en.wikipedia.org/wiki/Casein
3 corrections found
between 20% and 60% of the proteins in human milk
The upper end of this range is too high. Reviews describe human milk as generally containing about 20–40% casein, reaching about 50% in late lactation, not 60%.
Full reasoning
The claim says casein makes up "between 20% and 60%" of the proteins in human milk. That overstates the casein fraction.
Recent reviews and textbook-style summaries describe human milk as whey-dominant, with caseins typically accounting for about 20–40% of total proteins. Even when the whey:casein ratio shifts over lactation, cited sources describe it moving from about 90:10 in early lactation to 60:40 in mature milk and about 50:50 in late lactation. That means a casein share of roughly 10% to 50%, not up to 60%.
So the article's stated upper bound of 60% casein in human milk protein is inconsistent with these sources.
3 sources
- The composition and physico-chemical properties of human milk: A review
In general, human milk proteins can be classified into three groups: whey proteins, caseins, and MFGM proteins, accounting for 60–80%, 20–40%, and 1–4% of total proteins, respectively. The whey protein to casein ratio changes progressively during lactation, from 90:10 in early lactation, to 60:40 in mature milk and 50:50 in late lactation.
- Human Milk Proteins: Composition and Physiological Significance
HM is whey predominant; however, the whey/casein ratio of HM changes from 90/10 in colostrum to 60/40 in mature HM.
- Nutritional and physiologic significance of human milk proteins
The frequently cited ratio of 60:40 is an approximation of the ratio during the normal course of lactation, but it does vary from ≈80:20 in early lactation to 50:50 in late lactation.
Plant-produced beta-casein has been synthesized at least since 2026.
This date is wrong by decades. Beta-casein was already being expressed in transgenic plants in the 1990s and early 2000s, not first in 2026.
Full reasoning
The claim says plant-produced beta-casein has existed only "since 2026," but published research shows plant expression of beta-casein much earlier.
- A 1997 paper titled Expression of the human milk protein beta-casein in transgenic potato plants reported that "the above experiments demonstrate the expression of human milk beta-casein as part of an edible food plant."
- A 2001 paper titled Processing and localization of bovine beta-casein expressed in transgenic soybean seeds under control of a soybean lectin expression cassette likewise described bovine beta-casein expressed in transgenic soybean seeds.
So the article's date is incorrect: plant-produced beta-casein was reported at least by 1997, and again by 2001, long before 2026.
2 sources
- Expression of the human milk protein beta-casein in transgenic potato plants.
Published: 1997 Jul. The above experiments demonstrate the expression of human milk beta-casein as part of an edible food plant.
- Processing and localization of bovine beta-casein expressed in transgenic soybean seeds under control of a soybean lectin expression cassette.
Published: 2001 Jul. We have examined the processing and subcellular localization of a chimeric gene consisting of the bovine milk protein, beta-casein ... in the seeds of transgenic soybean plants.
There are also no disulfide bridges.
This absolute statement is incorrect. At least αs2-casein and κ-casein are known to contain disulfide bonds.
Full reasoning
The article is discussing casein as a family of proteins (αS1, αS2, β, κ), so saying there are "no disulfide bridges" is too absolute and is contradicted by the literature.
Evidence:
- A review/source on αs2-casein states that αs2-casein and κ-casein contain cysteine residues that normally exist as intermolecular disulfide bonds, and that αs2-casein usually exists as disulfide-linked dimers.
- A source on κ-casein states that bovine κ-casein occurs as monomeric and oligomeric forms linked by disulfide bonds, and that in monomeric κ-casein the two cysteines form an intramolecular disulfide bond.
- A PubMed paper specifically investigated the "localization of intrachain disulphide bridges in monomers of kappa- and alpha s2-casein from bovine milk," which directly contradicts the claim that there are no disulfide bridges.
Some individual caseins may lack disulfide bonds, but the blanket statement applied to casein generally is false.
3 sources
- alphaS2-casein - an overview | ScienceDirect Topics
αs2- and κ-caseins contain two cysteine residues, which normally exist as intermolecular disulphide bonds; αs2-casein usually exists as disulphide-linked dimers...
- Kappa-Casein - an overview | ScienceDirect Topics
κ-Casein purified from bovine milk occurs as both monomeric forms and oligomeric forms with up to eight or more monomers linked by disulfide bonds. In monomeric κ-casein, the two cysteines form an intramolecular disulfide bond.
- Disulphide arrangement in bovine caseins: localization of intrachain disulphide bridges in monomers of kappa- and alpha s2-casein from bovine milk.
Naturally occurring monomeric kappa-casein and alpha s2-casein in bovine milk were purified ... in order to localize potential intrachain disulphide bridges.