One cup of milk a day is not enough to keep your bones strong and healthy. A cup of milk contains about 300 mg of calcium. Twentysomethings need 1,000 mg of calcium each day (other RDAs: 1,300 mg/day for 9 - 18-year-olds; 1,000 mg/day for women and men ages 19 - 50 years, and 1,200 mg/day for folks older than 50). Keeping calcium intake at these levels throughout a lifetime will better protect bone density. So, 3-1/3 cups of milk a day, or the equivalent, is more like it for you.

Why do we need so much calcium? The short and sweet answer is: to maintain strong, healthy bones and good general nutrition, as well as to prevent osteoporosis. (See Calcium and osteoporosis and Women, calcium, and osteoporosis? in Alice's Fitness & Nutrition archive.) Calcium is an essential component in the life-long process of laying down new bone. Later in life, calcium helps our bodies maintain bone mass. Before you reach thirty, more bone is made than lost; after thirty, this trend reverses.

Women need to be especially vigilant about calcium. On average, women make less bone and lose it at a greater rate than men. A woman's calcium stores are drawn on during pregnancy and lactation. Adding to this, women generally live longer than men, giving their bones more time to become brittle, less dense, and prone to fracture (i.e., to develop osteoporosis).

It's difficult to determine who, exactly, is at risk of developing osteoporosis, and other bone problems, from inadequate consumption of calcium. The two best things you can do now to prevent future osteoporosis are: (1) include enough calcium in your diet; and, (2) exercise often, and include weight-bearing activities in your exercise routine. A family history of osteoporosis (i.e., genetics) and your body's ability to absorb calcium are other risk factors for osteoporosis. You have no control over these risk factors, but you can control how much calcium is in your diet and how much you exercise.

If drinking 3-1/3 cups of milk a day does not appeal to you, you can get calcium from a range of other dairy and nondairy sources. An easy way to keep track of the amount of calcium in your diet each day is what is known as the "rule of 300s." Every day, give yourself 300 mg of calcium (to account for small amounts of calcium in various foods you eat throughout the day), then add 300 mg for each cup of milk and yogurt, and for every 1.5 ounces of cheese, that you include in your daily diet. If your target intake is 1,000 mg, then you'll need to add 2-1/3 extra servings of dairy products a day. Some nondairy sources of calcium include:

Less than 100 mg of calcium

1 orange

1 cup of sweet potatoes or green beans

1 cup of cooked lentils, chick peas, navy beans, or pinto beans

3 ounces of shrimp, crab meat, or clams

100 - 199 mg of calcium

1 cup of cottage cheese

1 cup of cooked dandelion greens or kale

3 ounces of canned salmon with bones

1 piece of tofu (2.5" x 2.75" x 1")

200 - 299 mg of calcium

1 cup of cooked broccoli or turnip greens

1 cup of oysters

300+ mg of calcium

8 ounces of yogurt (flavored or plain — plain has much more)

1 cup of cooked collard greens

3 ounces of canned sardines with bones

Calcium in foods, versus supplements, is a better way to get calcium into your body. Lactose-intolerant folks, however, may need to take calcium supplements. If you're worried about the increased fat due to eating more dairy products, it might make you happy to learn that skim milk packs more calcium per serving, and considerably less fat and calories, than 2 percent or whole milk. A few other pointers on how to maximize the calcium in your diet: calcium is absorbed better in the presence of vitamins C and D and lactose (a sugar found in milk and dairy products); excess dietary fat, excessive amounts of fiber, and oxalic and phytic acids, which are found in whole grains and leafy green veggies, actually hinder calcium absorption. For instance, only a small percentage of the calcium in foods, such as spinach, kale, lentils and other beans, and whole grains, will be absorbed by your body because the calcium is locked into the food in a way that makes it hard to absorb. Alice doesn't recommend cutting them out of your diet — they are excellent sources of other vitamins, minerals, and fiber — just don't eat them along with other calcium-rich foods, because they can prevent calcium absorption from calcium-rich foods as well.

Three final thoughts on osteoporosis and calcium: salt, phosphorous, and caffeine. Regardless of how much calcium you get from your diet, researchers have found that adding a lot of salt to your food or eating foods high in sodium can lead to a loss of calcium. And most sodas are high in phosphorous, which has the potential to replace calcium in bones. If you drink lots of soda (and not enough milk), or if your diet has too much salt in it, consider ways you can cut back on sodas and salty foods. Add to that the fact that you drink three cups of coffee a day. Although it's a controversial issue, it's possible that caffeine could deplete the body of some calcium. For every 150 mg of caffeine, roughly the amount found in one cup of joe, the body may be "robbed" of about 5 mg of calcium. Supposedly, adding milk to your coffee helps offset this calcium loss. Your bones will thank you.

Alice

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