Milk may do a body good, but did you know that consuming copious amounts of calcium can actually be harmful? This was a discovery made early last century when adherents of a special diet for ulcers (called the Sippy diet) became ill after dosing themselves with extraordinarily high amounts of milk and cream every day, along with eggs, cereal, and antacid powders. Besides developing a distaste for dairy, many people also had nausea, vomiting, confusion, kidney problems, and even kidney failure—all signs of harmful levels of calcium in their blood (called hypercalcemia).
This disorder, dubbed the milk-alkali syndrome, became much less common once the Sippy diet fell out of favor (normal milk consumption doesn't cause the syndrome). But recently it has made a resurgence, according to a commentary in the Journal of the American Society of Nephrology. The reason? Overuse of over-the-counter calcium and vitamin D supplements.
These supplements became widely used in the 1990s—particularly among women post-menopause, who often need additional doses of these nutrients to help prevent and treat osteoporosis. Not coincidently, say the researchers, this is also when cases of milk-alkali syndrome—or, to use a more modern name, calcium-alkali syndrome—began to increase again.
The syndrome is now the third most common cause of high blood calcium levels, say researchers, accounting for between 8 percent and 38 percent of all hospital admissions due to hypercalcemia in the United States. (Hypercalcemia is also often caused by thyroid problems and cancer.) And, today, older women rank among those most often affected by the syndrome, rather than men with ulcers as in the past.
But this is not to say that calcium and vitamin D supplements are unsafe. Far from it. Taken at recommended doses, these supplements may help prevent osteoporosis and lower the risk of broken bones, with few (if any) side effects. The problem is, many people don't realize that they can get too much calcium, so they exceed their recommended daily amount—usually 1,000 mg for adults under age 50 and 1,200 mg for those over 50.
What you need to know. If you take calcium supplements, it's important that you use them as directed and don't take more than the recommended dose. If you're at all unsure about how much calcium to take, check with your pharmacist or doctor. Your doctor might also recommend having your blood calcium level tested each year if you regularly take these supplements.
—Sophie Ramsey, patient editor, BMJ Group
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