QUESTION: My father has come to live with us recently following my mother's death. He is 82 and quite healthy, except he complains a lot about being constipated. He has had a thorough checkup and his doctor says he has no medical problem that might cause constipation. But he takes more laxatives than I think he should. Do you have any suggestions?

ANSWER: Constipation, a very common complaint among older people, often results from a whole constellation of factors. Lifelong poor bowel habits, diet, over-reliance on laxatives, as well as a decline in the normal motility (motion) of the bowel all may contribute to the problem - or, at least, to the "problem" as it is perceived. In fact, we really don't have enough data to define what is "normal" for individuals 75 and over. Some evidence suggests that a decline in bowel function is not a universal phenomenon and that the definition of normal may not change with age. In one study, bowel movements were as frequent among those 60 and over as in a younger group.Nevertheless, whether the problem is real or perceived, older people turn more readily to laxatives. What is the alternative? In general, the most effective measures include establishing a regular time habit, taking in large amounts of fluids and gradually increasing fiber consumption by adding generous amounts of raw and lightly cooked fruits and vegetables and whole grains. In combination, these steps should take the place of irritant laxatives, which have potential side effects.

QUESTION: What's the difference between green and black olives?

ANSWER: They are exactly the same fruit. As picked, they are all green and bitter. The bitterness is removed by soaking them in a dilute alkaline solution. They are then rinsed and put into a salt solution. It is at this point that, if they are to become black, air is bubbled through the liquid to provide oxygen and an iron-containing compound is added to both fix and retain the black color.

There are no nutritional differences between the two hues of olives. Both provide little more than calories. At one extreme, the very smallest olives have just four calories each, while at the other, those labeled as "supercolossal" contain more than four times the amount, or18 calories each. Olives are quite high in sodium. The amount can vary considerably and tends to be higher in some imported brands sold in bulk. Obviously, if you're concerned about limiting your sodium intake, olives are a food to be eaten sparingly.

QUESTION: My doctor has advised me to take calcium tablets regularly since I don't succeed in getting enough into my diet. Because I'm borderline anemic, he also recommends that I take an iron supplement of ferrous sulfate. Recently I read that these two supplements fight with each other inside the body and that I may not be doing myself any good. Is this true?

ANSWER: It's true that ferrous sulfate and calcium supplements compete for absorption, but recent evidence provides a guide on how to get the best out of both. In a series of studies reported in the American Journal of Clinical Nutrition, Dr. James Cook and his colleagues at Kansas University Medical Center measured the absorption rate of calcium and iron in a group of normal volunteers under several conditions. The result: Just how much is absorbed depends on the type of supplements and whether they are taken with or apart from meals.

Calcium supplements taken at a meal affected the absorption of iron significantly. The type of food eaten was also a factor. Absorption was more inhibited when a breakfast meal of poor iron availability was served than when it was a hamburger meal of high iron content.

Given their findings, Cook and his colleagues suggest that to maximize absorption of iron from food and from supplements, women who are anemic might be better off taking their calcium apart from meals. Under these conditions, calcium carbonate seems to have little effect on the absorption of iron supplements taken at the same time.