Plant-based runner with digestive challenges – Simone do Carmo

Gastrointestinal distress is a common issue, especially among long-distance runners. Simone do Carmo shares an interesting case of a competitive plant-based runner, that shows how improving gut health can have a major impact on an athlete’s performance.

John was a 19-year-old, competitive long-distance runner and a full-time student with a typical A-type personality: ambitious, determined and competitive. He ran 80 to 120 km weekly, including long runs and high-intensity track sessions. He also incorporated core sessions, light cycling for active recovery, and a complete rest day. John approached me because gastrointestinal issues were compromising his performance.

During our first consultation, we looked at his timeline, a tool used in functional medicine, that looks chronologically into a client’s case history. John had developed IBS-like symptoms in one year prior, particularly loose bowels and bloating. These were more prevalent during his training sessions, which often had to be cut short so he could go to the toilet.

Gastrointestinal distress complaints are very common among endurance athletes (1). Considering his training and the timing of his symptoms, his running was likely a major trigger. The bouncing effect and reduced blood flow to the gut during exercise probably compromised his gut function (1,2). Heat stress was not overly a concern as he trained in cold-to-mild conditions.

Both of his grandfathers had suffered from bowel cancer, and his sister had been diagnosed with IBS and iron deficiency anaemia, so there may have been a genetic predisposition towards gastrointestinal problems and malabsorption. John also had a history of taking antibiotics: first in childhood for a toenail infection, and again a few months ago when he took a strong course of antibiotics for a blood infection, which he described as “very scary”. The antibiotics could also have been both a predisposing factor and a mediator of his compromised gut health since research shows that gut microbiota can be disturbed during antibiotic treatment and may take several months to recover (3,4).

John had turned vegan one year prior to consulting with me for animal welfare reasons. He felt good on the diet despite his symptoms and did not want to change. This was a lightbulb moment for me as the change in his diet was close to the time he developed symptoms – was this a major trigger? John additionally had started university around the same time, which could also have been a triggering event. Desperate for help with his gut problems, he’d asked his aunt, a doctor in Australia, for advice. She’d recommended a low-FODMAP diet, which has been shown to improve IBS symptoms (5), and since then he’d self-managed with this diet and also avoided gluten. Although he noticed minor initial improvements in his symptoms, he felt the low-FODMAP approach was not working. Since a low-FODMAP diet should only be followed for six weeks (6), and one of his main symptoms was loose stools, micronutrient deficiency and malabsorption were a major concern to me.

After analysing John’s diet, I determined his overall nutrition intake was good for a vegan following a low-FODMAP and mostly gluten-free approach. However, it lacked some variety as he often ate the same meals every day. But he met his energy demands and was conscious of his food choices. He took no supplements because he disliked the idea.

Regarding macronutrients, John’s intake was around 7.5 g/kg body mass/day of carbohydrates, 1.3 g/kg of protein and 1.6 g/kg of fat, which aligned with sports nutrition guidelines. However, his protein intake should potentially have been higher due to the lower digestibility of plant proteins compared to animal proteins (7,8). The only major concerns with his micronutrient intake, according to a professional nutrition analysis, were iodine, vitamin D and omega-3. 

First interventions in aiding his gut health

Based on John’s goal of improving his IBS-like symptoms, the focus of my intervention was to restore his gut health through a food-first approach supported by supplementation, training modifications and stress management strategies.

Testing and diet

I firstly advised John to have basic blood tests done to check his iron and vitamin B12 status since he was worried that he might be anaemic, and vegans often have subnormal vitamin B12 levels (8,9). The test was to give him specific measurements because he was analytical and wanted to see data before taking any tablets or supplements. Meanwhile, I encouraged him to ensure that his plant-based milk was fortified with vitamin B12, and to incorporate nutritional yeast into his diet, a good vitamin B12 vegan source (8). Further testing was not, however, possible due to budgetary constraints.

I encouraged John to introduce more variety into his diet and slowly implement non low-FODMAP foods and gluten, noting any negative reactions to particular foods. I also recommended that he stewed apples, a good source of pectin, which could help modulate his gut microbiota and improve his gut barrier function (10,11). And I recommended that he introduce a little fermented foods into his diet, such as sauerkraut, kimchi and tempeh, due to their enhanced nutritional and functional properties, and being a natural source of probiotics (12).

Other suggested changes included substituting his post-exercise cornflakes with a more nutritious post-exercise option, like a smoothie with added glutamine (discussed below). I also talked to him about using kefir or natural bio-yoghurt as a base of the smoothies, emphasising that although these were not vegan sources, they were a good way to get more natural probiotics into his diet, even if only for a short period. Flaxseeds, chia seeds and walnuts would also improve his omega-3 intake. All these changes would help his overall protein intake since he was not keen on taking supplemental protein. I proposed a food-first approach of incorporating some seaweed into his diet to improve his iodine intake. Lastly, I recommended he eliminate his pre-training morning coffee because the laxative effect of caffeine could be a contributory trigger to his bowel urgency (13).

Supplementation

Although John was not keen on supplements, I encouraged a prebiotic and probiotic blend with glutamine supplementation. I described the promising evidence behind these, particularly in improving gut health and integrity in runners (14,15). Glutamine is an amino acid in low supply in most vegan diets, which further supported the need for supplementation.

Training and stress management

Since John was experiencing symptoms during every training session and was becoming frustrated, I suggested that he do fewer running sessions, and substitute with some cycling or swimming, which should be less impactful on the gut. Finally, I recommended active restoration strategies, such as yoga and Pilates, to stimulate the parasympathetic system, attenuate stress or anxiety, and improve his GI symptoms (16).

Progress

I followed up regularly with John by email. Over the summer, he reduced his running to allow his gut to recover. He took my recommendations on board, and his GI symptoms reduced greatly, which allowed him to start ramping up his training again for the new season. We met for a second visit, and I immediately saw that John looked more vibrant and had gained some healthy weight. He rated his gut health as a seven out of ten, compared to two out of ten when I’d first seen him four months previously. We knew that we were on the right track, but we dug even deeper to see what else could further improve his gut health.

Follow-up interventions

John stated that he was experiencing some bloating in the mornings. After questioning his eating habits, he revealed that he would eat a pre-bed snack or smoothie late at night. I encouraged him to finish eating by 8 pm to see if this would make any difference.

I talked to him about my light-bulb moment when we first met. The fact that his symptoms appeared a few months after turning vegan made me question whether this dietary approach was suitable for him. I encouraged John to introduce certain animal-based foods into his diet that may have additional benefits for gut health, like dairy kefir for its natural probiotics and bone broth for absorbable forms of collagen, gelatine, and key amino acids such as proline, glycine, glutamine and alanine. Kefir could be easily incorporated into his smoothies and bone broth into his cooking.

I also encouraged him to introduce oily fish for omega-3s and eggs for choline – nutrients often deficient in a vegan diet. These foods would also help boost his protein intake, support recovery and bring musculoskeletal benefits. For example, a study in healthy young men showed that kefir supplementation improved glucose metabolism and attenuated the effects of muscle soreness after high-intensity exercise, which the researchers suspected may have been due to regulating antioxidant capacity (17). After discussing the evidence with John, he was keen to experiment with these foods.

As autumn was approaching, I recommended an Informed-Sport-approved vitamin D supplement and a multivitamin, thinking that since he may not be absorbing nutrients effectively, covering all the bases would be a good strategy. We also adjusted his glutamine timing. John had been taking it with a smoothie, often after training and then again in the evening. But I encouraged him to take it first thing in the morning on an empty stomach, so it would not compete with other amino acids, and after training sessions, especially high-intensity training or prolonged exercise periods. I also introduced some nutritional support during high-intensity or prolonged training sessions in DIY sports drinks to moderate his cortisol response, preventing muscle protein breakdown and immunosuppression (18,19).

I also emphasised a ‘pre-eating routine’ – a mindful practice that helps put the body in a relaxed state before eating by taking deep breaths, chewing well and noticing every mouthful. Drinking a glass of water with lemon juice or apple cider vinegar, smelling his food and visualising taking a bite of food would also activate the cephalic phase of digestion, stimulating gastric secretion to aid digestion and subsequent absorption of nutrients aiding in gut health.

Since John’s training had ramped up, I talked to him about some monitoring tools: a subjective quiz to do upon waking and a readiness-to-exercise app that would provide more objective data on his recovery and allow him to train more smartly. Since he had tried and enjoyed a yoga-based class, I encouraged him to do it more consistently.

Gut health performance outcomes and reflections

John had done some serious racing, including the university cross-country championships that he won, and a team relay in which they came third. Since I started working with him, he also improved his 10 km PB by a second (currently 31:40). He was extremely happy with his performance. He said that focusing on his gut health had significantly impacted his performance. He also believed that introducing the recommended animal-based foods had made a big difference quickly.

Six months after he’d first come to see me, two weeks before the Great Britain (GB) trials, we met again because he’d had a minor setback in a recent race that had knocked his confidence. We also discussed key points for tapering and race day, such as eating foods he knew would not affect his gut, minimising fibre intake three days ahead of the race, and cooking his food the night before and for breakfast. Most importantly, we talked about his unrealistic sense of urgency, typical of an A-type personality, as he was doing a lot of work for university, that he admitted was unnecessary because the deadlines were a month away. Still, he always felt the need to finish early! I encouraged him to focus on relaxing as race day approached and minimise unnecessary stress as it may exacerbate symptoms.

I illustrated this with a ‘threshold’ concept to help him understand his gut better – an imaginary line below which his symptoms are dormant. Still, when he added stress from training, competing and university work, he crossed that line, and the symptoms would manifest and may exacerbate over time if the stress was not managed properly. I emphasised the importance of staying under the threshold by using nutrition, training and stress management strategies. It is vital that an athlete learns how to listen to their body through intuitive thinking and regular monitoring to aid gut health.

Unfortunately, John caught a cold, preventing him from competing on the day. However, he learned from the experience and realised that had been unfairly imposing deadlines on himself to improve (usually target races). He has now decided to listen to his body more instead of over-competing and to focus on strategies for key races like the GB trials. He also revealed that he stopped consuming kefir and bone broth just before the relapse in his last race and believed that that may have contributed since he’d been doing well when consuming these regularly.

Take home message

This case study is a great example of an athlete’s health being the best ergogenic aid. This concept was discussed by Paul Ehren in his article on ergogenic acids from a different perspective. I focused on John’s gut health because this was the major lever that needed change. His gut health improved through a multi-faceted approach of nutrition, training and stress management strategies. This shows how we, as sports nutrition practitioners, can do so much more with an integrative view than the performance-centric view that often dominates the world of elite sport.