Proteins can be classified as high or low biological value proteins depending on their composition in essential amino acids, which are those amino acids that the body cannot synthesize and must be provided through food. In recent years, there has been growing interest in reducing the consumption of proteins of animal origin, leading to the search for more sustainable protein options, such as vegetable proteins. However, vegetable options do not have a complete profile of essential amino acids. In this sense, soy protein is considered the reference vegetable protein because it has an adequate amino acid profile. However, the amount of methionine is considerably lower than that of an animal source, and it also has a considerable allergenic potential. The mixture of two types of complementary vegetable protein sources could serve as a strategy to achieve the profile of essential amino acids like that of an animal protein.

The hypothesis of the present study is that the consumption of a mixture of vegetable proteins from legume and cereal sources will complement each other to achieve a bioavailability of essential amino acids equal to or greater than that observed when consuming soy protein.

An adequate protein intake is essential for the body's well-being and performance, because the body uses this nutrient in many cellular functions.

Proteins are nitrogen-containing substances made up of amino acids (AA). Not only the quantity but also the quality of protein in the diet is important for the body's proper functioning. Protein quality depends on the AA profile, among other factors. 20 total AA (TAA) have been identified as necessary for human growth and metabolism. Of the 20 TAAs, nine of them are defined as essential AA (EAAs, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine), and the remaining eleven are considered non-essential AA (NEAAs, alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine). In addition, branched-chain amino acids (BCAA, leucine, isoleucine, and valine) are found within the EAAs.

The NEAAs can be synthesized by the body, while the EAAs must be ingested from the diet. In this sense, proteins can be classified into two groups: high or low biological value, depending on the presence or absence of all the EAAs in their composition. Today, this distinction is usually called animal or vegetable proteins, respectively, because proteins from meat, eggs, and dairy products have higher amounts of EAAs, including leucine, while proteins from legumes, seeds, or nuts have a deficit in some of them.

In the diet, the consumption of a mixture of plant-based proteins (i.e., complementary proteins) is a common strategy to compensate for the fact that individual sources of plant-based proteins are often deficient in one or more EAAs. For example, the combination of rice protein (high in methionine but low in lysine) and pea protein (low in methionine but high in lysine) can produce a pea-rice protein blend with a balanced amino acid profile, free of deficiencies. Therefore, the formulation of a plant-based protein blend represents an opportunity to develop a high-quality protein option.

The present study has as its main objective to evaluate the postprandial bioavailability of EAA from two plant-based protein sources present in a complete powdered meal, where one will have soy protein and the other product with a protein source from a mixture of rice and pea protein.

The secondary objectives of the study are to compare the following kinetic parameters and the metabolic response of the two products with different plant-based protein sources.

• Bioavailability of AAT (AAT-AUC0-240min), AANE (AANE-AUC0-240min), BCAA (BCAA-AUC0-240min) and of each of the EAA individually (EAA-AUC0-240min).
• Time to reach maximum concentration of AAT (AAT-Tmax), AAE (AAE-Tmax), AANE (AANE-Tmax), BCAA (BCAA-Tmax) and of each EAA individually.
• Maximum concentration of AAT (AAT-CMax), AAE (AAE-CMax), AANE (AANE-CMax), BCAA (BCAA-CMax) and of each EAA individually.
• Insulinotropic response: insulin and blood glucose levels.
• Objective hunger and satiety modulation: blood levels of hunger and satiety regulating hormones: glucagon-like peptide-1 (GLP-1), peptide YY (PPY), ghrelin.
• Modulation of hunger and subjective satiety.
• Changes in the expression of genes involved in oxidative and inflammatory metabolism.

During the study there will be 3 visits: a preselection visit (V0), a visit for the first postprandial study (V1) and after one week washing period, a visit for the second postprandial study (V2).

Inclusion Criteria:

• Men and women between 18 and 50 years old.
• Be willing to limit intentional physical exercise during the 24 hours prior to each day of testing.
• Be willing to not consume alcoholic beverages 48 hours before the start of the study.
• Sign the informed consent.
• Be able to read, write and speak Spanish.

Exclusion Criteria:

• Present values of body mass index (BMI) ≤ 18kg/m^2 or ≥ 30 kg/m^2.

• Present allergy or intolerance to any of the ingredients of the products to be evaluated, mainly pea flour, rice flour, soy, flax, spirulina or olive oil.

• Follow a vegan or vegetarian diet.

• Use of medication that affects muscle anabolism or metabolism in general.

• Consume multivitamin supplements (Vit. D, Vit. E and Vit. C), minerals (Zinc, Selenium), essential fatty acids (omega-3), polyphenols, or any type of supplements that may affect oxidative or inflammatory metabolic pathways in the last 30 days before the start of the study.

• Consumption of alcoholic beverages:

  • Men: consume 4 or more Standard Drink Units (SDU) daily or 28 SDU weekly.
  • Women: Consume 2 or more Standard Drink Units (SDU) daily or 17 SDU weekly.

• Be an active smoker or have been one less than 6 months ago.

• Have a chronic disease with clinical manifestations: coronary disease, cardiovascular disease, diabetes, celiac disease, Crohn's disease, chronic kidney disease, active cancer, gastrointestinal diseases that may compromise the absorption of the compound.

• Take protein or amino acid supplements up to 1 week before the start of the study.

• Perform vigorous exercise for more than 3 hours a week.

• Have anemia.

• Have lost 3 kg or more in the last 3 months.

• Be pregnant or intend to become pregnant.

• Be breastfeeding.

• Not be able to follow the study guidelines.

• Be participating or have participated in a clinical trial or nutritional intervention study in the last 30 days prior to inclusion in the study.