Functional bowel disorders (FBDs) affect around 20% of the population worldwide and are associated with reduced quality of life and high healthcare costs. Dietary therapies are frequently implemented to assist with symptom relief in these individuals, however, there are concerns regarding their complexity, restrictiveness, nutritional adequacy, and effectiveness. Thus, to overcome these limitations, a novel approach, the 5Ad Dietary Protocol, was designed and tested for its efficacy in reducing the severity of a range of gastrointestinal symptoms in 22 subjects with FBDs. The protocol was evaluated in a repeated measures MANOVA design (baseline week and intervention week). Measures of stool consistency and frequency were subtyped based on the subject baseline status. Significant improvements were seen in all abdominal symptom measures (p < 0.01). The effect was independent of body mass index (BMI), age, gender, physical activity level, and whether or not the subjects were formally diagnosed with irritable bowel syndrome (IBS) prior to participation. Stool consistency and frequency also improved in the respective contrasting subtypes. The 5Ad Dietary Protocol proved to be a promising universal approach for varying forms and severities of FBDs. The present study paves the way for future research encompassing a longer study duration and the exploration of underlying physiological mechanisms.