PROBIOTIC FOODS are among the brightest rising stars in the functional food category. Products containing these “good” bacteria promote intestinal health, boost immunity and enable lactose-intolerant people to consume calcium.
Probiotic microorganisms are found naturally in the human intestinal tract, which hosts 100 trillion bacteria, mostly in the colon. These bacteria can get out of balance for various reasons, such as diet, the presence of antibiotics or pathogens, or aging. Replacing the good bacteria, through supplements or food, can improve digestive health and, because the intestine is the body's primary organ when it comes to the immunity, general health as well.
“It's like a set number of parking spots in a garage,” explained Dr. Michael Cabana, chief of general pediatrics at University of California-San Francisco Children's Hospital, who is studying probiotics' impact on preventing asthma in infants. “If Lactobacillus [one of the good bacteria] is parked there, there is no room for pathogens to park. It's better to have good bacteria in the gut than salmonella.”
While research has suggested that probiotics improve intestinal health, the science is just emerging and the picture is complex. “It's tempting to say that probiotics can do XYZ, but that's kind of misleading,” said Mary Ellen Sanders, a microbiologist and consultant to the probiotics industry.
For one thing, there are many different strains of probiotics, most of which have not been studied, and each with a distinct benefit. Indeed, many claims — including probiotics' ability to reduce allergies, protect against cancer, decrease bad cholesterol and high blood pressure, and prevent cavities and gum disease — have not been proven scientifically, although initial studies on some seem promising.
Most food products marketed as probiotic today contain one or more of three bacteria types: Bifidobacterium, Lactobacillus (often L. acidophilus or L. bulgaricus), and Streptococcus (S. thermophilus). Dr. Allan Walker, professor and head of the division of nutrition at Harvard Medical School, researches bacteria's interaction with the intestine at Massachusetts General Hospital in Boston. He explained that for a probiotic food to be effective, three factors have to be in place: The microorganisms have to be alive, they have to have a known health benefit, and they have to be present in large quantities.
The main category offering probiotic products today is dairy, particularly yogurt and kefir, which naturally contain small amounts of good bacteria. But they can be found in other foods as well. In fact, in the days before pasteurization, pickles, sauerkraut, olives and many other fermented foods contained probiotics.
Some examples of probiotic products on the market in North America include Dannon Activia and Stonyfield Farms yogurts, Lifeway Foods Basics Plus kefir, DanActive probiotic dairy drink, Horizon Organic Dairy probiotic yogurt, cottage cheese and sour cream, Kashi Vive Probiotic Digestive Wellness Cereal, and Oasis Health Break juice. There are even probiotic candy bars.
It should be noted that just because a product contains live bacteria, such as yogurts marked with the National Yogurt Association's Live Active Culture seal, does not mean they can be considered probiotic. For a product to be probiotic, manufacturers must add the good bacteria in sufficient quantities to result in a health benefit. But be cautioned: The LAC seal denotes that the product contains certain levels of lactic acid bacteria per gram at the time of manufacture, but doesn't specify how much remains in the package on the shelf or reflect current probiotic content.
Similarly, there is no set amount of bacteria that defines a product as probiotic, although manufacturers recommend a level of 10 million probiotic bacteria per gram or milliliter.
Many of the studies on probiotics have involved infants, but experts believe all age groups can benefit. For example, as humans age, their immune function decreases, so probiotics may help elderly people fight off disease better. The unanswered question, according to Cabana, is whether ingesting probiotic foods really makes a significant difference for the average person. Most studies have focused on medicinal uses of particular strains of probiotics and not on their effectiveness in foods.
“It might help somewhat, but we just don't know,” he said.
Probiotics are considered safe and side effect-free for most people. Exceptions include those with severe diarrhea or an underlying condition that impairs the immune function, as well as people with allergies to milk proteins such as casein or whey, who might react badly to probiotics cultured in those substances. Walker cautioned that taking large quantities of probiotic foods, such as 10 cartons of yogurt a day instead of one or two, could cause diarrhea.
While probiotics represent an emerging market sector, research suggests rapid growth ahead. Packaged Facts, the publishing division of MarketResearch.com, estimated the total market for cultured dairy products at $9.6 billion in 2005, after average yearly increases of 8.5% since 2001. The category is expected to grow 9.8% a year, on average, from 2006 to 2010. The research does not differentiate probiotic yogurts from other yogurts, but it does track kefir and probiotic shots. It pegged kefir as a $13.8 million market in 2005, and predicted annual growth of 21.4% from 2006 to 2010; probiotic shots were estimated at $19 million in 2005, with expected growth of 97.4% a year through 2010.
Walker recommends stocking probiotic products that are associated with respected brands. “A lot of companies want to ride the wave, but not all are what they say they are,” Walker said, adding that many make unsupported claims, or have not done adequate studies on effectiveness and safety.
Get Some Culture
U.S. sales of cultured dairy productsand select probiotic categories
|Total Cultured |
|NOTE: “CHANGE” PERCENTAGE IS THE COMPOUND ANNUAL GROWTH RATE 2005-2010 |
SOURCE: PACKAGED FACTS
Trend Watch: Prebiotics
Prebiotics are nondigestible food ingredients, primarily oligosaccharides, that promote the growth of good bacteria in the intestine. They occur naturally in some foods, and, like probiotics, can be included in functional foods.
Because prebiotics cause good bacteria to grow, they have an effect on health that's similar to probiotics. But because they are not live bacteria, “there might be more consumer acceptability,” said Dr. Michael Cabana of the University of California-San Francisco Children's Hospital.
As with probiotics, prebiotics are more available and accepted in Europe and Asia than in the United States. ProductScan Online estimated there have been 387 probiotic and prebiotic products introduced worldwide through Oct. 20 of this year, with less than 10% of those occurring in the United States.