Nutrition Wise - stdg head

by Karen Collins, MS, FD, CDN

Q:  Is eating yogurt daily enough to replenish bacteria in the body, or is a supplement best?

A: Bacteria normally live in our intestinal tract.  They ferment dietary fiber to form substances that may help protect against colon cancer.  They produce a form of vitamin K, and help to fight off growth of other bacteria that could make us ill.  Unless you’ve had antibiotic medication or other treatment that has wiped out the normal colonies of “good” bacteria, there’s no evidence that you need to take any special measures to support them.  If you have been on such medicines or had an intestinal illness, a week or so of yogurt with live active cultures may help, though some studies report that the cultures don’t always survive all the way through our digestive systems.  Suggestions that continuing yogurt consumption may have health benefits beyond their role as a source of nutrients are far from confirmed, and using bacteria supplements is certainly not supported by research.

Q: Dried fruit is often listed as a good source of vitamins, but isn’t it fattening?

A: No food can automatically be labeled “fattening.”  We increase our body fat when we eat more calories than we burn up.  Some foods have more calories than others, but their effect on weight depends on the total calories we’ve eaten that day.  A food can be high-calorie, but if we’re active and need all those calories, or if the rest of what we eat is fairly low in calories, then we would not necessarily gain weight.  Dried fruit makes it easy to overeat because just as it is concentrated in vitamins, a lot of calories are packed into small portions.  Only 15 dried apricot halves contain about 125 calories, and a half-cup of raisins, 220 calories.  People who are trying to cut back on calories might prefer fresh fruit most of the time, since it tends to be more filling with fewer calories.  But dried fruit can serve as a delicious and nutrient-rich snack when eaten in moderation.

Q:  What do you think of the fat-blocking products for weight loss?

A:  If you are talking about the over-the-counter weight loss products based on a substance called chitosan, research does not support their use.  It’s true that chitosan does absorb some dietary fat, but experts say that normal doses can’t absorb enough fat to cause weight loss while continuing a high-fat, high-calorie diet.  The European Journal of Clinical Nutrition published a study from the United Kingdom that used good quality “double blind” research techniques.  After four weeks on their normal diet, weight and blood cholesterol were no different in people who took chitosan twice daily than in those who took placebos (inactive “sugar pills”).  A Japanese study in rats cautions that, depending on the amount used, chitosan might decrease absorption of calcium and vitamin E (a vitamin that is absorbed along with fat).  Blood levels of vitamin E were not affected in the UK study, but this is certainly a concern that bears further investigation.  Some chitosan products may also contain herbs or other diuretic substances that cause significant water loss, which people might mistakenly assume is fat loss.

Q:  Is there any truth to the notion that cranberry juice can cure bladder infections?

A: Some studies have found that drinking a daily 10-ounce glass of cranberry juice reduces the incidence of bacterial infections of the urinary tract in elderly women by about 50 percent after four to eight weeks.  Evidence also suggests that cranberry juice could help treatment of bladder infections.  Cranberry juice, however, is not a substitute for medication.  If you think you might have a bladder infection, see your doctor.  It is important that bladder infections be completely resolved.  When buying cranberry juice, if you have diabetes or glucose intolerance, choose the artificially sweetened versions since regular cranberry juice cocktail contains about three tablespoons of sugar per cup.

Q: Is it true that where body fat is carried influences cancer risk?

A: The Journal of the National Cancer Institute reports that in a large study of people over age 65, men with waistlines more than 36 inches and women whose waists measured more than 32 inches faced twice the risk of colorectal cancer as those with thinner waistlines.  Fat deposited around the abdomen seems to be more metabolically active than lower body fat stores.  Large waistline fat stores seem to promote higher levels of insulin and insulin-like growth factors that previous research has shown to stimulate the growth of colorectal cancers.  The good news is that exercise and healthy eating choices are very effective at reducing excess waistline fat.  The exercise that matters here is not toning exercise (like sit-ups to tighten abdominal muscles), but aerobic exercise (like brisk walking) that will burn up the extra fat.

Q:  Is it true that lutein is helpful to fight macular degeneration?

A:  Macular degeneration is the leading cause of blindness in people over age 65.  It is a gradual destruction of the macula of the eye, the part of the retina responsible for acute vision.  Pigment in the macula is made up of two carotene-family phytochemicals called lutein and zeaxanthin. Tentative research suggests that diets high in these substances keeps macula pigment content higher, which in turn slows down age-related macula destruction.  Foods high in these substances for the prevention or treatment of macular degeneration have not been established.