Irritable Bowel Syndrome (IBS) is a common, global, functional gastrointestinal disorder. It
affects a significant number of people, i.e. between 9 - 23% of the world's population. The
aetiology and diagnosis of IBS is poorly understood due to the complexity, heterogeneity and
incomplete understanding of the pathology, thus well-defined treatments and protocols are
lacking. For example, impaired motility and sensitivity, changes in gut microbiome, increased
permeability, low-grade inflammation, gut endocrine cells, and alterations in the gut-brain
axis, all of which are identified to play a pivotal role in the pathophysiology of IBS. Thus,
it may be challenging to identify the cause of a patient's symptoms as the pathology is not
fully understood. IBS can also further be divided into four subtypes based on a patient's
stool patterns: constipation-predominant (IBS-C), diarrhoea-predominant (IBS-D), mixed
diarrhoea and constipation (IBS-M) and those whose bowel habits cannot be identified but meet
the criteria (IBS-U).
Dietary modifications in treating IBS have also received significant recognition, as many
patients report that foods appear to induce or exacerbate their symptoms, thus diet
intervention may be a very effective tool in the symptom management of IBS. Strategies to
relief symptoms include consuming a low fermentable oligosaccharides, disaccharides,
monosaccharides, and polyol (FODMAP) diet, inclusion of prebiotics and probiotics in diet.
Probiotics are defined as "live microorganisms that when administered in adequate amounts,
confer a health benefit to host". Previous studies suggest that consumption of probiotics
help to alleviate symptoms among IBS patients. However, there is still a lack of probiotic
intervention studies using lactose-free dairy products to determine the efficacy in relieving
IBS symptoms. The aims of this study are (i) to determine the prevalence of lactose
malabsorption among athletes suffering from IBS and (ii) to evaluate the potential of lactose
free probiotics dairy products in alleviating gastrointestinal symptoms among IBS patients.
Subject recruitment Twelve to 15 recreational athletes (age > 18 years) with diagnosed
irritable bowel syndrome will be recruited. A recreational athlete is defined as a person who
is physically active but does not train for competition at the same level of intensity and
focus as a competitive athlete. Participants will be recruited from the North West IBS
support group. The study will also be opened to staff and students at the university.
Hydrogen Breath Test Participants will be asked to follow an overnight (12 hour) fasting
period, not to smoke or vape for at least 24 hours prior to the test and not to exercise for
at least 1 hour before taking the test. Breath testing will be conducted in Nutrition and
Health Suite, Darwin Building, University of Central Lancashire to determine the baseline
hydrogen breath concentration using a portable breath analyser. Participants will then be
provided with 400 ml semi-skimmed milk for consumption following baseline sampling.
Subsequent breath samples will then be collected for re-testing every 15 minutes for 3 hours.
Lactose malabsorption is present if the peak of hydrogen breath excretion over the baseline
is ≥20ppm.
Lactose-free dairy products Participants will be randomised using computer random allocation
sequence into either the intervention group (lactose free probiotic yogurt) or the control
group (lactose free, non-probiotic yogurt). The lactose free probiotic yogurt and lactose
free non-probiotic yogurt (control) will be purchased and stored at the laboratory
refrigerator the day before the testing. Only lactose free probiotic yogurt containing
cultures such as Lactobacillus acidophilus and Bifidobacterium lactis will be selected.
Participants will be asked to consume 125g of lactose free products daily for 7 days,
followed by 1-week washout period and crossover to alternate treatment for 7 days.
Questionnaires
Participants will be asked to complete the following questionnaires at Week 0 (before the
start of the dietary intervention), end of Week 1 (upon completion of 1st dietary
intervention), end of Week 2 (upon completion of washout period) and end of Week 3 (upon
completion of 2nd dietary intervention):
i) Participants' characteristics, records of exercise, stool frequency and consistency ii)
IBS Severity Score Scale (IBS-SSS) iii) IBS Quality of Life (IBS-QOL)
