Submitted by: Linda B. Bobroff, Ph.D., RD, LD/N, Professor and Extension Nutrition Specialist.
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Introduction

The Dietary Guidelines for Americans (Dietary Guidelines) provide research-based dietary advice designed to promote health and reduce risk for the major chronic conditions and diseases that affect people in the U.S., including obesity, diabetes, cardiovascular disease, high blood pressure, cancer, and osteoporosis. The Dietary Guidelines are the cornerstone of federal nutrition policy and influence the numerous food and nutrition programs of the federal government. These include the Food Stamp Program, Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), National School Lunch Program and School Breakfast Program. The latest edition of the Dietary Guidelines was introduced in 2005.

Most Americans do not consume diets that are consistent with the recommendations of the Dietary Guidelines for Americans – 2005 (DG-2005). Nutrition education, such as that provided by Extension educators, can help consumers make healthful food choices to meet the DG-2005, within the context of their usual food patterns and cultural preferences. A recent report from USDA’s Economic Research Service (ERS) indicates that changes in food intake patterns to meet these recommendations have implications for American agriculture, which may be of interest to Extension and its partners.

Food Group Recommendations of DG-2005

The DG-2005 (1) encourages Americans to consume more fruits, vegetables (with specific recommendations for the five sub-groups of vegetables), fat-free or low-fat milk or milk products, and whole-grain products, while staying within caloric recommendations. These food group recommendations are outlined in the MyPyramid Food Guidance System, which was introduced in April 2005 (2) and which is available at http://mypyramid.gov. The amounts recommended constitute alterations in consumption of food from these food groups for many Americans, and thus have implications for American agriculture (3). Within USDA’s Food Guidance System, food patterns are based on calorie needs. For a person consuming a 2,000 calorie per day diet, the amounts recommended from these four food groups are as follows:

Fruits: 2 cups

Vegetables: 2 ½ cups

Grains: 6 ounce equivalents (eat at least 3 ounce equivalents of whole grain foods)

Milk: 3 cups (choose fat-free or low-fat)

Note: The fifth food group is Meats and Beans, and at the 2,000 calorie per day level, the recommended intake is 5 ½ ounce equivalents. Most people consume an adequate amount of protein, one of the key nutrients provided by this food group, but eat beans infrequently, and increased intake of beans is recommended (this is included in the recommendation to increase vegetable consumption, since beans are included in both food groups).

The average American diet falls short of the daily recommendations for fruits, vegetables (except for starchy vegetables which are over-consumed), whole grains, and milk and milk products in the DG-2005 and in the supporting MyPyramid Food Guidance System. The ERS report indicates that “if Americans were to bring their diets fully in line with these recommendations, changes in the mix and quantity of foods produced in the United States would undergo some major shifts.”

What Did The Study Find?

The following findings are reprinted from the ERS report (3):

If Americans were to fully meet the Guidelines’ recommendations for fruits, vegetables, total grains, and whole grains, U.S. agriculture would need to harvest 7.4 million additional acres of cropland per year, an increase of 1.7 percent of total U.S. cropland in 2002.

Additionally, U.S. dairy farmers would need to raise annual production of milk and milk products by an estimated 108 million pounds (about a 65 percent increase) for Americans to meet recommendations for dairy consumption. Such an increase in dairy demand would likely require an increase in the number of dairy cows, an increase in the volume of feed grains needed, and, possibly, an increase in the acreage devoted to dairy production.

Fruit. Americans would need to increase daily fruit consumption by 132 percent to meet the new dietary recommendations. The additional demand could require U.S. producers to more than double harvested fruit acreage to 7.6 million acres (from 3.5 million). U.S. fruit production is constrained by land, labor, and climate, making it likely that imports would continue to increase as a share of the total U.S. fruit supply.

Vegetables . To meet the new recommendations for vegetables, Americans’ daily vegetable consumption would need to rise by about 31 percent and the mix of vegetables consumed would need to change. For example, consumption of legumes would have to increase by 431 percent, and consumption of starchy vegetables would have to decline by 35 percent. To meet this increased demand, the area harvested for vegetables in the United States would need to increase by about 135 percent from 6.5 million acres to 15.3 million acres.

Milk and milk products. Americans would need to increase their consumption of dairy products, including fat-free or low-fat milks and equivalent milk products (e.g., nonfat yogurt) by 66 percent (requiring an additional 111 billion pounds of milk per year) to meet the new dietary recommendations. Domestic production could account for 108 billion pounds of that increase, most likely by expanding dairy cow inventories, an action counter to long-term industry trends.

Whole grains. To meet the dietary recommendations, Americans would need to increase their daily consumption of whole grains by an estimated 248 percent and reduce their consumption of total grains by about 27 percent. Because it takes less raw wheat to produce a whole-grain product than a similar refined-grain product and because of the decline in total grain intake, the overall drop in demand could translate to producers harvesting about 5.6 million fewer acres of wheat each year.

As noted above, the DG-2005 do not recommend an increase in meat consumption, and for many people, to meet the recommended intake from the Meat and Beans groups, they likely would need to decrease their meat consumption and increase consumption of legumes and fish. This ERS analysis did not include effects of meat, fats and oils, or caloric sweeteners, although one might expect possible implications for agriculture from these changes as well.

Implications for Extension

Extension has its roots in agriculture and agriculture still is a primary focus of Extension programming. The findings of this ERS report are interesting in that they bridge what may sometimes be considered a gap between Family and Consumer Sciences (FCS) (specifically Nutrition) programs and Agriculture programs in Extension. Although the focus of these programs, their target audiences, and their very nature vary, this report indicates that there is a mutual interest (or concern) that may warrant exploration.

Nutrition education programs and interventions are carried out to help consumers implement dietary guidelines that are jointly developed by the USDA and US Department of Health and Human Services for the purpose of improving the health and well-being of Americans. Programs are based on the most current research in the area of diet and health, and not based on potential impacts on agriculture at the national or even local level. Still, it is helpful for Extension FCS educators, who are primary providers of Extension nutrition education programs, to be familiar with potential implications for agriculture of the recommendations that they make as part of their nutrition programming, particularly when local commodities might be impacted.

Collaborative programming with FCS and Agriculture Extension agents to explore these issues may open the door to enhanced communications between professionals in these two fields.

References

1. U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary Guidelines for Americans, 2005. 6th Edition, Washington, DC: U.S. Government Printing Office, January 2005. Available at: http://www.mypyramid.gov/guidelines/index.html
2. U.S. Department of Agriculture. MyPyramid. 2005. Available at: http://www.pyramid.gov.
3. Buzby JC, Hodan FW and Vocke G. Possible Implications for U.S. Agriculture from Adoption of Select Dietary Guidelines. Economic Research Report No. ERR-31, November 2006. Available at: http://www.ers.usda.gov/Publications/ERR31/.

Linda B. Bobroff, Ph.D., RD, LD/N
Professor and Extension Nutrition Specialist

The number of people who are either overweight or obese is on the rise in the U.S. and many other countries. It is fairly well accepted that being obese can increase risk of death; however, it is not clear from the literature if being overweight (as opposed to obese) imparts a similar risk. Two recent papers examine this issue among older persons in the U.S. and Korea.

Background

Weight status often is defined as a ratio of body weight in kilograms to height in meters squared – the body-mass index or BMI. For adults, a BMI from 18.5 to 24.9 is defined as normal or healthy, 25.0 to 29.9 as overweight, and 30.0 or more as obesity (Adams 2006). In the U.S. during the last two decades the percent of adults who are overweight or obese has increased significantly. Approximately one-third of adults currently are classified as obese putting them at increased risk for diabetes, cardiovascular disease, and some cancers, and increasing their risk of premature death (USDHHS 2005).

Lifestyle practices often associated with obesity, including poor diet and physical inactivity, are second only to smoking as a leading cause of death, causing an estimated 400,000 deaths (16.6% of deaths) in 2000. These statistics, along with rising health care costs and an aging population, have stimulated significant interest in prevention and management of overweight and obesity (Mokdad 2004). The following studies examine the question of whether or not being overweight increases risk of death among adults in the U.S. and Korea.

U.S. Study (Adams 2006)

Researchers examined BMI in relation to the risk of death from any cause in a cohort of 527,265 men (313,047) and women (214,218) in six states in the U.S. who were 50 to 71 years old at their enrollment in the 10-year study. The researchers calculated BMIs from self-reported heights and weights, submitted via a mailed questionnaire. They calculated both current BMI, as well as BMI at age 50 based on recalled weight reported in a supplementary questionnaire mailed six months after the initial contact.

During the 10-year study, 61,317 participants died (42,173 men and 19,144 women). As expected, those in the lowest or highest categories of BMI (<18.5 and $40.0) had an increased risk of death. This was observed in men and women, all racial or ethnic groups, and at all ages at time of enrollment in the study. Among men, those in the BMI category <18.5 had a relative risk of death of 1.97 and those with a BMI $40.0 had a relative risk of death of 1.83. In other words, these men were approximately two times more likely to die than men in the healthy BMI range of 23.5-24.9 which was the reference group (relative risk = 1.00). In women, those in the BMI category <18.5 had a relative risk of death of 2.03 and those with a BMI $40.0 had a relative risk of death of 1.94, similar to the outcomes among men. These data constitute a U-shaped relation between BMI and risk of death, with the lowest risk in the middle BMI categories. With increasing age, the elevated risks at the two extremes of BMI declined slightly. These results support earlier studies that show increased risk of death in both underweight and obese persons.

When the researchers restricted their analysis to persons who were healthy and had never smoked, they found an increased risk of death in overweight as well as obese men and women. The associations were even stronger when they examined BMI in midlife (50 years of age) among those who had never smoked. In this cohort, the risk of death increased by 20 to 40 percent in overweight persons, and by two to three times among those who were obese.

Korean Study (Jee 2006)

This study also examined the association between BMI and risk of death. The subjects were 1,213,829 Korean men (770,556) and women (443,273) between 30 and 95 years of age, a wider age range. BMIs were calculated using height and weight measurements taken at physical examinations at local hospitals. The average BMI was 23.2.

In the 12 years of follow-up, 82,372 people died, including 58,312 men and 24,060 women. The lowest death rates were in men and women with BMI 23.0 to 24.9. As in the previous study, those at the lowest and highest BMI ranges had the highest death rates, although the differences were not as large in this study. In men, those in the BMI category <18.5 had a hazard ratio (basically the same statistic as the relative risk of the previous study) of 1.29 and those with a BMI $30.0 had a hazard ratio of 1.71. The reference in this study also was the BMI range of 23.0-24.9, with a hazard ratio of 1.0. In women, those in the BMI category <18.5 had a hazard ratio of 1.17 and those with a BMI $30.0 had a hazard ratio of 1.20. These are smaller difference than those observed in the U.S. study. There was little evidence of an effect of BMI on death risk among persons over 65 years of age.

Slightly higher death rates in persons with low BMIs in this population may be due to a relatively high incidence of respiratory diseases such as chronic obstructive pulmonary disease (COPD) and pneumonia in Korea, both of which are associated with severe weight loss. These researchers examined risk of death from specific causes. Risk of death from atherosclerotic cardiovascular disease increased with increasing BMI in men (hazard ratio 1.94 in men with BMI $32.0). Risk of death from cancer increased slightly among overweight persons and more significantly among those with a BMI over 30.

Overall, the BMIs of this cohort were lower than those of the U.S. cohort. However, the authors note that Asian populations tend to have higher percent body fat than do Western populations at a given BMI, placing them at higher risk for diseases at lower BMIs. Due to this difference, the World Health Organization has recommended that cutoff points for overweight and obesity should be lower for Asian populations (WHO 2000).

Implications for Extension

There is a substantial body of evidence that obese persons are at increased risk of disease and early death, although some health professionals disagree with this conclusion. The U.S. study reported here indicates that persons who are overweight also may be at risk of early death, although this likely will continue to be debated in the literature and the focus of future research. Both studies indicate that risk of death among older persons may be less affected by BMI, although this too may need further research.

As Extension professionals, we can make positive impacts in the lives of persons who are either overweight or obese by offering healthy lifestyle programs that focus on behaviors over which they have control (e.g., eating and exercise behaviors), and that promote health and physical fitness, regardless of body weight. Weight management programs may have their most positive impacts on persons in midlife who are obese since they are at high risk for chronic diseases and early death, and there is evidence that even small changes in body weight can greatly reduce risk of disease, such as diabetes (Knowler 2002). Still, our primary focus should be on positive lifestyle changes rather than weight loss, and on improved health parameters such as blood glucose, blood pressure, and blood lipids, since they indicate risk for the major disease that kill Americans.

The 11-session Toward Permanent Weight Management (TPWM) program recently was updated and is available for your use (CD will be available soon). TPWM focuses on healthful eating, physical activity, behavior modification, and size acceptance. Another weight management program, the University of Florida Women’s Weight Loss Research Program is part of an NIH-funded project that included the six-month weight loss intervention, followed by a 12-month maintenance program in three different formats (the research component). This study is being completed in six county Extension offices in north central Florida, and the team (Bobroff is one of the co-investigators) has applied for additional funding to test various program lengths and make it more adaptable for Extension.

References

Adams KF, Schatzkin A, Harris T, Kipnis V, Mouw T, Ballard-Barbash R, Hollenbeck A and Leitzmann MF. Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old. New Engl J Med. 2006;355:763-778.

Jee SH, Sull JW, Park J, Lee S0Y, Ohrr H, Guallar E and Samet JM. Body-mass index and mortality in Korean men and women. New Engl J Med. 2006;355:779-787.

Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346:393-403.

Mokdad AH, Marks JS, Stroup DF and Gerberding JL. Actual causes of death in the United States, 2000. JAMA 2004;291:1238-1245.

U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary Guidelines for Americans, 2005. 6^th Edition, Washington, DC: U.S. Government Printing Office, January 2005. Available at: www.healthierus.gov/dietaryguidelines. Accessed: September 28, 2006.