September 15, 2025
Medically Reviewed By Elizabeth A. Swick, MS, RDN

The Science Behind Peptide Absorption: Why Size Matters

Did you know that not all collagen supplements are created equal? When it comes to collagen powder, molecule size matters. Why? Because according to research, smaller peptides are better absorbed by the body.¹

This means hydrolyzed collagen, which is broken down into smaller peptides, is likely going to be absorbed better when taken orally than non-hydrolyzed collagen.

While both are useful, for most of us, using hydrolyzed collagen powder is going to offer more bang for your buck. Let’s break down why smaller peptides outperform larger ones, and why that makes a difference for your skin, joints, and overall health.

How Molecular Weight Affects Bioavailability

In science, bioavailability refers to how much of a nutrient or compound can be absorbed by the body and then is available for use. For peptides, bioavailability comes down to molecular weight.

Small peptides, which as you can guess, weigh less, are easier to pass through the digestive tract and into the bloodstream.

Larger peptides, which, you guessed it, weigh more, have a slightly harder time getting absorbed as quickly and efficiently as smaller ones.²

A 2024 study found that people taking low molecular weight collagen had improved bioavailability and enhanced absorption, noting this then helped improve muscle repair and reduced levels of inflammation.2

Small vs Large: Peptide Absorption

When you consume collagen powder, your body starts breaking it down into smaller fragments during the digestive process. The key is, if you start with smaller, low molecular weight peptides, that digestion and absorption can happen a lot faster and more fully.

Small peptides can:²

Cross the intestinal barrier intact
Reach target areas of the body (skin, muscle, joints) more quickly and efficiently
Help reduce inflammatory levels and provide overall support across the body almost immediately

In contrast, while larger peptides are still absorbed, the breakdown takes longer as they must be broken down even more, and this can lead to a slower and less efficient process.

Why Peptide Size Matters for Results

If you are taking collagen powder for many of the reasons most of us do, ie skin health, easing achy joints, strengthening bones, healing the gut or reducing inflammation, the better and quicker these peptides are digested, the faster your body can get to work using them.

For example:

^{Skin: Numerous studies have shown that collagen peptides can stimulate the production of new collagen and elastin while also improving skin hydration and firmness.3}
^{Joints: Hydrolyzed collagen powder has been shown to improve cartilage and reduce inflammation.4}
^{Gut lining: The health of the intestinal lining and overall digestion may be improved with the use of hydrolyzed collagen.5}
^{Bone health: Studies have shown that hydrolyzed collagen powder may help improve bone density.6}

For this reason, Body Kitchen offers a highly bioavailable, hydrolyzed collagen and elastin supplement that can provide comprehensive support in all of these areas.

Bioavailability of Different Peptide Types

With so many products on the market, choosing the best collagen powder can be confusing. From collagen powder blends to specific peptides such as the BPC 157 peptide now garnering more attention, the options are endless. Looking at the various types and their bioavailability can help make what to look for much easier.

Collagen peptides: These are often derived from marine or bovine sources. Typically hydrolyzed for enhanced absorption.
Multi-collagen peptides: These are blends of collagen peptides from various sources (marine, bovine, chicken, etc) to offer a wider spectrum of peptides and amino acids. Also usually offered hydrolyzed to maximize absorption.
Peptide powder blends: These can include a combo of collagen, elastin, keratin, or other functional peptides to target a number of health concerns. May or may not be hydrolyzed, so absorption may vary.
BPC-157 peptide: This is a very low-molecular weight synthetic peptide that has been studied for supporting tissue healing and gut health. While studies have shown numerous benefits, especially related to muscle healing, it should be noted this compound is not approved by the FDA and banned for use in elite athletes.⁷

Choosing a High-Absorption Collagen Supplement

If you want the best results from your collagen powder, here’s what to look for:

Low molecular weight: Choose products clearly labeled as hydrolyzed collagen peptides. This will ensure smaller peptide size and better absorption.
Multi-collagen peptides: A single collagen powder can provide good results, but why not make sure you get a wide range of functional peptides and amino acids? A blend of hydrolyzed collagens plus elastin and other supportive compounds can help improve absorption and results.
Powder form: While liquid options do exist, these are not typically the forms use in research studies. Use what studies have shown as effective.

A great example is Body Kitchen’s Collagen + Elastin powder, offering hydrolyzed collagen, functional peptides, and an easy-to-use powder form

Final Thoughts

When it comes to collagen peptides and effectiveness, the science suggests that size matters. Smaller peptides, whether from collagen peptide powders or multi-collagen peptide blends, offer better bioavailability. You get more of what you need and with greater results.

That’s exactly why Body Kitchen offers a hydrolyzed collagen + elastin blend that is easy to digest and highly bioavailable. By choosing a high-quality collagen supplement, you are giving your body powerful tools so you can look and feel better – fast.

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