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Calcium is important for achieving and maintaining optimum bone density. Some athletes, especially women with low body weight and/or amenorrhea, are at risk for serious bone loss and fractures.1, 2 Contributing to this risk are the diets of these athletes, which are frequently deficient in calcium.3 All athletes should try to achieve the recommended intakes of calcium, which are 1,300 mg per day for teenagers and 1,000 mg per day for adults. Other uses of calcium for sports and fitness, including prevention or relief of sports-related muscle cramps, have not been studied.
Constipation, bloating, and gas are sometimes reported with the use of calcium supplements.4 A very high intake of calcium from dairy products combined with large amounts of supplemental calcium carbonate (used as an antacid) was reported in the past to cause a condition called “milk alkali syndrome.” This toxicity is rarely reported today because most medical doctors no longer tell people with ulcers to use this approach as treatment for their condition.
People with hyperparathyroidism, chronic kidney disease, or kidney stones should not supplement with calcium without consulting a physician. For other adults, the highest amount typically suggested by doctors (1,200 mg per day) typically does not cause side effects. People with prostate cancer should avoid supplementing with calcium without medical supervision.
A combined analysis of 15 controlled trials found that long-term calcium supplementation was associated with a significant increase of approximately 30% in the incidence of myocardial infarctions (heart attacks).5 Since these studies were not designed to examine the effect of calcium on heart attack risk, it is possible that the findings in this post hoc (after the fact) analysis were due to chance. A more recent study found that long-term calcium supplementation did not result in an increased incidence of cardiovascular disease-related death or hospitalization.6 Moreover, a pooled analysis of randomized controlled trials found that supplementing elderly individuals with a combination of calcium and vitamin D significantly decreased the mortality rate by 7%.7
In the past, calcium supplements in the forms of bone meal (including microcrystalline hydroxyapatite [MCHC]), dolomite, and oyster shell have sometimes had higher lead levels than permitted by stringent California regulations, though generally less than the levels set by the federal government.8 “Refined” forms (which would include calcium citrate malate [CCM], calcium citrate, and most calcium carbonate) have low levels of lead.9 More recently, a survey of over-the-counter calcium supplements found low or undetectable levels of lead in most products,10 representing a sharp decline in lead content of calcium supplements since 1993. People who decide to take bone meal, dolomite, oyster shell, or coral calcium for long periods of time can contact the supplying supplement company to request independent laboratory analysis showing minimal lead levels.
Some studies have shown that calcium competes for absorption with a number of other minerals, while other studies have found no such competition. To be on the safe side, some doctors recommend that people taking calcium for long periods of time should also take a multimineral supplement.
One study has shown that taking calcium can interfere with the absorption of phosphorus, which, like calcium, is important for bone health.11. Although most western diets contain ample or even excessive amounts of phosphorus, older people who supplement with large amounts of calcium may be at risk of developing phosphorus deficiency. For this reason, the authors of this study recommend that, for elderly people, at least some of the supplemental calcium be taken in the form of tricalcium phosphate or some other phosphorus-containing preparation.
Vitamin D’s most important role is maintaining blood levels of calcium. Therefore, many doctors recommend that those supplementing with calcium also supplement with 400 IU of vitamin D per day.
Animal studies have shown that essential fatty acids (EFAs) increase calcium absorption from the gut, in part by enhancing the effects of vitamin D and reducing loss of calcium in the urine.12
Lysine supplementation increases the absorption of calcium and may reduce its excretion.13 As a result, some researchers believe that lysine may eventually be shown to have a role in the prevention and treatment of osteoporosis.14
Certain medicines interact with this supplement.
|Replenish Depleted Nutrients|
|Reduce Side Effects|
|Potential Negative Interaction|
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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2016.