Diet and Mortality
Although the U.S. Department of Agriculture's (USDA) nutrition guidelines, along with most health professionals, endorse a low-fat diet rich in fruits, vegetables, and fiber, there has been little research to support the health benefits of this diet. A groundbreaking study, "A Prospective Study of Diet Quality and Mortality in Women," published in the April 26, 2000, issue of the Journal of the American Medical Association, confirmed the role of diet and nutrition in the health and longevity of women.
The study was the first global measure of the relationship between diet and mortality. It is different from earlier research in several important ways—its large sample size, length of follow-up, and rigorous scientific design and research methods. Further, instead of examining the health risks or benefits of a single food group or nutrient, researchers looked at the health effects of complex diets involving multiple food groups and combinations of foods. Because Americans' diets are composed of a variety
FIGURE 10.7
Percent of adults aged 65 years and over who had ever received a pneumococcal vaccination, 1997–2003
of foods, this approach offers real-world applicability in terms of the findings.
Investigators tracked the health and diets of 42,254 women using a written sixty-two-item questionnaire. They calculated Recommended Food Scores (RFS) to measure overall diet quality for each woman. The RFS is calculated by assigning one point for each of twenty-three food items consumed at least once a week. RFS points were earned for fruits and fruit juices, dried beans, vegetables, green salad, potatoes, baked or stewed chicken or turkey, and baked or broiled fish. RFS points also were given for dark breads such as whole wheat, rye, or pumpernickel; cornbread, tortillas, and grits; high-fiber cereals such as bran, granola, or shredded wheat; cooked cereals; 2-percent milk and beverages with 2-percent milk; and 1-percent or skim milk.
The RFS was designed to measure healthy eating—dietary quality independent of reported amounts. This is important because the portion sizes of foods consumed often are reported inaccurately. In general, women who earned the higher RFS were those whose diets closely conformed with current USDA recommendations. Statistical analyses to assess the relationship between diet, health, and risk of mortality looked at the variables of age, race, education attained, BMI, smoking, alcohol consumption, energy intake, and physical activity. It also considered the interaction of diet with other factors, such as history of heart disease, cancer, or diabetes, and use of hormone replacement therapy during menopause.
FIGURE 10.8
Percent of adults aged 18 years and over who engaged in regular leisure-time physical activity, 1997–2003
The research found a clear relationship between dietary patterns and risk of mortality. As RFS increased, mortality decreased. The inverse relationship held true for all types of cancer, heart disease, stroke, and all other causes combined. The investigators stated: "Our study suggests that women reporting dietary patterns that included fruits, vegetables, whole grains, low-fat dairy, and lean meats, as recommended by current dietary guidelines, have a lower risk of mortality."
Women with the lowest scores were at the greatest risk of mortality—their risk was a full 30 percent higher than the risk of women with the highest RFS. The investigators concluded: "Our results provide evidence in support of the prevailing food-based dietary guidelines and suggest that diets complying with current dietary recommendations are indeed associated with improved health outcomes."
Childhood Overweight and Obesity
According to the CDC, since the early 1970s the percentage of children and teens who are overweight has more than doubled, reaching about 15 percent in 2004. A large number of overweight children are developing obesity-related medical problems rarely before seen in children, such as diabetes, high cholesterol, and high blood pressure. Obese children also are at increased risk
FIGURE 10.9
Percent of adults aged 18 years and over who engaged in regular leisure-time physical activity, by age group and sex, January–June 2003
of developing heart disease, osteoarthritis, and some cancers (breast, stomach, and pancreatic cancers) later in their lives. Compounding the health risks are psychological, emotional, and social problems faced by children who are overweight, especially preteen and adolescent girls.
WHAT CAUSES CHILDHOOD OBESITY?
Children are overweight or obese for the same reason as overweight adults—they consume more calories than they expend. Although there is evidence of a genetic tendency for obesity, children mainly become overweight from behaviors, attitudes, and preferences they learn early in life. Relationships with food develop in response to family and cultural values and practices and the influences of school, peers, and media. According to the CDC, 60 percent of young children and adolescents eat excessive amounts of saturated fat and sodium, and less than 20 percent eat adequate amounts of fruits and vegetables (Physical Activity and Good Nutrition: Essential Elements to Prevent Chronic Diseases and Obesity, 2002).
Why are so many kids overweight? Many health professionals point to high-fat convenience and fast foods and time spent playing video and computer games instead of taking part in outdoor, physical activities. Television viewing, media advertising, dwindling school physical education programs, and neighborhoods where it is unsafe for children to play also have been blamed. Parents also
FIGURE 10.10
Age- and sex-adjusted percent of adults aged 18 years and over who engaged in regular leisure-time physical activity, by race/ethnicity, January–June 2003
influence children's eating habits. For example, it is known that parents with eating disorders, obsessive dieters, and those with unhealthy eating habits are powerful, negative role models for children. More often than not, parents make food choices for their children.
Many Americans Are Making Healthier Food Choices
A 2002 nationwide survey conducted by the consumer research firm Yankelovich Monitor for the July 2002 issue of Cooking Light, a monthly magazine devoted to healthy eating, found that choosing healthy foods is a priority for many Americans. Two out of three survey respondents said making healthy food choices was more important than convenience, new flavors, or traditions. Forty-five percent said they eat more healthy foods than they did five years ago, and nearly one-fourth said they chose to prepare home-cooked meals so they could control the healthfulness of ingredients and preparation.
The survey results were consistent with the findings of USDA reports that found Americans have increased their consumption of fruit and vegetables (up more than 20 percent) and poultry (more than 100 percent) during the past thirty years; beef consumption has dropped by
FIGURE 10.11
Prevalence of obesity among adults aged 20 years and over, 1997–2003
more than 10 percent. The USDA also found that the American diet has less fat—thirty years ago Americans obtained 40 percent of their calories from fat, whereas fat now accounts for 33 percent of total calories consumed. Although these trends are promising, Americans are encouraged to modify their diets further to comply with the USDA recommendation that fat consumption be limited to less than 30 percent of daily caloric intake.
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