(P03-036-24) Lactose Maldigesters Do Not Adapt to a Two-Week Daily Consumption of Milk With A1/A2 β-Casein As Determined by Continued Bloating and Flatulence

Objectives: Beta-casein is a major protein in cow’s milk. The A1 and A2 β-casein variants differentially impact dairy tolerance. Milk containing A1 β-casein releases higher amounts of an opioid peptide, beta-casomorphin-7 (BCM-7) upon digestion, compared to milk containing only A2 β-casein and causes greater symptoms of intolerance.

We examined whether lactose maldigesters consuming milk containing both A1 and A2 β-casein for two weeks, would adapt to experience fewer intolerance symptoms, altered serum inflammatory markers, and/or altered glutathione levels compared to milk containing only A2 β-casein.

Methods: We conducted a double-blind, randomized, crossover trial, with a 6-day washout period between two interventions of 14 days each. We recruited 16 lactose maldigesters of diverse races and both genders. Subjects consumed 250 ml of either A1/A2 milk or the control, A2-only milk, twice daily with meals for 14 days. The participants recorded their dietary intake and daily symptom scores during the 14 days. On day 15, hydrogen levels in breath were measured for 6 hours following a challenge with the same milk consumed during the 14 days (containing a lactose dose of 0.5 g/kg body weight). Blood samples were collected to assess inflammatory markers and glutathione levels.

Results: Individuals consuming A1/A2 milk reported increased fecal urgency (p=0.04) during the 14-day intervention compared to consuming control A2 milk. On day 15, individuals challenged with A1/A2 milk reported increased bloating (p = 0.03) and flatulence (p = 0.02) compared to those challenged with A2 milk. There was no significant difference in the hydrogen, serum inflammatory markers and glutathione levels between treatments. Daily symptom scores seem to have persisted during the intervention in individuals consuming A1/A2 milk and are under further analysis.

Conclusions: Milk containing A1/A2 β-casein increased acute fecal urgency during milk consumption. Chronic consumption of A1/A2 milk increased bloating and flatulence following a milk challenge as compared to A2 milk in individuals with lactose maldigestion regardless of a 14-day adaptation period.

Funding Sources: Gift funds from A2 milk company