Collagen Peptides

Collagen peptides are short chains of amino acids that come from the breakdown of collagen found in animal tissues such as bovine hide, fish skin, and poultry. They usually contain the same basic amino acids as whole collagen, including glycine, proline, and hydroxyproline, arranged in smaller fragments that are easier for the body to use.

Collagen peptides are often taken to support skin elasticity and hydration because they provide amino acids involved in building skin structure. They are also used to promote joint comfort and mobility by supplying components that help maintain connective tissue. Many people use them to support overall hair, nail, and tissue strength.

Collagen peptides have been shown in clinical studies to improve skin and joint health. A randomized controlled trial of 120 people taking a liquid supplement with hydrolyzed collagen reported a 40 percent increase in skin elasticity and a 43 percent reduction in joint pain after 90 days ¹. A meta-analysis of 26 trials found that oral collagen significantly improves skin hydration and elasticity, especially after at least eight weeks of use ².

Collagen peptides also benefit joint function and pain. In a study of 182 adults with knee or hip discomfort, daily intake of 5 g of specific collagen peptides for 12 weeks reduced pain at rest and during movement ³. Another trial in active young adults similarly found that collagen peptides significantly reduced exercise-related knee pain compared to placebo ⁴. Systematic review evidence suggests that collagen supplementation paired with exercise improves joint function, accelerates recovery, and supports collagen synthesis in connective tissues. In sum, collagen peptides may enhance skin quality while reducing joint pain and improving mobility.

Clinical studies have reported that collagen peptide supplementation can cause mild gastrointestinal issues. In a randomized trial of people with osteoarthritis, nausea was reported by about 19 percent of participants, along with symptoms like constipation, bloating, acid reflux, and mild stomachache. Some people also experienced skin-related effects such as itching, redness, acne, or dry skin, and a few reported headaches or tingling sensations ^{5, 6}. A meta-analysis of collagen peptide use for knee osteoarthritis noted that gastrointestinal discomfort was the most common adverse event, followed by migraine, respiratory infections, and, in rare cases, septic arthritis ⁷. Overall, though some users report mild digestive discomfort, skin irritation, or neurologic symptoms, most of the reported side effects are mild and transient.

Collagen peptides are broken down in the gut into small di‑ and tripeptides (such as Gly‑Pro‑Hyp and Pro‑Hyp), which are absorbed into the bloodstream. Once in circulation, Pro‑Hyp acts on dermal fibroblasts to stimulate proliferation and increase hyaluronic acid synthesis via activation of HAS2 transcription and STAT3 signaling. These peptides also promote collagen production by upregulating procollagen via the TGF‑β/Smad pathway, while simultaneously downregulating matrix metalloproteinases (MMP‑1, MMP‑3), which reduces collagen degradation ^{8, 9}.

In the United States, collagen peptides are regulated as dietary supplements under the Dietary Supplement Health and Education Act (DSHEA), meaning they do not require pre‑market FDA approval but must comply with safety, labeling, and manufacturing standards. They are also generally recognized as safe (GRAS) for use in foods. From an athletic perspective, collagen peptides are not prohibited by WADA and are considered safe for use in sports.