Nutrition Science and Everyday Application - beta v 0.1

Protein in Foods and Dietary
Recommendations
In this section, we’ll discuss how to determine how much protein you need and your many
choices in designing an optimal diet with high-quality protein sources.
HOW MUCH DIETARY PROTEIN DOES A PERSON NEED?
Because our bodies are so efficient at recycling amino acids, protein needs are not as
high as carbohydrate and fat needs. The Recommended Dietary Allowance (RDA) for a
sedentary adult is 0.8 g per kg body weight per day. This would mean that a 165-pound
man and a 143-pound woman would need 60 g and 52 g of protein per day, respectively.
The Acceptable Macronutrient Distribution Range (AMDR) for protein for adults is 10%
to 35% of total energy intake. A Tolerable Upper Intake Limit for protein has not been set,
but it is recommended that you not exceed the upper end of the AMDR.
Protein needs are higher for the following populations:
• growing children and adolescents
• women who are pregnant (they’re using protein to help grow a fetus)
• lactating women (breast milk has protein in it for the baby’s nutrition, so mothers
need more protein to synthesize that milk)
• athletes
The Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of
Sports Medicine recommend 1.2 to 2.0 grams of protein per kilogram of body weight per
day for athletes, depending on the type of training. 1 Higher intakes may be needed for short
periods during intensified training or with reduced energy intake.
NITROGEN BALANCE TO DETERMINE PROTEIN NEEDS
The appropriate amount of protein in a person’s diet is that which maintains a balance
between what is taken in and what is used. The RDAs for protein were determined by
assessing nitrogen balance. Nitrogen is one of the four basic elements contained in all amino
acids. When amino acids are broken down, nitrogen is released. Most nitrogen is excreted as
urea in urine, but some urea is also contained in feces. Nitrogen is also lost in sweat and as
hair and nails grow. The RDA, therefore, is the amount of protein a person should consume
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