolomite. Animals concentrate calcium in their shells, and calcium is found in minerals in the earth. These forms of calcium are economical, and you can get as much as 500 mg to 600 mg in one tablet. However, there are concerns that the natural forms of calcium supplements may contain significant amounts of lead. 14 The level of contamination has decreased in recent years, but still may present a health risk. 15 Calcium supplements rarely list the lead content of their source, although they should. The lead concentration should always be less than 2 parts per million.
Refined Calcium Carbonate
This is the most common commercial calcium supplement, and it is also used as a common antacid. Calcium carbonate is one of the least expensive forms of calcium, but it can cause constipation and bloating, and it may not be well absorbed by people with reduced levels of stomach acid. Taking it with meals improves absorption because stomach acid is released to digest the food. 16 (See the section, Chelated Calcium, below.)
Chelated Calcium
Chelated calcium is calcium bound to an organic acid (citrate, citrate malate, lactate, gluconate, aspartate, or orotate). The chelated forms of calcium offer some significant advantages and disadvantages compared with calcium carbonate.
Certain forms of chelated calcium (calcium citrate and calcium citrate malate) are widely thought to be significantly better absorbed and more effective for osteoporosis treatment than calcium carbonate. However, while some studies support this belief, 17 others do not. 18 The discrepancy may be due to the particular calcium carbonate products used; some calcium carbonate formulations may dissolve better than others.
One study found that calcium citrate malate in orange juice is markedly better absorbed than tricalcium phosphate/calcium lactate in orange juice. 19 A form of calcium called active absorbable algal calcium (AAACa) has also been promoted as superior to calcium carbonate, but the study upon which claims of benefit are founded actually used quite questionable statistical methods (technically, post-hoc subgroup analysis). 20 Chelated calcium is much more expensive and bulkier than calcium carbonate. In other words, you have to take larger pills, and more of them, to get enough calcium. It is not at all uncommon to need to take five or six large capsules daily to supply the necessary amount, a quantity some people may find troublesome.
People who are deficient in calcium may be at great greater risk of developing high blood pressure.29,30,58 Among people who already have hypertension, increased intake of calcium intake might slightly decrease blood pressure, according to some but not all studies.31,59 In an extremely large randomized, placebo-controlled trial involving 36,282 postmenopausal women, 1,000 mg of calcium plus 400 IU of vitamin D given daily did not significantly reduce blood pressure over a 7 year period in women with or without hypertension.139
Also, some evidence hints that the use of calcium by pregnant mothers might reduce risk of hypertension in their children.107
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Calcium plays a number of roles in the body. For instance, calcium is involved in the contraction and dilation of blood vessels,28 both of which affect blood pressure.
People who are deficient in calcium may be at greater risk of developing high blood pressure.29,30,58 Among people who already have hypertension, increased intake of calcium intake might slightly decrease blood pressure, according to some but not all studies.31,59 In an extremely large randomized, placebo-controlled trial involving 36,282 postmenopausal women, 1,000 mg of calcium plus 400 IU of vitamin D given daily did not significantly reduce blood pressure over a 7 year period in women with or without hypertension.139
Also, some evidence hints that the use of calcium by pregnant mothers might reduce risk of hypertension in their children.107
People who are deficient in calcium may be at great risk of developing high blood pressure, so increasing your intake of calcium may help prevent hypertension. Among people who already have hypertension, increased intake of calcium might slightly decrease blood pressure.
Calcium plays a number of roles in the body. For instance, calcium is involved in the contraction and dilation of blood vessels,28 both of which affect blood pressure.
