You can get too much of a good thing- and this time its calcium again. We need calcium for bone health – but again the food supply is loaded with calcium, not only dairy foods.
But a new analysis from the Women’s Health Initiative has found that calcium supplements are associated with an increased risk of kidney stones.
The study involved 36,282 postmenopausal women and half of them were randomly assigned to take 1,000 milligrams of calcium carbonate supplements and 400 IU of vitamin D for seven years; the rest were given a placebo.
All the women averaged about 1,145 milligrams of calcium per day from diet and supplements but those in the supplemented group boosted their intake to at least 1800 mg a day and were 17% more likely to develop kidney stones than the placebo group. In other words, 449 women developed urinary tract stones compared to 381 in the control group.
Calcium is known to be a factor in the formation of most kidney stones. But this study used supplements to boost the intake. On the other hand, women in the study with the highest dietary intake of calcium were 65% less prone to kidney stones than those with the lowest calcium consumption from the diet.
Now most experts agree that calcium needs should be met with diet alone (foods high in calcium along with calcium fortified foods (cereals and orange juice). The threshold should be close to the Institute of Medicine’s recommendation of 1200 mg/day. But calcium supplementation can add to that recommendation quite easily. For example, if you take a multivitamin/mineral supplement, most have about 300-400 mg/ calcium per tablet; most calcium supplements contain at least 300 mg – 600 per tablet and if you take antacids such as Tums, they contain about 300-400 mg per tablet.
The best dietary sources of calcium can be measured as CALCIUM EQUIVALENTS (each represents about 300 mg. calcium)
Milk 1 cup
Yogurt (low-fat,non-fat) 1 cup
Cheese (hard) 1/1/2 ounces
Ricotta cheese, part skim, regular ½ cup
Cottage cheese 2 cups
Powdered skim milk ¼ cup
Frozen yogurt, milk based 1 1/2 cups
Pudding, low-fat, nonfat 1 cup
Calcium fortified soy milk 1 3/4 cup
Canned salmon with bones 1 ¾ cup
Sardines with bones 5 ounces
Tofu, processed with calcium 1 ½ cups
Collard greens 1 cup (less absorbed)
Other Calcium Sources (but usually less absorbed)
Bottom Line: For calcium, eat non-fat dairy, nuts, legumes, and leafy greens.
- Are You Getting Too Much Calcium? (foodworksblog.wordpress.com)