Proteins and amino acids are involved in a wide range of critical biological processes, including:

• Providing structural support to cells and tissues.  They make up a significant portion of our muscles, tendons, ligaments, skin, hair, and nails.

• Acting as enzymes, which facilitate biochemical reactions throughout the body.  Enzymes are responsible for numerous metabolic processes, including digestion and energy production.

• Being the basis for hormones, like insulin and growth hormones, which act as chemical messengers in the body's signaling pathways.  Hormones regulate various physiological processes, including growth, development, metabolism, reproduction, and blood sugar levels.

• Forming the immune system’s antibodies, which recognize and neutralize foreign substances (antigens) like bacteria, viruses, and toxins.  Antibodies play a crucial role in defending the body against infections and diseases.  Ironically, the immune system also plays a role in chronic inflammation, which is an attribute of many chronic diseases.

• Transporting vital molecules, such as oxygen (hemoglobin in red blood cells) and lipids (fats), throughout the body and storing important substances like iron and AAs for future use.  Note that AAs may be scavenged from skeletal muscle tissue in the case of chronic protein malnutrition.

• Being cell membrane receptors, which act like conduits for the transmission of signals from the external environment to the interior of the cell.  These signals regulate various cellular processes, including cell growth, differentiation, and apoptosis (programmed cell death).

As previewed above, amino acids (AAs) are the parts that make up proteins.  There are 20 standard AAs that can be combined in different sequences to form specific proteins.  Some AAs can be made by the body, but not all of them.  A special set of amino acids called indispensable (also called essential) cannot be produced by the body and can only be obtained through diet.  The indispensable amino acids (IAAs) for humans are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

A fundamental driver of our research is to increase the understanding of the importance of the widely known finding that the proteins, in the various foods that we eat, are not the same.  The differences are a consequence of the varying ratios of IAAs which make up the proteins in our food.  These differences directly affect the quality of protein, which can positively or negatively impact health and wellbeing.

Regarding the relationship between protein quality and IAA composition consider the following charm bracelet analogy.   A charm bracelet is a type of bracelet which carries one or more charms.  Each charm is a decorative pendant or trinket.  The types of charms that make up a charm bracelet establish the price and quality of the bracelet.  A charm bracelet that contains multiple pendants, each pendant comprised of platinum and diamond, for example, would universally be considered to have a much higher quality than a charm bracelet solely consisting of pendants containing lead and glass crystals.

A chain is only as strong as its weakest link

Per the charm bracelet analogy, protein is equivalent to a charm bracelet and an amino acid is equivalent to a charm.   So, it follows that different proteins (charm bracelets) consist of different combinations of amino acids (charms) and that the dietary protein quality of a specific type of food (e.g., vegetable, fish, meat, dairy, or other) is a function of the types and amounts of amino acids (charms) contained in the protein (charm bracelet).   And, since IAAs can only be obtained through eating, a food’s protein quality is a function of the IAA composition of the protein content in the food.

Again, referring to the charm bracelet analogy, each of the nine IAAs--histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine--are the must-have charms of a protein charm bracelet.  Foods containing the highest quality protein contain each of the IAAs (charms) in the optimal proportion needed for the creation, growth, and maintenance of every cell and tissue in our bodies.  In contrast, lower protein quality foods completely lack, or contain extremely low amounts of certain IAAs (charms).  Therefore, as different foods have different protein quality and protein quantity characteristics, care must be taken to properly construct one’s overall diet in the context of both.

A balanced and varied diet is crucial for obtaining an adequate supply of each IAA, ideally on a daily basis.  If you consume insufficient protein, your body will start to break down muscle tissue to get the protein it needs.  This can lead to muscle weakness, fatigue, and a loss of lean body mass.  Higher quality, protein-rich foods such as meat, fish, poultry, dairy, legumes, nuts, and seeds are good sources for IAAs.  Note that vegetarians and vegans may need to pay special attention when combining plant-based protein sources to ensure that they obtain the required IAAs, because plant based proteins may lack certain IAAs.  Future posts will explore the topics of protein quantity and protein quality in greater detail.

In summary, the protein and amino acids charm bracelet is essential for the creation, growth, and maintenance of every cell and tissue in our bodies.  IAAs are involved in numerous biological processes, including structural support, enzymatic reactions, hormone production, immune function, transport and storage of molecules, and cell signaling, which are all critical for our wellbeing.  Because protein quantity and protein quality are both important considerations, consuming a diverse diet that provides all of the IAAs in adequate proportions is essential for maintaining optimal health.

References:

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