Consumption of A1 β-casein milk has been linked to increased gut inflammation, worsened digestive and cognitive symptoms, and delayed transit, suggesting that some lactose intolerance symptoms may actually result from A1-induced inflammation and can be avoided by switching to A2-only milk.
Calmer stomachs with A2‑only milk
Preschoolers who drank milk that contained only A2 β‑casein had milder digestive symptoms on visual‑analog scales, needed fewer trips to the bathroom, and had more “normal” stool consistency than when they drank regular milk that contains both A1 and A2 proteins.
Lower inflammation and oxidative stress
After regular milk, children showed higher blood levels of the inflammatory messenger interleukin‑4, several immunoglobulins (IgG, IgE, IgG1), and the peptide beta‑casomorphin‑7 (BCM‑7), along with lower glutathione (an antioxidant). These changes were far smaller, or absent, after consumption of A2‑only milk.
Sharper thinking on quick‑response tests
On the Subtle Cognitive Impairment Test (SCIT), accuracy improved after A2‑only milk, whereas children who drank regular milk posted slower reaction times and more errors.
