What is Acidophilus?
A nice review by students from the University of North Carolina School of Pharmacy
A Nutritional Approach to Immunity
Many studies show that immune function depends on nutrients found primarily in whole, unprocessed foods.  Researchers have also confirmed that physical activity and a healthy emotional state are essential for proper immune function. [3,4] A healthy diet and lifestyle may be the cornerstones of a strong immune system, but what specific measures can be taken when a person is faced with an immune challenge such as the annual cold and flu season?
Probiotics Effective Against Viral Infections
A recent study on the prevention of gastrointestinal infections suggests that probiotics may also be effective against viral infections. In this study, a group of 81 children was randomized to receive either a strain of lactobacillus (Lactobacillus GG) or placebo after hospital admission. Because many infections are acquired in the hospital (termed nosocomial infections), the researchers decided to test the protective effects of probiotics in this setting.
The Probiotic Solution for Colitis
Colitis, or irritable bowel disease (IBD), is a group of conditions characterized by gut–wall inflammation. Conventional medicine generally addresses IBD symptoms with steroids and other drugs. Probiotics, or "friendly" bacteria, address the root cause, most importantly by acting antagonistically toward pathogenic bacteria that cause intestinal inflammation. Valuable probiotics include various species of Lactobacillus and Bifidobacterium. You may also want to refer to the Inflammatory Bowel Disease & Essential Fatty Acids Page for more on this topic.
Bacteria That Strengthen The Immune System
Richard N. Podell, M.D. writes: "As a practicing physician and nutritionist, I hear that question at least three times a day. The good news is we can strengthen the immune system's resistance to infection by taking supplements of Lactobacillus acidophilus or Bifidobacterium bifidum, two breeds of "friendly" bacteria that normally live in the human gastrointestinal (G.I.) tract."
The Yeast Within
The predominant organisms normally found in the vagina are Lactobacillus acidophilus and Corynebacterium vaginale.  These organisms maintain an acidic vaginal environment with a pH of 4 to 4.5.  Since lactobacillus and corynebacterium are responsible for metabolizing the sugars glycogen and glucose, which are favorite foods for candida and other yeasts, a healthy amount of these organisms can stave off candida overgrowth. 
Factors Involved in the Increased Intestinal Permeability
Associated With Irritable Bowel Disease
Stress, sugar, alcohol and previous exposure to Antibiotics head the list of items which kill off beneficial intestinal flora, setting the stage for yeast and other patogenic bacteria from disturbing intestinal permeability.
A Probiotics Primer
Ever since Louis Pasteur formulated the germ theory of disease in the late 1800s, humans have been locked in mortal combat with microorganisms. The zealous use of antibiotics, disinfectant
chemicals and sanitary packaging attests to our fear and loathing of all things microbial. In this age of antisepsis, it seems ironic that each of our intestinal tracts harbors tens of
trillions of bacteria. This number, by some estimates, exceeds the total number of cells making up the human body. Even more ironic is that many of these bacteria are beneficial. Probiotic– – or life–enhancing organisms within the intestinal tract perform such a wide variety of physiological functions that they have been likened to an accessory organ.