The quality of probiotic supplements depends on two main factors: (1) the characteristics of the strains contained in the supplement, and (2) adequate viability, so that sufficient numbers of bacteria are viable at the point of consumption. Viability at consumption depends on factors such as proper manufacturing and the "hardiness" of the strain, as well as packaging and storage of the product in the right amount of moisture and at the correct temperature.
Strains of bacteria can be likened to different breeds of dogs. All dogs belong to the genus Canis and the species familiaris. Within this one species is great diversity in size, shape, strength, and other physical characteristics — ranging from the Saint Bernard to the Chihuahua. A similar division occurs within species of bacteria; each species of bacteria comprises a multitude of strains. Some probiotic strains are resilient and strong, able to survive passage through the upper gastrointestinal and inhibit pathogenic bacteria, and others are weak and can't survive or kill pathogenic bacteria.
What all of this means is that consumers must utilize products developed and manufactured by companies that have done the necessary research to insure the viability of their product. With probiotics, as with other supplements, be a smart consumer and read up on the top manufacturers, or talk to the supplement consultant at your local health food store.
Specific Applications of Probiotic Supplements
To a very large extent, the intestinal flora plays a major role in the health of the host. Therefore, probiotic supplements can be used to promote overall good health. However, there are numerous specific uses for probiotics based upon clinical studies. One of the best-documented applications of probiotic supplements is in the prevention and treatment of urinary tract infections (UTIs). The normal microflora of the vagina and urethra in women is dominated by lactobacilli, where they play a significant role in acting as a barrier to UTIs.
Another important application of probiotic supplements is preventing and treating antibiotic-induced diarrhea. Although it is commonly believed that acidophilus supplements are not effective if taken during antibiotic therapy, research actually supports the use of probiotics while you're taking antibiotics. If you take the antibiotic at night, take the probiotic supplement in the morning. In other words, take the two as far apart as possible.
Lastly, probiotics are very important for children for several important reasons, including an ability to boost immune function and prevent gastrointestinal infection. Formulas that are specially designed for children are best.
The dosage of probiotic supplements is based solely on the number of live organisms present in the product. Therefore, I recommend using products that list the number of live bacteria at expiration versus at time of manufacture. Successful results are most often attained by taking between 5 billion and 20 billion viable bacteria per day.