There is ample documentation for a therapeutic role of metronidazole and other antibiotics in Crohn's disease and rheumatoid arthritis[90-98]. The mechanism underlying the response has been in dispute. In the case of tetracyclines, one group has asserted that mycoplasma in the joints cause rheumatoid arthritis, others have countered this argument by demonstrating that minocycline is directly immunosuppressive in vitro [99]. Because all patients with arthritis have used NSAIDs, and because NSAID enteropathy is associated with bacterial senisitization, it is possible that the the antibiotic-responsiveness of some patients with inflammatory diseases is a secondary effect of NSAID-induced bacterial sensitization which then exacerbates the Leaky Gut Syndrome. Altering gut flora through the use of antibiotics, synthetic and natural, probiotics, and diet is a third strategy for breaking the vicious cycle in Leaky Gut Syndromes. With regard to diet, patients whose disease responds to vegetarian diets are those in whom the diet alters gut ecology; if vegetarian diets does not alter gut ecology, the arthritis is not improved[100].

Cycle Four: Hepatic Stress
The liver of Leaky Gut patients works overtime to remove macromolecules and oxidize enteric toxins. Cytochrome P-450 mixed-function oxidase activity is induced and hepatic synthesis of free radicals increases. The results include damage to hepatocytes and the excretion of reactive by-products into bile, producing a toxic bile capable of damaging bile ducts and refluxing into the pancreas [4, 5]. In attempting to eliminate toxic oxidation products, the liver depletes its reserves of sulfur-containing amino acids [101]. These mechanisms have been most clearly demonstrated in ethanol-induced hepatic disease [47]. Sudduth [102] proposes that the initial insult is the ethanol-induced increase in gut permeability which creates hepatic endotoxemia. Endotoxemia can further increase permeability, alter hepatic metabolism, and stimulate hepatic synthesis of reactive species which are excreted in bile. This toxic bile, rich in free radicals, further damages the small-bowel mucosa, exacerbating hyperpermeability.

A Practical Approach

Suspect a pathological increase in gut permeability when evaluating any patient with the diseases listed in Table 1 or the symptoms listed in Table 2. Measure permeability directly using the lactulose/mannitol challenge test. Indirect measures of gut permeability include titres of IgG antibody directed against antigens found in common foods and normal gut bacteria. These tests may be useful but cannot substitute for the direct permeability assay, especially when one is following the response to treatment.

IF ALL COMPONENTS OF THE LACTULOSE/MANNITOL TEST ARE NORMAL, repeat the challenge after a test meal of the patient's common foods. If the test meal produces an increase in lactulose excretion (signifying hyperpermeability) or a decrease in mannitol excretion (signifying malabsorption), specific food intolerances are likely and further testing for food allergy is warranted. Once the patient has been maintained on a stable elimination diet for four weeks, repeat the lactulose/mannitol challenge after a test meal of foods permitted on the elimination diet. A normal result assures you that all major allergens have been identified. An abnormal result indicates that more detective work is needed.