Jejunum Health: Function, Disorders & Tips

What Is the Jejunum?

The jejunum is the middle section of the small intestine, located between the duodenum and the ileum. It accounts for approximately two-fifths of the total length of the small intestine, measuring roughly 2.5 to 3 metres in length. The jejunum plays a central role in digestion and the absorption of nutrients from food into the bloodstream. Maintaining a healthy jejunum is therefore essential for overall well-being, energy levels, and the adequate supply of vital nutrients throughout the body.

Functions of the Jejunum

The jejunum performs numerous critical functions within the digestive system:

• Nutrient absorption: Carbohydrates, proteins, fats, water-soluble vitamins (e.g. B vitamins, vitamin C), and minerals are primarily absorbed in the jejunum.
• Enlarged absorption surface: The mucosa of the jejunum is rich in circular folds (plicae circulares), villi, and microvilli, expanding the surface area to up to 200 square metres.
• Peristalsis: Rhythmic muscular contractions propel the food bolus (chyme) forward through the intestine.
• Digestive enzyme production: Mucosal cells of the jejunum produce enzymes that assist in the breakdown of nutrients.

Factors Affecting Jejunum Health

Diet and Nutrition

A balanced, fibre-rich diet promotes a healthy intestinal mucosa and supports optimal jejunum function. Dietary fibre serves as a fuel source for beneficial gut bacteria and helps maintain the intestinal barrier. Highly processed foods, alcohol, and nutritionally poor diets can damage the jejunal mucosa and impair nutrient absorption.

Gut Microbiome

The microbiome of the small intestine -- the collective community of microorganisms residing in the jejunum -- significantly influences mucosal integrity, immune function, and nutrient availability. An imbalance in the gut flora (dysbiosis) can promote inflammation and reduce the absorptive capacity of the jejunum.

Inflammation and Disease

Several medical conditions can directly affect the health of the jejunum, including:

• Coeliac disease: An autoimmune reaction to gluten that damages the intestinal villi and severely impairs nutrient absorption.
• Crohn disease: A chronic inflammatory bowel disease that can affect all parts of the gastrointestinal tract, frequently involving the small intestine including the jejunum.
• Short bowel syndrome: Develops following surgical removal of large sections of the small intestine, leading to significant absorption deficits.
• Small intestinal bacterial overgrowth (SIBO): An excessive proliferation of bacteria in the small intestine that can cause bloating, diarrhoea, and nutrient deficiencies.

Symptoms of Impaired Jejunum Function

When the jejunum is not functioning optimally, the following symptoms may occur:

• Chronic diarrhoea or fatty stools (steatorrhoea)
• Unintended weight loss and malnutrition
• Nutrient deficiencies (e.g. iron, folate, vitamin B12)
• Abdominal pain and bloating
• Fatigue and general weakness
• Anaemia

Diagnosis of Jejunal Disorders

Examining the jejunum requires specialised diagnostic procedures, as the middle section of the small intestine is difficult to reach with standard gastroscopy or colonoscopy. The following methods are commonly used:

• Capsule endoscopy: The patient swallows a small camera capsule that captures images as it travels through the intestine.
• Double-balloon enteroscopy: A specialised endoscope allows direct visualisation and biopsy of the small intestine.
• Imaging techniques: MRI enterography or CT enterography provide detailed views of the small intestine from outside the body.
• Blood and stool tests: Used to identify nutrient deficiencies, inflammatory markers, and signs of malabsorption.

Supporting Jejunum Health

There are several measures that can actively support the health of the jejunum:

• Balanced diet: Plenty of fruits, vegetables, whole grains, and high-quality proteins promote mucosal health.
• Probiotics and prebiotics: These can positively influence the small intestinal microbiome and strengthen the gut barrier.
• Adequate hydration: Water and low-calorie beverages support digestion and nutrient transport.
• Avoiding harmful substances: Alcohol, nicotine, and certain medications (e.g. NSAIDs) can irritate the small intestinal mucosa.
• Stress management: Chronic stress can affect the motility and barrier function of the small intestine via the gut-brain axis.
• Regular medical check-ups: Persistent digestive complaints should be assessed by a healthcare professional at an early stage.

References

1. Longo, D. L. et al. (eds.): Harrison's Principles of Internal Medicine, 21st edition. McGraw-Hill Education, 2022.
2. World Health Organization (WHO): Nutrition and Food Safety. Available at: https://www.who.int/health-topics/nutrition (accessed 2024).
3. Sleisenger, M. H. & Fordtran, J. S.: Gastrointestinal and Liver Disease: Pathophysiology, Diagnosis, Management. 11th edition. Elsevier, 2021.