Table 2.

Use of A2 milk in experimental animal trials to treat or prevent different health issues.

Animal Model	Dosage and Time of Exposure	Health Function	Main Findings	Reference
48 Wistar rats	36–48 h milk-based diets in which the β-casein component was either the A1 or A2 type	Gastrointestinal function	-A1 β-casein in rats relative to the consumption of A2 β-casein caused a delay in gastrointestinal transit. -Increased colonic myeloperoxidase dipeptidyl peptidase-4 activities.	[61]
24 male Swiss mice	Basal diet and β-casein variants (A1A1, A2A2, and A1A2) at a dose of 85 mg/animal/day suspended in 200 μL phosphate-buffered saline for 30 days	Gastrointestinal inflammation	-Consumption of A1-like variants (A1A1 and A1A2) significantly increased the levels of myeloperoxidase, inflammatory cytokines, immunoglobulin and leukocyte infiltration in intestine. -Expression for toll-like receptors (TLR-2 and TLR-4) was also upregulated on administration of A1-like variants.	[62]
24 aging Balb-c mice (20 months old)	4 weeks, with either a control diet, a diet supplemented with bovine milk containing A1/A2 β-casein (A1A2), or a diet containing A2/A2 β-casein (A2A2)	Gut morphology and histopathological alterations, gut microbiota	-Consumption of A2 milk significantly changed gut microbiota and increased content of short-chain fatty acids in gut. -Consumption of A2 milk increased content of intestinal lymphocytes in the intraepithelial compartment and improved villi tropism with respect to A1 milk.	[63]
3 different animals colonies (NOD/Ba mice, NOD/NZ mice, and BB rats)	250 days for mice and 150 for rats in which casein components were made from either β-casein A1/A1 or A2/A2 phenotype	Type 1 diabetes	-A1 or A2 β-casein diets were protected from developing diabetes. It is unlikely that diabetes could be prevented solely by removing or altering the cow’s milk component of the diet.	[64]
36 male Wistar rats	Rats were fed with respective A1 and A2 casein hydrolysate diets for 50 days. On 51st day, each group was divided into 2 subgroups (n = 6) and diabetes was induced in one subgroup of each group using Streptozotocin	Type 1 diabetes	-The results suggest that A1 and A2 casein hydrolysates did not have any marked effect on various health parameters.	[65]
NOD/shiLtJArc mice	Diet supplemented with A1 or A2 β-casein ad libitum during 30 weeks	Type 1 diabetes	-Dietary A1 β-casein may affect glucose homeostasis and type 1 diabetes progression.	[66]
60 rabbits	Oral diets at concentrationsof either A1- or A2 β-casein at 10%, 3.5%, or 20% concentrations for 6 weeks	Cardiovascular health	-Different cardiovascular health markers such as cholesterol, tryglicerides, LDL fatty streak lesions in the aortic arch were significantly higher in rabbits fed with A1 than for A2 β-casein.	[67]
24 male Swiss albino mice	The experimental groups were fed with basal diet and β-casein variants (A1A1, A2A2, and A1A2) at a dose of 85 mg/animal/day suspended in 200 μL phosphate-buffered saline (PBS)	Inflammatory response	-A1-like variants of β-casein induced an inflammatory response in gut by activating Th2 pathway as compared to A2 variants.	[62]
male BALB/c mice	Mice received water purified by reverse osmosis, A1A1, A1A2, and A2A2 β-casein variants of milk, respectively, at a dose rate of 10 mL/kg body weight, 5 days/week by oral gavage	Pulmonary inflammation	-Mice fed with A1 milk exhibited increased airway hyperresponsiveness with increasing concentration of bronchoconstrictor (methacholine), and inmunoglogulins, which was not observed in mice fed with A2 milk.	[68]