Are Americans getting enough calcium? I’ve heard that health officials here
may recommend more calcium than is necessary. How much do people really need?
Calcium is an essential nutrient, but the optimal intake is an unsettled issue.
For adults over 50, the definition of adequate intake in the United States is
1,200 milligrams per day; in the United Kingdom, this is 700 milligrams per day;
and the World Health Organization, looking at the same data, concluded that 500
milligrams per day is adequate. The primary justification for high consumption
of calcium has been prevention of osteoporosis and fractures, and much of the
disagreement is due to the use in the United States of short-term studies of
calcium deposition in bones to set the value for adequate calcium intake.
Long-term studies do not support benefits of high intake of calcium or milk in
preventing fracture risk. The WHO conclusions were influenced by the observation
that most adults worldwide consume little or no dairy products, have calcium
intakes below 500 milligrams per day, and tend to have lower rates of fractures
than we do in America and Europe, where calcium and milk intake are relatively
high.
The issue of optimal calcium intake is complicated by evidence that high
intakesthe amounts in about three glasses of milk per dayprobably increase
risks of fatal prostate cancer and, when taken as supplements with vitamin D,
will increase risks of kidney stones. Given all the evidence, the British
definition of adequate intake of 700 mg per day for adults seems to be
reasonable, and this can be obtained with about one glass of milk per day in
addition to an otherwise good diet. Other factors, especially adequate vitamin D
and regular physical activity, are far more important than high calcium intake
in preventing fractures. For growing children, intakes should be higher because
of the need to accumulate calcium in growing bones, but the exact number is
still not clear.
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US News & World Report
