KLOW vs GLOW: The Difference Between the Two Peptide Blends Explained

LynxLab · 24 October 2026 · 7 min read

GLOW is BPC-157, TB-500 and GHK-Cu in a 70mg vial; KLOW adds KPV to make 80mg. What the 10mg difference is and which research question suits each blend.

Photo: Jess Loiterton, Pexels

Anyone searching for skin-repair peptides in 2026 meets two names that look like typos of each other. GLOW is a three-peptide blend. KLOW is the same three with a fourth added, and the K at the front is the clue to what that fourth is. This post explains the two blends for a buyer who has seen both and wants to know what the difference means in practice.

The two blends side by side

GLOW contains BPC-157, TB-500 and GHK-Cu, co-lyophilised in a single 70mg vial. KLOW contains those same three plus KPV, co-lyophilised in a single 80mg vial.

The arithmetic is the first thing to settle. If KLOW is GLOW plus KPV, then the extra 10mg is the KPV fraction, and the three shared peptides account for the same 70mg in both vials. The four-peptide blend is therefore not a stronger version of the three-peptide one. It is the same thing with an additional, different compound.

Everything else about the two products is the same: freeze-dried cake, fixed ratio set at manufacture, one lab report per batch, and research-use-only status in the UK.

What the three shared components bring

The three peptides common to both blends are each studied against a later stage of tissue repair.

BPC-157 is a 15-residue fragment of a gastric protein. The Zagreb group's 2021 review in Frontiers in Pharmacology lists its skin models: incisional wounds, deep burns, diabetic ulcers and alkali burns, all in animals. Its proposed role is in angiogenesis and granulation.

TB-500 is the actin-binding fragment of thymosin beta-4. Malinda and colleagues (Journal of Investigative Dermatology, 1999) found the parent protein increased re-epithelialisation of rat wounds by 42% at day 4 and up to 61% at day 7, and stimulated keratinocyte migration two- to three-fold at 10 picograms. Its proposed role is cell migration.

GHK-Cu is a copper-binding tripeptide. Maquart and colleagues (FEBS Letters, 1988) showed it stimulated collagen synthesis in cultured fibroblasts from 10^-11 M. Its proposed role is matrix and collagen.

A buyer comparing the two blends should notice what is missing from that list. None of the three is primarily an inflammation peptide.

What KPV adds to KLOW

KPV is the three-amino-acid tail of alpha-melanocyte-stimulating hormone, residues 11 to 13. Its research is about inflammation. Dalmasso and colleagues (Gastroenterology, 2008) showed nanomolar KPV inhibited NF-kappaB and MAP kinase signalling in human epithelial and T cells, and reduced chemically induced colitis in mice.

That is the gap it fills. Textbook wound healing has four phases, and the three GLOW peptides are studied against the last two. KPV is the component aimed at the inflammatory phase, which is why a buyer whose model includes an inflammatory insult tends to buy klow rather than the three-peptide blend. The sibling post on what KPV adds to a repair blend goes through the colitis studies and the signalling in detail.

KPV has no published human trial for any indication. The FDA's category 2 list states it has found no human exposure data on KPV by any route. That is a smaller evidence base than any of the other three components, and a buyer should weigh it.

Which research questions suit each blend

The useful way to choose is to name the variable under study.

A collagen or fibroblast question, such as matrix deposition in a dermal model, is served by the three-peptide GLOW blend; adding KPV introduces a compound with no collagen literature.
A migration or angiogenesis question, such as endothelial tube formation or keratinocyte scratch assays, also fits GLOW; the three components already cover those readouts.
An inflammatory question, such as a burn, an irritant, a cytokine challenge or a bacterial exposure, is where KPV's NF-kappaB literature becomes relevant and the four-peptide blend earns its extra component.
A comparison question, where the aim is to test whether KPV changes the effect of the other three, needs both vials, since the shared 70mg is identical.

The last point matters for experimental design. Because the three shared peptides are present in the same amounts, running GLOW alongside KLOW isolates KPV as the single difference, which is as close to a controlled comparison as a blend format allows.

Has either blend been tested as a combination?

No. There is no published study of the three GLOW peptides together, and none of the four KLOW peptides together. Searching PubMed for either combination returns nothing.

The nearest evidence is a two-peptide rat study. Biçer and colleagues (Joint Diseases and Related Surgery, July 2026) compared BPC-157, TB-500 and the pair in Achilles tendon repair over four weeks. Both agents alone improved tendon histology, TB-500 alone improved load to failure, and the combination "did not confer additional benefits compared to either agent alone".

That is tendon rather than skin and one exploratory study, but it is a reminder that combining mechanisms on paper does not guarantee an additive result in tissue. A klow peptide vial is a tool for testing that question, not an answer to it.

Regulation, sport and the research-use label

Both blends sit in the same regulatory position, with one extra line for KLOW. In the United States, the FDA's category 2 list covers BPC-157, the thymosin beta-4 fragment LKKTETQ (TB-500), injectable GHK-Cu and KPV, so none can be compounded in US pharmacies. The FDA's compounding advisory committee voted narrowly on 23 July 2026 to recommend BPC-157, TB-500 and KPV for the 503A list; the agency has not acted on the vote.

In sport, the World Anti-Doping Agency's 2026 Prohibited List names "Thymosin-ß4 and its derivatives e.g. TB-500" under S2, and BPC-157 is treated as an S0 non-approved substance. Both blends therefore contain prohibited substances for any tested athlete.

In the UK, neither blend is a licensed medicine. A klow uk listing, like a GLOW one, is a laboratory reagent sold for research use only.

Buying either blend: what to check on the lab report

A blend certificate should separate the components. On an HPLC chromatogram, a GLOW vial should show three main peaks and a KLOW vial four, each identified by mass spectrometry and each with its own purity figure. A single purity number for a multi-peptide vial has not separated the components and says nothing about ratio.

LynxLab stocks KLOW for research use as an 80mg blend vial at £79.99 and GLOW as a 70mg blend vial at £59.99, with every component tested to 99% purity and the lab report on each product page. The batch lab reports are published, and the klow 80mg certificate should show KPV as the fourth peak.

Storage is the same for both. Sigma-Aldrich's peptide handling guidance recommends keeping lyophilised peptides at -20°C or colder, away from light and moisture, with solutions kept to about a week at 4°C and frozen in single-use aliquots rather than repeatedly thawed. A klow peptides follows the general peptide rules; the fourth component does not change them.

Frequently asked questions

What is the difference between KLOW and GLOW?

GLOW is BPC-157, TB-500 and GHK-Cu freeze-dried together in a 70mg vial. KLOW is the same three peptides plus KPV in an 80mg vial. The 10mg difference is the KPV, so KLOW is not a stronger GLOW but GLOW with an anti-inflammatory tripeptide added.

Is KLOW better than GLOW?

Neither has been tested as a combination, so "better" has no trial behind it. GLOW suits collagen, migration and angiogenesis questions; KLOW adds KPV for models with an inflammatory component. The right choice depends on the variable the research is designed to measure.

Why is KLOW 80mg and GLOW 70mg?

Because KLOW contains everything GLOW does plus 10mg of KPV. The three shared peptides account for the same 70mg in both vials, which is what makes the two blends useful as a paired comparison with KPV as the only difference.

Can I buy KLOW and GLOW in the UK?

Both are sold in the UK for laboratory research only. Neither is a licensed medicine, and in the United States all four components sit in the FDA's category 2 for compounding. Suppliers should publish a lab report that identifies each peptide separately by mass and purity.

Sources

Research use only

KLOW from LynxLab

80mg vials from £79.99. ≥99% purity, lab report on the page. Same-day dispatch, UK stock.

Buy KLOW