Milk free of A1 β-casein supports superior gains in cognition and quality of life, relative to conventional milk, in older adults with mild cognitive impairment.

OBJECTIVES

To determine whether the regular consumption of milk free from A1 β-casein (A1PF milk) improves cognitive performance to a greater extent than conventional milk, and if so, whether such improvements are associated with an increase in the serum titres of reduced glutathione (GSH).

DESIGN

A multi-centre, double-blind, randomised controlled trial with two parallel arms, conducted from 7 March 2023 to 13 October 2023.

SETTING

Two hospitals in Tianjin, China.

PARTICIPANTS

Volunteers (N = 96) diagnosed with mild cognitive impairment (MCI) and aged between 65 and 75 years.

INTERVENTION: A1PF skim milk powder or conventional skim milk powder, diluted into liquid form (200 mL) and consumed twice daily for 90 days.

MEASUREMENTS: The primary outcomes were cognitive performance (assessed with the Subtle Cognitive Impairment Test [SCIT]) and serum titres of GSH. Secondary outcomes included performance on two other cognitive tests, serum levels of 25-hydroxyvitamin D3, subjective quality of life (QoL), muscle strength (hand grip scale), faecal and blood inflammatory markers.

RESULTS

Data from 91 participants were analysed (A1PF milk group: n = 45; conventional milk group: n = 46). A1PF milk improved performance on all three cognitive tests to a greater extent than conventional milk; however, this improvement was not associated with an increase in serum GSH. When compared with conventional milk, A1PF milk resulted in higher increases in serum levels of 25-hydroxyvitamin D3, greater subjective improvements in QoL and improved left hand grip strength. There were no between-group differences in inflammatory markers, calcium absorption or bone density markers.

CONCLUSION

Daily intake of A1PF milk for 90 days significantly improved cognition, QoL and muscle strength in a sample of older people with MCI. While these outcomes appear to be linked to increased serum titres of 25-hydroxyvitamin D3, further investigations are needed to confirm this association.

CLINICAL TRIAL REGISTRATION: NCT05741047 (clinicaltrials.gov).