Probiotic Strains

What’s the Difference with Different Probiotic Species and Strains?

Different strains of probiotic bacteria have been shown to have different functions and are concentrated in various places along the digestive tract and in and on the body. For supporting the general microbiome, I usually recommend products that contain multiple strains of Lactobacillus, Bifidobacterium, and other species.

Some strains have been identified as having particular health effects:

• L. acidophilus: supports digestion, nutrient, immune health, and urinary tract and vaginal health in women
• L. fermentum: supports digestion and detoxification
• L. rhamnosus: can be helpful for traveler’s diarrhea and vaginal health in women
• L. plantarum: for digestion and immune health
• B. longum: helps maintain gut integrity and process toxins
• B. bifidum: supports digestion and nutrient absorption
• B. infantis: supports digestion and can help with occasional bloating and constipation

At times I recommend a specific strain that has been clinically studied for a particular condition. For example, L. rhamnosus GR-1 and L. reuteri RC-14 are two highly studied probiotic strains for women’s health. The letters and numbers that appear after the name is the particular pedigree of the bacteria and, although not necessary for a good product, indicate that the company is using a pure, genetically characterized strain.

What to Look For

Many probiotic bacteria, particularly those with live cultures, are naturally sensitive to heat and moisture and should be refrigerated and kept out of humidity. However, freeze-dried probiotics in blister packs have longer shelf lives and may be fine as long as they are not exposed to heat above room temperature. Probiotic yeast (Saccharomyces boulardii) and some of the spore-forming bacteria, such as Bacillus coagulans, generally do not require refrigeration.

Look for a supplement that contains at least both Lactobacillus and Bifidobacterium families and with at least five to twenty billion live bacteria per dose. Take once or twice daily for general purposes. Those with specific health concerns may require higher-dose supplements such as VSL#3, which has 250 billion live bacteria per dose.

The best probiotic supplements will use delivery systems that ensure a significantly high percentage of bacteria will reach your intestines alive. Expiration dates on probiotic supplements indicate that the bacteria in the product should be active and potent at the levels indicated on the label until that date. Usually the expiration date is based on formulation and stability testing data, which means a company is paying attention to those matters. Look for reputable brands; you do get what you pay for.