Departmental News

ADDRESSING COMPLEX NUTRITIONAL ISSUES: Guiding Policy-Makers and Health Professionals

Dr. Peter J. GarlickPeter J. Garlick, PhD, professor of surgery and director of our surgical research division, played a major role in the landmark nutrition report, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients), released in September 2002 by the National Academies' Institute of Medicine. A specialist in protein metabolism, Dr. Garlick chaired the Protein and Amino Acid Section of the Panel on Dietary Reference Intakes for Macronutrients; the 21-member panel included distinguished scientists from both the United States and Canada.

This report, the sixth in a series, develops new guidelines for the U.S. and Canada for the consumption of energy, carbohydrates, fiber, fat, fatty acids, cholesterol, protein, and amino acids, collectively known as macronutrients.

In addition to the other nutritional requirements, the report establishes age-based requirements for the first time for all nine of the essential amino acids found in dietary protein. Values are included for pregnant women, infants, and children based on their special needs. Using new data, the report reaffirms the previously established recommended level of protein intake, which is 0.8 grams per kilogram of body weight for adults. However, the recommended intake of protein during pregnancy is increased.

Because data on the potential for high-protein diets to produce chronic or other diseases are often conflicting or inadequate, tolerable upper intake levels for consumption could not be determined for protein or for the individual amino acids. However, given the lack of data on overconsumption for some of these amino acids and protein, caution is warranted in consuming levels significantly above those normally found in foods.

"Most people are not at risk of either under- or over-consumption of protein," says Dr. Garlick. "However, there is a possibility that some young men might take excessive protein supplements in the belief that additional protein will aid in muscle building. On the other hand, there may be a risk for older persons, whose appetites are diminished, to suffer muscle wasting through consuming too little protein.

"The new guidelines should help individuals to design the most appropriate diet for health, but their main function is to give advice to the government, and to organizations, such as those who provide meal services to schools and residences for the elderly."

In the past, recommended dietary allowances (RDAs) have served as the benchmarks of nutritional adequacy in the United States. The new dietary reference intakes (DRIs) are established using an expanded concept that includes indicators of good health and the prevention of chronic disease, as well as possible adverse effects of overconsumption.

Collectively, Dr. Garlick and his fellow panel members assessed thousands of scientific studies linking excessive or inadequate consumption of fats, carbohydrates, and protein with increased risk for dietary deficiency diseases, obesity, heart disease, diabetes, and other chronic illnesses. The DRIs include not only recommended intakes, intended to help individuals meet their daily nutritional requirements, but also tolerable upper intake levels (ULs) that help them avoid harm from consuming too much of a nutrient.

This study was sponsored by the U.S. Department of Health and Human Services Office of Disease Prevention and Health Promotion; Health Canada; U.S. Food and Drug Administration; National Institutes of Health; Centers for Disease Control and Prevention; U.S. Department of Agriculture; U.S. Department of Defense; Institute of Medicine; the Dietary Reference Intakes Private Foundation Fund, including the Dannon Institute and the International Life Sciences Institute-North America; and the Dietary Reference Intakes Corporate Donors' Fund, contributors to which include Roche Vitamins Inc., Mead Johnson Nutrition Group, and M&M Mars.

The Institute of Medicine's Food and Nutrition Board has been responsible for developing recommended dietary allowances or RDAs for the United States for the last 60 years. The Institute is a private, nonprofit organization that provides health policy advice under a congressional charter granted to the National Academies (formerly National Academy of Sciences).

Dr. Garlick's work at Stony Brook has included numerous studies of surgery's effect on the body's protein metabolism.

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