The dangers of heat-induced gut stress

26th June 2025

3 minutes read

With climate change increasing the frequency and severity of heatwaves, understanding how high temperatures affect human health is more important than ever. While most people are aware of the risks of dehydration or heatstroke, one area remains underappreciated: the digestive system, and more specifically, heat-induced gut stress.

What is heat-induced gut stress?

Heat-induced gut stress occurs when the digestive system becomes impaired due to excessive body temperature and reduced blood flow. As the body redirects circulation to the skin to release heat, it deprives internal organs—like the intestines—of sufficient oxygen and nutrients. This hypoperfusion can compromise the gut barrier, disrupt digestion, and trigger inflammatory responses.

Biological mechanisms involved

Once core temperature surpasses 39°C, intestinal cells experience oxidative stress. The tight junctions that maintain the integrity of the intestinal lining begin to break down. This results in increased gut permeability, commonly referred to as “leaky gut.” Bacterial toxins such as lipopolysaccharides (LPS) may enter the bloodstream, prompting the immune system to release pro-inflammatory cytokines. This chain reaction can lead to systemic inflammation, impacting not just the gut, but also muscles, the liver, and the central nervous system.

Scientific research

A number of studies have highlighted the link between heat and gastrointestinal distress. Research at Maastricht University found that more than 70% of endurance athletes suffer from digestive issues when exercising in temperatures above 30°C. These problems are intensified by fasting, high-fat meals, and the use of NSAIDs, which further weaken the intestinal lining.

Long-term health risks

Chronic exposure to gut stress may lead to dysbiosis (imbalance in gut flora), weaken the immune system, worsen inflammatory bowel diseases (IBD), and contribute to metabolic disorders such as type 2 diabetes. There’s also growing evidence that it affects brain function through the gut-brain axis, possibly increasing the risk of anxiety or mood disorders.

Who is most at risk?

Vulnerable groups include:

Outdoor workers (construction, agriculture, delivery services)
Endurance athletes (runners, cyclists, triathletes)
Children, whose thermoregulation is less developed
Elderly individuals, who may not feel thirst adequately
People with chronic illnesses, such as hypertension or kidney disease

Warning signs to watch for

Common symptoms of heat-related gut stress include:

Persistent abdominal cramping
Diarrhea or watery stools
Nausea and vomiting
Fatigue, headaches, dizziness
Loss of appetite
Mucus or blood in the stool (in severe cases)

Practical advice to prevent gut stress

Stay hydrated: Sip water regularly, even without feeling thirsty. Electrolyte-rich drinks can be helpful in extreme heat.

Eat mindfully: Avoid heavy, greasy, or spicy meals. Choose light, easy-to-digest foods like steamed vegetables, fruits, whole grains, and fermented foods.

Digestive rest: Break meals into smaller portions, avoid lying down right after eating, and allow digestion to complete before physical activity.

Helpful supplements: Probiotics, L-glutamine, and herbal teas (fennel, chamomile, peppermint) may support gut health during heatwaves.

Heat-induced gut stress is an overlooked but serious condition. It can compromise not only digestive health but also systemic well-being. By understanding the signs, adopting protective habits, and acting promptly when symptoms appear, individuals can better protect their health during hot weather. As global temperatures continue to rise, raising awareness of this hidden risk becomes increasingly important.