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Intestinal fermentation

So the idea of a yeast-like gut pathogen that lives on starches and sugars and causes bowel disturbance is far from new. It seems to enjoy a vogue in medical circles every few decades and then lapses out of sight once again. The reason is probably that, as in the 1980s, some doctors become convinced they know what causes the syndrome, but then can’t seem to a workable proof that affords a satisfactory explanation. This casts doubt on the basis of the theory.

So it is today with ‘Candida.’

One thing is certain, there is virtually no correlation between Candida in the stool sample and the existence of the ‘yeast syndrome.’ Indeed, Candida albicans is rarely identified in specimens, despite its known very wide occurrence. This lack of correlation is disappointing but hardly surprising, especially if we are looking for the wrong culprit.

It is true that treatment directed towards this type of organism can be highly effective in selected individuals, so clearly a real phenomenon exists. But that doesn’t prove that Candida is the true culprit and I want to make sure readers do not fall into this logical trap. In fact I’d like to set the debate alight with the claim that the culprit may not be Candida at all, or that Candida is only one of many potential suspects.

Other available flora that might be at work include the yeasts of the genus Saccharomyces (food yeasts), many different types of bacteria, viruses, protozoa, parasites and other strange organisms calledarchea. In fact I would like to suggest this whole thing is never just one organism, but many.

On-board Brewery

Historically, Sarcina ventriculata is an important organism. In the old days, when surgeons operated in top hats and frock coats, often smoking a cigar while they butchered, once in a while they would literally blow up their patients as the alcoholic gases generated by Sarcina were released from the patient’s stomach when cut open; the cigar would ignite the fumes and a fireball was the disastrous result!

These ‘on-board breweries’ are probably quite common. In the early 80s we began to realize that an individual could present with quite high levels of blood alcohol and yet be a non-drinker. There have been several celebrated cases, including one of my own, in which individuals who were guilty of driving under the influence of alcohol were able to show they had not been drinking but that they did have significant infections with Candida and so escaped the laws.

It may help to do a carbohydrate fermentation test: to fast, followed by a challenge dose of fermentable sugars, and serial blood tests. This will show if the sugars are being fermented or not.

But just as Candida isn’t the only contender for the role of pathogen, ordinary ethyl alcohol is not the only product of biological fermentation we seem to be dealing with. Many other substances can be derived from the breakdown of sugars and starches, including tartaric acid and short-chain fatty acids such as acetate, proprionate, succinate and butyrate, and other alcohols such as iso-propanol, butanol and 2,3-butylene glycol. Testing for these substances is now available commercially in certain centers and may provide useful insights.

Of course it is not just about what the body produces on board but the further fate of these compounds. Such substances should be swiftly eliminated by the detoxification process. But if detoxification pathways are blocked due to overload, many other non-alcohol but equally unwanted metabolites will accumulate, such as epoxides, aldehydes and even chloral hydrate, the potent ingredient of the classic ‘Mickey Finn’. Typically this chemical produces a tired and ‘spacey’ feeling. Here is at least part of the reason these patients can’t take alcoholic drinks.

The hydrogen breath test will also reveal compounds in exhaled air which can give a clue to the state of bowel flora.

Breath hydrogen test

In Man, only anaerobic bacteria in the colon are capable of producing hydrogen in our bodies. They do this by fermenting sugars, such as lactose, sucrose, sorbitol, fructose, lactulose etc. (depending on the purpose of the test). The hydrogen enters the bloodstream and is outgassed via the lungs. This gives rise to the possibility of testing breath for hydrogen content as a means of estimating bacterial activity in the colon.

Prior to hydrogen breath testing, individuals fast for at least twelve hours. At the start of the test, the individual blows into a balloon, filling the balloon. The concentration of hydrogen is measured in a sample of breath removed from the balloon. The individual then ingests a small amount of the test sugar. Additional breath samples are collected and analyzed for hydrogen every fifteen minutes for three to five hours.

Any significant production of hydrogen means that there has been a problem with digestion or absorption of the test sugar and that some of the sugar has reached the colon.

When rapid intestinal transit is present, the test dose of nondigestible lactulose reaches the colon more quickly than normal, and, therefore, hydrogen is produced by the colonic bacteria soon after the sugar is ingested. When bacterial overgrowth of the small bowel is present, ingestion of lactulose results in two separate periods during the test in which hydrogen is produced, an earlier period caused by the bacteria in the small intestine and a later one caused by the bacteria in the colon.

The short-chain fatty acids in the stool and urinary metabolite panel also referred to should help in firmly establishing that something is definitely wrong.