A composition and a method for improving the gastrointestinal (GI) health of a human subject by promoting the activity of amylolytic and short-chain fatty acid (SCFA) producing (e.g. acetogenic and/or butyrogenic) microbes in the GI system of a human subject. The composition includes a mixture of microbiota accessible carbohydrates (MACs) that includes at least two different resistant starches and at least two different non-starch polysaccharides. A blend for inclusion in a dietary supplement includes, or is, the mixture.一種藉由增進一人類主體胃腸系統(GI system)內分解澱粉以及產生短鏈脂肪酸(SCFA)(如產乙酸及/或產丁酸)的微生物之活性來改善人類主體胃腸健康的組成物及方法。該組成物包含一微生物相可利用碳水化合物(MACs)混合物，其包含至少二種不同的抗性澱粉及至少二種不同的非澱粉多糖類。一種可包含於膳食增補品內的調合物，其包含(或其係)該混合物。
