Q. I'd always thought that during pregnancy, assuming you'd started out at normal or near normal weight, you were supposed to gain about 25 pounds. Now I'm pregnant and my obstetrician told me he'd like to see a weight gain of 30 to 35 pounds. Is there a reason why more is better?
A. In addressing this question, keep in mind three points. One, recommendations must be based not on a single strand of data but on the bulk of the evidence. Two, every woman is different. And three, weight gain is only one of the factors that helps insure the birth of a healthy baby.
Current evidence indicates that babies who weigh between 7 pounds 12 ounces and 8 pounds 13 ounces seem to do best, meaning that they're more likely to survive and be born with fewer problems. If larger babies appear to fare better, the obvious goal is to mark out factors that influence infant birth weight. Among these, the mother's weight gain has long been recognized as very important. Studies show that a gain of 30 to 35 pounds in women of normal weight is most closely linked to birth weights in the target range.
A second key factor is pre-pregnancy weight. It's recommended that women who are underweight when they become pregnant try to make up the deficit during pregnancy. As for concerns that excess weight gain will promote the necessity for Caesarean section, evidence suggests that the risk among normal women increases only when weight gain exceeds 45 pounds. The recommended weight gain has not been associated with raised rates of problems during pregnancy nor with obesity after delivery.
These findings emerged from a special panel set up to identify levels of weight gain by pregnant women that would be likely to lead to healthy births without risking the health of the mother. Their recommendations are being used in a project conducted by the University of Minnesota School of Public Health in cooperation with the Minnesota Department of Health.
The last word, though, rests with your own care giver. We cannot emphasize too strongly that monitoring individual weight gain is best left to the obstetrician as part of your overall care during pregnancy.
Q. A couple of years ago, after reports that oat bran lowers cholesterol, I rediscovered oatmeal, and I continue to enjoy it. But recently I read an article saying that oats had been overrated and were of little value. Was that true?
A. The article you mention caused a mini furor by questioning the effectiveness of oat bran at the precise moment that oat-containing products seemed to have permeated every aisle in the supermarket. But hold onto your hats -- and your oats -- folks, because once scientists had time to scrutinize the report, they found it studded with flaws.
The study on which it was based looked at how oat bran affected cholesterol level in subjects following different diets, and found oats were no great shakes. But the high-fiber diets were considerably higher in both total and saturated fat than the low-fiber diets. This fat component might have contributed to the observed lack of effect of oats.
Also, the subjects' usual diets were much closer to American Heart Association guidelines than those of the general public and so, too, were their cholesterol levels. With already low-blood cholesterol levels, it's possible that these subjects would be least likely to show an effect. Furthermore, the study subjects consumed, at baseline, about twice as much fiber as the typical American. And even on the "low-fiber" diet, their intake provided more than 18 grams compared to 12 grams consumed by the average person. This relatively higher fiber intake might have blunted the effect of the oat bran.
The upshot? When it comes to lowering your cholesterol, adding oat bran is no match for cutting back on saturated fat. On the other hand, the study to which you refer just doesn't have the scientific clout to refute the many other trials showing oat bran to be of benefit.
Q. Is it safe to use glass containers I already own but which aren't designated "microwave safe" in my microwave oven?
A. Not always. The FDA recommends the following procedure to test glass products for oven use. Simply put the empty container in the oven and set the timer for one minute. If at the end of that minute it's cool, you may consider it safe. If it's merely lukewarm, it should be used for reheating only. And if it's any warmer it should not be used in the microwave.
Q. I love avocados, but should I worry about cholesterol when I eat them?
A. No. Only animal foods contain cholesterol, so avocados have none. But they do have something that sets them apart from all other fruits: oil. This translates into extra calories.
Exactly how much oil you'll get depends on the type of avocado. By law, California avocados cannot contain less than 8 percent fat. At times they might have as much as 20 percent fat, depending on the season. Florida doesn't set standards for the amount of fat in its avocados; they also tend to be lower in fat.
Three ounces of raw Florida avocado would provide approximately 95 calories, 68 of them from fat. Three ounces of California avocado would have about 153 calories, 134 of them from fat (and most of the rest from carbohydrate).
Avocados are believed to be native to Mexico. They weren't grown commercially in this country until the turn of the century.
Q. Does pumpernickel bread have a lot of fiber?
A. The best answer we can give you is a qualified "sometimes." Most often, the answer is probably no.
Why the uncertainty? The reason is that there are many kinds of pumpernickel. If the bread is made mainly from whole-wheat flour, along with dark-rye flour and unbolted cornmeal, it will indeed be high in fiber. But some bread that goes by the name of pumpernickel is actually made with refined white flour and de-germed cornmeal and may have very little fiber -- aside from what's provided by any caraway seeds it might contain.
When we checked five pumpernickel recipes, we were surprised by some of the ingredients. Four of the five listed mashed potatoes. One used cocoa, and another chocolate. At the supermarket, the labels revealed that the most prevalent ingredient in several loaves was refined bleached flour. Others used whole grains, but it wasn't always clear how much. If you're looking for a fiber-rich pumpernickel, one option is to bake it yourself, using lots of whole grains. Another is to inquire at local bakeries until you find one that prepares pumpernickel using primarily unrefined flour.
Q. My young son is allergic to peanuts. Is this likely to disappear as he grows older?
A. His sensitivity to peanuts will probably persist. A study, reported last year, tracked 32 of 46 children in whom a diagnosis of peanut allergy had been confirmed by skin testing two to 13 years earlier. Of those individuals, who ranged in age from 3 to 25, eight had avoided peanuts completely since the original diagnosis. Twenty-four others had inadvertently consumed peanuts, and all experienced symptoms. In 19 of the cases, the interval between the diagnosis and the accidental peanut consumption was at least seven years.
This study echoed the results of an earlier investigation, in which peanut oil was not linked to a reaction. In the newer study, four subjects were given a food challenge in which neither they nor the researcher knew whether they were getting the oil or a placebo. Virtually all peanut oil produced in the United States is processed by a single manufacturer and contains no detectable protein, which would cause the reaction.
Nonetheless, S.A. Bock and F.M. Atkins of the National Jewish Center for Immunology and Respiratory Medicine in Denver, who conducted the recent study, advise treading cautiously. They suggest that peanut oil and oils used to fry peanut-containing foods (and presumably reused) could retain peanut allergens and might pose a threat to sensitive individuals. They therefore recommend avoiding them.