This study aimed to assess the effects of a yacon-based product (YBP) on constipation in adults, including the elderly. Forty-eight individuals were recruited and divided into equal intervention groups named the test and control groups. The YBP (test) and the control (maltodextrin) were dissolved in commercial orange juice. The volunteers for the YBP/test group consumed, on a daily basis, orange juice containing 10 g fructooligosaccharide (FOS)/inulin per day. The control group consumed, on a daily basis, orange juice containing 25 g of maltodextrin. The study had a span of 30 days. We evaluated the participants' frequency of evacuation, consistency of the feces, constipation score, abdominal symptoms (flatulence, pain, and abdominal strain), and effects upon the microbiota, pH, lactate, and short-chain fatty acids (SCFAs) of the feces. The study showed an increased number of evacuations after the consumption of the YBP as well as an improvement in the consistency of the feces and a reduction in the constipation score. After 30 days of intervention, the group that consumed the YBP showed higher counts of Bifidobacterium, lower Clostridium and enterobacteria counts, and lower fecal pH. In relation to SCFAs, no significant change was found after the intervention. However, the lactate concentration was higher in the test group when compared to the post-treatment control group. The YBP was effective in improving constipation symptoms; not only was its functional characteristic in reducing constipation symptoms evident but it also demonstrated usefulness as a potential therapy.