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Plain English Summary

Background and study aims
Oily fish such as mackerel and sardines contain natural omega-3 fatty acids (O3FAs). They are commonly used as nutritional supplements in capsule form, with evidence suggesting numerous health benefits including improved cognitive performance, maintenance of a healthy heart and even possible anti-cancer effects. There is however little known about the amount of O3FA that enter an individual’s large bowel after taking O3FA capsules. This is of particular interest as O3FAs may have numerous effects on the environment within the bowel, including anti-bowel cancer effects and possible changes in the type and balance of bacteria. The aim of our study is to measure the amount of O3FAs present in the stoma fluid after taking daily O3FA capsules for 4 weeks. We will also examine how O3FAs alter the balance of bacteria within the gut.

Who can participate?
Patients aged 50 or over with a temporary ileostomy (An ileostomy is where the bowel is diverted through an opening in the tummy [stoma] to collect waste products in a bag. They are performed to allow the bowel to heal after surgery to treat bowel cancer).

What does the study involve?
Participants are required to take two O3FA gelatin capsules twice a day with meals for 4 weeks. The O3FA capsules contain naturally occurring fatty acids found in oily fish such as mackerel and sardines. They are widely available for people to buy over the counter from pharmacies and supermarkets. The amount of O3FA within the stoma fluid is measured after taking the O3FA capsules for 4 weeks. Participants provide a stoma fluid sample at three separate visits over the 4 week period. At the start and end of the study participants also provide blood samples to measure the levels of O3FAs in the blood.

What are the possible benefits and risks of participating?
Although O3FA supplementation is associated with many health benefits, taking part in this study is unlikely to directly help participants. However, the results of the study may help plan future research exploring the beneficial effects of O3FAs against bowel cancer. Participants may get some mild side-effects such as indigestion-type symptoms (including belching or change in stoma volume), at which stage they can decide whether to reduce or stop supplementation temporarily or permanently. Sometimes symptoms disappear if the daily dose is reduced. If participants stop taking the capsules during the 4 weeks, a stoma fluid sample and blood test is still required at the end of the study.

Where is the study run from?
St James University Hospital Leeds (UK)

When is the study starting and how long is it expected to run for?
October 2015 to June 2019

Who is funding the study?
Leeds Teaching Hospital Charitable Trust (UK)

Who is the main contact?
Dr Henry Watson

Trial website

Contact information



Primary contact

Prof Mark Hull


Contact details

Level 9
Wellcome Trust Brenner
St James’ University
United Kingdom
+44 (0)113 343 8650

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

A pilot study to measure omega-3 fatty acid levels in terminal ileal content following four weeks of omega-3 fatty acid supplementation in patients with a temporary ileostomy


Study hypothesis

After 4 weeks of O3FA supplementation there is an increase in terminal ileal EPA and DHA levels compared with basal levels.

Ethics approval

Yorkshire & The Humber - Leeds West Research Ethics Committee, 05/01/2016, ref: 15/YH/0547

Study design

Single-centre pilot study

Primary study design


Secondary study design

Non randomised study

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to requesta patient information sheet.


Participants with a loop ileostomy following anterior resection for colorectal cancer.


All participants take two O3FA containing soft gel capsules twice daily with meals (total 1000 mg EPA and 1000 mg DHA daily) for 4 weeks. They are asked to provide a stoma fluid sample at 3 separate visits over the 4 week period. At the start and end of the study participants are also asked to provide a blood sample to measure the levels of O3FAs in their blood.

Intervention type



Drug names

Primary outcome measure

Change in terminal ileal fluid EPA and DHA concentration at four weeks compared with baseline.

Secondary outcome measures

1. Change in percentage erythrocyte membrane content of EPA and DHA at four weeks compared with baseline.
2. Change in terminal ileal fluid EPA and DHA concentration within 24 hours of taking the first O3FA dose.
3. Tolerability and adverse events related to O3FA supplementation.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Aged 50 years or over
2. Either gender
3. Temporary ileostomy fashioned at least 2 months prior to commencing study
4. Able to self medicate
5. A minimum period of 2 months availability for the study prior to planned ileostomy reversal

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Seafood allergy
2. Ongoing and/or previous use (within 4 weeks of commencing the study) of other O3FA or cod-liver oil supplements
3. Previous small bowel resection
4. Metastatic colorectal cancer
5. Less than 4 weeks since any chemotherapy or radiotherapy
6. Inflammatory bowel disease or other intestinal disease (e.g. coeliac disease)

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

St James University Hospital
United Kingdom

Sponsor information


University of Leeds (UK)

Sponsor details

Faculty Research Office
Room 10.110
Level 10
Worsley Building
Clarendon Way
United Kingdom
+44 (0)113 343 7587

Sponsor type




Funder type


Funder name

Leeds Teaching Hospital Charitable Trust

Alternative name(s)

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Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date


Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

24/08/2018: The following changes were made to the trial record: 1. The recruitment end date was changed from 30/06/2018 to 30/12/2018. 2. The overall trial end date was changed from 31/07/2018 to 30/06/2019. 3. The intention to publish date was changed from 31/07/2019 to 30/06/2020. 30/10/2017: Internal review. 22/09/2017: Recruitment end date has been updated from 20/04/2016 to 30/06/2018. Overall trial end date has been updated from 01/10/2016 to 31/07/2018. 14/06/2016: Plain English summary added.