Desmond Leddin, MB, MSc, on the Impact of Climate Change on GI Health

Scientific consensus holds that Earth’s average surface temperature has been rising since the late 19th century—a change driven largely by increased carbon dioxide and other greenhouse gases. A new article, published in Journal of Clinical Gastroenterology, explored the relationship between climate change and gastrointestinal (GI) health.¹

Lead author on the paper, Desmond Leddin, MB, MSc, who is an adjunct professor of medicine (gastroenterology) at Dalhousie University in Halifax, Nova Scotia, and chair of the World Gastroenterology Organization research committee, spoke to Gastroenterology Consultant about his paper.

GASTRO CON: How has climate change effected health, specifically GI health, in people today?

Desmond Leddin: One of the characteristics of climate change is that it exaggerates the typical weather conditions in a region. All of the heat energy going into the atmosphere supercharges the atmospheric environment and tends to make weather events more extreme. Increased severity of storms, wildfires, and flooding will be associated with health care infrastructure disruption. Gastroenterology care is infrastructure-intense and GI care can be disrupted by infrastructure loss.

There is a large volume of literature on health, a large volume on climate change, and recently increasing literature exploring the connections between the two. So far, our understanding of the impacts of climate change on GI health is in its infancy. The effects on food and water security are obvious areas of vulnerability. Global production of most crops is projected to decrease as temperature rises, which may result in rising prices and difficulty accessing balanced nutrition for some populations.

Increased rainfall events can overwhelm drainage systems, resulting in contamination of drinking water and in enteric infections. This has been reported in North America as well as in developing countries. Changes in disease patterns include an increasingly favorable environment for Vibrio cholerae in the northeastern United States, as water temperature increases. It is difficult to know how significant a threat this might be, but at least we should be aware of it. There are no specific signals yet on the effect a warming environment will have on the gut microbiota or on common GI diseases such as inflammatory bowel disease or colon cancer.

GASTRO CON: In addition to a rise in global temperatures, climate change has been implicated in causing more, and more extreme, weather events, as you mentioned. How can these kinds of conditions affect GI health and the nutrition that some patients may require?

DL: Parts of the United States were prone to drought even before the onset of significant global warming. This will become more pronounced. Drought affects GI health by decreasing crop production and increasing water stress. Drought also creates conditions favorable for wildfires, as we have seen very recently in Canada and the United States. Wildfires can cause severe disruption to health services, and lead to considerable loss of life in humans and livestock.

Prolonged dry periods in summer will contrast with a greater risk of spring flooding. Flooding can contaminate drinking water supplies with a variety of enteric pathogens. Although winters are projected to be milder, heavy snowfall events may be more frequent. Warmer air holds more moisture and can precipitate as heavier amounts of snow.

All of North America is projected to warm. Milder winters in the northern United States and Alaska and hotter summers will be the norm, especially in the southwest United States. Precipitation is projected to increase in much of the US and Canada but decrease in the southwest United States. The risk of high-precipitation events will vary by region and season.

GASTRO CON: How might climate change affect not only the supply of food in general, but also the availability of specific types of foods (such as whole grains, fruits, and vegetables) necessary for GI health?

DL: Climate change will negatively affect crop production, especially from mid-century on. Effects will vary by region and crop, but unfortunately, a warming climate and increased rainfall—which might be expected to increase growth—may not result in a benefit when other factors are taken into account. Climate change will stress food supply rather than enhance it. Increased variability in crop yields from year to year will inevitably lead to fluctuations in prices, which will affect the ability of underserved communities to access optimal nutrition

GASTRO CON: What are the implications of climate change for the long-term health of specific populations, such as children, underserved communities, or patients with comorbidities?

DL: North America, by virtue of its wealth and variety of climate zones, may avoid some of the worst manifestations, at least in the short term. The impact of climate change has been, and will continue to be, most severe in the developing world.

Climate change impacts the fundamental human needs for adequate clean water, food, and shelter. When individuals lose access to these basics, they often migrate to areas where they can meet these needs, such as the United States and Canada. The GI needs of migrant populations will need to be addressed, but the United States is already a multicultural society, and physicians are familiar with most of the diseases they are likely to encounter among migrants. Health care coverage for undocumented migrants will need to be addressed

The major health impacts of climate change are heat stress, cardiovascular, renal, and respiratory diseases. Individuals with comorbidities that affect these systems may experience worsening outcomes. Children and the elderly are particularly vulnerable to heat stress, and care needs to be taken to ensure that they have access to a cooler environment. One of the main risks to underserved communities will be access to a nutritious diet, as global and national prices may rise.

GASTRO CON: In your opinion, what role should gastroenterologists in the United States play in addressing the issue of climate change and its impact on their patients?

DL: The most important things that gastroenterologists in the United States can do is to educate themselves on climate change, recognize that it is a threat to GI health (especially nutrition), and advocate for increased action by their national peer GI groups on the issue. It is vital to educate politicians and help them move the public to a place where action is accepted.

The primary role of gastroenterology at this point is to advocate for recognition of the threat and for solutions. Physicians are strong role models. The greening of gastroenterology practices and of endoscopy and colonoscopy centers—by reducing energy and water use, careful disposal of hazardous wastes, and using sustainable practices in every aspect of operation—sends an important message to patients, the public, and politicians, and is a good first step in creating the climate for change.

Reference:

1. Leddin D, Macrae F. Climate change: implications for gastrointestinal health and disease. J Clin Gastroenterol. 2020;54(5):393-397. https://doi.org/10.1097/mcg.0000000000001336