Do oral marine peptides work?
Last reviewed November 9, 2026.
Disclosure. This site is run by an employee of Pürblack, a peptide supplement brand, in a personal capacity. Pürblack does not fund, review or direct the site, and its costs are paid by its operator. This page covers a product category that Pürblack sells, so read it with that in mind; the studies are linked so you can check them yourself.
Short answer
Partly. Fish-derived collagen peptides have randomised trials for skin, and a few small human studies exist for blood pressure, sleep, memory and recovery. Most are small, several report funding ties to a company with an interest in the product, and some found no benefit over placebo. For joints and tendons, immune function and vision, we found no human trials.
What the studies show, system by system
“Marine peptides” here means peptides swallowed in a supplement that come from fish or other marine sources: marine (fish-derived) collagen peptides, fish protein hydrolysate, and defined peptides such as the sardine peptide valyl-tyrosine. We counted ten human studies.
Skin and hair
Limited human evidence
Two randomised trials of fish-derived collagen peptides report better wrinkle, elasticity, cellulite and hair results. One gives no sample size or dose, and several of its results are changes from baseline or self-rated.
Studies: Evans et al., 2021; Hwang et al., 2026 · Full evidence page
Blood pressure and blood vessels
Limited human evidence
A 29-person trial of one sardine peptide and a 100-patient trial of marine collagen peptides added to usual care found lower blood pressure. A single dose of fish hydrolysate did not improve blood-vessel dilation. All are small.
Studies: Kawasaki et al., 2000; Zhu et al., 2010; Oliveira et al., 2020 · Full evidence page
Sleep, memory and stress
Limited human evidence
The sleep trial found no difference from placebo. The memory trial was positive but the product also contained omega-3s. The anxiety study had no control group. All three report ties to a company with an interest in the product.
Studies: Eckert et al., 2024; Chataigner et al., 2026; Oddoux et al., 2022 · Full evidence page
Muscle and recovery
Limited human evidence
Fish hydrolysate raised blood amino acids like whey does, but it did not improve recovery between two cycling sessions. Neither study measured muscle growth over weeks of training.
Studies: Mjøs et al., 2019; Cordeiro et al., 2020 · Full evidence page
Joints and tendons
No human trials found
Laboratory and biomaterial work on fish collagen and cartilage exists. We found no controlled human trial of swallowing marine collagen peptides for joint or tendon problems.
Immune function
No human trials found
We found no controlled human trial of oral marine peptides on immune outcomes.
Vision and eye health
No human trials found
We found no controlled human trial of oral marine peptides on eye or vision outcomes.
What this evidence does not show
- Most studies are small. Several enrolled 9 to 53 people, and some abstracts give no sample size or dose.
- Products differ. A sardine dipeptide, a collagen peptide and a general fish hydrolysate are different substances, so one result does not carry over to another. Some tested products also contained omega-3 fatty acids, magnesium or vitamins.
- Funding. Four of the ten studies report funding or authorship ties to a company with a commercial interest in the product tested. For the others, the PubMed record states none, which is not the same as none.
- Negative results. One sleep trial found no difference from placebo and one recovery trial found no benefit, though the sleep authors still described the supplement as helpful.
- The mechanism is not the proof. Showing a peptide can block an enzyme or raise a blood marker is not the same as showing it helps people.
How we searched
On November 9, 2026 we searched PubMed for human trials and meta-analyses using terms for marine and fish collagen, fish protein hydrolysate, marine peptides and sardine or bonito peptides, combined with skin, blood pressure, joints, muscle, sleep, memory, stress, immune and eye outcomes. We read each abstract and kept human studies of products taken by mouth. We did not search other databases or trial registries, so a “no human trials found” verdict means we did not find one, not that none exists. Read the methodology for how studies are summarised.
Related
Educational information only. It is not medical or legal advice, and nothing here is a recommendation to use any peptide. Talk to a clinician before starting a supplement or treatment.