益生菌被认为对人类健康有着重要影响。然而，益生菌多半是通过食物、饮料或者其他携带益生菌的介质进入人体的。因此，如果希望通过益生菌来改善人类健康，那么这些食品或者饮品可能会有着很大功劳。最新的研究表明，益生菌进入人体的方式（食品或者饮品），会影响益生菌对人体健康的作用。
加州大学戴维斯分校的科学家们，通过为患肠炎小鼠提供益生菌（干酪乳杆菌BL23）的实验发现，通过奶制品一起携带益生菌进入小鼠的实验组，小鼠的症状有明显的减轻。干酪乳杆菌作为一种益生菌常常被加入到奶制品中，但是实验使用的干酪乳杆菌BL23菌株并不是商用的添加菌，但是和商用的菌株有很高的遗传相似性。
相比于没有益生菌摄入的小鼠，以及非食品摄入益生菌的小鼠，实验组（牛奶携带益生菌）表现出更好的恢复效果。而且，在益生菌摄入前后，小鼠小肠上皮上面的肠道菌群的整体种群结构和比例并没有受到很大影响。这就说明了，症状减轻确实是因为益生菌改变了肠道的代谢。分子生物学数据显示，通过牛奶摄入益生菌会导致小鼠的肠炎相关的细胞因子数量下降，这也证明了炎症的免疫反应下降。
这个发表在美国微生物学会期刊《Applied and Environmental Microbiology》的研究，证明了通过不同方式摄入益生菌（干酪乳杆菌）会对小鼠产生不同影响。通过奶制品携带益生菌摄入会导致肠炎小鼠症状减轻更明显，炎症也有减少。通过奶制品携带的益生菌，这种微生物和环境的相互作用使得其相对于其他摄入方式，对微生物而言可能会更加利于微生物的存活或者代谢。这个研究虽然是在小鼠完成的，但是对人类可能有类似的效果。因此，通过优化不同的食物基质类型，使得食物携带的益生菌的效果得到最大发挥，对人体健康有着重要意义。
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Attenuation of colitis by Lactobacillus casei BL23 is dependent on the dairy delivery matrix
The role of the food delivery matrix on probiotic performance in the intestine is not well understood. Because probiotics are often provided to consumers in dairy products, we investigated the contributions of milk to the health-benefiting performance of Lactobacillus casei BL23 in a dextran sulfate sodium (DSS) - induced murine model of ulcerative colitis. L. casei BL23 protected against the development of colitis when ingested in milk but not in a nutrient-free buffer simulating consumption as a nutritional supplement. Consuming (acidified) milk alone also provided some protection against weight loss and intestinal inflammation but was not as effective as L. casei and milk in combination. In contrast, L. casei mutants deficient in DltD (lipoteichoic acid D-alanine-transfer protein) or RecA (recombinase A) were unable to protect against DSS-induced colitis, even when consumed in the presence of milk. Mice fed either L. casei or milk contained reduced quantities of colonic pro-inflammatory cytokines, indicating that the L. casei DltD- and RecA- mutants as well as L. casei BL23 in nutrient-free buffer were effective at modulating immune responses. However, there was not a direct correlation between colitis and quantities of those cytokines at the time of sacrifice. Identification of the cecal microbiota by 16S rRNA gene sequencing showed that L. casei in milk enriched for Comamonadaceae andBifidobacteriaceae, however, neither the consumption of L. casei nor milk resulted in the restoration of the microbiota to resemble healthy animals. These findings strongly indicate that probiotic strain efficacy can be influenced by the food/supplement delivery matrix.