What Is Leaky Gut Syndrome (Intestinal Permeability)?

Leaky gut syndrome (or intestinal permeability) is a condition that affects the lining of the intestines. This can result in symptoms like persistent muscle or joint pain, poor concentration, indigestion, gas, mood swings, nervousness, skin rashes, recurrent bladder or yeast infections, constipation, or anxiety.

However, there is no scientific data in humans that a leaky gut resulting in increased intestinal permeability causes symptoms outside the gastrointestinal (GI) tract. Leaky gut syndrome is considered a theory, rather than a condition traditionally recognized by the general medical community.

Symptoms of Leaky Gut Syndrome

Symptoms of leaky gut include:

• Abdominal pain
• Asthma
• Chronic joint pain
• Chronic muscle pain
• Confusion
• Gas
• Indigestion
• Mood swings
• Nervousness
• Frequent colds
• Recurrent vaginal infections
• Skin rashes
• Diarrhea
• Recurrent bladder infections
• Poor memory
• Shortness of breath
• Constipation
• Bloating
• Anxiety
• Irritability
• Fatigue

Causes

Potential causes of leaky gut syndrome include:

• Chronic stress
• Intestinal infections
• Small intestine bacterial overgrowth
• Environmental contaminants
• Excess alcohol
• Poor diet
• Nonsteroidal anti-inflammatory drugs (NSAIDs) and other medications

Alternative practitioners sometimes associate leaky gut syndrome with the following conditions:

• Autoimmune disease
• Celiac disease
• Crohn's disease
• Environmental illness
• Hives
• Acne
• Allergies
• Inflammatory joint disease/arthritis
• Intestinal infections
• Pancreatic insufficiency
• Ulcerative colitis
• Giardia (a parasitic intestinal infection)
• Chronic fatigue syndrome
• Eczema
• Psoriasis
• Food allergies and sensitivities
• Liver dysfunction
• Rheumatoid arthritis
• Irritable bowel syndrome

The lining of the intestines creates a barrier that normally allows only properly digested fats, proteins, and starches to pass through and enter the bloodstream. It allows substances to pass in several ways.

Chloride, potassium, magnesium, sodium, and free fatty acids diffuse through intestinal cells. Amino acids, fatty acids, glucose, minerals, and vitamins also cross through cells, but they do it by another mechanism called active transport.

There's a third way that substances can pass through. The spaces in between the cells that line the intestines are typically sealed. These tight junctions are called desmosomes. When the intestinal lining becomes irritated, the junctions loosen and allow unwanted larger molecules in the intestines to pass through into the blood. The immune system sees these unwanted substances as foreign (because they aren't usually present in the blood). This triggers an antibody reaction.

When the intestinal lining becomes further damaged, even larger substances, such as disease-causing bacteria, undigested food particles, and toxins, pass directly through the damaged cells. Again, the immune system is alerted, and antibodies and substances called cytokines are released. Cytokines alert white blood cells to fight the particles. This fight produces oxidants, which cause irritation and inflammation throughout the body.

Diagnosis

The standard test for leaky gut syndrome is the mannitol and lactulose test. Both are water-soluble molecules that the body can't use. Mannitol is easily absorbed by people with healthy intestinal linings. Lactulose is a larger molecule and is only slightly absorbed.

For the test, a person drinks a mannitol and lactulose solution. Urine is collected for six hours, and the amount in urine reflects how much of each was absorbed by the body.

A healthy test shows high levels of mannitol and low levels of lactulose. If high levels of both molecules are found, it indicates a leaky gut condition. If low levels of both molecules are found, it indicates general malabsorption of all nutrients.

A Word From Verywell

It's important to keep in mind that there is limited research about leaky gut syndrome. It's also important to note that self-treating a condition and avoiding or delaying standard care may have serious consequences. If you're experiencing any symptoms or are concerned about your health, consult your physician.