Americans took far more prebiotics and probiotics in 2018 than in preceding years, and this marked increase in the use of supplements and other products was likely motivated by a growing public interest in gut microbiome health, according to researchers with the National Institutes of Health.

The study, published April 23 in Gastroenterology, reported that one in 20 U.S. citizens have used non-food probiotics, prebiotics or synbiotics in the past 30 days. Prebiotics are similar to dietary fiber, as these non-digestible foods encourage the growth of beneficial bacteria in one's colon. Synbiotic products are made up of both prebiotics and probiotics that act in a synergistic way.

The uptick in consumption of probiotics, or live microorganisms commonly found in kombucha, pickles, yogurt and other foods, is particularly notable. The bacteria in probiotic foods and supplements differ from harmful bacteria that cause infections; in fact, they can help the digestive health of humans get back on track by creating a barrier against damaging microorganisms. Most people bought and consumed probiotics, prebiotics and synbiotics without guidance from a health care provider, with over 65% of users opting to take dietary supplements of their own accord. 

Probiotics are often touted as a way to remedy indigestion and are prescribed by doctors to offset microbiome imbalances in people's bodies after they take antibiotics, which can cause diarrhea. The global market for probiotics reached nearly $50 billion in 2018 and is continuing to grow, largely thanks to consumers who are self-motivated to buy supplements for their digestive health, said Ashley Vargas, a registered dietitian nutritionist and corresponding author of the paper. 

"I grew up in the suburbs of Detroit, Michigan and my mother used to take us to the 'health food store' pretty often. I recall being excited about chewing on sweet licorice root and being fascinated by the array of products that seemed to mimic the uses of medicines at our local pharmacy," Vargas told The Academic Times. Her early childhood experiences kindled an interest in how health is moderated by diet and dietary supplements.

Today, Vargas studies precision nutrition, a personalized approach to diet. This nutrition approach takes into account factors that vary with every person, including one's gut microbiome, or the microorganisms and bacteria present in the digestive tract. 

Vargas and her colleagues examined data from a national survey on health and nutrition, then used text mining to identify prebiotics, probiotics or synbiotics in product labels and ingredient lists. The survey was designed to be nationally representative of all U.S. citizens who are not currently in the military, prisons, mental facilities or assisted living facilities.

The team supplemented the survey data with in-person questionnaires on demographics, dietary supplements and prescription medications. One key question asked if a supplement was prescribed by a health provider or if the respondent decided to take it voluntarily. Other questions asked about ethnicity, age and diet quality.

The current study builds on earlier NIH research on the prevalence of pre- and probiotics among U.S. citizens. In 2012, 1.6% of adults reported taking either of these products within the last 30 days. In 2018, roughly 5% of children and adults reported using non-food probiotics and roughly 2% reported using non-food prebiotics — a three-fold increase in recent years, Vargas noted. "This is a relatively high prevalence for nonvitamin or nonmineral dietary supplements," the authors stated in the paper.

"A caveat of the work is that we only had data on whether someone had used probiotics or prebiotics in the last 30 days, so we could not capture infrequent use or past use," said Vargas. The same holds for the NIH's 2012 study on prebiotics and probiotics.

Age and socioeconomic status were shown to have a clear impact on use. Older adults were most likely to use either prebiotics, probiotics or synbiotics, as up to 11% of individuals 60 years of age or older had used one of those products in the last month. People with a higher education and a higher income were also more likely to use these products. Race played a role as well, with non-Hispanic whites reporting a 2.5% higher rate of use than non-Hispanic Blacks.

"This [study] is a reminder to physicians to ask their patients about any supplement use at visits to be sure they are understanding the whole gastrointestinal picture of their patients," Vargas said. 

As a program official at the Nutrition for Precision Health Center, Vargas will help to advance new research through a cross-disciplinary study that combines artificial intelligence with nutrition. "There's no such thing as a perfect, one-size-fits-all diet," the program website states: because of this, the program aims to create algorithms to predict an individual's reaction to certain foods or dietary patterns. Vargas and her team plan to use AI and microbiome research in a new approach to custom nutrition.

Another project that Vargas is helping to spearhead is an exploration of the very first food known to humans: human milk. Aside from nutrients that are essential to infants, breast milk has live microbes and other components similar to prebiotics, Vargas said. "There is a growing recognition of the [importance] of the first few years of life on health and disease risk. Exploring what makes human milk so amazing will help infants and the life-long health of all people," she added.

Vargas' advice for the average citizen? She keeps it simple: "Moderation and variety. Boring, I know, but keep portion sizes in moderation and try new foods – be adventurous to expose your body, including your taste buds, to new foods." 

She thinks the patterns she documented are no temporary trend:  "I don't have a crystal ball, but based on my data, I would suspect continued trends in increasing use."

The study, "Non-food prebiotic, probiotic, and synbiotic use has increased in U.S. adults and children from 1999 to 2018," published April 23 in Gastroenterology, was authored by Lauren E. O'Connor, Kirsten A. Herrick, Jaime J. Gahche, Cindy D. Davis, Nancy Potischman and Ashley J. Vargas, National Institutes of Health.