Probiotics and Prebiotics
Probiotics are live microorganisms that beneficially affect the host when ingested in sufficient amounts by improving the balance of intestinal microflora. Lactobacillus and Bifidobacterium are the species most often added to foods and dietary supplements.
Bifidobacteria are normal inhabitants of the human and animal colon. Lactobacilli are normal inhabitants of the human intestine and vagina.
Prebiotics are non-digestible food or dietary supplement ingredients that may beneficially affect the host by selectively stimulating growth and/or activity of beneficial microorganisms in the colon. Prebiotic ingredients generally used in foods and dietary supplements are fructo-oligosaccharides (FOS) and inulins. Both of these stimulate the growth of beneficial bacteria, particularly bifidobacteria, in the colon.
These ingredients also provide other benefits normally associated with increased dietary fiber.
FOS generally refers to s chain oligosaccharides (containing 3-5 monosaccharide units) comprised of D-fructose D-glucose. They are produced on a commercial scale from sucrose using a fungal fructosyltransferase enzyme.
Inulins are a group of naturally occurring fructose containing oligosaccharides. They are derived from the room of chicory end artichokes. Inulins are comprised primarily of fructose units and typically have a terminal glucose.
Probiotic Foods and Supplements Promote Health
The benefits of probiotic o rg anisms in bot h - intestinal health and immune system support are - well established and backed by science . That doesn't mean that if you take daily probio t ic supplements or eat foods containing probiotics every day, you will be protected from all intestinal disorders or that you will nev e r get sick again. But it could mean better digestion of foods and absorption of nutrients, improved regularity and a stronger immune system. You may get sick less often, and when you do, your immune sys tern is better able to fight off invading organisms, so you get well faster.
Probiotic Strain for the Illness Matters
The tendency to generalize about probiotic effects is widespread. Underlying such generalizations is th e erroneous assumption that research on specific probiotic strains can be appl i ed to any product marketed as a probiotic. The current body of published literature suggests that similar effects are observed for a variety of different strains. Effects on diarrhea, immune responses and symptoms of lactose intolerance are associated with more than one strain. Therefore, multiple strains of the same species may have functional traits in common ...but they may not.The chart below lists strains commonly used in foods and supplements that are shown in cont r olled human studies to be efficacious.
STRAIN |
HUMAN DATA |
| L. acidophilus |
Symptoms of lactose intolerance; reduced small-bowel bacterial overgrowth |
| L. rhamnosus |
Immune enhancement, infectious diarrhea in children, primary prevention of atopic dermatitis |
| L. casei |
Immune enhancement, superficial bladder cancer recurrence intestinal microbiota |
| L. fermentum |
Immune enhancement for athletes in training |
| L. ptentensm |
Irritable Bowel Syndrome, post-surgical gut nutrition |
| B. infantis |
Irritable Bowel Syndrome |
| B.longum |
Allergy symptoms, intestinal micro-ecology |
| B.lactis |
Immune enhancement especially in elderly, diarrhea in children |
| B. animalis |
Normalizes intestinal transit time |
| L acidophilus B. bifidum combination |
Reduction of C. difficile toxin in feces |
| L. helveticus, L. rhamnosus combination |
L. H. pylori eradication, diarrhea in children |
The effectiveness of probiotics is related to their ability to survive the acidic stomach environment and the alkaline conditions in the duodenum, as well as their ability to adhere to the intestinal mucosa to colonize the colon. Dansico and other manufacturers have developed heat and acid resistant strains of L. acidophilus, L. casei, L. rhamnosus and B. longum bacteria for that purpose. Enteric coated tablets and capsules also protect organisms from stomach acid, but heat used in processing these products may kill many of the organisms.
When probiotics colonize the colon they reinforce the barrier function of the intestinal mucosa. L. bulgaris (used to make yogurt), which does not adhere well to the intestinal mucosa, is much less effective against enteric pathogens. This strain and others including L. casei, L rhamnosus (also called Lactobacillus GG) and L. plantarum (from sourdough bread) have, however, demonstrated immune-regulatory effects that may protect against some allergic disorders.
One way all probiotic strains promote health is simply by "crowding out" harmful bacteria. However, some strains have more specific immune-enhancing effects. L. casei increases levels of circulating immunoglobulin A (IgA) in infants infected with rotavirus. L. rhamnosus has also been shown to potentiate intestinal immune response in rotavirus infected children. L. acidophilus and B. bifidum appear to enhance the nonspecific immune phagocytic activity of circulating blood granulocytes.
These "friendly" organisms also produce large amounts of lactic and acetic acid which may create an environment that is unfriendly to many pathogenic organisms.
There are in vitro, animal and some preliminary human data suggesting that prebiotics can bind and inactivate some carcinogens, can directly inhibit the growth of some tumors and can inhibit bacteria that convert precarcinogens into carcinogens. L. acidophilus and L. casei have exhibited the latter activity in human volunteers. L. rhamnosus has been shown to inhibit chemically induced intestinal tumors in rats. It appears to alter the initiation and/or promotion of tumors. Dairy products containing L. acidophilus have been credited with lowering cholesterol levels in some animal experiments.
