§ Claim under review · Mixed
"L'Oréal's 'Keratin Alpha Sleek' serum (Serie Expert) contains no actual keratin; the name refers to the hair structure it targets, not a keratin ingredient, and the 5% figure refers to a 'Keratin-Alpha Sealer' rather than keratin protein content." (Post caption: "Keratin in the name. Zero keratin in the formula.")
Verdict
Mostly accurate
Confidence
MediumSummary
This post is mostly accurate. L'Oréal's own published ingredient list for the Keratin Alpha Sleek Mirror Sleek Serum has seven items, and keratin is not one of them. The first three are silicones and the rest are fragrance and fragrance allergen components. L'Oréal states in its own product material that the serum does not contain keratin, and describes the product as sealing the hair's own keratin structure, which is what the "keratin alpha" in the name refers to. The advertised "5%" is the brand's figure for a complex it calls a Keratin Sealer, not a measure of keratin protein, and the amount of each silicone is not disclosed. The post slightly misnames that complex, calling it a "Keratin-Alpha Sealer", which does not change its point. What remains unclear is what the 5% complex is made of, and whether the "up to 10 washes" figure was measured using the serum on its own or the full product routine, since the brand's testing footnotes refer to a multi-product routine and that testing has not been published or independently repeated.
The readings
key figures from the evidencebranded Keratin Sealer complex in the serum
routine applications behind the 10-washes durability test
Why this verdict
Evidence
The manufacturer's own ingredient list for this serum has seven entries: DIMETHICONE, BIS-(MORPHOLINOMETHYL C1-4 DIALKOXYSILOXY) DIMETHICONE, BIS-CETEARYL AMODIMETHICONE, PARFUM / FRAGRANCE, LINALOOL, CITRONELLOL, GERANIOL . No keratin, hydrolyzed keratin or keratin amino acid appears on it. The first three entries are all silicone materials, and the last three are declared fragrance allergen components.
The brand states the marketing figure as a complex, not a protein level: "Formulated with 5% Keratin Sealer, this serum seals the hair structure for smoothness, frizz, and volume control that lasts up to 10 washes." The brand's own range copy carries the explicit statement that keratin is an animal-derived ingredient also found in human hair , and retailer pages reproducing L'Oréal's copy for this serum carry the sentence "Keratin is an animal-derived ingredient, also found in human hair. This product does not contain Keratin." alongside the same INCI list. A second retailer carrying L'Oréal copy reproduces "This product does not contain keratin. *Instrumental tests. Instrumental test with a routine of 4 applications of Shampoo + Smooth Transformer + Mirror Sleek Serum."
On what the name points at, the brand describes the action as being on the hair's own keratin: the serum "seals hair outer keratin structure for up to 10 washes" , and range copy for the companion product describes smoothing at the keratin alpha level, described as the deepest level of hair . In the scientific literature, alpha-keratin is described as an alpha-helical fibrous protein found in mammals, birds and reptiles, and the primary component of hair, horn, nail and the epidermal layer of skin . So "keratin alpha" is a real structural term for hair protein, consistent with the brand's stated framing.
On the durability figure, the brand attaches an instrumental-test footnote: "Instrumental tests *Instrumental test after 4 applications of Keratin Alpha Sleek Shampoo + Smooth Transformer + Serum." Several headline performance figures are therefore measured on the full routine rather than the serum alone.
On rules, the EU instrument governing cosmetic claims applies to names as well as text: Regulation (EU) No 655/2013 applies to claims in the form of texts, names, trademarks, pictures and other signs that convey product characteristics or functions, in labelling, marketing and advertising , and the Commission's guidance addresses the situation where a product claims to contain a specific ingredient . No regulator finding about this specific product was located, and the post does not allege illegality.
Findings
✓ What's accurate 7
- The manufacturer's published ingredient list for this serum contains no keratin and no keratin derivative. The seven listed ingredients are three silicone materials, fragrance, and three fragrance allergen components.
- L'Oréal itself states that this product does not contain keratin. The statement appears in the brand's own range material and in retailer pages reproducing brand copy, so the post's "L'Oréal confirms" is supported.
- The "5%" figure in the brand's copy is attached to a complex the brand calls a Keratin Sealer. It is not presented by the brand as 5% keratin protein, and since the product contains no keratin, it cannot be a keratin content figure.
- The name points at the hair's own structure in the brand's own framing: the brand describes the serum as sealing the hair's outer keratin structure, and alpha-keratin is the recognised term for the helical protein that makes up hair.
- Three silicones lead the ingredient list, which is consistent with a smoothing and conditioning function. Dimethicone is used as a hair-coating emollient and amodimethicone-type silicones are used as conditioning agents.
- The percentage of each individual silicone is not disclosed on the label. Only the 5% figure for the branded complex is given.
- The "up to 10 washes" figure is the brand's own and carries an instrumental-test footnote, as the post says.
≈ What's misleading 2
- The post reports the figure as "5% Keratin-Alpha Sealer". The brand's wording for this serum is "5% Keratin Sealer"; "Keratin-Alpha Shaper" is the term used for other products in the range. This is a small naming slip that does not change the substance of the point.
- Nothing else in the post's checkable core overstates the sources. The caption "Zero keratin in the formula" matches the manufacturer's own statement rather than exceeding it.
? What's uncertain 5
- What the "Keratin Sealer" complex actually consists of is not disclosed by the manufacturer. It is plausibly one or more of the listed silicone materials, but no source located states its composition, so the post's reading of the 5% as a non-keratin complex is correct while the complex itself remains unspecified.
- Whether the "up to 10 washes" figure was measured on the serum alone or on the full routine is not consistently stated. Some brand footnotes specify four applications of shampoo plus Smooth Transformer plus serum, which is a routine-level condition rather than a serum-alone one.
- No independent, peer-reviewed or regulator testing of this product's performance claims was located. The durability and smoothness figures rest on manufacturer instrumental testing that has not been published in full.
- Whether formulations are identical in every market was not established. The US and international brand listings carry the same seven-ingredient list, but market-specific variants were not exhaustively checked.
- Whether a product name containing "Keratin" for a keratin-free product satisfies the EU common criteria for claims has not been tested by any regulator decision located for this product. The post makes no legality allegation, so this does not bear on the verdict.
Sources
3 of 5 linked to recordsL'Oréal Professionnel US official product page, full INCI list for Keratin Alpha Sleek Mirror Sleek Serum
L'Oréal Professionnel international product and range pages, "5% Keratin Sealer", claim footnotes, and the keratin statement
Retailer reproductions of the brand's official copy carrying the full disclosure sentence and INCI
Commission Regulation (EU) No 655/2013 and its Commission guidelines, common criteria for cosmetic claims
US patent literature describing alpha-keratin as the helical structural protein of hair