NEWSBREAKS INCLUDE:
Folate Deficits: Higher Early Miscarriage
New Advice on Blood Pressure
Biotech and Genes in Gut Bacteria
Teen Girls: Call to Action
By the time they are 16 or 17 years old, teenage girls (56% of black girls and 31% of white girls) say they have no regular leisure-time physical activity, according to a recent New England Journal of Medicine study (9/5/02). Researchers surveyed 1,213 black girls and 1,166 white girls enrolled in the National Heart, Lung and Blood Institute Growth and Health Study from ages 9 or 10 to 18 or 19 years. Activity decline was positively associated with pregnancy in black girls, cigarette smoking in white girls, and lower levels of parental education in both groups. These teenagers are setting themselves up for obesity and other disease risk factors and need age-specific motivators to incorporate regular sports or physical exercise as a regular part of leisure-time activities.
Folate Deficits: Higher Early Miscarriage
Adequate folate during pregnancy lowers the risk of neural tube defects (NTD), but it may also minimize the risk of early miscarriage. A recent study of Swedish women and at the National Institute of Child Health and Human Development (NICHD) showed that low blood folate levels in pregnant women are associated with higher early miscarriage risk. The study compared blood folate in 468 women who had an early (6-12 week) miscarriage with 921 women 6-12 weeks' pregnant and found that folate deficit (but not adequate or excess levels) were positively associated with a 50% increase in early miscarriage risk. Swedish women were studied because grain in Sweden is not folate fortified as it is in the United States. Folate occurs naturally in beans, leafy green vegetables, and citrus fruits.
New Advice on Blood Pressure
The National High Blood Pressure Education Program (NHBPEP) recently updated its recommendations, advising adequate potassium intake and a diet rich in fruits, vegetables, low fat dairy, and reduced saturated and total fat to help prevent hypertension (Journal of the American Medical Association, 10/16/02). The advisory repeated its early recommendations for physical activity, keeping a normal body weight, and limiting sodium and alcohol intake. Although hypertension is now better prevented than in the past, still more than 50% of adults age 60 years and older have high blood pressure, and even people with normal levels run a high risk of developing hypertension in later life.
Protein Ping-Pong
Advice on healthy protein intakes has bounced from one extreme to the other, high in the 1960s, then low, then up again, with protein recommendations ranging from 10% to 35% of daily calories. Dietitians at the recent Annual Meeting of the American Dietetic Association (ADA) in Philadelphia concluded that no one knows for sure how much protein is "just right." The issue is complex for many reasons: protein may appear in different forms (solid, hot, dry and chewy, or cold and liquid; high fat or fat free, animal or vegetable, and with or without carbohydrate). What experts do agree is that we all need protein in our diet, and it should be obtained by making healthy eating choices. The newly issued Macronutrient Report of the National Academy of Sciences is a useful reference for expert opinion.
Obesity: The Numbers
With all the talk about America's escalating obesity levels, do you ever wish you had some numbers to give your clients and friends? Here are a few statistics from the 1999-2000 National Health and Nutrition Examination Survey, where the heights and weights of 4,115 adults and 4,722 children were measured. Overweight and obesity were determined by body mass index, where a rating of 25 or higher was considered overweight, 30+ as obese, and 40+ as extremely obese:
* 64.5% of adults are overweight (10 to 30 lbs higher than healthy levels) or obese (more than 30 lbs overweight);
* 50% of black women are obese compared with 40% Mexican American and 30% white women; among men there were no differences between races;
* Overall, 5% of the general population, but 15% of black women, are extremely obese;
* 15% of children ages 6 to 9 years are overweight;
* In 1980, only 15% of American adults were obese.
(JAMA 10/9/02)
Lemon or Honey?
Touting the miraculous health benefits of single-food items is the stuff of which food fads are made. Such claims have fed media campaigns in various forms for ages. Soybeans, mushrooms, cranberries-"These days it's difficult to find a fruit or vegetable without a press agent and a Web site," notes Patricia Winters Lauro of the New York Times (10/18/02). One of these "hot" items this fall is ordinary tea (green or black). In September it featured in an International Scientific Symposium on flavonoids. Green and black teas, as well as nonherbal teas, contain some flavonoids in abundance. New studies are exploring the role of flavonoids in heart health, reduced cancer risk, increasing low-density lipoprotein (LDL) cholesterol, and high antioxidant activity. Most studies measured the effects of 3 or 4 cups of tea per day. More research is needed. Also a food flavonoid database is needed-USDA's Agricultural Research Service is working on one that should be issued in 2003. Bottom line for now: As the September Consumer Reports on Health (14[9]:8-9) concludes, don't make tea a substitute for a varied diet rich in fruits and vegetables.
Acrylamide Uses Asparagine
Scientists exploring the mystery of acrylamide, usually in plastics, produced in high-temperature cooking, have found one clue in the puzzle: asparagine, a naturally occurring amino acid, which produces the potential cancer-causing agent when it is heated with certain sugars. Asparagine is found in many vegetables but only a few, such as potatoes, are regularly deep fried at high temperatures and consumed in quantity. Research continues, but both US and Canadian food manufacturers are already seeking ways to alter this reaction. (AP 9/30/02)
Biotech and Genes in Gut Bacteria
Research continues to support the argument that the DNA in foods produced by biotechnology is safe. "It is extremely unlikely that genes can end up in the bacteria in the gut of people who eat them," asserts Food Standards Agency (FSA) experts. For recent studies on this still-controversial topic, visit the following links:
* For a report on "Animal Biotechnology: Science-Based Concerns," visit http://www.nap.edu.
* On survival of ingested DNA in the gut: http://www.food.gov.uk/multimedia/pdfs/rowett1.pdf.
* Evaluating risks: http://www.food.gov.uk/multimedia/pdfs/gmnewcastlereport.pdf.
* On transferring antibiotic resistance: http://www.food.gov.uk/multimedia/pdfs/gmleedsfinalreport.pdf.
* On genetically modified DNA and rumen microorganisms: http://www.food.gov.uk/multimedia/pdfs/rowett2.pdf.
No UL, but Keep Trans Low
The Food and Nutrition Board, Institute of Medicine, National Academy of Sciences, has released Report on Dietary Reference Intakes for Trans Fatty Acids. The chair of the panel was Joanne R. Lupton, PhD, of Texas A&M University. The report concluded that there is a positive linear trend between trans fatty acid intake and total and low-density lipoprotein (LDL) cholesterol concentration, and therefore an increased risk of coronary heart disease, suggesting a tolerable upper intake (UL) of 0. However, achieving such a level is extremely difficult because trans fatty acids are unavoidable in ordinary diets. Eliminating foods such as dairy products and meats that contain trans-fatty acids would present potential health risks. Therefore, the committee proposed no UL but recommended that trans fatty acid consumption be as low as possible while maintaining a nutritionally adequate diet. The report is available at http://www.iom.edu/reports.
That Five-Year-Old Hunger
Five-year-old girls whose parents reported restrictive feeding practices were, if given a choice, more likely to eat even when they were not hungry, and this overeating persisted even at age 7, according to a recent study of 192 non-Hispanic white girls (American Journal of Clinical Nutrition. 2002;76:226-231), tested at ages 5 and 7. When given free access to snack and dessert foods after a lunch they said made them "full," the "low snackers" nibbled an additional 49 and 76 calories at ages 5 and 7, respectively, whereas the "high snackers" took in 201 and 263 calories. "Children should be encouraged to focus on their own hunger and fullness as a guide to when eating begins and ends," the authors conclude.
Postmenopause: Lifestyle Therapy
With numbers of postmenopausal women opting out of hormone replacement therapy (HRT), Boston-area experts remind us that the alternative to HRT "is not decrepitude." Diet, exercise, and positive lifestyle changes can help keep away the weight gain, osteoporosis, and heart disease that may follow with aging. "Avoiding weight gain is the most important thing you can do," says Alice Lichtenstein, Director of the Cardiovascular Nutrition Research Program at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. Decrease dietary fat gradually, but permanently, choosing foods not supplements, says Walter Willett, chairman of the Department of Nutrition at Harvard School of Public Health. And exercise for healthy bones, recommends Miriam E. Nelson, Director of the Center for Physical Activity and Nutrition at Tufts, and coauthor of Strong Women, Strong Bones. As Lichtenstein also notes, take on changes temperately: enjoy life, enjoy food, and enjoy exercise. (Boston Globe Online, 10/2/02).