My patients ask about calcium more than any other mineral. Their concerns center around the prevention of bone loss. Recently, I had dinner with three friends - an orthopedist, a family doctor and a chiropractor. We were talking about nutrition; when the subject of minerals came up, they all agreed that calcium generated more questions from patients than any other mineral.

Q: When should women start calcium supplementation?

A: A woman will achieve peak bone mass in the years ranging from her late teens to her middle 20s. After that, her bone mass will stabilize providing she has adequate external stimulus to maintain stability (weightbearing exercise) and adequate micronutrients needed to synthesize osseous tissue (calcium, vitamin D and other support factors).

In Western society, especially in the U.S., many women do not get enough exercise, nor do they consume enough calcium and other bone-building vitamins and minerals. Thus, it is not uncommon for women in their 30s and 40s to lose between 1-2 percent of their bone mass per year. By the time they reach menopause, loss can be 25 percent or more. When menopause occurs, the rate of bone loss is greatly accelerated. Thus, the strategy for avoiding osteoporosis is twofold. First, prevent any premonopausal bone loss. Second, reduce the level of postmenopausal bone loss.

Q: What are the best natural ways to protect my bones?

A: The best ways, in order of importance, are:

regular weightbearing exercise;

calcium: 1,000 mg per day until age 50; 1,200 mg per day after age 50;

vitamin D: 400 IU until age 50; 600 IU after age 50. If a family history of osteoporosis is present, add 200 IU per day. During the winter in northern latitudes, add another 200 IU a day. A woman in Minnesota who is over 50 with a family history of osteoporosis should consumer 1,000 IU of vitamin D during the winter and 800 IU of vitamin D in the spring and summer;

magnesium: 500 mg per day until age 50; 600 mg per day after age 50;

RDA levels of the trace minerals zinc, copper and manganese;

silicon, boron and vitamin K: People whose daily diets include six to eight servings of fruits and vegetables along with whole grains will not get plenty of silicon, boron and vitamin K. For the average person who does not follow this type of diet, silicon, boron and vitamin K should be supplemented at levels of approximately 5-10 mg of silicon, 1-3 mg of boron and 100-500 mcg of vitamin K.
Q: What are the recommendations for calcium?
A: Depending on the source (RDA or RDI), there are slight variations. I recommend that teenagers consume 1,300 mg of calcium per day from dietary and supplemental sources. Adults between 20-50 should get at least 1,000 mg per day. Adults over age 50 should consume at least 1,200 mg per day.

Q: Should women take more calcium than men?

A: They already do. By recommending the same dietary levels for both men and women, women do get more calcium than men. Remember: the average man is 20-30 percent larger than the average woman.

Q: I heard that a high protein diet may negatively affect my calcium balance. Is this true?

A: Protein helps the rate of calcium absorption in the small intestines. However, high protein diets can cause an increase in the calcium excreted, because some proteins like beef and poultry have an acid residue when digested.

To maintain proper pH, the body will release stored calcium to offset the acid residue from protein. On average, each gram of protein consumed will cause approximately 1-1.5 mg of calcium to be excreted. Thus, if a 110-pound woman changes her diet from RDA levels of approximately 55 grams of protein a day to a high protein level of 110 grams, she should increase her dietary calcium intake by 60 to 80 mg per day. This is easily accomplished by eating only two or three ounces of plain yogurt.

Q: Are there other commonly consumed foods that cause calcium loss?

A: Both sodium and caffeine also cause calcium to be mobilized and excreted. Fifty milligrams of sodium will cause one milligram of calcium to be lost. Fifteen milligrams of caffeine will also cause one milligram of calcium to be excreted in the urine.

Q: How do you feel about cheese as a source of dietary calcium?

A: Commonly consumed cheeses such as cheddar, jack, mozzarella and swiss all contain over 200 mg of calcium per ounce, making cheese an excellent dietary source. Unfortunately, cheese is also high in calories, total fat, saturated fat and sodium - all of which are excessive in the Western diet. Thus, most people should consume cheese in moderation.

Next month, we will continue our discussion on common questions concerning calcium and bone loss. Included will be a way to determine (in your kitchen) whether the calcium tablet you take is dissolving properly.