New study reveals how climate change is affecting our gut health

Climate change is having ruinous effects on weather systems, ecosystems, and communities, with adverse weather conditions becoming more common and potent around the world as the years roll by.

It threatens land mass thanks to sea level rises, animal and plant life that’s finely-tuned to the conditions they’ve evolved within, supply chains and food supply thanks to damaged or destroyed crop yields, and floods and droughts are causing havoc for communities worldwide.

Climate change-associated droughts threaten global food supply chains (Xuanyu Han/Getty Images)

If all that wasn’t enough cause for concern, new research claims it’s got a gut-punch effect too. Gradually increasing average temperatures across the globe are impacting upon our digestive systems, the study claims, along with the food we eat.

Published in Lancet Planetary Health, the review said that our gut microbiomes are adversely affected by heat stress. According to HSE, heat stress is triggered when our bodies’ natural temperature-regulating systems start to fail in hot conditions.

You’ve likely experienced some of its symptoms before, not least in the summer of 2022 when the UK reached 40 degrees centigrade for the first time on record. Those symptoms include: a loss of concentration, muscle cramps, heat rashes, dehydration, fatigue, headaches, nausea, confusion, and, in extreme cases, severe thirst, fainting, convulsions, unconsciousness, and even death.

According to a press release covering the study, high temperatures have the potential to ‘induce complex changes in the gut, including shifts in microbiota composition, increased oxygen levels and overproduction of stress hormones’ said a release about the review. The effects of this can be far-reaching’.

When the body is under stress, we release cortisol. This hormone, known as the ‘stress hormone’ impacts the gut in various ways.

For one, it can ‘speed or slow the time it takes for food to transit through the intestines’, according to Time, potentially triggering ‘dysbiosis’, an ‘imbalance in the number, type and distribution of the trillions of bacteria, viruses and fungi that make up the microbiome inhabiting the digestive tract’.

This could spell bad news for your digestion, but also for other processes around the body. It’s widely believed that the microbiome plays an essential role in overall physical and psychological wellbeing.

Speaking to Time, medicine professor Desmond Leddin from Dalhousie University added: "One of the causes of heat stroke is thought to relate to intestinal permeability."

Our gut microbiomes play key roles in our wider health (Peter Dazeley/Getty Images)

Time explained that decreased intestinal permeability, or a ‘leaky gut’, allows ‘organisms that make up the intestinal microbiome — which are supposed to remain in the intestines — to migrate into the bloodstream and spread infection. The microbes that remain behind, meantime, can be thrown entirely out of balance’.

While there isn’t a whole lot we can do at an individual level to combat climate change directly, this research points to an increased need to take care in hot conditions. When the big heat hits this summer, do your best to stay in the shade, hang out somewhere with air conditioning, stay well hydrated, and avoid intense physical exercise if you can help it.