"Ounce-equivalents" in the Protein Foods Group: Benefits of Quality

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 (i.e., Recommended Dietary Allowances) from the Food and Nutrition Board of the Institute of Medicine (IOM) into practical nutritional advice for the American public. Although the DGAs are intended to incorporate additional scientific evidence, the lack of appropriate focus on protein nutrition is a major shortcoming of the DGAs. Not only is the amount of protein not a major focus, absolutely no mention is made of protein quality. In general, animal proteins have much higher the Digestible Indispensable Amino Acid Scores (DIAASs) than plant proteins, often by as much as two fold. Account has not been taken of DIAAS, or even the general concept of the importance of the amount and profile of essential amino acids in individual proteins, in formulation of MyPlate or the scientific report of the DGAs Committee. This is because a classification does not apply to most plant proteins, despite the fact that in the IOM report stating the Recommended Dietary Allowance for protein it is specified that this refers to "high quality 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 and 1/4 cup (0.5 ounces) of cooked kidney beans. But are they really equivalent? This indicates that the "ounce equivalents" of protein foods in MyPlate are not equivalent in any parameter that might be used to assess nutritional benefit, and demonstrates that the bias against animal proteins is in the Dietary Guidelines. The misrepresentation of the equivalencies of various food sources of protein in MyPlate raises the question of the process by which this occurred, and how can the process be influenced to more accurately reflect that high quality of animal proteins? Therefore, developing convincing data to correct the MyPlate "ounce equivalents" of protein foods is an achievable goal. In general, dietary protein intake serves many physiological roles, but the most prominent is the maintenance or gain of body protein. This is accomplished by stimulation of protein synthesis, the inhibition of protein breakdown, or a combination. Thus, the functional response to consumption of a given amount of a protein food source is best assessed by quantifying the rates of protein synthesis and breakdown at the whole body level as well as at the muscle level in order to calculate the anabolic response. The investigators propose to make these measurements in response to intake of "equivalent "(according to MyPlate) amounts of pork, mixed nuts and tofu. Moreover, the functional responses to these varied sources of protein we will examine coincide with the predictions from the USDA nutrient data base, and calculation of the DIAAS will provide needed support to redefine "ounce equivalents" of protein food sources according to those data bases for all animal and plant sources of protein.

• Pork intake (Dietary supplement): Each participant will consume 2 ounces of cooked lean pork.
• Mixed nuts intake (Dietary supplement): Each participant will consume 1 ounce of mixed nuts.
• Tofu intake (Dietary supplement): Each participant will consume 2 ounces of tofu.

Primary outcomes

• Net Protein Synthesis Rate [Change from 4.5 to 8.5 hours.]: Net protein synthesis rate is determined in the 4.5-hours basal fasted period and 4-hours post-meal period over the 8.5-hour experimental period.

Sex: All, ages: 18 Years to 40 Years, accepts healthy volunteers

Inclusion Criteria:

* Men and women, ages 18-40 years
* BMI from 20 to 29.9 kg/m2

Exclusion Criteria:

* Current diagnosis of diabetes
* History of malignancy in the 6 months prior to enrollment
* History of a chronic inflammatory condition or other chronic diseases (Lupus, HIV/AIDS, etc)
* History of weight reduction surgery (Lapband, gastric sleeve, etc.)
* Pregnant females
* Subjects who do not or will not eat animal proteins
* Subjects allergic to pork, tree or peanuts, or soybeans
* Subjects who cannot refrain from consuming protein or amino acid supplements during their participation in this study
* Subjects who report regular resistance training exercise > one per week
* Hemoglobin < 9.5 g/dL at the screening visit
* Platelets < 250,000 at the screening visit
* Concomitant use of corticosteroids (ingestion, injection or transdermal)
* Any other disease or condition that would place the subject at increased risk of harm if they were to participate, at the discretion of the study physician

Participant flow

Outcome results

• Net Protein Synthesis Rate (Primary), Mean, grams: Pork Intake 8.65 +/- 1.6; Mixed Nuts Intake 1.97 +/- 1.04; Tofu Intake 5.69 +/- 0.54 (p <0.05)

Adverse events

Time frame: Adverse events were collected from the time a subject enrolled through their last study visit (e.g. 1 month more or less).

• Study Protocol and Statistical Analysis Plan (PDF, 2018-03-28)