More data not to take calcium pills
Taking 800 mg/day in calcium pills increased major markers for risk of a
heart attack (blood cholesterol and plaques in arteries) of 50- to 60-year-
old post-menopausal women (Am J Clin Nutr., published online Sept 18, 2013).
More than 60 percent of North American women over 60 take calcium supplements
to help prevent bone fractures (U.S. Centers for Disease Control and
Prevention's National Center for Health Statistics, 2011).
Calcium Pills Have Not Been Shown to Prevent Bone Fractures
Half of post-menopausal women will suffer an osteoporosis-related fracture in
their lifetimes. The U.S. Preventive Services Task Force analyzed studies on
the effects of vitamin D and calcium pills on bone strength (Annals of
Internal Medicine, published online February 26, 2013). They found no
evidence that taking pills with 400 international units of vitamin D and
1000mg of calcium help to prevent bone fractures. They advise healthy older
women not to take calcium supplements.
Calcium Pills Not Necessary
Adult men and women need 1,000 to 1,200 milligrams of calcium daily,
according to the National Institutes of Health. You get that amount from a
cup of yogurt, a glass of milk and a slice of cheese. If you avoid dairy
products, you could meet your calcium requirement with a bowl of enriched
cereal, a glass of fortified orange juice, half a cup of tofu and a piece of
The prestigious Institute of Medicine issued a report recommending that adult
North Americans need only 1000 mg of calcium, and that most people do not
need supplements. Taking too much calcium may cause kidney stones, and taking
calcium without also taking vitamin D may increase risk for heart disease.
Very large amounts of vitamin D may increase risk for fractures. The authors
believe that adolescent girls may be the only group that is getting too
little dietary calcium (Report from the Institute of Medicine of the National
Academies, November 30, 2010).
Studies Showing Calcium Pills Increase Heart Attack Risk
• A German study followed 24,000 men and women, ages 35 to 64, for 11 years
and found that those who took calcium supplements were 86 percent more likely
to suffer heart attacks than those who do not (Heart, published online May
• Another study showed that calcium pills can increase risk for heart attacks
by 25 percent (British Medial Journal, published online July 2010). Thus if
1000 people were given calcium for five years, there might be 26 fractures
prevented but there would also be 14 heart attacks, 10 strokes and 13 deaths
more than in people not taking calcium pills.
• Eight studies followed more than 10,000 patients, average age of 68 years,
for an average 3.8 years, taking 500 to 1400 mg calcium daily. They had 1.3
times the chance of suffering a heart attack as people taking no calcium
pills. (British Medical Journal, 2010;341:3691).
Calcium and Prostate Cancer
Increased risk for both benign prostate cancer and aggressive prostate cancer
is associated with high blood calcium levels (Cancer Epidemiol Biomarkers
Prev, 2012;21:1768-1773). The risk for death from prostate cancer triples in
men with high blood calcium levels, greater than 10.1 mg/dL (Cancer Epidemiol
Biomarkers Prev, 2008;17:2302-2305).
Men who take in more than 600 mg/day of calcium have increased risk for both
prostate cancer in general and for the aggressively malignant type of
prostate cancer that can kill them (Cancer Epidemiol Biomarkers Prev,
11/07/2012). Men who have the gene, VDR Cdx2, that reduces calcium
absorption, are at reduced risk for prostate cancer (J Bone Min Res,
2012;27:187-194), and men with this genetic defect who restrict calcium
intake are less likely to develop prostate cancer.
How Too Much Calcium May Harm
We do not know how high levels of calcium in the blood increase risk for
prostate cancer and heart attacks. A possible explanation may be that high
levels of calcium prevent your kidneys from converting vitamin D from its
inactive to its active form. Low levels of vitamin D appear to increase risk
for both heart attacks and prostate cancer.
Calcium supplements raise blood calcium levels which increases chances of
forming clots, a major cause of heart attacks and strokes (J Bone Miner Res.
1997;12:1959-70). Calcium supplements can thicken neck artery plaques
(Atherosclerosis, 2007;194:426-32) and calcify main arteries (J Bone Miner
Res, 2010;25:505-12). Taking calcium without also taking vitamin D increases
heart attack risk even further, because calcium blocks the activation of
vitamin D to cause a relative deficiency of that vitamin.