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What are probiotics?
01:16 - Source: CNN

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"There's now probiotics that come in chocolate ... cheese ... bread," expert says

If you're already healthy, there may be no need for added probiotics, research suggests

CNN  — 

Probiotic supplements may be a growing trend among health-conscious consumers, but the tiny bacteria that have been stuffed into capsules and stacked on pharmacy shelves coexisted with us before we were even aware of them.

These live microorganisms are akin to the valuable microorganisms already residing in our bodies, a vast ecosystem of microbial species, including bacteria and yeast.

Now that products containing probiotics are sold as yogurt, drinks and dietary supplements, there seems to be some confusion around how to define probiotics and how beneficial they really are.

“It’s taken a while for the scientific community to actually form a consensus of what we mean when we say probiotics, because people might mean different things,” said Lynne McFarland, an associate professor of medicinal chemistry at the University of Washington in Seattle.

She wrote a paper on the history, development and current use of probiotics, which was published in the journal Clinical Infectious Diseases in 2015.

“The most recent recommendation and consensus is that they have to be alive. They can be a bacteria or a yeast. They have to be used in an adequate dose, and they have to have some proven beneficial health effect,” McFarland said of probiotics.

“Probiotics have been around for a long time,” she said. “It took a while for science to catch up with what’s going on.”

How has our understanding of probiotics changed over time? Here’s a look at probiotics’ steady rise in popularity, from Europe to America, and where health experts now stand on their benefits.

Prehistory: Storing sushi in the early days of fermentation

About the time our hunter-gatherer ancestors took up farming, 11,000 years ago, they started to consume probiotics without even realizing it, said Dr. Cate Shanahan, a Newtown, Connecticut-based family physician who also consults as a nutritionist with the Los Angeles Lakers.

As farmers settled into communities, they developed the habit of storing more of their food. “With anything that you store, microbes are just going to start growing in it,” Shanahan said. This sometimes resulted in the fermentation of foods.

Fermentation, when microorganisms grow on and break down food, can make that food item rich with probiotics. The process also may increase the shelf life of a food and make some foods more digestible, Shanahan said.

For instance, in Asia, sushi was originally a fermented food, Shanahan said.

“They had so much fish that they’d catch all at once. … So they would store it, and they discovered that packing it in rice would help store the fish so that it would basically rot, but in a way that wasn’t disgusting and more controlled,” she said. “We now know it was because there was special bacteria, called Bacillus bacteria, in the rice that was helping out.”

In other words, the bacteria in the rice helped store the fish.

Around the same time, many other examples of fermentation were emerging in other parts of the world. Some research suggests that ancient Egyptians fermented their beverages through complex brewing methods.

“They have the hieroglyphics of the pharaoh being served something in a bowl, and people who have translated those have gone, ‘OK, this is sort of a fermented milk product,’ ” McFarland said.

As agriculture expanded, so did our relationship with probiotics.

13th century: Did Marco Polo drink kefir?

Marco Polo, the Venetian merchant traveler who ventured across Asia, was known to speak of probiotic-rich fermented beverages such as kefir in his travels.

It is believed that when nomadic shepherds and travelers journeyed with raw milk carried in leather, the milk would accidentally ferment over time.

Some studies suggest that this process led to the creation of kefir, a fermented milk drink that originated in the Caucasus Mountains.

It’s believed that the word kefir derives from the Turkish word keyif, meaning “pleasure” or “feeling good” after its ingestion. The beneficial health properties of kefir and other dairy products were a part of folklore until the idea of probiotics arose.

19th-20th centuries: The ‘father of probiotics’

In the late 1800s, French biologist Louis Pasteur identified the bacteria and yeasts responsible for the process of fermentation, but it was Russian biologist Elie Metchnikoff who linked those microorganisms to health outcomes.

Metchnikoff had long theorized that the microorganisms in our guts could have beneficial or adverse effects on our health.

In 1905, Metchnikoff studied how many residents of poor communities in Eastern Europe were centenarians, living to be 100 or older. He associated their longevity with the type of bacteria used to ferment the yogurt they would eat, and he became known as the “father of probiotics.”

“He’s the first one who published a book looking at Bulgarians and saying, ‘Gosh, they live longer,’ and it wasn’t due to their diet. It wasn’t due to the yogurt that they consumed but actually the bacteria that was used to ferment the yogurt,” McFarland said. “That clever Russian. … He’s the one who kind of went, ‘You know, bacteria aren’t all bad.’ “

In 1908, Metchnikoff shared a Nobel Prize in physiology or medicine with German physician Paul Ehrlich for their research on the immune system.

Many other scientists followed Metchnikoff’s research efforts into the bizarre micro-world of bacteria, including Henry Tissier, a French pediatrician who discovered “good” bacteria called Bifidobacterium in the guts of infants. He proposed that the bacteria could be used to treat patients with diarrhea.

However, the concept of probiotics quietly drifted to the background of medical focus until it re-emerged in the mid-1950s in Europe.

“They were always more popular in Scandinavia and Europe,” McFarland said.

1950s-1980s: Making a name for probiotics in Europe

In 1953, German bacteriologist Werner Kollath first used “probiotic” to describe various supplements believed to restore the health of malnourished patients. The term was derived from Latin and Greek, meaning “for life.”

In the next year, German scientist Ferdinand Vergin used the term to describe “active substances” beneficial for health.