There's Life in Them Thar Guts! Quiz

Answer: cattle

The normal strains of E. coli native to the human intestine are completely harmless, and in fact quite useful. The new and dangerous strains have come to us from other animals. Of course, this is no consolation to those who have died or suffered other serious effects.

Water safety boards have always tested for E. coli, but until the new strains appeared they were only doing so to answer the simple question, "has this water been contaminated with feces, yes or no?"

Answer: all of these

Every time I write a new quiz I make a new discovery! I had long known that Lactobacillus helps us by producing vitamin B and by competitively suppressing yeasts. Only today, when doing an Internet search on this topic, did I find a couple studies, one at the Oklahoma State University and another at the University of Kentucky, which show significant reductions in serum cholesterol by increasing the amount of L. acidophilus in the gut!

Answer: L. bulgaricus

The Bulgars are believed to have invented yoghurt, and the dominant bacterial species in yoghurt culture honours their name. (Western industrial-scale yoghurt manufacture depends more on chemical catalysts and is often poor in bacteria. Yoghurt afficionados believe it's worth spending the money on the traditionally-cultured variety. Not only is it healthier, but you can taste the difference.) L. bulgaricus is one of the top lactase producers in its family. It is, therefore, very helpful to people with lactose intolerance.

Unfortunately, L. bulgaricus cannot survive in your intestine indefinitely; the colonies eventually die out. To keep a healthy L. bulgaricus population going, you should eat yoghurt at least once a week.

Answer: facultative anaerobes(can use oxygen, but can also live without it)

There is a gradual progression. Most aerobes are close to the beginning of the gut, where oxygen is still (relatively) plentiful. As you proceed through the gut and the oxygen is depleted, you find fewer aerobes and more anaerobes. The facultative anaerobes, of course, can live at both ends and are thus the most common. Escherichia, Listeria, Staphylococcus and many other common intestinal bacteria are facultative anaerobes. So are most internal yeasts.

Answer: Bifidobacterium

The composition of probiotic cultures varies, but from the above list only Bifidobacterium is a plausible answer. Yersinia, Treponema, and Mycoplasma are all harmful, disease-causing bacteria that you would not deliberately ingest. Bifidobacterium is growing steadily in popularity; there is a growing body of evidence that it helps to prevent allergies and other autoimmune disorders.

Besides the digestive tract, Bifidobacterium is also present in human breast milk, which may be one of the reasons breast-fed babies are healthier than bottle-fed babies.

Answer: probiotics might be a big waste of money

No, you can rest assured that there are no serious health risks associated with probiotic cultures. About the worst thing ever reported is sometimes a mild case of diarrhea. The main reason to be cautious is that they might not do anything at all, and being expensive they might waste your money.

The bacteria in your system have been there a long time; many of your internal bacterial colonies are descended from colonies in your mother's vagina and have been with you since birth. They are well evolved to living in your particular body chemistry. New-comers have a hard time adapting; the strains in the probiotic tablets are bred from colonies that lived in cheese and yoghurt and have never seen the inside of a human body. There is much evidence that they just can't compete with the natives and soon die off. So, while probiotics won't hurt you in any way, they might not help much, either. The key word there is "might" -- if you've tried them and found them helpful then by all means carry on!

Answer: Listeria

All of the above are bacteria named after scientists, but Lister is the only one who was British. S. Burt Wollbach was American, Nancy Millis was Australian, and Edwin Klebs was German.

Listeria can cause serious diseases, but most of the time is relatively harmless. About 10 percent of the average person's intestinal flora is composed of Listeria species, especially L. monocytogenes.

Answer: yeast

Like most of our internal flora, Candida is harmless at normal population levels. It only becomes a problem when it breeds out of control. But how much of a problem? Mainstream doctors do not believe that Candida in the intestine has any serious effects. (External Candida overgrowth is a recognized medical problem known as "thrush", but in this quiz we are only dealing with intestinal flora.)

Naturopaths are far more adventurous in their opinions, sometimes blaming Candida for everything from migraine headaches to chronic fatigue syndrome to colon cancer. Some of these allegations are based on no evidence whatsoever. Nonetheless, I wouldn't completely dismiss Candida as a suspect in some health problems.

Candida loves sugar and is in direct competition with Lactobacillus; a good, strong population of Lactobacillus is the best way to prevent Candida overgrowth. (There's that yoghurt again!) If an overgrowth has occurred, the traditional folklore remedy is garlic, and lots of it.

Answer: C. difficile

Two of these (tetani and botulinium) have their diseases in their name, so even if you didn't know, you had a 50/50 choice between perfringens (the cause of gas gangrene) and difficile (which sometimes causes pseudomembranous colitis, but most of the time is benign.)

C. difficile most often breeds out of control and causes colitis when we use antibiotics. Because it is less sensitive to antibiotics than other bacteria, a time of antibiotic therapy is a golden opportunity for Clostridium to expand.

Answer: Saccharomyces

The French scientist Henri Boulard saw the natives of Indochina chewing lychee nuts to control cholera. He investigated and isolated the yeast involved, which is called Saccharomyces boulardii in his honour. This yeast is absolutely incredible in its ability to suppress harmful bacteria in our guts. It has been found effective against Clostridia, Vibrio, Salmonella, and others.

Virtually all the different species of Saccharomyces, including the ones that are used to brew beer, are often found in the human digestive tract. However, they are usually present in fairly small numbers, so when more is needed (as in the case of S. boulardii) concentrated cultures are administered.

This example is one of many that show the inter-relatedness of our internal flora. There are 500 or more species living in the average person's gut, all competing in a delicate balance. As long as all stay in balance, we are healthy. The problems occur when one species is impaired, allowing another to grow to unreasonable populations.