For 25 years, Jeffrey Roberts, a technology consultant in Toronto, battled frequent diarrhea and abdominal pain. Roberts, who suffers from irritable bowel syndrome, was unable to attend his children's soccer games and often had to cancel or postpone family vacations. "I'd hold my family back because I'd have a lot of discomfort," he says.
But three years ago, he started taking a powdered drink mix that contains eight strains of probiotic bacteria. "It dramatically changed my symptoms," he says.
Roberts is one of many turning to probiotics. In an ad campaign for Dannon, actress Jamie Lee Curtis cozies up on a green sofa, rubs her tummy and says, "First, the bad news: 87% of this country suffers from digestive issues like irregularity."
The good news, Curtis explains, is she that has discovered Activia yogurt, which is laced with probiotics -- live, "friendly" bacteria -- that the company claims are "clinically proven to regulate your digestive system in two weeks."
Activia has also proved itself with consumers. In 2007, its second year on the market, sales grew by 48% to $181.3 million. Indeed, probiotics are turning up in myriad foods: Naked Juice fruit drinks, Lifeway Foods' energy bars, even a probiotics popsicle recently launched in the United Kingdom.
Last year was a banner one for probiotics, with 158 new food products hitting grocery shelves, compared with just four launches five years earlier, according to Datamonitor's Productscan Online, a database of consumer goods.
Companies claim that the daily consumption of probiotics can provide consumers with benefits such as a boost to the immune system and relief from intestinal distress -- and researchers think that certain probiotic strains hold promise in a number of areas.
But how significant these benefits are is a matter of debate. And it can be tough to decipher which products offer verifiable health claims and which are piggybacking on the hype of the booming industry.
A recent lawsuit filed in Los Angeles has questioned Dannon's probiotic health claims made for Activia and DanActive and charged that the company used scientific-sounding language to deceive customers. And studies have reported that some companies misidentify the probiotic strain they contain or deliver inadequate amounts of bacteria.
What's in a strain?
The World Health Organization defines probiotics as "live microorganisms that when administered in adequate amounts confer a health benefit on the host." Most products contain bacteria isolated from milk products, typically species of Lactobacillus or Bifidobacterium.
In marketing probiotics, companies either make health claims based on research on their own product or make references to the wide range of studies conducted with various probiotic strains.
Dannon says that DanActive "helps strengthen your body's defenses." Lifeway Foods cites "myriad health benefits" including "healthy gastrointestinal functions, increased immunity, and [preventing] the development of cancer-causing toxins." Culturelle claims to offer "numerous health benefits by helping to restore and maintain a nourishing level of good bacteria."
A slew of studies has shown that probiotics can, indeed, boost the immune system. A January report in the journal Surgery examined 14 randomized-controlled trials on the use of probiotics in abdominal surgery, liver transplantation and severe trauma. Nine showed a significant decrease in infectious complications. "We are enthusiastic about preoperative probiotics," says Dr. Mark Besselink, an author on the study at the Utrecht University Medical Center in the Netherlands.
There also is evidence that Lactobacillus rhamnosus GG, sold in capsules by Culturelle, boosts the immune system. Toddlers receiving the bacterium have fewer and less severe milk allergies. In adults, it boosts immune response to vaccines and reduces respiratory infections in athletes.
Probiotics also can be used to counteract the side effects of taking antibiotics, which upset the balance of naturally-occurring microbes in the gut, enabling proliferation of a diarrhea-causing bacterium, Clostridium difficile. In a clinical study of 135 patients published last year in the British Medical Journal, antibiotic diarrhea incidence was reduced by 22% in those consuming a probiotic drink that contained a billion live Lactobacillus and Streptococcus bacteria per milliliter.
Indeed, many companies are targeting the digestive health market because that is the area in which probiotics have shown the most promise
Procter & Gamble has recently begun marketing Align, a pill that contains a proprietary strain of Bifidobacterium infantis, online and in several target cities. In a 2005 study, researchers from Procter & Gamble and the University College of Cork in Ireland compared Procter & Gamble's Bifidobacterium with another probiotic, Lactobacillus salivarius, and a placebo. A total of 80 subjects with irritable bowel syndrome consumed probiotics in a milk beverage. During the eight-week study, Bifidobacterium reduced bloating and abdominal pain more than Lactobacillus or placebo.
Dannon's Activia has been designed for people with less severe digestive problems, says Miguel Freitas, director of scientific affairs at Dannon. He says that stress and traveling can often slow down the digestive system, which results in bloating and heaviness.
Activia uses a strain of Bifidobacterium animalis, and the company's clinical studies have shown that it can reduce constipation by up to 40%. The company's 2002 report studied 36 healthy women during four 10-day periods. During two of them, women ate 3 cups of Activia a day and exhibited more frequent bowel movements than during two periods when they ate a fermented dairy product without the probiotic.
There are also indications that a variety of probiotics can reduce colic in infants and that two strains, Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, can fight vaginal infections.
Ten years of published research on Lactobacillus casei, found in DanActive, suggests that it reduces intestinal infections in athletes and diarrhea in children.
But just because studies show benefits does not mean that probiotics will work for everyone, experts say. Each person has his or her own gut flora, and it's hard to know which microbes may be out of balance.
And probiotic products are not all the same. There are many species of Lactobacillus on the market, and each comes in different strains that may or may not confer the desired health goal. Also, companies market their products under scientific-sounding trademark names, which differ from names used in scientific literature (Activia's Bifidus regularis, for example, is Bifidobacterium animalis DN17010 in the journals). This can make it hard to assess health claims.
"I don't know how to tell consumers to sort through it," says Mary Ellen Sanders, executive director of the industry-funded International Scientific Assn. for Probiotics and Prebiotics. "Companies need to pause and reflect on the level of validation of the claims."
In late March, the industry's International Probiotics Assn. announced the first attempt at a labeling scheme for its 41 member companies. Seals, which may start appearing in six months, will include a guaranteed minimum bacterial count and a clear identification of the bacterial strain based on widely accepted nomenclature. If a trademarked name is used, the actual genus and species must be on the label too.
For consumers, says Besselink of Utrecht University, it's best to stick to products that have been tested in published, peer-reviewed trials -- many of which are featured on a company's websites. The American Society for Microbiology recommends that consumers never assume that a study conducted on one probiotic strain will apply to another, even one of the same species.
It may be possible to consume too few probiotic bacteria to get a benefit, but researchers say eating too much isn't likely to cause a problem. But there are important exceptions.
After reviewing the probiotics literature, Besselink and collaborators conducted a study on 298 patients with acute pancreatitis, many of whom fail to respond to antibiotics. There were clear indications probiotics could help.
But the alarming study, published February in the Lancet, found that probiotics more than doubled risk of death. This was the first study to show a negative effect of probiotics.
Perhaps, to tap probiotics' potential and avoid harm, scientists need more information. In December, the National Institutes of Health launched an effort to sequence genomes of some 600 microbial species found in the human body. One goal is to find out if every human harbors the same microbial community or if we differ in subtle but important ways -- which may explain why one probiotic works and another doesn't, or why a strain works for one person but not another.
"It's so tempting to talk about probiotics as if they were one thing," Sanders says. "You can't just generalize that because one probiotic does one thing, they'll all do it."