Gut Function Profiles
The gut is a major primary interface between the individual and the environment. Disturbances in gut function can result in devastating ill health effects on the individual. Increased gut permeability can cause absorption of potentially toxic dietary substances and products of incomplete digestion, which are regarded by the body as foreign substances requiring 'attack' when in fact with adequate digestion and normal permeability they would not compromise optimum function. Abnormal gut flora also results in the production of toxic substances which may reduce the level of patient health.
Breath hydrogen (and methane) in the assessment of gut function
For small intestinal bacterial overgrowth and intestinal motility, or, using a different protocol, for lactose malabsorption.
General method using lactulose
[Patient should ideally attend the laboratory for all of these tests. No food from midnight the previous evening]
June 2009 update - We are now offering breath hydrogen test kits for patients to use at home to collect their breath samples for analysis. If you would like further details please see the appropriate instruction sheets (below) or contact us directly (info@biolab.co.uk).
Standard tests using lactulose for small intestinal bacterial overgrowth Download home testing kit instructions
Test for lactose intolerance Download home testing kit instructions
Test for fructose intolerance Download home testing kit instructions
Sample report (lactulose breath hydrogen)
D-lactate in blood
The presence of D-Lactate (D-lactic acid) in the blood is a reflection of bacterial overgrowth in the gastro-intestinal tract. D-lactate is not metabolised by mammals and its elimination from the body depends mainly on renal excretion.
D-lactate is produced from non-absorbed carbohydrates by colonic bacteria (which may also proliferate in the ileum).
The D-lactate test is specific for the presence of D-lactate-producing bacteria in the gut (probably Enterococcus and Streptococcus spp.).
[Grey top fluoride oxalate tube - sample should reach Biolab within 24 hours of collection]
PEG 400 as a probe for the investigation of intestinal permeability was first proposed in 1977. The rationale was that PEG (polyethylene glycol) contains a mixture of inert, water-soluble molecules of different sizes, whose absorption is independent of dosage, displaying decreasing mucosal transport with increasing molecular size. PEG 400 is also nontoxic, not degraded by intestinal bacteria, not metabolised by tissues, and rapidly excreted in the urine. PEG is polymerised ethylene oxide and is not the substance - ethylene glycol – which is found in anti-freeze.
Patients are given a 3gm oral dose of PEG and collect all urine passed for the following 6 hours. We then measure the PEG at 11 different molecular weights in the urine to establish the quantity of each absorbed through the gut wall. The results are reported graphically; results above the upper reference limit are suggestive of increased permeability, those below the lower reference limit suggest malabsorption.
Patentst should fast for 3 hours before starting the test, limit water intake and observe the pre-test precautions detailed in the patient instruction sheet (see below). A 20 mL aliquot of urine may be sent for analysis if the volume of the total collection can be accurately measured.
Postal samples must reach Biolab within 3 days of collection.
Gut Permeability - patient instructions
Sample report - Gut Permeability Profile
The patient is given 1 gramme of glucose in hardened gelatine capsules (2 x 500mg capsules) with 4 grammes of glucose dissolved in 80-100ml of water. The glucose solution prevents the capsules from disintegrating in the stomach and this ensures that an adequate amount of glucose passes into the duodenum. A blood sample is taken one hour later and the plasma is analysed for simple and complex alcohols along with short chain fatty acids. Comments are added when abnormalities of bacterial fermentation or a possible yeast overgrowth are indicated by the results.
[Grey top fluoride oxalate tube (DO NOT USE ALCOHOL SWAB), No food for 3 hours and no alcohol for 24 hours before the test, kit available from the laboratory]
Sample report - Gut Fermentation Profile
Biolab Publications:
Abnormal gut fermentation: Laboratory studies reveal deficiency of B vitamins, zinc and magnesium Eaton KK, Mclaren-Howard J, Hunnisett A, Harris M. J.Nutr. Biochem. 1993;4:635-638 Abstract
Gut fermentation (or the 'Autobrewery') Syndrome: A New Clinical Test with Initial Observations and Discussion of Clinical and Biochemical Implications. Hunnisett A, Howard J, Davies S. J.Nutr.Med. 1990;1:338. Abstract
Short-chain polypeptides (SCPPs)
Many hormones, cytokines, chemotactic agents and CNS-active metabolites are SCPPs. These substances are also produced during incomplete digestion of proteins. They are relatively small molecules and are easily absorbed into circulation where they can mimic hormones and moderators of immune function. They can also affect CNS metabolism and further disturb endocrine function through inappropriate feedback signals to the pituitary.
There are too many of these substances to measure them individually. The results are reported as the total concentration of SCPPs for each group according to the number of amino acids. Reference ranges are provided for adult males, adult females and for pre-puberty children aged 3 years and over. The test is not appropriate for babies.
A heparinised blood sample is taken 1-to-2 hours after a meal that includes proteins. The foods chosen should reflect the usual main meal of the day and have regard for any dietary restrictions already in place. Failure to do this can lead to false negative findings.
Increases in SCPPs are associated with digestive problems and/or increased gut permeability. However, raised levels are sometimes found in patients without any clinical evidence of gut dysfunction.
Indications for the test include unexplained endocrine disorder and immune dysfunction as well as digestive/permeability problems.
[Green heparin tube taken 1.5 - 2 hours after a protein containing meal - "normal" meal]
Trace and toxic elements and related functional tests