Probiotics are live microorganisms. When administered in adequate amounts, they presumably confer a health benefit on the host. They are often associated with promoting gastrointestinal health, alleviating such digestive issues as diarrhea, irritable bowel syndrome and ulcerative colitis. Newer trials are looking at their effects on the immune system, from relieving allergies to eradicating antimicrobial-resistant organisms.
The first rumblings of probiotics came more than a century ago when Russian biologist Ilya Mechnikov gave fermented dairy products to Bulgarian peasants. From this experiment, Mechnikov, who won the Nobel Prize in 1908 for his work on immunity, found health properties from the intake of lactic acid bacteria. All those years ago, he recognized that microbes in food helped change flora in the body and inserted good bacteria into the gut.
The term probiotics occasionally popped up in the literature over the last century but the field really took shape over the past decade. Yet despite the more than 100 probiotics-related research trials per year, many questions remain unanswered, particularly about their long-term safety. Meanwhile, millions of people take probiotics every day, said Hibberd.
Hibberd said studies are needed in animals, humans, in vitro and in simulation to understand the host and microbe response to probiotics.
Photos: Ernie Branson
“What was such a simple concept before 2008—take a probiotic, get a beneficial effect, feel better—now has become a highly complex proposition,” she said. Hibberd said studies are needed in animals, humans, in vitro and in simulation to understand the host and microbe response to probiotics.
As scientists continue to study the microbiome, we’re learning more about the microbial community living on and in us. Hibberd said probiotics might be beneficial by inserting good bacteria into our GI tract. But with so many kinds of organisms throughout the body, probiotic functions may vary in different parts of the body.
“Probiotics are not going to do the same thing in everybody, certainly in terms of altering organisms present in the GI tract,” she said, “but they may have similar effects based on function.”
Hibberd is researching the potential for probiotics to improve immune response in the elderly. Preliminary studies show the common probiotic Lactobacillus GG (LGG) boosts the immune response to mucosally administered vaccines. In a current study, Hibberd and her lab partners administered LGG to adults over age 65 to observe whether it would improve their response to the flu vaccine. They are in the early stages of analysis of the microbiome and immune response of study subjects. But they have already found some interesting results on the transcription profile of LGG in subjects receiving the probiotic.
The goal of their research, she said, “is to prevent, treat, mitigate or cure infectious diseases at the extremes of age or [given] immune compromise.”
Other population studies have shown probiotics may have a large impact if they’re introduced in the first 3 years of a child’s life, she said, but further study is needed. So much affects what colonizes the GI tract in children—the mother, birth process, feeding, antibiotic exposure—and these variables must be taken into account during studies of probiotic effects.
“Probiotics may have effects we’re not even thinking about,” she said. “We do need to think beyond the positive beneficial effects so many people are focused on, in part because of the definition of probiotics.” Such studies will not only involve the ability of probiotics to prevent or treat disease but also help determine which population groups might best respond to them.
Current and future research into probiotics will require looking at the potential for improving immune response while evaluating their long-term safety. “Since 2001, when probiotics were such a simple concept, enthusiasm has persisted but the scientific basis and mechanism studies still lag,” Hibberd said. This remains an emerging field with many unanswered questions. It will take a multidisciplinary approach, she said, “to figure out whether probiotics are hype or reality.”