Is it safe to eat the leaves of broccoli? How do they differ nutritionally from regular broccoli?

ANSWER - Yes, it is safe to eat the leaves. In fact, broccoli rabe, a popular vegetable in Italian cuisine that has a medium-sharp flavor, is actually more leaf and stem than flower. Specific information about the nutrient content of broccoli rabe and the leaves of regular broccoli is not available, but it's reasonable to assume that they're in the same league with the flower and stalk you usually eat. A half-cup serving will give you nearly double the Adult Recommended Dietary Allowance for vitamin C, close to half the day's vitamin A, and a good spread of B vitamins as well.Among the vegetables, broccoli is one of the best sources of calcium, with a half cup providing as much as you'd get from two-thirds of a cup of milk. Broccoli is also rich in potassium. And all that for just 23 calories in the half-cup serving!

In addition to the leaves, you can also eat a lot of the stem. Many cooks trim broccoli much more severely than necessary. If the lower end of the stalk appears to be too tough, rather than cutting it off, just peel away a thin slice of the outer layer to reveal the more tender part beneath.

QUESTION - I'm trying to make sure I get all the calcium I need. I heard that the pasteurization of milk interferes with absorption of calcium. Also, can you really get some of your calcium from vegetables or is the calcium in them too hard for the body to absorb?

ANSWER - Let's first allay your fears about pasteurization. The calcium in milk is highly available to the body, and pasteurization does not hinder absorption.

Where vegetables are concerned the answer depends on the particular one you're talking about. The calcium in broccoli, kale and cauliflower, and in turnip, mustard and collard greens, is absorbed almost as efficiently as the calcium in milk, making these foods tops in the calcium-vegetable field. To give one example, a half-cup of kale can provide as much as 17 percent of the day's adult allowance.

On the second rung, the calcium in carrots, lettuce and green beans can be absorbed only slightly less by the body. But when you get down to chard, beet greens and spinach, oxalic acid present in them ties up the calcium in a form the body cannot use. Of course, there are other reasons to eat these vegetables, even though they don't make it in the calcium department.

QUESTION - With all the publicity directed toward lowering fat intake, I am curious to know whether there is any evidence that the public has responded.

ANSWER - The Department of Agriculture recently released data showing that some people have. Comparing fat intakes of women age 19 to 50 from two different nationwide studies - one conducted in 1977 and the other in 1985 - the researchers found that overall, fat intake fell from nearly 42 percent of total calories to a little over 37 percent of calories, still well above the population target of not more than 30 percent of the total. Of particular interest is the fact that higher educated people had not made more drastic cuts than those who had not had as many years of schooling.

When it comes to just what fats they had cut out, progress in lowering saturated fat intake is less clear. And it is higher saturated-fat intake that is associated with higher levels of blood cholesterol. In 1985, women were getting less fat from red meat, but more from other foods, among them dairy products, which contain highly saturated fat.

If you are curious about why the comparison was limited to women since, after all, men in this age range are more vulnerable to cardiovascular disease, the reason is simple. The data used in these analyses were obtained from two different surveys. The one conducted in 1977 (which is done every 10 years) includes both men and women, but the 1985 survey (an annual update), monitors only women between 19 and 50 and their preschool children.

QUESTION - I recently read an article on diet that said it takes calories to digest food. I never realized that. How many does it take?

QUESTION - Digestion is just one step in the journey food makes from the mouth to the body's cells. The processes of absorption, transport, metabolism and storage all require energy, as do certain nutrient-related nervous-system functions.

Taken together, the energy needed for all these steps is referred to as the "thermic effect" of food, or TEF. Scientists haven't yet figured out all the factors that can affect TEF. It's estimated to represent about 10 percent of the day's caloric expenditure.

1991, Washington Post Writers Group