Probiotic supplements and foods containing “friendly” bacteria or yeast have become popular among people hoping to improve bowel function, immunity and even mood. However, many products contain only a fraction of the probiotic organisms they claim, according to new tests from ConsumerLab.com, White Plains, NY. A recent review found that out of 19 probiotics for humans, five contained only 16-56% of the listed amounts of organisms. Levels of organisms in probiotics for pets were so low as to question their usefulness—including one product apparently reformulated to provide less than 2% of the organisms it had in the past.

“Consumers who don’t do their homework with probiotics might not get what they want or think they’re paying for,” said Tod Cooperman, MD, president of ConsumerLab.com. “Not every product has what it claims and even those that do may not have the right type and amount of organisms for a specific condition.”

Probiotics represent one of the largest and fastest-growing segments of the dietary supplement market, with 2012 sales up 24.5% to $947 million in the U.S., according to Nutrition Business Journal.

ConsumerLab.com found products listing anywhere from one to more than 30 different strains of Lactobacillus, Bifidobacterium, Streptococcus or Saccharomyces (a yeast). The quantity of organisms in products for humans ranged from 100 million to more than 900 billion in a daily dose, a difference of nearly 900,000%. Much lower amounts of organisms were found in pet probiotics.

A disturbing trend identified by ConsumerLab.com among probiotic supplements is the inclusion of footnotes on labels qualifying the listed amounts of organisms to be “At time of manufacture.” This disclaimer holds no value with the FDA, which expects products to contain 100% of what they list.

ConsumerLab.com also recently evaluated 11 Garcinia cambogia extract supplements on the market and tested each for its amount of hydroxycitric acid (HCA), a plant compound believed to be important to Garcinia’s biological effects. ConsumerLab.com found that six of the supplements contained only 16% to 81% of the listed amount of HCA. Two products having the lowest percentages (16% and 22%, respectively) of their listed HCA appeared to be promoting false endorsement by Dr. Oz.

Garcinia is typically taken three times a day approximately one hour before meals, to provide a total daily dose of about 900 mg to 1,500 mg of HCA. However, one of the products that failed ConsumerLab.com‘s tests provided less than 100 mg of HCA per day. Even among products which contained what they listed, the amount of HCA in a suggested daily serving ranged from as little as 250 mg to as much as 3,150 mg of HCA.

Among the five products that passed testing, the cost to obtain an equivalent amount (1,500 mg) of HCA ranged from 74 cents to $2.08. In products that did not contain what they claimed, this cost was as much as $11.39 based on the amounts of HCA actually present.