Minerals // Calcium

Disease Risk Reduction

Osteoporosis

Osteoporosis is a bone disorder affected by many factors. With it, bone strength is considerably reduced. Osteoporosis is most prevalent among white postmenopausal women (10). There are some ways of reducing the likelihood of the type of bone damage linked to osteoporosis, including reaching peak bone mass and the limiting bone loss later in life. Calcium the most important mineral for preventing osteoporosis and attaining peak bone mass, but sufficient vitamin D supply is also necessary to be able to absorb optimal amounts of calcium.  

There are several ways to achieve higher peak bone mass, including high-impact activity like running and weight training in conjunction with sufficient calcium (1,200 mg/day) and vitamin D supply (600 IU/day) early in life (11, 10, 12). Even though low-impact exercise like walking, swimming, and cycling has positive health effects, its effects on bone loss is negligible. Increased bone and muscular strength and decreased likelihood of falls can be achieved well into old age (past 90) through exercise, reducing the risk of hip fractures (10).

Colorectal cancer

Dietary factors seem to cause some forms of colon cancer, while genetic factors seem to influence others.

Supplementation with 1,200–2,000 mg of calcium a day was shown to bring about a slight decrease in the incidence of colorectal cancer in controlled clinical trials (5, 6, 7). Participants with the highest calcium consumption (1,087 mg/day from food and supplements) were 22% less likely to develop colorectal cancer compared to those with the lowest intake (732 mg/day), according to a pooled analysis of ten prospective cohort studies following 534,536 participants (8)

Only a slight risk reduction through calcium supplementation has been noted in the majority of prospective studies. This could be explained by differing responses to calcium by different people (9)

Further studies on the different calcium responses of various subgroups of the population are required before we can come to any conclusions relating to calcium supplementation and colon cancer risk reduction. 

Stroke

One epidemiological study found that increased calcium intake among women reduced the risk of stroke over a 14-year period (21)

More studies are required before any benefits can be confirmed.

Kidney stones

Unusually elevated levels of calcium in the urine have been linked to a higher risk of developing kidney stones. Urinary calcium has been shown to increase with high consumption of salt (sodium chloride), protein, and calcium (13, 14)

A considerably heightened incidence of kidney stones was linked to calcium supplementation (1,000 mg/day) in conjunction with vitamin D supplementation (400 IU/day) in a randomized controlled trial following 36,282 postmenopausal women (15).

In the past, people with a history of kidney stones were advised to limit their calcium consumption. However, salt was found to be the factor most closely linked to calcium levels in the urine during a cross-sectional studyfollowing 282 participants with calcium oxalate stones (16). The authors then suggested that it should perhaps be salt that kidney stone sufferers are advised against rather than calcium (17)

Increased water intake is currently the sole dietary change that has been clinically proven to reduce the likelihood of kidney stones. 

Additional research on the relationship between supplemental calcium and kidney stones is needed. 

Pregnancy-induced hypertension (PIH) 

Onset of high blood pressure brought about by pregnancy takes place sometime after the 20th week of pregnancy in 10% of cases. Preeclampsia causes severe swelling (edema) and urinary protein excretion ('proteinuria') (18). Calcium metabolism would seem to be a causal factor of PIH but this is not fully comprehended. 

A link between low calcium consumption and heightened risk of PIH has been indicated by results from epidemiological studies . However, data from research on supplementation with calcium and PIH have been less conclusive. Calcium supplementation was shown to decrease the risk of high blood pressure in pregnant women at risk of PIH in a review of randomized controlled studies. The findings were the same for pregnant women with low dietary calcium consumption (19)

No effect however was found on PIH in a large clinical trial following more than 4,500 pregnant women with an average supplemental calcium consumption of 2,300 mg/day (20).

Generally, achieving calcium intake recommendations when pregnant may help prevent PIH. Additional studies are needed before conclusions can be reached as to whether women at risk of developing PIH would benefit from supplementation with calcium above the levels currently recommended.  

Lead toxicity

The consequences of sustained exposure to even small amounts of lead in childhood include possible learning disabilities, behavioral problems, and low IQ. Exposure of expectant mothers to lead during pregnancy can lead to growth and neurological defects in children. Kidney damage and hypertension may occur as a result of lead toxicity in adults (22). Sufficient consumption of calcium may protect against lead poisoning by limiting the uptake of lead in the digestive system and by stopping lead stored in bones from being freed through bone loss (resorption). 

Women with insufficient calcium supply during the second half of their pregnancy were more at risk of heightened lead levels in the blood, according to one study. This is most likely due to increased bone resorption, which mobilizes lead stored in the bones and allows it to enter the bloodstream (23). Increased calcium supply has also been linked to lowered levels of lead in the blood among postmenopausal women (24).

Authored by Dr Peter Engel in 2010, reviewed and updated by Dr Igor Bendik-Falconnier on 17.10.17