Effect of Food Matrix and Administration Timing on the Survival of Lactobacillus rhamnosus GG During In Vitro Gastrointestinal Digestion

Probiotics' potential to enhance gut health is often limited by their poor survival during gastrointestinal (GI) transit, a challenge influenced by the composition and timing of co-ingested foods. Addressing the lack of dietary guidelines for optimal probiotic administration, this in vitro study examines how consuming <i>Lactobacillus rhamnosus</i> GG (LGG) with different foods at varying timings affects bacterial survival during simulated digestion. The results showed that simultaneous intake with durum wheat pasta or soy milk improved bacterial viability compared to standalone probiotics. The pasta outperformed the soy milk, yielding higher viable counts (5.92-6.38 vs. 4.93-5.39 log CFU/g) due to greater buffering capacity. Timing of administration also played a critical role: consuming probiotics with (5.39-5.92 log CFU/g) or after a meal (5.19-6.38 log CFU/g) enhanced viability compared to an empty-stomach scenario (4.93-6.04 log CFU/g). Additionally, LGG co-ingestion facilitated starch and protein digestion, increasing the pasta starch digestibility from 84.80% to 89.00% and the soy milk protein digestibility from 78.00% to 80.00%, suggesting synergistic bacteria-food interactions between the probiotic and food matrix. These findings emphasize the importance of food matrix selection and administration timing in optimizing probiotic efficacy. The study provides practical insights for healthcare professionals and consumers, advocating for meal-aligned probiotic intake with buffering-rich foods like pasta to maximize viability.