Probiotics such as bifidus, lactobacillus and saccharomyces boulardii are known first of all for their benefit to digestive health, and especially for their ability to help resolve various types of diarrhea (from antibiotic-associated diarrhea to “traveler’s diarrhea”).

But as they promote gastrointestinal tract health and good digestion, probiotics also support immune function and increase the body’s resistance to infection. This is because probiotic organisms produce compounds like lactic acid, hydrogen peroxide and acetic acid that increase the acidity of the intestine and slow the reproduction of many harmful bacteria. It’s also been discovered that probiotics produce substances called bacteriocins, which act as natural antibiotics to kill undesirable bacteria.

One example of recent research on probiotics and immune function: a double blind trial that looked particularly at supplementation with Bifidobacterium lactis showed that it significantly enhanced immune function in a group of healthy elderly people. This study, reported in 2000, showed immune function enhancement after six weeks of supplementation.

For further information on individual probiotics, see the NYBC entries:

Probiotics

Saccharomyces boulardii (as Florastor/Biocodex)

Bifidus (as Bifidus Balance/Jarrow)

Lactobacillus/Bifidus (as Jarrodophilus/Jarrow)

Lactobacillus/Bifidus (as Jarrodophilus EPS–needs no refrigeration)

See also the entry for the green foods supplement Pro Greens (Nutricology), which includes a substantial lactobacillus/bifidus component.

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References:
–De Simone C, Vesely R, Bianchi SB, et al. The role of probiotics in modulation of the immune system in man and in animals. Int J Immunotherapy 1993.
–Barefoot SF, Klaenhammer TR. Detection and activity of Lactacin B, a Bacteriocin produced by Lactobacillus acidophilus. Appl Environ Microbiology 1983.
–Arunachalam K, Gill HS, Chandra RK. Enhancement of natural immune function by dietary consumption of Bifidobacterium lactis. Eur J Clinical Nutrition 2000.