Most people would benefit from a high potency, multiple strain formula. If needed, you can also choose formulas that are specific to certain areas of concern including colon health or vaginal support.
While you should choose a child-specific formula for kids, adults do not need age-specific formulas. Instead, if you are middle-aged, choose a multi-strain formula with at least 30 billion bifidobacteria. After the age of 50, the levels of probiotics (specifically bifidobacteria) begin to decline in number so probiotics are an important daily supplement.
When reading labels, look for the culture counts. This refers to the total number of bacteria per serving. They can widely vary from product to product. A probiotic suited for general health, is a lower potency containing anywhere from 2-6 billion bacteria per serving. If you are treating a health condition, or have just finished a round of antibiotic therapy a therapeutic strength with a high culture count (between 50 and 100 billion bacteria per capsule) is better suited.
Speak with your local nutrition house Natural Health Product Advisor to help you choose the right probiotic.