Dear Dr. Gott: Is calcium citrate better than calcium carbonate?

Reply: For most people, no. Both types of calcium are absorbed similarly by healthy people. Calcium carbonate is more commonly available and is usually less expensive. It is more readily absorbed when taken with food. Calcium citrate is generally more expensive but is often more easily absorbed by those with lower levels of stomach acid. It is readily absorbed by the body with or without food. The supplements also contain different amounts of elemental calcium. Carbonate is 40 percent by weight, and citrate is 21 percent.

Calcium absorption decreases as the amount of elemental calcium per dose increases. In order to get the most out of your calcium supplements, you should take several smaller doses. If you are taking 1,000 milligrams per day, for example, try taking 500 milligrams twice a day. Your body will use more of the calcium, thus providing greater benefits.

Calcium is also added regularly to certain foods. It is common to find calcium-fortified breads, orange juice, cereals and tofu. Dairy products are naturally high in calcium, so consuming three servings of low-fat milk, cheese or yoghurt can provide significant amounts.

Calcium supplements are most often recommended for people who have osteoporosis or are at risk for it. It is important to take supplemental vitamin D to aid absorption. Supplements are also important for vegans, strict vegetarians and those with lactose intolerance.

Speak with your primary-care physician regarding which treatment is best for you. He or she is your best resource for information regarding your health. If you are simply looking for information, visit the National Institutes of Health Office of Dietary Supplements website at http://dietary-supplements.info.nih.gov/index.aspx.

Dear Dr. Gott: If a doctor recommends that you (an elderly person) monitor blood pressure a couple of times a week, is there a time of day when it is best to take it? Is it lower in the morning, afternoon or evening?

Reply: To get an accurate measure of what your blood pressure is averaging, it is usually best to check in the morning and again at night. Be sure to keep a record of what time you take the readings. It may also be helpful to make a list of physical activities each day and what time they occurred, since exercise, for example, can raise the blood pressure during and immediately following. Salt may also increase blood pressure. If you have a digital blood-pressure monitor, have it calibrated by your physician before use. He or she should also review its usage so you will be able to obtain more accurate readings.