How
many bread products should I eat every day?
How much cheese equals a glass of milk?
Consumers
are interested in knowing how much and what type of foods to eat
for continued or improved health. Two federal nutrition education
tools use standard serving sizes: the Food Guide Pyramid and the
Nutrition Facts label. The Pyramid was released by the U.S. Department
of Agriculture (USDA) in 1992. The Nutrition Facts label, which
is under the regulation of the Food and Drug Administration (FDA),
has been required on virtually all food labels since August 1994.
While both tools contain serving sizes that are standard—thus
enabling nutritional and caloric comparisons of similar foods—serving
sizes for a particular food are not necessarily the same between the Pyramid and the Nutrition Facts label. Attempts to directly
compare Pyramid and label servings may, therefore, generate confusion.
For
many foods, the serving sizes in the Pyramid and on the label are
the same—such as 1 cup of milk and 1/2 cup of cut-up fruits
or vegetables–but there are notable differences. For example,
the Pyramid serving size for pasta is 1/2 cup cooked (about 1 ounce
uncooked), while on the label it is about 1 cup cooked (2 ounces
uncooked). To understand why serving sizes are sometimes different
for the Pyramid and the Nutrition Facts label, it is important to
understand the purpose of each and to distinguish how these serving
sizes were derived for individual foods. These are explained and
a way to help consumers use both more effectively is proposed in
this Insight.
Food
Guide Pyramid
The
Food Guide Pyramid translates recommendations of the Dietary
Guidelines for Americans(1) and nutrient standards like the
Recommended Dietary Allownaces into food group-based advice for
a healthful diet. The Pyramid graphically illustrates a research-based
food guidance system built on the foods typically eaten by Americans,
the nutrients in these foods, and recommen-dations on how to make
the best food choices to promote good health.(2) The Pyramid
suggests the type and amount of foods to eat each day without prescribing
rigid guidance, and can be used as a general guide in choosing individualized
healthful diets from a variety of common foods. Since its release,
the Pyramid has been widely used by nutrition educators, teachers,
the media, and the food industry, in nutrition curricula, articles,
and food packaging and advertising.(3)
Determination
of Serving Sizes in the Pyramid
To
establish serving sizes for the food groups in the Pyramid, four
factors were considered: typical portion sizes (from food
consumption surveys), ease of use, nutrient content, and tradition (of use in previous food guides). For some food
groups, certain factors were given more emphasis than others.
For
example, the serving size for cooked or raw cut-up fruits and vegetables
was set at • cup based on typical portion sizes and
for easy recognition and use. Although fruits and vegetables vary
in nutrient content, the number of different serving size units
was kept to a minimum to make the Pyramid easier to use. For the Milk group, on the other hand, nutrient content was
a more important consideration in determining serving sizes. Serving
sizes were set to be equivalent in calcium content to a typical
portion size for milk, which is 1 cup. In the Meat and Beans
group, was also an important consideration. The specified amount
of eggs, nuts, and dry beans provide about the same protein and
mineral content as 1ounce of meat. In the Grains group, the traditional serving size of 1 slice of bread was maintained as the serving size.
For other grain products nutrient content was considered,
as serving sizes were set to be approximately equivalent in calories
to one slice of bread.
Nutrition
Facts Label
The
Nutrition Facts label lists the serving size of the food and the
number of servings per container. It also identifies and quantifies
key nutrients in a serving as a percentage of Daily Values (%DV)
for a 2,000-calorie diet. Before FDA regulation, the choice of serving
sizes on food labels was up to the discretion of individual food
manufacturers. Serving sizes are now more uniform. The Nutrition
Facts label, therefore, enables nutritional comparisons of similar
foods. The label is now ubiquitous on food packages and widely recognized
by consumers.(4)
Determination
of Serving Sizes on the Nutrition Facts label
Nutrition
Facts label serving sizes are based on–but not necessarily equal to—the amount of food customarily eaten at one
time (called the “reference amount”) as reported from
nationwide food consumption surveys. As explained next, label serving
sizes and reference amounts are related but not necessarily the
same. Serving sizes are based on reference amounts in one of three
ways.(5) For bulk products, such as cereals and flour,
the Nutrition Facts labels use common household terms such as cup,
tablespoon, teaspoon, and fluid ounce at a quantity that is closest
to the reference amount for that item. For products that are usually
divided for consumption, such as cake or pizza, the serving size
is a fractional amount of the product (e.g., “1/4 pizza”).
Products that come in defined, discrete units—such as
eggs and sliced products—are normally listed as the number
of whole units that most closely approximates the reference
amount. For example, cookies have a reference amount of 30g. Thus,
the serving size on a package of cookies weighing about 30g each
would be “1 cookie.” For foods like cookies that come
in discrete units, serving sizes for a single item may vary from
50 to 200 percent of the reference amount. Another example is bread—with
a reference amount of 50g. The Nutrition Facts label serving size
for bread which weighs 25g per slice could either read “1 slice
(25g)” or “2 slices (50g).” Additionally, it is possible
for a single slice of two different types of bread, with very dissimilar
weights, to be listed as a serving on a food label.
Because
serving sizes may vary from the reference amount, and because the
reference amount for different foods may vary widely in caloric
content, there is considerable variation in the calories in a label
serving for different products from the Grain group (figure 1).
The caloric variation between a single Pyramid serving of these
foods is less, which reflects the effort to make Pyramid serving
sizes nutritionally similar. For example, the number of calories
in a Pyramid serving of the foods shown in Figure 1 ranges
from about 60 to 110, while the number of calories in a label serving
ranges from about 55 to 250.
Why the Differences?
Serving
sizes in the Pyramid and on the Nutrition Facts label are sometimes
different because the two serve different purposes. The Pyramid
is designed to help people meet daily nutrient recommendations.
Serving sizes in combination with the recommended number of daily
servings are an educational component of the Pyramid to help consumers
select appropriate amounts to eat daily. Therefore, the Pyramid
provides relatively few, easy-to-remember serving sizes for each
of the food groups that, in most cases, are nutritionally comparable.
Nutrition
Facts label serving sizes, on the other hand, provide detailed nutritional
information on a food for easy comparison with similar foods. The
label is deliberately specific for similar food products to allow
consumers to determine differences in important nutrients among
these foods and to select among similar foods based on nutritive
values of comparable quantities.
If
the purposes of the Pyramid and the Nutrition Facts label are understood,
the two can be used together to compliment each other and to help
consumers make food choices for a healthful diet from a wide variety
of foods. The usefulness of both tools would be enhanced and confusion
lessened if food product labels included a statement of the number
of Pyramid servings contained in one label serving.
Contributors:
David Herring, M.S., Patricia Britten, Ph.D., Carole
Davis, M.S., R.D, and Kim Tuepker, B.S. (student intern).
References
Nutrition
Insights is
issued by the Center for Nutrition Policy and Promotion, an organization
of the U.S. Department of Agriculture. Nutrition Insights may be accessed at the CNPP Web Site at 