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Calcium

Calcium is a dietary macromineral found in high amounts in dairy products, and to a lesser extent in vegetables. Used primarily to support bone health, calcium also has a role in maternal and cardiovascular health.

Our evidence-based analysis on calcium features 152 unique references to scientific papers.

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Summary of Calcium

Primary Information, Benefits, Effects, and Important Facts

Calcium is one of the 24 vitamins and minerals required for good health in the human body. It is a macromineral due to the relatively large amounts required in the diet (at times exceeding a gram a day) and is predominately found in dairy products and vegetables. Similar to many other nutrients, calcium does follow the general advice of "if the diet is sufficient in calcium then supplementation is unnecessary" and excessive intakes of calcium do not promote greater benefits to health and may simply promote constipation.

The major benefit of calcium is preventative, mitigating the risk of developing osteoporosis during the aging process. Osteoporosis can be at least partially seen as a condition resulting from long-term calcium insufficiency and, while not fully preventative, maintaining adequate calcium intake throughout life is associated with significantly reduced risk.

Calcium can come from any source be it supplementation, food, or even food-derivatives such as whey protein. Each form does have their benefits and drawbacks, such as coral calcium technically being better absorbed than calcium carbonate, but due to calcium's ability to be absorbed at all points in the intestine the issue of calcium absorption is one that is greatly influenced by the diet. Diets high in fermentable fibers (usually found in vegetables) and high enough in bulk and fiber to slow the rate at which food passes through the intestines increase calcium absorption; simply taking a calcium supplement on top of a low fiber/low bulk diet will not be as effective as consuming the calcium through dairy or even vegetables.

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How to Take

Medical Disclaimer

Recommended dosage, active amounts, other details

Supplementing calcium should be done in accordance with your overall intake of calcium from the diet, in an attempt to get as close to the recommended daily intake (RDI) as possible. This intake is:

  • 700 mg for those 1-3 years of age

  • 1,000 mg for those 4-8 years of age, as well as for adults between the ages of 19-50

  • 1,300 mg for those between the ages of 9 and 18

  • 1,200 mg for adults over the age of 71 and for females above the age of 50 (males between the ages of 50-70 only require 1,000 mg)

Calcium from all sources, including dairy-derived protein supplements such as whey protein or casein protein should be included and there is no specific timing of calcium supplements required. They can be taken at any point in the day, although preferably with a meal to aid in absorption.

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Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects calcium has on your body, and how strong these effects are.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-b Notable Very High See all 4 studies
Calcium supplementation appears to be quite potent in reducing the risk of pre-eclampsia when supplemented at 1,000mg a day, with more efficacy in those with lower dietary calcium intake.
grade-c Minor Very High See all 10 studies
Studies are largely in agreement that calcium supplementation in high doses (500-1000 mg daily) can reduce the symptoms of PMS, largely when it comes to affective and pain-related outcomes.
grade-c - - See 2 studies
grade-c - - See study
grade-c - - See study
grade-c - - See study
grade-d - - See study
grade-d - - See study
grade-d - - See study
grade-d - - See all 3 studies
grade-d - - See study
grade-d - - See study

Studies Excluded from Consideration

  • Confounded with vitamin D.[6]

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Things to Note

Primary Function:

Also Known As

Ca2+, Ca, Coral Calcium

Goes Well With

  • Vitamin D, Vitamin K, and Magnesium (Preventative supplements for bone health)

  • Fermentable fiber sources (Inulin, vegetables; aids absorption)

Caution Notice

  • The maximum dose of elemental calcium that should be taken at one time is 500 mg, to avoid unwanted effects on absorption of calcium and parathyroid hormone.[1] 

  • Reported adverse effects of calcium use include constipation, excessive abdominal cramping, bloating, severe diarrhea, and abdominal pain.[2] 

  • Additionally, high serum calcium levels, also known as hypercalcemia, has been associated with an increased risk of cardiovascular events, myocardial infarction, and stroke.[3][4][5]

  • Calcium is found in both over-the-counter products and prescription medications such as calcium carbonate, calcium citrate, calcium lactate, calcium phosphate. Use of these medications can result in increased serum calcium levels.

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Click here to see all 152 references.