The activities of cells in the body are controlled by protein molecules, which are huge conglomerations of amino acids. The real activity of the protein molecule, though, is actually a very small section of the molecule - usually just a few amino acids linked together. These are peptides.
This analogy might make it easier to understand. Sometimes people carry large rings of keys. When they want to open a lack, they don't throw the ring of keys at the lock in hopes the lock will spring open. Instead, they very carefully select the one key that is right for the lock, insert and turn it to open the lock. Think of peptides as the key on the key ring - or the amino acid chain on the protein that accomplishes the desired task.
Peptides have been identified for a wide group of body activities. Some help muscles and joints to recover more quickly from over use. Some help with weight loss, others help with mental alertness. Some stimulate the immune system and some help you get a deeper tan. And that is just the start!
Peptides are pleotropic, meaning the effect is not limited to just one action.
Thymosin alpha-1: This peptide is key in what is referred to as cell mediated immunity, which involves specific types of immune cells that identify and destroy unwanted cells, such as viruses. It has been used to treat hepatitis B and C, Chronic Fatigue Syndrome and Lyme Disease.
Thymosin beta-4: This peptide functions to stimulate the T cells of the immune system, and has been used to treat illnesses such as influenza. In addition, this peptide has been found to have a role in tissue repair and regeneration, and is sometimes used to threat acute injuries.
BPC-157 (Body Protective Compound) is sometimes referred to as the "healing peptide." It has been found to promote both muscle and tendon healing, and is used to treat diabetic wounds. BPC-157 counteracts NSAID lesions in the GI tract and has been used to treat IBD.
Growth Hormone production decreases significantly after puberty. While some patients seek replacement growth hormone, peptides act by stimulating the brain to produce it.
Sermorelin: Stimulates production of GH to assist in wound healing and reduction of inflammation.
Ipamorelin: Stimulates production of GH but can cause a reduction in GH if overdosed, so is only used for 6 weeks at a time.
Ibutamoren: Stimulates GH production without affecting cortisol. Stimulates the appetite.
Melanotan II - This peptide is one that stimulates melanocytes to produce melanin and induce skin tanning. Some people use this to have a constant tan about two shades darker than normal.