Table 1.

Summary of health effects of A1 and A2 β-casein consumption

Health Condition	Effects of A1 β-casein consumption	Effects of A2 β-casein consumption	References
Type 1 diabetes (T1D)	Associated with increased risk of T1D	–	Chia et al. (2018), Elliott et al. (1999), and Laugesen and Elliott (2003)
Cardiovascular diseases (CVD)	Associated with increased risk of CVD, atherosclerosis, and IHD	–	De Noni et al. (2009), Heinecke (1999), Laugesen and Elliott (2003), McLachlan (2001), Tailford et al. (2003), and Torreilles and Guerin (1995)
Gastrointestinal disease	Associated with chronic constipation, altered gastrointestinal transit, inflammation, and lactose intolerance symptoms	A2 milk is easier to digest and better absorbed than A1 milk Milk containing only A2 β-casein induces fewer symptoms of lactose intolerance than milk containing both A1 and A2 β-caseins	Andiran et al. (2003), Brooke-Taylor et al. (2017), Defilippi et al. (1995), Park and Haenlein (2021), Ramakrishnan et al. (2020), and Summer et al. (2020)
Autism and neurological disorders	BCM-7 is implicated in the pathogenesis of autism and other neurological disorders	–	Cade et al. (2000), Cieslinska et al. (2015), Dohan (1980), Jarmolowska et al. (2019), Kost et al. (2009), Lindstrom et al. (1984), Osman et al. (2021), and Sokolov et al. (2014)
Sudden infant death syndrome (SIDS)	BCM-7 may inhibit the respiratory center in infants leading to apnea and SIDS	–	Kost et al. (2009), Sun et al. (2003), and Wasilewska et al. (2011)
Allergy	BCM-7 may influence inflammation and allergies	–	Fiedorowicz et al. (2011), Fiedorowicz et al. (2014), Fiedorowicz et al. (2016), and Trivedi et al. (2015)
Glutathione production	Consumption of milk with both A1 and A2 β-casein led to a decrease in plasma glutathione concentration	Consumption of milk with only A2 β-casein led to an increase in plasma glutathione concentration	Deth et al. (2016), Sheng et al. (2019), and Trivedi et al. (2014)