The following case study looks at the nutritional advice given to a best in class marathon runner who suffered from gastrointestinal issues.

The case study discusses the effect increased fibre had on their performance.

Name: Kristy Coleman

Title: Registered Nutrition Practitioner at Private Nutrition Clinic in London

Case study athlete:  Female Marathon Runner – best in class, 29 years old

Kristy Coleman

The Practitioner

Kristy is currently studying for her Exercise and Sports Nutrition MSc. Kristy runs a private nutrition clinic in London, provides a range of nutrition consultancy services to brands, runs retreats and writes for a number of publications on nutrition. With her evidence based, practical and back to basics approach, Kristy’s mission is to empower her clients to manage and maximise their health and wellbeing and optimise performance.

Kristy’s journey into nutrition was not a conventional one, she spent the beginning of her career as a solicitor specialising in intellectual property and food law, which, alongside her love for sport and exercise, is where her passion for nutrition started. Kristy understands the pressures many of her clients are under, from training pressures to stress and builds this into her advice.

Through her clinic, events, retreats and writing, Kristy shares her passionate evidence-based knowledge on nutrition.

Summary of case study athlete:

The athlete has been competing for four years and runs in four marathons a year and maintains top ten best in class position. Over the past 2 years the runner has noticed an increase in gastrointestinal discomfort, including sporadic bloating, dissention and constipation. Symptoms have been investigated by her GP, no diagnosis or cause of symptoms identified. In addition, she has experienced fatigue during long training runs and tiredness shortly after eating. Overall, she rated her symptoms a 7-8 out of 10 on Measure Yourself Medical Outcome Profile (MYMOP).

Usual nutrition strategies and areas to improve:

The client’s primary concerns around diet and training were that a diet higher in fibre would trigger frequent and/or loose bowel movements during long training runs and while competing. She was also concerned that weight gain would inhibit performance and so has increasingly reduced consumption of carbohydrates overall, including whole grains, fruit and root vegetables, which had significantly reduced her intake of fibre to around 15g of fibre per day. Her dietary choices remained the same throughout all training periods.

An analysis of 3 weeks of food recording, identified that the runner’s diet contained approximately 15g of fibre per day, which may have been contributing to her gastrointestinal symptoms. Due to her fears over gaining weight and the risk of “runners tummy” (urgency to go during running and loose stools), the client was initially reluctant to increase foods sources of fibre.


Nutrition strategies put in place:

The client was recommended to start with 1 sachet of Bimuno per day (3.6g) stirred into her post training yogurt and 1 additional portion of vegetables or a cupped hand of whole grains for a period of 2 weeks. Bimuno introduced post training to reduce the risk of further gastrointestinal discomfort during training. This provided her with approximately 5g of additional fibre per day. Suggesting Bimuno allowed the client to experiment with how increasing dietary fibre could support her gastrointestinal health whilst negating the fears around weight gain and excessive fibre. Every two weeks the client’s dietary fibre intake was adjusted by 5g to reach 30g of fibre per day, including 3.6 from Bimuno.

Adherence to Bimuno

The client found it easy to carry around Bimuno DAILY sachets in her training bag to add to her post training yoghurt easy. However, she found that some days she forgot to add the sachets, so she started labelling the sachets according to the day to support compliance. Over a period of travel, she switched to Bimuno TRAVELAID pastilles (3 pastilles = 2g fibre) for convenience and consumed these throughout the day. Again, the pack was marked with a permanent marker for compliance.


Within 6 weeks, the client’s bowel movements had become regular and well formed, without urgency to go during training or constipation. Her bloating and distention had reduced significantly and only occurred when the client was extremely stressed. The client’s fear around increasing fibre intake had been alleviated and she felt she was able to perform better due to increased energy levels, achieving a PB in her most recent marathon. Overall, she rated her symptoms a 1 out of 10 on MYMOP.

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