Weighing In on FATS
The 2005 Dietary Guidelines for Americans
included—for the first time—recommendations that folks in the United
States limit their intake of fats and oils that are high in trans fatty
acids. Landmark research conducted earlier by scientists at the
Beltsville [Maryland] Human Nutrition Research Center (BHNRC)
contributed to that conclusion.
One of those early studies was authored by BHNRC’s
Joseph Judd, now retired, and nutritionist Beverly A. Clevidence, with
colleagues. They fed 58 male and female volunteers, aged 26 to 64, four
controlled diets, characterized as moderately high trans fat, high
trans fat, high saturated fat, and high “heart healthy” oleic acid. LDL
cholesterol levels were measured each time the volunteers completed one
of the diets for a 6-week period. The study showed that after they
consumed any of the trans-fat or saturated-fat diets—as opposed to the
oleic-acid diet—their LDL cholesterol levels were significantly
increased.
Trans fats cause metabolic changes that increase the
amount of circulating LDL cholesterol, which in turn can get deposited
in blood vessel walls.
The scientists also reported that it’s important not to replace dietary trans fats with saturated fats. In fact, the 2005 Dietary Guidelines
recommend consuming less than 10 percent of daily calories from
saturated fatty acids. That’s 22 grams or less for a 2,000-calorie
diet.
Saturated fat and trans fat tend to be solid at room
temperature. The thick, yellow grease that forms in a cool pan after
cooking meat is saturated fat. Both types of fats can collect in the
body and clog arteries, leading to heart disease.
A 2007 ARS
data analysis shows that U.S. consumers aren’t winning the battle on
staving off fats. The researchers studied the levels and sources of
saturated and unsaturated fats in the American diet. The analysis—which
was based on nationally representative dietary-intake survey data from What We Eat in America/NHANES 2003-2004—was
led by nutritionist Alanna J. Moshfegh. She heads the Food Surveys
Research Group at BHNRC. The researchers found that about 64 percent of
adults in the United States exceed the dietary recommendation for
consuming saturated fat.
People can keep an eye on their fat intake by reading
food labels. New labeling laws require foods to be labeled for their
trans fat as well as their saturated fat content.
For example, a croissant has about the same number of
calories as a bagel. But a croissant, which is a buttery puff pastry,
has 32 times as much saturated fat (6.6 grams compared to an oat-bran
bagel’s 0.2 grams). This information and more can be found in two key
tables on saturated fats and trans fats in chapter 6 of the 2005 Dietary Guidelines for Americans.
The source of the tables on fat content is the ARS Nutrient Database
for Standard Reference, Release 17. Release 20, the current version of
this data, is available at www.ars.usda.gov/Services/docs.htm?docid=8964 as the newest resource for checking the nutrient and fat content of foods.
To access the Dietary Guidelines online, go to www.MyPyramid.gov/guidelines/index.html.—By Rosalie Marion Bliss, Agricultural Research Service Information Staff.
This research is part of Human Nutrition, an ARS national program (#107) described on the World Wide Web at www.nps.ars.usda.gov.
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
is with the USDA-ARS Food Components and Health Laboratory,
Beltsville Human Nutrition Research Center, 10300 Baltimore Ave.,
Beltsville, MD 20705-2350, phone (301) 504-8367, fax (301) 504-9098.
"Weighing In on FATS" was published in the March 2008 issue of Agricultural Research magazine.
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