Rice proteins

Intense and prolonged physical exercise has temporary, but significant effects on the immune system: it favors infections in the upper respiratory tract brought on due to exposure to unfavorable weather conditions, breathing through the mouth (thereby bypassing the nose’s natural filtering function), stress due to competitive situations, etc. (Gleeson, 2007; Nieman, 1994).

Glutamine is a nutrient that has a direct effect on the immune response by increasing the proliferation of lymphocytes. Glutamine is stored in muscle and released during physical effort or stress. This amino acid decreases during prolonged intense physical effort because immune cells use it as an energy source. The availability of this amino acid in the blood is therefore essential.

Many studies have shown that food supplementation with glutamic acid induces increases the amount of glutamine in the blood, leading to a decrease in respiratory tract infections via its effect on the immune system (Bassit et al., 2000).

Nitric oxide is the main vasodilator produced in the vascular endothelium. It has vasomoteur properties. It is synthesized from L-arginine via a reaction with nitric oxide synthase (eNOS).

Arginine deficiency causes NOS to preferentially form superoxide anions, which are reactive oxygen species (ROS). ROSs are instable molecules that can react immediately with cellular components, such as DNA, lipids, carbohydrates, etc. A deficit in arginine thus favors oxidative stress.

An increase in the production of nitric oxide can improve some body functions such as vasodilation (blood flow). Thus, arginine supplementation is recommended (Clarkson et al., 1996). “In healthy, ill or at-risk individuals, a massive dose of arginine increases the production of nitric oxide and improves functions such as artery dilation, resistance, etc.” (Preli et al., 1999).

Arginine is beneficial for athletes, because it promotes the synthesis of nitric oxide, a powerful vasodilator.

L-arginine can improve wound healing through its action on collagen synthesis.

The urea cycle is the only metabolic pathway that can eliminate excess nitrogen from the body. The urea cycle takes place primarily in the liver and converts ammonia (from exogenous and endogenous proteins) into urea; its reactions occur in the cytosol and mitochondria of liver cells. (Deignan, 2007).

After a protein-rich meal or following protein degradation, it is necessary to eliminate the excess ammonium. Glutamine facilitates the transfer of ammoniac in a neutral state from various organs to the liver. Ammonium (NH4+) is transformed into carbamoyl phosphate in a reaction with carbamoyl phosphate synthetase (CPS-I). To function, CPS-I must be activated by N-acetylglutamate synthase, which is activated by arginine. “Thus, following an increase in the cellular content of N-acetylglutamate, CPS-I activity increases, allowing an increase in the efficiency of the conversion of ammonium into urea”, reports AFSSA in its 2007 report on “Protein supplementation: consumption, quality, needs and recommendations”.

In the cytosol of enterocytes, arginine is converted into ornithine and urea via arginase. It is thus important to consume sufficient amount of arginine and glutamine, because these non-essential amino acids play a major role in the urea cycle.

Rice proteins and rice protein hydrolysates have many properties:

• Solubility: peptides are particularly soluble in acidic conditions (fruit juice). They play an essential role in the protein enrichment of non-alcoholic beverages or juice-based beverages.
• Heat stability: enzymatic hydrolysis leads to a peptide solution that is highly stable at high temperatures (no precipitation).
• Organoleptic properties: they may retain some bitterness.

Several health claims can be used for proteins:

• “Protein contributes to the increase in muscle mass”
• “Protein contributes to the maintenance of muscle mass”
• “Protein contributes to the maintenance of normal bones”

Regulation No. 432/2012 on health claims stipulates that “The claim may be used only for food which is at least a source of protein as referred to in the claim SOURCE OF PROTEINS as listed in the Annex to Regulation (EC) No. 1924/2006”.

A food is called

• “High in protein” if at least 20% of the energy value of the food is provided by protein.