Probiotics and Prebiotics 

Probiotics and Prebiotics

Gabe Mirkin, M.D.

There are two absorption systems in your body. Food that is easily 
broken down is absorbed into your upper intestinal tract. If you 
cannot absorb a particular food, it goes to the lower intestinal 
tract (colon), where bacteria in your colon ferment it to smaller 
products that can be absorbed. 

Your colon is loaded with good and bad bacteria. Bad bacteria such 
as clostridia that are kept in check by good bacteria. If you take 
an antibiotic that knocks off the good bacteria, the clostridia can 
overgrow and cause diarrhea. 

The good bacteria break down soluble fiber to form chemicals such as 
short chain fatty acids that are absorbed into your bloodstream and 
travel to your liver where they block the liver from making 
cholesterol and help to prevent heart attacks. These short chain 
fatty acids also reduce inflammation, so they help to control the 
bloody diarrhea and ulcers caused by Crohn's disease. They also 
reduce swelling and pain of arthritis, diabetes and psoriasis, and 
some studies show they may even improve your immunity to help you to 
kill germs. 

If you wish to encourage the growth of good bacteria in your colon, 
you have two choices: probiotics or prebiotics. Probiotics are 
living microorganisms, the good bacteria, that live in the colon and 
reduce inflammation and help prevent and treat Crohn's disease, 
psoriasis, arthritis, and perhaps even certain types of cancers. 
Prebiotics are nondigestible food ingredients that cannot be 
absorbed in the upper intestinal tract and travel to the colon where 
they serve as a medium to encourage the growth of the good bacteria. 

Live-culture yogurt is a readily available source of good bacteria. 
However, the lactobacilli that are in live cultures of yogurt will 
not colonize in your intestines, so they disappear if you stop 
eating yogurt every day. Most yogurt products do not contain live 
cultures; read the labels carefully.

One strain of good bacteria that has been studied extensively and 
has been shown in controlled scientific studies to have the ability 
to colonize in the intestines is called lactobacillus GG. It was 
isolated from intestines of humans by two professors at Tufts 
Medical School named Sheldon Gorbash and his colleague named Golden, 
hence the name lactobacillus GG. They have patented their product 
and make a lot of money from it. 

Several studies show that Lactobacillus GG can help control the 
frequency and severity of infectious diarrhea in children. Diarrhea 
that is often caused by taking antibiotics can be prevented by 
taking either Lactobacillus GG or Saccharomyces boulardii with the 
antibiotics. A probiotic preparation (VSL=3 - 6 g/day) that uses a 
combination of three species of Bifidobacterium, four strains of 
Lactobacillus and one strain of Streptocccus has been shown to 
maintain remission in ulcerative colitis as well as in preventing 
the postoperative recurrence of Crohn's disease. Taking probiotic 
compounds is well tolerated and safe.

Prebiotics are found in certain foods that are not completely 
absorbed in your upper intestinal tract pass to your colon and form 
the food that encourages growth of the good bacteria. Soluble fiber 
is the part of these foods that is most likely to encourage the 
growth of good bacteria. Prebiotic supplements are available, but it 
is easier and cheaper just to eat plenty of the foods that provide 
this benefit. Good sources of soluble fiber are whole grains, beans, 
seeds, vegetables and nuts. 

The use of probiotics in gastrointestinal disease. Canadian Journal 
of Gastroenterology, 2001, Vol 15, Iss 12, pp 817-822. KL Madsen. 
Univ Alberta, 536 Newton Bldg, Edmonton, AB T6G 2C2, CANADA

Checked 2/20/12