Project Plant Protein: the P3 Study in Humans
Condition: Pre-diabetes; Obesity
MeSH terms: Prediabetic State
Study type: Interventional

Summary: 
      The objective of this study is to compare the effects of adding three plant-based proteins
      (rice, oats and pea proteins) to a breakfast beverage on the glycemic response, appetite and
      subsequent food intake of healthy adults.
    

Detailed description: 
      A diet or a meal higher in dietary protein has been reported to promote satiety and suppress
      food intake in humans in several previous studies. It was suggested that the presence of
      amino acid in the blood as a result of higher protein intake served as signals that suppress
      appetite in humans. More recently, it has been observed that incomplete or lower quality
      proteins, i.e. those missing one or more essential amino acids, may suppress hunger more than
      complete proteins, as the ingestion of incomplete proteins in the long term may lead to
      deficiency of essential amino acids. Plant proteins are generally considered incomplete
      protein when compared to animal proteins, which mean that plant protein may have higher
      appetite-suppressing effects.

      Dietary carbohydrates are the most potent stimuli of insulin secretion. However, the addition
      of dietary protein in a carbohydrate-rich meal has been shown to further stimulate insulin
      release.The insulinotropic effect of dietary protein is thought to be attributed to the
      branched-chain amino acid (BCAA) content of the protein-rich meal. Interestingly, there is a
      hierarchy of effects induced by protein from different sources. For example, milk protein has
      been shown to be superior to fish or plant protein in stimulating insulin secretion following
      a meal.Even within milk protein, whey protein stimulated insulin secretion more than casein
      protein. One of the factors that distinguish whey from casein proteins was the digestibility
      or the digestion rate of these proteins. Protein that is digested faster appear to increase
      blood amino acid levels faster, and increase insulin release faster.This implies that plant
      proteins that have lower digestibility rate relative to animal proteins may have lower
      insulinotropic effects, and the effective dose required to achieve optimal insulin secretion
      may be different from animal protein and warrants further investigation. In addition, the
      amino acid profile (in addition to lower digestibility) of plant proteins may differ from
      animal protein, especially the BCAA content that is associated with the stimulation of
      insulin secretion.

      Dietary patterns and cuisines vary between countries and cultures. Unlike in the Western
      countries, plant-based foods are more commonly consumed in an Asian cuisine. Based on the
      statistics released by Food and Agriculture Organization, cereals and meat are the top two
      protein sources in both Western (29.1% and 26.4% respectively) and Asian (58.8% and 8.6%
      respectively) countries. The third major source of protein is dairy (16.7%) in Western
      countries, and pulses in Asia (7.4%). In addition, vegetarianism is widely practiced in Asian
      countries. Studies investigating the appetitive and the blood glucose regulating effects of
      dietary protein have been focused predominantly in animal protein, with a number of studies
      included plant-based protein such as soy protein. Since cereals and pulses are an important
      part of an Asian cuisine, it is important to understand and compare the effects of proteins
      from these sources on blood glucose and appetite regulation. Since the amino acid profile and
      the digestibility of these plant-based proteins differ from animal protein, it is important
      to also understand the effective dose that exerts optimal effects.
    

Intervention name(s): Protein Powder
Intervention type(s): Dietary Supplement
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Basic Science