Autoimmunity in sport: case study of a recreational marathon runner – Amy Desborough

Autoimmunity is not a ‘disease’ state specific only to very unhealthy individuals. Integrative nutrition practitioners, like Amy Desborough, are seeing multiple cases of autoimmunity in sport, many of which can be addressed by attention to patterns of nutrition and lifestyle.

Dietary diversity matters: Dominique’s limited diet, although macronutrient balanced, lacked phytonutrients, fibres, and antioxidants that are crucial for microbiome diversity, immune modulation, and the reduction of inflammation.”

Dominique was a 33 year old woman who was training for her second marathon, following a training plan set by her coach. She worked full time in a busy office, had one young child, and was studying a postgraduate course in the evenings. Her first marathon, which she’d completed the previous year, had gone very well and she’d enjoyed the experience, but this time she was feeling lethargic, rating her average energy to be 4 out of 10, with notable muscle weakness and slow recovery following exercise. Dominique had also gained some weight since her first marathon, and was experiencing a very low mood psychologically. Additionally, she was experiencing constipation, only opening her bowels on average twice a week, plus significant gastrointestinal bloating. Her sleep was poor, often taking several hours to fall asleep and then waking at 3 am and not going back to sleep; finding it hard to switch off and often lying awake for many hours.

After recently presenting to her GP with these symptoms, Dominique had received a diagnosis of Hashimoto’s disease and was subsequently prescribed thyroxine medication; a relatively common case of autoimmunity in sport.

Dietary intake

Dominique had been following a diet plan that was set by her coach, which purposely covered all the required macronutrients for her training plan, especially carbohydrates. However, there was little dietary variety, and her food significantly lacked colour and plant-based nutrients.

Considerations of autoimmunity in sport

The state of constipation can result in endotoxins and toxicants being reabsorbed into the bloodstream, and microbial dysbiosis has been noted as a major trigger and mediator of inflammation and disease progression. In terms of the effects of bacterial imbalance on inflammation, low levels of Akkermansia have been linked to increased intestinal permeability, Bifidobacterium are a keystone species necessary for the whole cross-feeding of the microbiome, and Lactobacillus is an important species for the promotion of regulatory T cells (Mo et al., 2024).

Stress, which was very prominent in Dominique’s life, is thought to cause activation of the sympathetic nervous system and increased inflammation (Reiche et al., 2004), both of which can increase the aggression of autoimmune antibodies, thereby increasing the likelihood of autoimmunity in sport. Dietary wise, gluten is well recognised as a potential trigger or mediator of inflammation in autoimmune cases – what’s more, it has a molecular structure that closely resembles protein structures within thyroid tissue cells, and it has been found that gluten sensitivity in an individual can trigger immune activation of thyroid tissue (Esfahani et al., 2024). Additional specific considerations for autoimmunity in sport may include viral and toxicant load, plus vitamin D levels.

When Dominique was requested to undertake a comprehensive stool test, low levels of the beneficial species Akkermansia muciniphila, Bifidobacterium spp., Lactobacillus spp. and Bacteroides were revealed, along with high levels of the liposaccharide-producing bacteria Fusobacterium nucleatum. Additionally, her vitamin D test revealed an extremely low serum 25-hydroxyvitamin D concentration of 40 nmol/L.

Lifestyle approaches taken

Based on her current state of health, Dominique was recommended to limit hard running training for the coming months to enable the Hashimoto’s flare to subside. Sea swimming and daily walking were offered as alternative cardiovascular exercise modalities, plus Pilates was suggested to help muscular strength and mobility during her recovery. Additionally, activities to calm the nervous system and improve sleep hygiene, such as yin yoga, mediation, walks in the fresh air and breathwork were suggested. Cold water therapy (such as sea swimming) and sauna therapy (due to the production of heat shock proteins), when used moderately, can be mild hormetic stressors that can immune responses over time (Kunutsor et al., 2024).

Dietary approaches taken for digestive health

As noted in Chapter 5 of Integrative Sport and Exercise Nutrition, in order to support overall immune health, it is vitally important to start with gastrointestinal health. This approach is particularly important in cases of autoimmunity in sport, where gut-based immunity becomes a fundamental part of the partitioner’s support of their client. Recommendations made in the case of Dominique included:

• Increase variety in the diet in order to encourage a more diverse microbiome, including the provision of anti-inflammatory nutrients.
• Improve Akkermansia species growth with foods such as red quinoa, red rice, pomegranates and cranberries.
• Follow a gluten-free diet, substituting gluten-containing grains (e.g. wheat, rye and barley) with sweet potatoes, oats, buckwheat, quinoa, brown rice and root vegetables.
• Include PHGG, a prebiotic fibre, in a daily drink or smoothie to enhance bowel function and stimulate Bifidobacterium growth and butyrate-producing bacteria in the large intestine.
• Consume hot water and apple cider vinegar first thing in the morning: this can help alleviate constipation by ensuring a more balanced pH in the colon, which should also reduce levels of dysbiosis.
• Include omega-3 oils, which are essential in managing autoimmune conditions by supporting the healing of the gut mucosa; they are also precursors for hormones that regulate inflammation within the immune system. Aim for two to three sources of omega-3 rich fish per week (e.g. salmon, mackerel and sardines).
• Daily consumption of a variety of foods that are rich in fats and oils, including extra virgin olive oil, nuts, seeds, real farm butter, avocados and coconut oil.
• Consume good sources of protein, for repair of the mucosal membrane. e.g. eggs, beans, legumes, lean meat, fish, nuts and seeds.
• Increase vegetable consumption to half the plate with a rainbow of colours to help increase the levels of vitamins A, C and E and antioxidants.
• Aim to consume drinks that include ginger, fennel and peppermint, which can be calming to the digestive system.
• Introduce fermented foods that contain probiotic bacteria, such as kefir, kimchi, sauerkraut and miso. These can support immune strength, improve gastrointestinal health, and lower the risk of inflammation. The introduction of these foods should be slow and measured to assess for digestive tolerance.

Dietary approaches taken for immune health

In addition to the dietary inclusions for gastrointestinal health, Dominique was recommended to include a large variety of phytonutrients within her diet; these are plant nutrients which serve as immune modulators through their ability to favourably influence cellular signalling systems.

Phytonutrient groups include (Pop et al., 2023):

• Polyphenols, including non-flavonoids: Stilbenes (resveratrol in grapes and blueberries), lignans (in flaxseed, sesame seeds, broccoli and carrots), coumarin (in cinnamon and figs).
• Polyphenols, including flavonoids: Flavanols (in green tea, apple and berries), isoflavones (in soya beans, lentils and peas), anthocyanins (in blueberries, blackberries and raspberries), flavonols (in onion, kale and broccoli), flavanone (in oranges and lemons) and others – see Pop et al., 2023 for a comprehensive review on polyphenols.
• Terpenoids (Carotenoids; in carrots, sweet potatoes and pumpkins).
• Glucosinolates (in broccoli, cauliflower and radishes).
• Phytosterols (in olive oil, nuts and legumes).
• Omega-3 fatty acids (in fish, chia seeds, walnuts and seaweed).
• Probiotics (in fermented foods such as sauerkraut, miso and kimchi).

These plant nutrients also support the provision or growth of probiotics, which are vital for overall immune function, and particularly autoimmunity in sport. For more detail about phytonutrients, refer to Chapter 10 of Integrative Sport and Exercise Nutrition.

Recommended supplements, with rationale

• Vitamin D3 5000 IU 1 per day for three months, then retest to establish if the levels are within range; testing any sooner than three months, may give an inaccurate picture. It is important to establish improvements to ensure there is adequate absorption. Once more optimal levels are shown, the supplemented dose can be reduced to avoid any toxicity (vitamin D is stored in fat and so can become toxic if too high a dose it taken for too long).
• Magnesium glycinate (200 mg/day) in the evening to relax her nervous system, aid sleep and improve bowel movements.
• Thyroid-focussed multi-nutrient to take alongside thyroxine medication: containing L-tyrosine, an amino acid used as a building block to make thyroid hormones; iodine, a vital mineral which forms part of the hormones T3 and T4; selenium, an important co-factor in the conversion of T4 to T3; and a range of nutrients and botanicals, including phenylalanine, L-carnitine, liquorice, B vitamins and vitamin C, which are also helpful for supporting thyroid function.

Autoimmunity in sport – case outcome after 1 month

During the follow up consultation Dominique reported the following:

• She had been trying to follow the ’30 plants per week’ initiative to increase her variety of vegetables and fruit, to include a rainbow of colour, and she enjoyed the process.
• Her bowel movements had improved substantially, with frequency increasing to every other day as opposed to twice a week. However bloating after meals was still sometimes an issue.
• Dominique completely forgot to take the PHGG prebiotic.
• Gluten was completely eliminated from her diet and the overall change in food consumption helped with some weight loss.
• Her sleep improved in that Dominique found it was a deeper sleep, but often it would take an hour or two before falling to sleep. However it was established on further discussion that Dominique used her mobile telephone and/or laptop up until bedtime, which could negatively impact her sleep quality.
• Her lethargy reduced with an improved energy rating of 7 out of 10, and her muscles felt stronger. However, following an attempted harder training session, she felt exhausted for a couple of days, which negatively affected her mood. She did recover after this, but it had left her feeling anxious about future training schedules.
• Dominique had not done any cold water swimming, but she had introduced cold showers to her regime a couple of times a week, plus the occasional sauna. She was trying to introduce calming actives, but found meditation ‘impossible’ and yoga frustrating! However, she had been doing daily walks and some breath work, but not pilates.

Further recommendations and rationale

• Outlining the reason behind the importance of taking PHGG; namely that as a prebiotic fibre it should enhance bowel function, improving stool consistency, weight and frequency, accelerating colonic transit time, and relieving associated abdominal pain and bloating. Dominique agreed to be consistent in taking PHGG going forwards.
• To eat slowly and chew thoroughly to help reduce gastrointestinal bloating.
• To stop using the mobile telephone and laptop at least one hour before bed. The blue light from the screens can interfere and suppress melatonin production, which is necessary for good sleep. The blue light exposure at night can also confuse the circadian rhythm, resulting in being more alert at night.
• Instead of meditation, try listening to relaxing podcasts and/or audio books.
• Include pilates for muscle strength and flexibility, continue walking, and consider including some swimming.
• Include a 5-HTP formula at night to aid sleep, improve mood and improve intestinal motility, thus reducing constipation. 5-HTP supports serotonin production, which can be converted into melatonin, which is important for sleep. Serotonin is also key regulator of the enteric nervous system, which controls GI functions like motility and secretion, which in turn can support immunity and reduce the risk of autoimmunity in sport. The formula suggested also contained hops and magnesium citrate. Hops can aid sleep by calming the nervous system. One of the active compounds in hops, humulone, act on the GABA receptors in the brain, which helps to induce relaxation and reduce the time it takes to fall asleep. The magnesium citrate should act like an osmotic laxative, helping the bowels relax while drawing more water into the intestines.
• The magnesium glycinate supplement could still be taken in the evening, but if bowels become too lose, it could be switched to being a morning supplement.

Key learnings from Dominique’s case

1. An integrative approach to autoimmunity in sport is essential: Conditions such as Hashimoto’s disease require a multidisciplinary approach, working alongside pharmaceutical intervention, and factors like addressing gut health, nutrient status, stress and sleep are fundamental to recovery.
2. Dietary diversity matters: Dominique’s limited diet, although macronutrient balanced, lacked phytonutrients, fibres, and antioxidants that are crucial for microbiome diversity, immune modulation, and the reduction of inflammation.
3. Gut health underpins immune regulation: The presence of dysbiosis and low beneficial bacterial species highlighted the gut–immune connection. Targeted use of prebiotics, fermented foods and fibre diversity were central to improving bowel function and reducing systemic inflammation.
4. Lifestyle stressors can exacerbate autoimmunity in sport: Chronic stress, inadequate rest and overtraining risk aggravating autoimmune activity. Modifying exercise intensity and introducing nervous system-calming practices were key in reducing Dominique’s symptom burden.
5. The role of sleep hygiene: Poor sleep quality both contributed to Dominique’s fatigue and limited her capacity to recover from training. Addressing screen use, implementing sleep-supportive supplements, and introducing circadian-friendly routines were essential interventions.
6. Gradual recovery is necessary in sport: A phased and flexible return to training ensures that energy, immune function, and mood stabilise before high physical loads are resumed.

This case underlines the importance of an integrative and personalised plan for autoimmunity in sport, balancing medical treatment with nutrition, lifestyle, and functional support.