Gastroenteritis (“stomach flu”) is a term that refers to gut inflammation – the stomach, small intestine, and colon -- caused by a virus, bacteria, parasite, or fungus. Globally, the burden of disease for gastroenteritis caused by norovirus alone is 685 million. There are over 179 million cases in the United States each year. As gut issues are a common complaint in functional medicine and integrative medicine practices, we break down the causes, symptoms, risk facts, and management approach from a root-cause perspective.

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What Causes Gastroenteritis?

Inflammation of the stomach, large and/or small intestine occurs when a pathogen – usually a virus or bacteria – attacks the tissue lining. The inflammatory response is the way in which these cells attempt to fight the pathogen and prevent widespread damage.

In both children and adults, norovirus is the most common pathogen, causing up to 20 million cases in the US a year. In children, most gastroenteritis is viral, typically norovirus or rotavirus. In adults, the most common pathogens are norovirus, adenovirus, Campylobacter, salmonella, shigella, E.coli, yersinia, and giardia. Notable, adenovirus causes both respiratory (coughing and sneezing) and gut symptoms. Most hospital-acquired gastroenteritis is caused by Clostridium difficile. COVID-19 can also present with gastroenteritis. Occasionally, accidental or prescribed drug/medication ingestion can cause gastroenteritis symptoms.

Gastroenteritis of viral or bacterial origin is highly contagious and spreads through contact hand-to-mouth with an affected individual. It can also be “foodborne” in origin, i.e. acquired through contaminated food.

Symptoms of Gastroenteritis

Acutely, gastroenteritis can cause the following symptoms:

• Abdominal pain & cramping
• Nausea and vomiting
• Diarrhea (with or without blood and mucus)
• Fever
• Mild dehydration and mild electrolyte (sodium, chloride, and potassium) disturbances
• Appetite loss
• General malaise and fatigue

In rare cases, usually secondary to either moderate to severe dehydration (with electrolyte imbalance) or severe multi-system involvement (sepsis), gastroenteritis can be severe enough to lead to hospitalization. Pregnant women, immunocompromised individuals, infants, and older adults are at the highest risk for severe complications. Hemolytic Uremic Syndrome is a severe, multi-system complication of E. coli gastroenteritis.

Risk Factors for Gastroenteritis

Exposure to the causal pathogen remains one of the main risk factors for gastroenteritis. Other risk factors and high-risk groups include:

• Close contact (e.g. living and/or working in close quarters)
• Immunocompromise (e.g. chronic illness such as diabetes, chemotherapy, HIV/AIDS)
• Older age (secondary to chronic disease and a weakened immune system)
• Pregnant women (secondary to a weakened immune system)
• Infants (secondary to weaker immune systems), especially premature infants
• Young children/toddlers (secondary to daycare exposure, weaker immune systems, the likelihood of hand-to-mouth contact with contaminated objects)
• Travel (“travelers diarrhea”) due to exposure to foreign pathogens/contaminated food

While gut permeability has been theorized as increasing the risk of gastrointestinal disturbances such as gastroenteritis, there is no clear evidence supporting this currently.

Preventing Gastroenteritis

Handwashing and safe food handling (thoroughly washing produce, laundering hand towels and napkins, sanitizing food preparation utensils, and disinfecting cooking surfaces) are all key ways to prevent gastroenteritis. In children under the age of 5, a vaccine for rotavirus (a common cause of gastroenteritis in this age group) can help prevent a large proportion of infections.

Other ways to reduce the risk of severe infection include optimizing lifestyle habits (e.g. sleep hygiene, exercise, movement, stress reduction) can allow the immune system to function optimally if infection occurs.

There is limited evidence supporting supplement use with probiotics and prebiotics as a ‘preventative measure,’ even if these supplements help maintain good overall gut flora.

Conventional Labs for Gastroenteritis

These labs may be ordered by conventional practitioners:

Conventional Stool Test

A conventional stool test may assess ova and parasites but is low yield. Specific pathogens can be tested as well: commonly norovirus, rotavirus, adenovirus, campylobacter, shigella, salmonella, and yersinia.

Serum Electrolytes

Used to assess dehydration, measuring serum electrolytes through a blood test is usually reserved for moderate to severe cases requiring hospitalization.

Functional Medicine Labs to Test for Root Cause of Gastroenteritis

These labs assess for the root causes of gastroenteritis:

Comprehensive Stool Tests

The GI-MAP PCR-based stool test identifies over 50 pathogens of viral, bacterial, parasitic, and fungal origin. This test also measures Zonulin, which is a marker for leaky gut.

The Doctor’s Data Comprehensive Stool Analysis + Parasitology is a stool test where the sample is evaluated for bacteria and yeast, infectious pathogens, and parasites. It also tests for antimicrobial susceptibility to prescription and natural agents as well as key markers of digestion, absorption, and inflammation. This information can help determine the causes of gastrointestinal symptoms and chronic conditions.

After symptoms resolve, doctors may want to order an assessment of overall gut health to assess recovery. The GI Effects® Comprehensive Profile from Genova Diagnostics is an in-depth analysis of stool samples to provide a detailed examination of the gut microbiome.

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Conventional Treatment for Gastroenteritis

A conventional approach to uncomplicated gastroenteritis would be supportive – fluid/electrolyte management, diet changes (a simple BRAT diet to start), and symptom (pain and fever) management. In more acute situations requiring hospitalization, IV fluids may be required. These situations may also require antivirals, antibiotics, antifungal and/or anti-parasite medication. In very severe cases, oral or IV steroids may also be needed.

Root Cause Approach to Gastroenteritis

At Rupa, in addition to conventional management, we support looking at the root causes of disease. This includes an assessment of environmental exposures (through contaminated food of infectious contacts), lifestyle (sleep, stress, exercise, smoking), hormonal shifts, and dietary patterns (particularly consumption of highly processed foods, lactose, and gluten).

Nutritional Recommendations

Acutely, a BRAT (Bananas, Rice, Applesauce, Toast) Diet may be most gentle on the gut lining. Then, as part of the healing process and for overall gut health, the anti-inflammatory diet or Mediterranean diet may be adapted to the patient. A high-fiber diet, which provides prebiotics, is also recommended for overall gut health. Probiotics may be useful for gut health but have limited evidence for acute gastroenteritis.

Supplements & Herbs

Ginger, peppermint, and chamomile have some evidence to support acute gastroenteritis and chronic gut health concerns. Herbs like goldenseal do not have strong evidence for use in gastroenteritis. After the acute phase, gut lining repair may be facilitated by L-glutamine.

The evidence for curcumin, fish oil, and acupuncture, all of which can help with chronic gut issues, remains limited for acute gastroenteritis.

Complementary and Integrative Medicine

In the acute phase, an integrative approach to healing gastroenteritis includes fluid replacement, a holistic approach to pain management (e.g. breathwork), acupressure and heat therapy for pain, and plenty of rest.

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Summary

In summary, acute gastroenteritis is a condition that affects millions of adults in the US and is most often caused by viruses and bacteria. It can be prevented by handwashing and careful food preparation, and optimizing gut flora and lifestyle factors can help reduce the risk of disease severity. A functional approach to gastroenteritis includes looking at the root cause factors and may include a wider panel of tests for both pathogens and gut flora that may be protective against severe disease, all of which can help address the condition effectively and help restore overall gut health.