Type 2-resistant starch and Lactiplantibacillus plantarum NCIMB 8826 result in additive and interactive effects in diet-induced obese mice.

Little is known about how combining a probiotic with prebiotic dietary fiber affects the ability of either biotic to improve health. We hypothesized that prebiotic, high-amylose maize type 2-resistant starch (RS) together with probiotic Lactiplantibacillus plantarum NCIMB8826 (LP) as a complementary synbiotic results in additive effects on the gut microbiota in diet-induced obese mice and other body sites. Diet-induced obese C57BL/6J male mice were fed a high-fat diet adjusted to contain RS (20% by weight), LP (10 cells every 48 hours), or both (RS+LP) for 6 weeks. As found for mice fed RS, cecal bacterial alpha diversity was significantly reduced in mice given RS+LP compared with those fed LP and high-fat controls. Similarly, both RS+LP and RS also conferred lower quantities of cecal butyrate and serum histidine and higher ileal TLR2 transcript levels and adipose tissue interleukin-6 protein. As found for mice fed LP, RS+LP-fed mice had higher colonic tissue TH17 cytokines, reduced epididymal fat immune and oxidative stress responses, reduced serum carnitine levels, and increased transcript quantities of hepatic carnitine palmitoyl transferase 1α. Notably, compared with RS and LP consumed separately, there were also synergistic increases in colonic glucose and hepatic amino acids as well antagonistic effects of LP on RS-mediated increases in serum adiponectin and urinary toxin levels. Our findings show that it is not possible to fully predict outcomes of synbiotic applications based on findings of the probiotic or the prebiotic tested separately; therefore, studies should be conducted to test new synbiotic formulations.