How do our bodies react under the stress of physical exercise? Fatigue, under performance, gastrointestinal distress, food sensitivities and mood disturbances are all inherently linked and notably common amongst athletes, particularly at the elite level. During intense exercise, we cause the release of stress hormones. These include hormones such as cortisol, inflammatory cytokines, and microbial molecules, which may have an influence on overall gut health (1).
1. Clark and Mach, 2016
Gut health
Upwards of 70% of the immune system is located within the gut. Maintaining a “leak proof” gut wall and thriving populations of diverse gut bacteria is crucial. The extent to which diet affects the immune system is commonly underestimated.
Intense exercise and digestive function
Strenuous exercise directly affects the gut barrier integrity by loosening its tight junctions, causing increased intestinal permeability (leaky gut) (1). The stress hormone cortisol has also been suggested to affect intestinal integrity, making the gut more permeable leading to increased antigen trafficking across the gut wall (2).
1. Ballantyne, 2017
2. Kelly et al, 2015
How exercise impacts gut health
To prioritise the heart and skeletal muscles during intense exercise, blood flow is diverted from the gastrointestinal tract and other visceral organs (1). Lack of sufficient blood flow to the gut further disrupts the intestinal barrier and subsequently increases intestinal permeability (2). As a result of increased intestinal permeability, larger molecules, or antigens (such as partially digested food proteins) that would normally remain within the gut, are able to cross into the bloodstream (3) stimulating the production of IgG antibodies to those specific food antigens. Over time, if food-specific antibodies are not broken down and cleared by the immune system and continue to rise, an IgG-mediated food sensitivity may result (4). This leads to a build-up of inflammation, especially chronic, low-grade, sub-clinical inflammation.
1. Brouns and Beckers, 1993
2. Lambert, 2008
3. Rapin and Wiernsperger, 2010
4. Gocki et al, 2016
The IgG antibody food sensitivity test
The results of a study conducted in 2017 showed that elimination diets based on IgG-mediated food sensitivity test leads to a significant improvement in gastrointestinal discomfort symptoms and sport performance (1).
1. Kostic-Vucicevic et al, 2017