Effect of Supplementary Dietary Protein (21g Per Day) on Lean Mass and Strength in Sedentary, Adult Vegetarians

The American Dietetic Association states that based off of evidence, it is possible for a vegetarian to obtain the recommended amount of nutrients with a properly planned diet. By mixing various sources of plant proteins throughout the day, a person can obtain all the amino acids needed for growth and tissue maintenance and repair. Yet, many vegetarians struggle to eat a substantial diet, especially when it comes to protein. This is because plant protein has protein bioavailability that is 10-30% lower than animal protein. As a result, current research suggests that there needs to be a separate protein dietary reference intake (DRI) for vegetarians and it needs to be larger than the protein DRI for omnivores. Whenever considering protein bioavailability, the quality must be assessed by analyzing the digestibility, chemical integrity, and freedom from interference in metabolism of the amino acid. This is a major concern because inadequate protein intake can affect bone health and alter muscle mass. Importantly, research has shown as a result of inadequate protein intake, vegetarians tend to have less lean body mass and less muscle strength than omnivores. Currently, all research available on this topic included strength training as a variable for increasing lean muscle mass, and no research has been reported that analyzed the impact of increased dietary protein on lean body mass without a training component. This parallel arm study will examine the effect of supplemental plant protein on strength and lean body mass in adult, non-athletic vegetarians in the Phoenix area.

Inclusion criteria

• vegetarian or vegan for at least one year
• healthy by self-report

Exclusion criteria

• supplement use such as protein powder or creatine
• previous diagnosis of heart disease, cancer, stroke, diabetes, autoimmune disorders, or thyroid condition
• competition in any athletic event in the past year
• moderate to strenuous exercise exceeding 150 minutes per week
• pregnant or planning to become pregnant.