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Hot Weather Can Increase Risk of IBD Flares and Other Stomach Woes


Inflammatory Bowel Disease (IBD) is a broad term that describes a condition of inflammation in the gastrointestinal tract. The two most common conditions are ulcerative colitis and Crohn’s disease. As many as 1.4 million persons in the US suffer from these diseases and it is one of the top gastrointestinal disease burdens in the United States with an overall health care cost of more than $1.7 billion.

The cause of IBD is unknown, but thought to involve a combination of genetic, immunologic and environmental factors.

One environmental factor never before discussed is climate change. Could hotter weather make IBD symptoms worse? Researchers with University Hospital in Zurich, Switzerland believe so.

Gastroenterologist Christine Manser and her team reviewed the hospital’s admission records over a five-year period, which included 17 heat waves – defined as any period of six or more days with high temperatures rising above the average daily high by more than 9 degrees Fahrenheit. A total of 738 patients with Inflammatory bowel disease and 786 patients with infectious gastroenteritis were admitted during these hot spells. A control group of 506 people hospitalized for noninfectious GI problems were used as comparison.

Periods of extreme hot weather led to a 4.6% increase in risk of people needing to be hospitalized with a relapse of inflammatory bowel disease for every additional day the heat wave lasted. There was also a 4.7% increased risk of people sickened by infectious gastroenteritis, an inflammation of the stomach and intestines caused by a bacteria or virus with symptoms that include vomiting and watery diarrhea in addition to fever, abdominal cramps, nausea and headache.

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Dr. Manser says that several potential mechanisms may explain this phenomenon. The heat waves could induce physical stress, which has been shown to cause flares of IBD. For IG, heat can change the bacterial composition of the GI tract which leads then to symptoms.

This study did not include patients with Irritable Bowel Syndrome, an unrelated illness that involves a functional problem with the GI tract that causes symptoms such as abdominal pain or discomfort (cramping), diarrhea, constipation, or both. But a search of IBS online support discussion boards finds that many people do report symptoms worsening during high heat.

Could this be related as well? Perhaps, as stress plays a role in IBS as well plus one cause of irritable bowel is thought to be an imbalance of gut bacteria.

The high heat of summer is actually responsible for many illnesses and deaths each year in the United States. During extremely hot and humid weather, the body’s ability to cool itself is affected, which can lead to fluid loss and dehydration, heat cramps, heat exhaustion, and heat stroke.

To stay safe in the heat, the National Weather Service offers the following tips:
• Slow down. Reduce, eliminate or reschedule strenuous activities until the coolest time of the day. Children, seniors and anyone with health problems should stay in the coolest available place, not necessarily indoors.
• Dress for summer. Wear lightweight, light-colored clothing to reflect heat and sunlight.
• Put less fuel on your inner fires. Foods, like meat and other proteins that increase metabolic heat production also increase water loss.
• Drink plenty of water, non-alcoholic and decaffeinated fluids. Your body needs water to keep cool. Drink plenty of fluids even if you don't feel thirsty. Persons who have epilepsy or heart, kidney or liver disease, are on fluid restrictive diets or have a problem with fluid retention should consult a physician before increasing their consumption of fluids. Do not drink alcoholic beverages and limit caffeinated beverages.
• During excessive heat periods, spend more time in air-conditioned places. Air conditioning in homes and other buildings markedly reduces danger from the heat. If you cannot afford an air conditioner, go to a library, store or other location with air conditioning for part of the day.
• Don't get too much sun. Sunburn reduces your body's ability to dissipate heat.
• Do not take salt tablets unless specified by a physician.

Journal Reference:
Christine N. Manser MD et al. Heat Waves, Incidence of Infectious Gastroenteritis, and Relapse Rates of Inflammatory Bowel Disease: A Retrospective Controlled Observational Study. Am J Gastroenterol advance online publication 13 August 2013; doi: 10.1038/ajg.2013.186

Additional Resources:
Center for Disease Control and Prevention
National Weather Service, Office of Climate, Water and Weather Services