The 5Ad Diet for Functional Bowel Disorders

The 5Ad Diet for Functional Bowel Disorders: A Randomised Controlled Trial Against the Low FODMAP Diet

The goal of this randomised controlled trial (RCT) is to compare the efficacy of the newly developed 5Ad diet against the widely researched low fermentable oligo-, di-, monosaccharide and polyols (FODMAP) diet in reducing gastrointestinal symptoms associated with functional bowel disorders/food intolerances.

The primary aims of this RCT are to determine:

• Whether the 5Ad diet is at least as effective as the low FODMAP diet in reducing gastrointestinal symptoms associated with FBDs/food intolerances.
• Whether either the 5Ad diet or the low FODMAP diet are effective in reducing mental and physical fatigue.

To achieve the above aims, an RCT will be conducted with the 5Ad diet in one arm vs the active phase of the low FODMAP diet in the other arm, in a cross-over design with a 7 days washout phase in between. Both dietary protocols will be followed by each participant for 7 days.

Researchers will compare the results from the 2 dietary protocols in order to ascertain the superiority of one over the other in regards to 6 gastrointestinal symptoms (abdominal pain, bloating, flatulence, bowel urgency, straining and incomplete defecation), stool form and frequency of defecation.

Study Overview

• Status: Completed
• Conditions: Irritable Bowel Syndrome; Food Intolerance; Functional Bowel Disorder; Food Intolerance Syndromes
• Intervention / Treatment: Other: The 5Ad Diet; Other: The Low FODMAP Diet

Detailed Description

Functional Bowel Disorders (FBDs) are characterised by chronic gastrointestinal symptoms including abdominal pain, constipation, bloating, diarrhoea, alternating abdominal symptoms, and irregular frequency of bowel movements among others in the absence of any intestinal abnormality. The prevalence of FBDs ranges from 15 - 20% worldwide, with remarkable economic burden on health systems and significant impact on the quality of life of sufferers. It is estimated that between 60% - 89% of individuals that suffer from FBDs find that foods exacerbate their symptoms. Therefore, dietary therapies are frequently implemented to assist with symptom relief in these individuals.

Although the low FODMAP diet is the most commonly followed diet for the treatment of FBDs, there are concerns regarding it's complexity, restrictiveness, nutritional adequacy, and effectiveness. Therefore, the 5Ad diet was designed to fill a gap in the existing research and to overcome the limitations associated with existing dietary approaches.

Preliminary findings from the first study in 2019 suggested that the 5Ad diet might be a promising universal approach for varying forms and severities of FBDs. Therefore, an RCT is needed to substantiate these previous results. Thus, this RCT aims to determine whether the 5Ad diet is at least as effective as the low FODMAP diet in reducing gastrointestinal symptoms associated with FBDs/food intolerances.

• Study Type: Interventional
• Enrollment (Actual): 52
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Suffolk
    • Ipswich, Suffolk, United Kingdom, IP4 1QJ
      • University of Suffolk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Individuals are eligible for the study if all of the following criteria are met:

• Suffers chronically from either constipation, diarrhoea, or an alternation of both, bloating, flatulence or abdominal pain, incomplete defecation, straining and bowel urgency.
• Symptoms must be present for ≥ 2 times per week, with symptom onset occurring at least 3 months prior to participation.
• Participants taking prescribed medications which may affect bowel function are included only if the intake is maintained throughout the entire intervention period.

Exclusion Criteria:

Individuals are excluded from the study if any of the following criteria are met:

• Pregnant.
• Known underlying pathology (e.g., Crohn's disease, ulcerative colitis, celiac disease).
• History of abdominal/gastrointestinal surgery within 1 year prior to participation.
• History of antibiotic use in the last 6 weeks prior to participation.
• Allergic to the foods specified in both the 5Ad diet and the low FODMAP diet.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: The 5Ad Diet; Participants are required to follow the 5Ad diet for 7 days, followed by a washout phase for 7 days, before crossing over to the active phase of the low FODMAP diet for 7 days.	Other: The 5Ad Diet; Participants are to follow the 5Ad diet.; Other: The Low FODMAP Diet; Participants are to follow the active phase of the Low FODMAP diet.
Active Comparator: The Low FODMAP Diet; Participants are required to follow the active phase of the low FODMAP diet for 7 days, followed by a washout phase for 7 days, before crossing over to the 5Ad diet for 7 days.	Other: The 5Ad Diet; Participants are to follow the 5Ad diet.; Other: The Low FODMAP Diet; Participants are to follow the active phase of the Low FODMAP diet.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Abdominal Pain	Abdominal pain will be recorded daily in a symptom diary and measured using a 4 point Likert-type scale, coded from 0 - 10 for conversion into continuous variables (None = 0; Mild = 1 - 3; Moderate = 4 - 6 ; Severe = 7 - 10).	Assessed daily throughout both dietary protocols (7 days for each dietary protocol)
Abdominal Bloating	Abdominal bloating will be recorded daily in a symptom diary and measured using a 4 point Likert-type scale, coded from 0 - 10 for conversion into continuous variables (None = 0; Mild = 1 - 3; Moderate = 4 - 6 ; Severe = 7 - 10).	Assessed daily throughout both dietary protocols (7 days for each dietary protocol)
Flatulence	Flatulence will be recorded daily in a symptom diary and measured using a 4 point Likert-type scale, coded from 0 - 10 for conversion into continuous variables (None = 0; Mild = 1 - 3; Moderate = 4 - 6 ; Severe = 7 - 10).	Assessed daily throughout both dietary protocols (7 days for each dietary protocol)
Bowel Urgency	Bowel urgency will be recorded daily in a symptom diary and measured using a 4 point Likert-type scale, coded from 0 - 10 for conversion into continuous variables (None = 0; Mild = 1 - 3; Moderate = 4 - 6 ; Severe = 7 - 10).	Assessed daily throughout both dietary protocols (7 days for each dietary protocol)
Straining	Straining will be recorded daily in a symptom diary and measured using a 4 point Likert-type scale, coded from 0 - 10 for conversion into continuous variables (None = 0; Mild = 1 - 3; Moderate = 4 - 6 ; Severe = 7 - 10).	Assessed daily throughout both dietary protocols (7 days for each dietary protocol)
Incomplete Defecation	Incomplete defection will be recorded daily in a symptom diary and measured using a 4 point Likert-type scale, coded from 0 - 10 for conversion into continuous variables (None = 0; Mild = 1 - 3; Moderate = 4 - 6 ; Severe = 7 - 10).	Assessed daily throughout both dietary protocols (7 days for each dietary protocol)
Stool Form	Stool form will be measured using the Bristol Stool Form Scale. Type 1 - Separate hard lumps, like nuts (hard to pass), Type 2 - Sausage shaped, but lumpy, Type 3 - Like a sausage but with cracks on its surface, Type 4 - Like a sausage or snake, smooth and soft, Type 5 - Soft blobs with clear cut edges (passed easily), Type 6 - Fluffy pieces with ragged edges, a mushy stool, and Type 7 - Watery, no solid pieces, entirely liquid. Stool Types 1 and 2 are associated with constipation, while stool Types 5 - 7 are associated with diarrhoea. Stool Types 3 and 4 are considered normal stools.	Assessed daily throughout both dietary protocols (7 days for each dietary protocol)
Frequency of defecation	Frequency of defecation will be recorded daily in a symptom diary.	Assessed daily throughout both dietary protocols (7 days for each dietary protocol)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fatigue	Fatigue will be recorded and measured using the Fatigue Assessment Scale (FAS) (Michielsen et al., 2003), using a 5 point Likert-type scale, coded from 1 - 5 for conversion into continuous variables (None = 1; Sometimes = 2; Regularly = 3; Often = 4; Always = 5). Question 1 - I am bothered by fatigue; Question 2 - I get tired very quickly; Question 3 - I don't do much during the day; Question 4 - I have enough energy for everyday life; Question 5 - Physically, I feel exhausted; Question 6 - I have problems starting things; Question 7 - I have problems thinking clearly; Question 8 - I feel no desire to do anything; Question 9 - Mentally, I feel exhausted and Question 10 - When I am doing something, I can concentrate quite well. Question 4 and 10 are to be reverse scored. Total scores can range from 10, indicating the lowest level of fatigue, to 50, denoting the highest.	Assessed on the last day of both dietary protocols (Day 7 of each dietary protocol)
Mental Fatigue	Mental fatigue will be measured using the Fatigue Assessment Scale (FAS), using a 5 point Likert-type scale, coded from 1 - 5 for conversion into continuous variables (None = 1; Sometimes = 2; Regularly = 3; Often = 4; Always = 5). Only questions 6 - 10 will be used to calculate the mental fatigue score. Question 6 - I have problems starting things; Question 7 - I have problems thinking clearly; Question 8 - I feel no desire to do anything; Question 9 - Mentally, I feel exhausted and Question 10 - When I am doing something, I can concentrate quite well. Question 10 is to be reverse scored. Total scores can range from 5, indicating the lowest level of fatigue, to 25, denoting the highest.	Assessed on the last day of both dietary protocols (Day 7 of each dietary protocol)
Physical Fatigue	Physical fatigue will be measured using the Fatigue Assessment Scale (FAS), using a 5 point Likert-type scale, coded from 1 - 5 for conversion into continuous variables (None = 1; Sometimes = 2; Regularly = 3; Often = 4; Always = 5). Only questions 1 - 5 will be used to calculate the mental fatigue score. Question 1 - I am bothered by fatigue; Question 2 - I get tired very quickly; Question 3 - I don't do much during the day; Question 4 - I have enough energy for everyday life; Question 5 - Physically, I feel exhausted. Question 4 is to be reverse scored. Total scores can range from 5, indicating the lowest level of fatigue, to 25, denoting the highest.	Assessed on the last day of both dietary protocols (Day 7 of each dietary protocol)

Collaborators and Investigators

• Sponsor: University of Suffolk
• Investigators: Principal Investigator: Camilla Bunn, University of Suffolk

Publications and helpful links

General Publications

• Lewis SJ, Heaton KW. Stool form scale as a useful guide to intestinal transit time. Scand J Gastroenterol. 1997 Sep;32(9):920-4. doi: 10.3109/00365529709011203.
• Michielsen HJ, De Vries J, Van Heck GL. Psychometric qualities of a brief self-rated fatigue measure: The Fatigue Assessment Scale. J Psychosom Res. 2003 Apr;54(4):345-52. doi: 10.1016/s0022-3999(02)00392-6.
• Ibrahim F, Stribling P. A 5Ad Dietary Protocol for Functional Bowel Disorders. Nutrients. 2019 Aug 17;11(8):1938. doi: 10.3390/nu11081938.
• Ibrahim F, Stribling P. Reply to "A Gluten Reduction Is the Patients' Choice for a Dietary 'Bottom Up' Approach in IBS-A Comment on "A 5Ad Dietary Protocol for Functional Bowel Disorders" Nutrients 2019, 11, 1938". Nutrients. 2020 Jan 3;12(1):140. doi: 10.3390/nu12010140.
• Gibson PR, Shepherd SJ. Personal view: food for thought--western lifestyle and susceptibility to Crohn's disease. The FODMAP hypothesis. Aliment Pharmacol Ther. 2005 Jun 15;21(12):1399-409. doi: 10.1111/j.1365-2036.2005.02506.x.

Study record dates

Study Major Dates

• Study Start (Actual): May 8, 2022
• Primary Completion (Actual): April 1, 2025
• Study Completion (Actual): April 1, 2025

Study Registration Dates

• First Submitted: March 15, 2024
• First Submitted That Met QC Criteria: March 27, 2024
• First Posted (Actual): March 29, 2024

Study Record Updates

• Last Update Posted (Actual): November 24, 2025
• Last Update Submitted That Met QC Criteria: November 21, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: Irritable Bowel Syndrome; Functional Constipation; The 5Ad Diet; The Low FODMAP Diet; Functional Diarrhoea; Functional Bloating
• Additional Relevant MeSH Terms: Signs and Symptoms, Digestive; Intestinal Diseases; Digestive System Diseases; Gastrointestinal Diseases; Colonic Diseases; Colonic Diseases, Functional; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Food Intolerance; Irritable Bowel Syndrome
• Other Study ID Numbers: USuffolk

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No