What foods can I eat to assure that I'm getting enough calcium?

A diet rich in calcium will make it less likely that you will need calcium supplementation. Dairy sources of calcium include milk (all types, from skim to whole to buttermilk), yogurt, and cheese (varies with type). It is important to check the serving size of the food you're eating. For example, Table 4 (Question 47) lists foods in descending order by the amount of calcium they contain. You will note that 8 ounces of low-fat plain yogurt contain 300 mg of calcium, but when you go to the supermarket, yogurt may be sold in a 6-ounce container, giving you less calcium.

A diet rich in calcium will make it less likely that you will need calcium supplementation.

Instead of listing the amount of calcium (in mg), sometimes nutrition labels list the percentage of calcium that the food provides toward your recommended daily allowance (RDA). This RDA is actually based on 1000 mg of calcium. So if a nutrition label says you are getting 30% of your daily amount of calcium, you are getting 300 mg. But if you are postmenopausal, that is only about 20% of the RDA for you.

Cheese presents an interesting comparison of calcium amounts. You have to eat 1 cup of cottage cheese to get the same amount of calcium in 1/4 cup of part-skim mozzarella. As much as we would all love to credit ice cream with being a great source of calcium, there is generally only about 85 mg of calcium in a V2 cup serving. That's not a good source, because it provides only about 6% of your required amount of elemental calcium but adds up to 170 calories to your daily calorie intake.

If you are lactose intolerant, you may need to be especially careful about getting adequate calcium because most calcium in a normal diet comes from dairy sources. But you can still get adequate amounts of calcium from such foods as tofu (soybean curd), salmon, and sardines (with bones). Eating calcium-fortified cereal and orange juice will help increase your calcium intake without consuming dairy products.

When should I take calcium supplements? Is there any particular time of day that makes calcium more effective? Should I take it before meals, with meals, or between meals?

Depending on the type of calcium supplements you take, you may want to adjust the time of taking them. Because calcium carbonate tends to cause more stomach upset and needs stomach acid to be absorbed, it's best to take it immediately after a meal. Calcium citrate can be taken any time.

Although calcium carbonate is generally absorbed best after meals, there are some substances and foods that can interfere with the absorption of any type of calcium.

For example, too much fiber in your diet can slow the rate at which calcium is absorbed by your body. However, a high-fiber diet has also been associated with healthful changes, such as decreased risks of breast and colon cancer. Increasing fiber in your diet can also decrease the constipation associated with calcium carbonate. Dividing the amount of calcium that you need into smaller doses to take throughout the day may provide better absorption and fewer side effects of bloating and gas.

High levels of protein can also interfere with calcium absorption because protein binds to the calcium before it can be absorbed. Don't take calcium with iron, caffeine, or excessive salt, because they also decrease absorption or speed excretion. It's best to avoid taking calcium with a big salad because the oxalates in leafy green vegetables combine with calcium to make an insoluble compound, rendering the calcium useless to you. The best time to take calcium supplements that are not in the calcium carbonate form is before meals or at bedtime, when your stomach is relatively empty and absorption will not be influenced by foods, vitamins, or supplements.

If you are taking a medication such as Prilosec (omeprazole), its intended effect to reduce stomach acid production will interfere with your ability to absorb calcium carbonate, which should be taken when your stomach is most acidic (usually right after a meal). It's important to take your Prilosec or any stomach acid-inhibiting medications at a time other than with calcium carbonate so that you can absorb calcium more efficiently. Some clinicians believe that Prilosec and other medications that prevent acid production keep

The best time to take calcium supplements that are not in calcium carbonate form is before meals or at bedtime.

stomach acid low even following meals, so other forms of calcium might be best if you need these medications.

It sounds like there are a lot of restrictions around when it's best to take calcium. To make it somewhat easier to figure out a schedule, try this: Take all forms of calcium supplements except carbonate before breakfast. Take calcium carbonate after breakfast as long as you don't have caffeine, foods containing excessive salt or iron, or a leafy green salad. If you are dividing up the calcium carbonate supplements (e.g., two tablets in the morning and two at night), you might try taking them after an evening snack when you're less likely to have the foods or substances that interfere with absorption. Other forms of calcium can be taken between meals throughout the day.

50. There's always a lot of emphasis on eating dairy products for calcium. I can't drink milk or eat cheese because I have lactose intolerance. What can I do to get the calcium necessary for my bones?

Lactose intolerance is common. In fact, an estimated 25% of the population of the United States has lactose intolerance. White men and women are affected less often than all other minorities, with 90% of Asians being affected with lactose intolerance.

Lactose intolerance[1] occurs when the small intestine does not make enough lactase, the enzyme required to break down the lactose (milk sugar) in milk products before they enter the large intestine. When the undigested milk products enter the large intestine, you can get bloating, pain, gas, and diarrhea. The symptoms usually appear 30 minutes to 2 hours after eating milk products. Some people can tolerate some milk or milk products if they are eaten in small amounts through the day. The form of lactose intolerance that happens at birth is rare but permanent. Adults can acquire lactose intolerance and sometimes, because of an illness, can have lactose intolerance temporarily.

Don't be discouraged. You might be intolerant, but sometimes you can recondition your body by eating very small amounts of foods that contain lactose and slowly increase the amount over time. For example, you might start with one teaspoon of yogurt for a few days, then a tablespoon for a few days, increase that to a quarter cup for a few days, and so on. The key is to have lactose-containing foods as a regular part of your diet. What you are trying to do is to train your small intestine to start making lactase again. This is a good example of a "use it or lose it" phenomenon. Yogurt is the best tolerated milk product and will also provide you with 200 to 300 mg of calcium per 6- to 8-ounce serving. Hard cheeses, such as cheddar, Swiss, and parmesan, also tend to be easier to digest than milk.

If you try this reconditioning program and it doesn't work, you can certainly get calcium from other sources or try over-the-counter tablets that contain lactase, such as Lactaid® tablets, to help with the digestion of milk products. Whatever you do, be sure that you get adequate calcium because in a recent study, lactose intolerance was associated with low bone mass and increased risk of fracture. Table 4 lists foods that are rich in calcium. You will note that there are non-milk products to choose from.

There is some concern among pediatric clinicians that encouraging dairy product intake in children is not necessary. In fact, there is little evidence that intake of dairy products is associated with increased bone density in children. Children (and adults) can get the same amount of calcium that is in 8 ounces of milk if they consume 8 ounces of fortified orange juice, 1V2 cups of calcium-fortified cereal, 2 slices of calcium-fortified bread, or V2 cup of tofu (with calcium sulfate).

If you are unable to tolerate any milk products or if you are a strict vegetarian who consumes no dairy products, you should be doubly careful about getting calcium in other foods as well as supplements. Green leafy vegetables do contain calcium, but it is not absorbed as well as the calcium found in milk products, and therefore only very small amounts of calcium actually make it into the bloodstream. You will not be able to determine the amount of elemental calcium you need in supplements based on the formula described in Question 47. Instead, calculating the amount of calcium you need in the form of supplements might vary somewhat unless you are consistent about the kinds of calcium-rich and calcium-fortified foods you eat. Using Table 4, add up the milligrams of calcium typically found in the foods you eat every day. Subtract that number (you will probably have to average several "typical" days) from the amount of calcium required for your age and sex, found in Table 3. The result is the amount of elemental calcium you need in the form of supplements.

  • [1] Occurs when the small intestine does not make enough lactase, the enzyme required to break down the lactose (milk sugar) in milk products before they enter the large intestine; can cause bloating, pain, gas, and diarrhea.
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