Prolonged Consumption of A2 ß-Casein Milk Reduces Symptoms Compared to A1 and A2 ß-Casein Milk in Lactose Maldigesters: A Two-Week Adaptation Study.

Approximately 30% of milk protein is ß-casein. We aimed to determine whether lactose maldigesters who chronically consumed two cups of A1/A2 milk (containing 75% A1 ß-casein and 25% A2 ß-casein) would adapt to have fewer intolerance symptoms, lower serum inflammatory markers, and/or altered glutathione levels similar to those consuming A2 milk (containing 100% A2 ß-casein). A double-blinded, randomized, crossover trial was conducted. Sixteen confirmed lactose maldigesters consumed 250 mL of A1/A2 milk and A2 milk twice daily with meals for two weeks. At the end of the adaptation period on day 15, lactose maldigestion was measured after a challenge with the same milk used for adaptation (0.5 g of lactose per kg of body weight) with a hydrogen breath test. Fecal urgency was higher during the two-week consumption of A1/A2 milk compared to A2 milk (p = 0.04, n = 16). Bloating (p = 0.03, n = 16) and flatulence (p = 0.02, n = 16) were also higher on the 15th day with A1/A2 milk compared to A2 milk challenge. However, day-to-day symptoms, hydrogen, serum inflammatory markers, and antioxidant concentrations were not different after A1/A2 and A2 milk consumption adaptation periods. Adaptation over two weeks did not improve lactose digestion or tolerance of A1/A2 milk to match that of A2 milk.

A Narrative Review of Human Clinical Trials to Improve Lactose Digestion and Tolerance by Feeding Bifidobacteria or Galacto-Oligosacharides.

Supplementation with the probiotic Bifidobacterium and prebiotic galacto-oligosaccharides (GOS) could improve gut health and benefit lactose intolerant individuals. A narrative review was conducted to identify human clinical trials that evaluated lactose digestion and/or tolerance in response to consumption of Bifidobacterium, GOS, or both. A total of 152 studies on Bifidobacterium and GOS or both were published between 1983 and 2022. Out of the 152 studies, 20 were human clinical trials conducted in lactose intolerant subjects; 8 studies were conducted with Bifidobacterium supplementation and 3 studies involved GOS supplementation. Five studies reported favorable outcomes of Bifidobacterium supplementation in managing lactose intolerance (LI). Similarly, three studies reported favorable outcomes with GOS supplementation. The other three studies reported neutral outcomes. In conclusion, most studies reported a favorable effect of Bifidobacterium and GOS on managing the symptoms of LI. No study has examined the effects of combined supplementation with Bifidobacterium and GOS in lactose intolerant subjects. Future research could examine if co-supplementation with Bifidobacterium and GOS is a more effective strategy to reduce the dairy discomfort in LI individuals.