Calcium

New York Times, October 20, 1998
Finding Calcium Sources Outside the Dairy Case
By Jane .E Brody

Achieving the recommended daily amounts of calcium is not difficult for people whose diets are rich in dairy products. Children who drink three or four glasses of milk a day, for example, would easily meet their needs. But there is much confusion about other food sources of calcium and the ability of calcium supplements to compensate for a dietary deficiency.

Facts About Foods

Food is nearly always a better source of calcium than supplements, if for no other reason than food provides more nutritional benefits than just calcium, including nutrients that help the body use calcium. A consensus conference convened by the National Institutes of Health concluded in 1994 that "to attain optimal calcium levels, a change in dietary habits, including increased consumption of dairy products and/or calcium-rich vegetable sources, is needed."

 

The experts might have also cautioned Americans about eating too much salt and protein, especially animal protein, which increases the loss of calcium in urine. Eating just one fast-food hamburger leads to a net loss of 23 milligrams of calcium, according to Dr. Robert P. Heaney, a calcium expert at Creighton University in Omaha. However, despite earlier concerns about caffeine, it only minimally increases calcium loss, by about 2 or 3 milligrams for a cup of coffee, Heaney said.

 

Dairy Products

Milk remains the best dietary source of calcium for two reasons: the lactose (milk sugar) naturally in milk and the vitamin D added to it enhance calcium absorption through the gut. (For those who have trouble digesting lactose, ample calcium is absorbed from lactose-reduced milk and from yogurt with active cultures, which is also low in lactose.) Ounce for ounce, nonfat plain yogurt has more calcium than milk, although it contains no vitamin D. Among frozen dairy desserts, nonfat frozen yogurt is a much better source of calcium than ice cream or ice milk.

 

Hard cheese, high or low in fat, is quite rich in calcium. Ricotta cheese is also an excellent, but cottage cheese, creamed or otherwise, is not nearly as good a source as milk and yogurt unless calcium is added by the maker. Using less water when reconstituting dry milk and adding nonfat dry milk powder to other drinks and foods are excellent ways to increase calcium. For children allergic to cow's milk or who become constipated when consuming it , soy milk fortified with calcium or a daily calcium supplement may be substituted.

 

Vegetables

Some of the best vegetable sources of calcium include kale, collard greens, turnip greens, mustard greens, Chinese cabbage, chicory and bok choy. Broccoli, chard and acorn squash, though not as rich in calcium, are more common sources. Although spinach has a lot of calcium, it also contains a substance -- oxalic acid -- that binds up its calcium and prevents absorption of all but about 5 percent of it. However, the oxalic acid in spinach and foods like rhubarb does not interfere with absorption of calcium from other foods eaten at the same time. Phytic acid, another substance in foods like dried beans and peas, also depresses calcium absorption somewhat, but less than oxalic acid. Most forms of fiber have little or no effect on calcium absorption. Wheat bran, though, can partly block absorption of calcium from other foods, for example, the milk in a bowl of bran cereal.

 

Other Food

Canned sardines with their bones included are especially rich in calcium -- 3 ounces of sardines have more calcium than 8 ounces of milk. Canned salmon, also with bones, is about half as good. Other sources include dry-roasted soybeans, blackstrap molasses, figs, some beans and peas (black-eyed peas, white beans, great northern beans, navy beans and soybeans, although the calcium in beans is only about half as available to the body as that in milk), poppy and sesame seeds, tahini, almonds, oranges and calcium-fortified orange juice. The acid in the juice enhances calcium absorption, and is especially good for older people short on stomach acid. ...

And don't forget vitamin D. Many Americans do not get enough of this vitamin to assure optimal calcium absorption. And the latest studies suggest that adults need 800 International Units a day, not 400 as is now recommended. Although milk is supposed to be fortified with vitamin D (400 units per quart), the actual amount in milk varies widely. About 90 percent of the vitamin D people get is made in skin exposed to the sun's ultraviolet-B rays. Try to expose some part of your body (without sunscreen) to the sun for 10 or 15 minutes a day year-round. Alternatively, eat fatty fish or take cod-liver oil or a supplement with D.