MM: I have always wondered why I seemed to react so negatively when I am taking lots of probiotics. Many probiotics that I’ve seen and taken contain maltodextrin (a type of sugar) as a filler ingredient. Well, I just learned that maltodextrin has a glycemic index that is HIGHER than pure glucose. This is BAD, if your blood sugar regulation is off.
Polly: Some have dextrin in them, which is also a type of sugar. Lactose is milk sugar, and you might find this in some products too. If you are sensitive to it, be careful. Read labels thoroughly. I found one product with added corn syrup. The company had the audacity to label the product hypoallergenic. If you can tolerate undenatured whey or lactoferrin, these also support the growth of favorable bacteria and they don’t have sugar in them. Some products will put in fructo-oligosaccharides (FOS) as food for the bacteria. Not everyone will be able to tolerate the FOS either.
Fructo-oligosaccharides (FOS), Oligofructose, and Inulin
Polly: Fructo-oligosaccharides (FOS) are included in many probiotic preparations as a food for bacteria. Be careful when using FOS. Although it has some highly beneficial properties, it is not perfect for everyone. It has made several of our forum members sicker.
FOS is a sweet tasting carbohydrate found in foods such as onion, garlic, artichoke, asparagus and lettuce. Certain bacteria can break down FOS into sucrose (a type of sugar) and used it to fuel their growth. Humans are unable to breakdown or absorb the FOS, so it will usually reach the colon to feed the bacteria there. However, if you have an overgrowth of bacteria in the small bowel, where the bacteria do not belong, then the FOS might feed this bacteria and make you sicker.
FOS increases the growth of Bifidus bacteria. For some people this is wonderful. Bifidus bacteria excrete chemicals that may keep other less desirable bacteria from growing.  Also the Bifidus keeps the colon more acidic, which reduces the amount of ammonia absorbed.  Unfortunately, FOS can feed some bacteria that are harmful; Klebsiella, Bacteroides fragilis, and peptostreptococci bacteria will grow on FOS.  Baker’s yeast will grow on FOS, and therefore there are probably many other types of yeast that can use it too.  Therefore, if you try FOS, watch your reactions closely, and/or get tested for the type of bacteria present and their location. If you want to test your reaction to just the FOS, Allergy Research/Nutricology makes a supplement of just FOS. Or try a product without FOS first and compare your reaction to a product that has FOS.
Sometimes product labels will state that they contain inulin or oligofructose. These are just different forms of FOS. Oligofructose has fewer degrees of polymerization than does inulin. Because of the higher degree of polymerization, the inulin is probably the better product; it will likely have less plain fructose in it.
Here are some articles from the American Journal of Clinical Nutrition and the Journal of Nutrition on the subject of FOS and inulin.
“Prebiotics and probiotics: are they functional foods?” by Marcel B Roberfroid. June 2000
“The Effect of Synbiotics on Colon Carcinogenesis in Rats” by Daniel D. Gallaher2 and Jinmo Khil. 1999
“Possible Mechanisms by Which Pro- and Prebiotics Influence Colon Carcinogenesis and Tumor Growth” by Bandaru S. Reddy. 1999
“Dietary Modulation of the Human Gut Microflora Using the Prebiotics Oligofructose and Inulin” by Glenn R. Gibson, 1999
These carbohydrates appear to increase the Bifidus bacteria population faster than pathogenic bacteria like Clostridia. Unfortunately, those with the yeast syndrome or fibromyalgia have a poorer flora to start with, and therefore might have a different reaction to FOS or inulin than the test subjects in these studies.