What is a peptide?

An often-cited fact is that the majority of the human body is made up of water (about 60%). But it’s really the 40% solid component that makes us who we are. Similar to how a sandcastle is made up of sand and water, the human body is made up of water and solid components. The solid components not only build us up physically, but when dissolved, may participate in the complicated communication pathways required for functioning. These soluble solid components may contain amino acids, carbohydrates (sugars), lipids (fats), nucleic acids, minerals, and trace elements.

Amino acids are the components of interest when we talk about peptides. The human body uses 20 standard amino acids to build proteins, plus a rare 21st amino acid called selenocysteine. Amino acids link together like beads on a string to form peptides and proteins. What’s the difference? It mostly comes down to size. Peptides are relatively short chains of amino acids – typically around 50 or fewer amino acids in length. If the chain grows longer (more than ~50 amino acids), we usually start calling it a protein. (This is a general guideline, not a strict rule. For example, the hormone insulin has 51 amino acids but is still considered a peptide hormone).

Your body naturally produces thousands of different peptides that regulate countless physiological functions. Peptides act as messengers and signaling molecules, telling cells how to behave and coordinating processes throughout the body. To name a handful of these processes, peptides are responsible for controlling calcium homeostasis (e.g., calcitonin), managing blood sugar levels (e.g., insulin and glucagon), modulating pain sensation (substance P), and even having a role (when misfolded) in causing Alzheimer’s disease (β-amyloid).

Given their importance in biology, it’s no surprise that peptides have become a major focus in medicine. In fact, many breakthrough drugs are peptides or were derived from peptides. A well-known example is insulin, used since the 1920s to treat diabetes. Today, there are over 100 peptide-based medications approved for use, treating conditions from hormonal disorders to cancer and autoimmune diseases. Pharmaceutical companies and researchers are actively exploring hundreds of new peptides in clinical trials as potential therapies.

Looking to the future, peptides hold promise in some truly cutting-edge areas of health and wellness, including the treatment of chronic diseases, improving longevity and potentially reversing aging, improving mood and cognitive function, and even improving human aesthetics.