Digestive health has been linked to myriad facets of well-being — immunity, cardiovascular health, bone and skin health, mental health, mitigation of symptoms of diabetes and asthma, and even dental health. Emerging evidence suggests digestive health ingredients also can be used to target specific conditions, such as Alzheimer’s disease and non-alcoholic fatty liver disease, as well as to reduce recurrence of certain viral infections.
According to a 2020 global survey on gut health conducted by HealthFocus International, when selecting food products for digestive health, 81% of consumers are interested in overall wellness versus selecting a product that will address a specific issue. Moreover, 54% of consumers are extremely or very interested in the gut microbiome.
As is often noted, digestive and gut health are closely linked with immune health. One of the main factors involved is that of gut-associated lymphoid tissue, which comprises up to 70% of immunocytes in the human body. With viruses such as Coronavirus and influenza being an immediate concern, it is worth recognizing that consumption of prebiotics and probiotics has demonstrated an ability to help reduce incidence and severity of respiratory infections.
Synbiotics — a combination of pre- and probiotics — could be useful in preventing diarrhea from Rotavirus. This powerful combo also might provide a boost in immune response against future infections, according to recent animal studies.
X Marks the Spot
Xylo-oligosaccharides (XOS) are prebiotic carbohydrates found in corn cobs, sugar cane, algae, and seaweed. Available in powder form for easy inclusion in food and beverage products, this prebiotic has been shown to have a high digestive tolerance with low side effects. Its health benefits include such capacities as increased fasting high-density lipoprotein (HDL) cholesterol and immunomodulation. XOS has been confirmed in several studies to increase Bifidobacteria populations both in vitro and in human subjects.
As with all prebiotic fibers, XOS stimulates production of short-chain fatty acids (SCFA), as is well documented in multiple studies. Research conducted at the University of Minnesota indicated that XOS tends to produce more acetate and less propionate than inulin or beta-glucan in vitro, while butyrate production was similar among the three fibers studied.
A different study investigated XOS from corn cobs, which enhanced antimicrobial activity of Lactobacillus plantarum-S2 in vitro. Interestingly, XOS coupled with the same also showed synergistic antioxidant activity in vitro compared to the prebiotic or bacteria alone.
One of the more fascinating mechanisms behind the possible health benefits of XOS ingestion is increased mucus production in the gut. The epithelium in the intestinal tract is covered by a mucus layer that, when disrupted, allows pathogens and harmful bacteria to directly access epithelial cells. Investigators in Switzerland demonstrated an increase in mucus production in an in vitro cell model as a result of exposure to effluent of XOS fermentation.
It is well established that prebiotic consumption influences gut microbiota and this has been observed in prediabetic individuals as well as healthy adults. Researchers at the University of California, Los Angeles, studied the impact of XOS on specific bacterial species associated with prediabetes in adult subjects.
Bacterial species in the genera Enterorhabdus, Howardella, and Slackia were higher in prediabetic subjects compared to healthy subjects, with XOS ingestion causing a decrease in these bacteria in both study arms. Additionally, supplementation with XOS led to a decreased insulin. Although the effect didn’t quite reach statistical significance, further research could support adding XOS to the group of fibers that help manage blood sugar levels.
XOS consumption could have other metabolic benefits as well. A study on obese rats fed XOS alone or alongside Lactobacillus paracasei HII01 showed improvement in gut inflammation and a decrease in total body weight, total cholesterol, and LDL cholesterol levels.
In Europe, galacto-oligosaccharides (GOS) have been enjoying growing popularity as a Bifidobacteria-supporting fiber that has demonstrated impressive health benefits. Better-for-you product makers may want to consider adding it to their arsenal of ingredients suitable for food and beverage formulations in this popular family of fibers.
Experts in the field of digestive health recently suggested that some consumers can benefit from certain prebiotic fibers more than others. A 2018 study examined the effects of galacto-oligosaccharides (GOS), xylo-oligosaccharides (XOS), and beta-glucans on gut microbiota. Results suggested the composition of an individual’s gut microbiome impacts which short-chain fatty acids (SCFA) are produced from different prebiotics. An individual’s SCFA profile could be an indicator of how the subject will respond to prebiotic fiber supplementation. Butyrate is the SCFA that serves as the primary energy source of colonocytes and affects regulation of other cell functions. Acetate and propionate also are produced in significant quantities in the gut by beneficial bacteria.
Myco and Micro
Innovations in the investigation of gut health now distinguish between colonies of bacterial species and those of fungal species in the gut microbiome. “Several recent studies have provided evidence that gut mycobiome — the fungal community — can directly influence weight, digestion, the immune system, and mood,” notes Mahmoud Ghannoum, PhD, professor and director of the Center for Medical Mycology at Case Western Reserve University and University Hospitals Cleveland Medical Center.
Ghannoum recognizes that distinguishing between these two facets and understanding the symbiosis between them as well as with the body is ripe for exploration. He says, “Although the published literature continues to provide supporting evidence, it is important to remember that this is a new area of study, [both] about the microbiome at large as well as how the microbiome affects our health and disease status.”
New evidence suggests that conditions such as inflammation and obesity are tied to disturbances in gut mycobiome balance. Ghannoum suggests that new food formulations aimed at digestive health should include beneficial bacteria and fungi as well as prebiotic fibers to promote balance between different constituents of the gut microbial population.
As science continues to better elucidate the benefits of prebiotics, probiotics, and synbiotics, food scientists will have increasing options for formulating products that aid in improving overall digestive health. This also could provide options for targeting specific digestive-related conditions and ailments.
Old Mainstays, New Additions
Digestive fibers and starches that have become mainstream ingredients for digestive health are enjoying a popularity boost due to expanding consumer interest in immunity and digestive health. Resistant starch, inulin, isomaltulose, and others — while not quite household names — are increasingly recognized by consumers as beneficial ingredients on nutrition labels.
Resistant starches remain an attractive choice for achieving fiber content claims and assisting with digestive health. High-amylose corn starch and certain native starches, such as tapioca starch, have been used successfully in baking and snack applications with minimal changes in flavor, color, and texture of the final products. In fact, resistant starch can actually increase volume slightly in risen baked goods, creating fluffier textures.
What makes these starches especially favorable is that in processing, they behave like starches, but after being ingested, they behave like fibers. This capacity allows some of them, such as high-amylose corn starch, to be included on nutrition panels as fiber yet retain labeling as starch.
Other tactics for boosting the benefits of g.i. health-oriented ingredients are expanding the digestive health toolkit. New methods are being implemented to improve the viability of probiotics in finished food and beverage products. One example is pre-adaptation, which involves subjecting bacteria to environmental stressors, such as adding acid or altering oxygen content.
Another approach is the inclusion of ingredients to protect probiotic bacteria cells during processing while promoting their growth. Several advances have been made in the encapsulation arena, which to date is the most researched technique for enhancing probiotic viability. Extrusion, emulsion, freeze-drying, and spray-drying all have shown levels of effectiveness at protecting probiotics. Encapsulation allows beneficial bacteria to be utilized more widely in beverages without risk of growth or spoilage, as proven by the recent launch of a shelf-stable hard kombucha made with Bacillus coagulans-SNZ 1969.
For some encapsulated compounds, the capsule itself can be the prebiotic. For example, cyclodextrins — cup-shaped fiber compounds used in formulation to protect lipids from oxidation — have been used as maskers and for bringing water-solubility to lipid compounds. But it turns out that one form, alpha-cyclodextrin, has prebiotic capacity. With the field of synbiotics gaining traction, cyclodextrins could show great promise.
PHOTO: “Health Focus 2020 Gut Health Report,” Irwin Broh & Associates, Inc./Health Focus International (www.healthfocus.com)
More Than Skin Deep
Aloe vera is a fresh addition to the prebiotic ingredient realm due to the fructan and acemannan content of the inner leaf. Aloe has been shown to support the growth of beneficial bacteria and recent clinical evidence points to health benefits such as easing mild constipation and reducing blood cholesterol and glucose levels.
Other advantages related to digestive health are linked to aloe vera gel, produced from pulp in the inner leaves of the plant, and compounds in the outer rind have demonstrated antimicrobial potential. In vitro studies at the University of Chile showed that acemannan from aloe promoted beneficial bacterial growth at a level comparable to that of inulin, one of the most well-established prebiotic fibers. Fructans from aloe fostered even higher growth of Bifidobacterium spp. and resulted in greater production of SCFA.
Another study from researchers in Italy and the Czech Republic investigated the effect of Aloe barbadensis and Aloe aborescens in fermented milk. Results showed that 5% aloe gel from the inside portion of aloe leaves added to the fermented milk increased Lactobacillus growth. However, the addition of extracts from the green outer rind of aloe leaves inhibited growth due to the presence of antimicrobial phenolic compounds, highlighting the need to use the correct portion of the aloe plant when formulating a product with prebiotic benefit.
There is evidence to suggest that aloe may be beneficial to patients with irritable bowel syndrome (IBS). A recent clinical trial indicated aloe extract reduced the severity of IBS symptoms on par with the inulin control, although this may depend on the gut microbiotic profile of the patient.
A clinical study in South Korea showed that a prebiotic compound of aloe vera gel in concert with inulin and lactitol significantly decreased fecal content of the Firmicutes phylum of bacteria, which includes a number of common pathogenic gut bacteria that have been linked to the development of obesity and diabetes. Conversely, the experimental compound significantly increased concentration of Roseburia hominis, a beneficial butyrate-producing species. Other limited studies suggest aloe gel could help reduce fasting blood glucose and triglyceride levels.
Recent evidence suggests bovine colostrum has benefits for digestive health. Colostrum is the milk mammals produce during the first few days postpartum. In humans, the composition of colostrum implies its purpose is to provide immunological benefits rather than nutrition, with the composition of milk changing in the first two weeks postpartum to provide essential nutrition for newborns.
Human milk oligosaccharides, which vary among women, function as a prebiotic and reduce the ability of pathogens to bind to the gut barrier. Researchers recently demonstrated that bovine colostrum improved gut maturation and body growth in preterm piglets compared to infant formula, showcasing the unique properties of this mammal-produced nutritious liquid that is hard to mimic outside of the body.
The mechanism behind the health benefit of bovine colostrum likely lies in the free oligosaccharide content. Several experiments show bovine colostrum improves the integrity of the epithelial barrier in the small intestine. A recent study published in Applied Microbiology and Biotechnology determined that bovine colostrum increased adherence of commensal bacteria to human intestinal cells in vitro.
Researchers in New Zealand found that bovine colostrum retained this beneficial gut health effect in vitro after being processed into colostrum milk protein concentrate. This phenomenon also was observed in a small clinical study of athletes, which concluded bovine colostrum is a safe ingredient for lowering intestinal permeability.
An interesting concept surrounding bovine colostrum is that it can be manipulated to provide specific immunological benefits by vaccinating cows during gestation. One such study showed that the resulting hyperimmune bovine colostrum could be produced with antibodies targeting Clostridium difficile. Even without such manipulation, bovine colostrum has the potential to alleviate other gastrointestinal issues.
A pilot study conducted last year investigated the effects of Bifidobacterium infantis and bovine colostrum supplementation on children with autism and g.i. symptoms. While limited in size, the study found the treatment was well-tolerated and certain GI symptoms and aberrant behaviors were reduced. A more substantial clinical study in 2016 demonstrated that bovine colostrum reduces recurrent diarrhea and respiratory infections in children 1-6 years of age.
Apple pomace also could potentially serve as a source of probiotics. A new study on oligosaccharides derived from pectin via acid and enzymatic hydrolysis of apple pomace showed increased lactic acid bacteria growth and decreased binding of pathogens to intestinal cells in vitro. And new research suggests that flavonols in green tea could be exploited as a prebiotic. An in vitro study by researchers in Korea showed that green tea fractions containing high amounts of glycosides and aglycones stimulated growth of Lactobacilli spp. and Bifidobacteria spp, with butyrate being the most abundantly produced SCFA.
Probiotics' Next Step
The science of probiotics moves beyond digestive health.
by Meghan Disch
With decades of rising interest driving the digestive health trend, and sales growth continuing from year to year, “probiotics” certainly has become an “it” word in beverage and food formulation. New products continue to launch at a rapid pace to leverage this macro trend. Yet what many consumers and product developers might not realize is that there has been, and continues to be, more promising research on probiotics in areas beyond gut health.
While it seems that probiotics are everywhere, and that surely, decades of research must have taught us everything we need to know about the beneficial biologicals, we likely understand only the tip of the iceberg when it comes to their full benefits. It now is widely accepted that these microbial creatures work in synergy with our entire physiology.
A recent human study in Austria suggests that certain probiotics could impact higher-order cognitive processes. Studies on this and other aspects of the so-called “gut-brain axis” suggest correlations between a healthy microbiome and mood, emotional well-being, and other aspects of overall well-being.
Other recent research has shown that supporting the microbiome with beneficial bacteria has the potential to relieve fatigue and stress in athletes.
There even are ongoing studies attempting to understand and define the impact of probiotics on aging, oral health, and skin health. “These are areas to watch, but more human studies should be completed before claims in these spaces can be validated,” says Armin Salmen, PhD, vice president of R&D and QA for NextFoods, Inc., makers of GoodBelly Probiotics.
While this research is promising, since the field is still relatively new, most products launching today focus on digestive and/or immune health. However, with the number of studies being conducted on the hundreds of probiotic strains and subspecies suspected of having some health benefit, and the encouraging results coming out of this research, it is safe to say other claims for certain probiotic bacteria will be forthcoming.
Until other claims are validated and allowed, the core benefit of digestive/immune health will continue to attract an expanding number of consumers. And due to growing scientific evidence and increased press coverage on the importance of gut health, the market for probiotics is booming.
According to Euromonitor International, foods positioned with a digestive health benefit accrued global sales of $70.5B in 2018, making digestive health the second largest positioning platform behind general well-being. In turn, continued market growth has raised consumer consciousness of probiotics such that today, some 90% of consumers claim to be aware of them.
While consumers know what probiotics are, and have a general sense of their benefits, there remains a lack of knowledge about which strains provide what benefits, and what counts — literally, the number of active bacteria — are needed to be effective. Probiotic digestive and immunity claims have been studied for years and proven in numerous human studies. These studies have typically been strain-specific and either focused on immunity, as with Bifidobacterium lactis HN019, or digestive health, as with Lactobacillus plantarum 299v or B. lactis (BB-12).
With consumer awareness of probiotics being so high, brands will need to innovate within existing channels and seek new channels in which to expand beyond their current consumer base. Solutions will need to be created for increasingly knowledgeable and sophisticated consumers and their individual or demographic needs in order to deliver a product they will want to enjoy every day. “At GoodBelly, we provide products that taste delicious; we strive for a ‘feel the effect’ experience,” says Alan Murray, former CEO of NextFoods. “We want consumers to look forward to having their probiotics every day, while knowing it will help their digestive health.”
While there is an expansion in probiotics today, expect a shakeout in brands and categories over the next two to four years. The brands and products that succeed in the marketplace must be effective and use strains and counts that are backed by scientific research. Consumers might not understand the details of the science — nor do they necessarily need to — but they do know if they feel a difference in their gut health and are comforted by brands with integrity and honesty.
“We always tell consumers that strains matter and numbers matter,” says Erica Gardner, a food scientist at NextFoods. “Brands should have this information on the packaging so consumers know what they are getting. By providing the strain, consumers who wish to may look up if that strain is backed by human studies and at what probiotic count. Such information provides transparency on what the brand is putting in their products.”
Prebiotics are beginning to show up on consumers’ radar. In simple terms, prebiotics are considered the “food” for probiotics, making their addition to food and beverage products a logical extra benefit. We can expect to see multiple brands incorporate carefully crafted combinations of prebiotic fibers and probiotic bacteria into their products. As consumers’ understanding of the relationship between prebiotics and probiotics grows, there is great untapped potential for expansion into product solutions for consumers in the world of gut health and other benefit areas.
Meghan Disch is vice president and a researcher for NextFoods, Inc., makers of GoodBelly Probiotics beverages, shots, and other products. She can be reached at firstname.lastname@example.org.