Research highlights the risk of gut issues when working in hot weather

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Wednesday, 2 August, 2023 – 12:30
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Australians working in physical jobs for extended periods in hot weather or environments risk gut damage and blood poisoning that may lead to serious illness.

Recent research has identified the point at which people face potentially serious ‘exercise-induced gastrointestinal syndrome’ (EIGS), and the corresponding degree of seriousness.

EIGS can cause a range of debilitating signs and symptoms, as a result of pathogenic agents (e.g. bacteria or bacterial endotoxins) in the gut leaking into blood circulation.

The research, which was led by a team from Monash University, found this situation may lead to more serious clinical implications such as sepsis if the body’s immune system can’t cope with these pathogens in the blood. EIGS mimics similar health conditions such as ischaemic bowel disease, irritable bowel syndrome, and inflammatory bowel disease.

Published in Temperature(link is external), the study found that a rise in core body temperature to 39°C, and above, from two hours of exercise in hot conditions can predict the onset of gut damage and the movement of pathogens from the gut into the bloodstream, as part of EIGS.

As core body temperature increased, the extent of gut damage, bacterial endotoxin, systemic inflammatory responses, and gut symptoms also rose.
Lead author Kayla Henningsen, a dietitian and exercise gastroenterology PhD candidate at Monash University’s Department of Nutrition, Dietetics and Food, said EIGS could occur during sports activities or even work.

“Physically demanding fields, such as the mining industry, military, agriculture and firefighting services, are notorious for not only the exertional activity required to fulfil the role of the occupation but also for the potential of heat exposure,” Henningsen said.

“Occupations that require high levels of physical labour while being exposed to extreme heat conditions could also experience gut symptoms from exertional-heat stress, leading to an increase in the risk of systemic shock, infections in the bloodstream, or even death if not treated appropriately.”

EIGS can occur when prolonged exertion in the heat diverts blood flow to the body’s periphery (e.g., limbs) to help cool the body. This causes the wall of gut cells to break and open as less blood is surrounding the gut and providing the cells with the nutrients they need to stay tightly sealed.

Toxins and microbes can then move from the gut into the bloodstream, causing EIGS symptoms such as nausea, vomiting, diarrhoea, and possibly a full-body inflammatory response, or even death if left untreated.

Organisations that require physically laborious work duties to be performed in the heat must be aware of the health risks involved for their staff, according to Henningsen.

“If physically demanding work is performed in the heat for prolonged durations (two hours and beyond), staff are at risk of gastrointestinal damage which if left untreated can progress into detrimental health outcomes,” she said.

“The key to mitigating these effects is to prevent gastrointestinal disruption from occurring in the first place. By ensuring that adequate blood flow remains around the gut we can minimise the risk of gastrointestinal leakage occurring.”

To do this, Henningsen recommended individuals that who perform a physically laborious activity in hot conditions consume foods rich in carbohydrates before and during the physical activity.

“Ensuring that carbohydrate-rich foods are present within the gut during the exertional-heat stress allows for gastrointestinal integrity to be maintained and prevents pathogens from moving from the gut into the bloodstream,” said Henningsen, who also noted that while all parts of Australia were hot for part of the year, those working in temperate climates such as Queensland, Northern Territory and Western Australia could be at even greater risk.