#17-001

Complete

Category

Date Full Report Received

09/26/2018

Date Abstract Report Received

09/26/2018

Investigation

Institution:
Primary Investigator:

Over the past 35 years the United States Department of Agriculture (USDA) Dietary Guidelines for Americans (DGAs) has sought to translate recommendations on nutrient requirements into practical nutritional advice for the American public. The most recent (2015) included specific advice to “vary your protein” and to rely less on meat as a source of protein. To help the consumer meet protein needs while achieving the goal of varied protein food sources, the DGAs Committee published “ounce equivalents” in the protein foods group. It is stated, among other equivalents cited, that 1 ounce (oz) of meat is equivalent to 1 tablespoon (Tbsp) of peanut butter or 1/2 cup (0.5 oz) of cooked kidney beans. This study investigated the metabolic response to the ounce-equivalents of these protein sources. Three groups of 8 subjects, balanced for gender, were randomly given 2 ounce-equivalents of various protein sources, including: 2 oz of pork loin, 4 oz of tofu, or 1 oz of mixed nuts. The response of muscle and whole-body protein was studied, with particular emphasis on determining body protein accretion. The gain of protein, metabolically called net balance, was greatest with pork. The primary mechanism responsible for a greater gain in body protein with pork intake was a significant decrease in the loss, or breakdown, of body protein. These results indicate that the ounce-equivalents of protein sources are not equivalent in terms of the amount or quality of protein, the caloric content, and most importantly, the resultant metabolic response of body protein. These findings strongly suggest that the recommendation of dietary protein intake based upon the “ounce equivalents” in the DGA guidelines requires revision.