UC Irvine Study Highlights Critical Link Among High Temps, Aging and Disease Risk

• Aging and extreme heat together weaken gut and immune function.
• The combination heightens risk of illness from a deadly, waterborne bacterium.
• Findings suggest probiotics may help restore immune health in older individuals.

Irvine, Calif., June 24, 2025 — As we age, extreme heat causes many heat-related illnesses that can lead to serious health issues. A new study from the University of California, Irvine’s Joe C. Wen School of Population & Public Health adds to that list.

The UC Irvine researchers have discovered that the combined effects of aging and heat waves are putting people’s health at greater risk by weakening gut and immune system function, which heightens our risk of infection from a deadly, waterborne bacterium called Vibrio vulnificus that is increasingly found in warmer ocean waters.

With more frequent and intense heat waves and the population continuing to age, this research, published in the journal Science of the Total Environment, offers insight into how these two factors work together to weaken the immune system, damage the gut and elevate the risk of severe infection. The work was supported by the National Institute of Environmental Health Sciences.

As many around the world experience record-breaking June heat waves, the study arrives at a crucial moment in the ongoing effort to understand how rising temperatures affect human health.

“While Vibrio vulnificus infections are already a growing concern in warming coastal regions, our findings show that extreme heat, especially with older individuals, may further compromise the immune system and gut microbiome in ways that make people more susceptible,” said corresponding author Saurabh Chatterjee, PhD, professor of environmental & occupational health, and medicine. “It’s a double hit: Aging weakens immune defenses, and heat stress accelerates that decline.”

Read the full press release in UC Irvine News.