Fermented foods and beverages are increasingly popular with consumers, as evidenced by market approval of products like kombucha, yogurt and kimchi. On the supplement side, many digestive health ingredients are created using fermentation, including postbiotics (a byproduct of probiotic activity).
Further, some digestive ingredients—including prebiotics—deliver their benefits when fermented by gut bacteria.
During fermentation, microorganisms (e.g., bacteria, yeast or fungi) break down carbohydrates like starch and sugar. In ancient history, fermentation was used to preserve food. Today, common foods such as wine, cheese, sauerkraut, kefir and tempeh are created using fermentation.
When it comes to nutrition, fermentation—inside and outside of the body—can yield compounds that provide powerful health benefits.
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Fermentation in the gut
Prebiotics, by definition, must:
• Escape digestion in the upper part of the digestive tract;
• Be selectively fermented by bacteria, changing the activity or composition of gut bacteria;
• Confer health benefits to the host.1
Nutritionally, dietary fiber is a prominent source of prebiotics. Numerous other sources occur naturally in small amounts or have been developed as functional ingredients, including extracted polysaccharides like gums, oligosaccharides such as fructans, polydextrose, resistant maltodextrins and resistant starch.
Fermentation plays a key role in the ability of prebiotics to provide health benefits.
Short-chain fatty acids (SCFAs) are the byproduct of intestinal microbial fermentation—mainly of undigested dietary carbohydrates, specifically resistant starches and dietary fiber.2
“SCFAs are a major source of energy for colonic cells and are known to promote immunity and suppress inflammatory responses in the intestine and other organs,” Justin Green, Ph.D., director of scientific affairs for Cargill’s health technologies business, said.
These organic acids are taken up by colon cells and by the body’s systemic circulation, where they provide beneficial properties from gut health to anti-inflammatory actions, James DiNicolantonio, Pharm.D., director of scientific affairs, AIDP, explained.
Butyrate is a well-researched SCFA that provides energy to colonocytes (the epithelial cells of the colon) and is involved in the maintenance of colonic mucosal health. Many researchers point to butyrate for its potential to reduce colorectal cancer risk, as well as inflammation and oxidative stress, although this impact is a matter of great debate in the research community.3
AIDP’s Green Banana Flour is a new fruit-based ingredient naturally rich in resistant dietary starch, which provides beneficial prebiotic dietary fiber. Green banana flour, derived from bananas collected at a particular ripening stage, provides lift in baked goods, water binding activity in meat alternatives and emulsification in beverages and sauces, and is an excellent source of dietary fiber, DiNicolantonio said.
Research suggests resistant starch promotes a higher proportion of butyric acid than other indigestible carbohydrates.4
Fermentation before the gut
“Today, we also recognize that the fermentation process can produce metabolites with health-supportive benefits, the end whole food product being called a postbiotic,” Green said.
Using an analogy, he explained prebiotics fuel the microorganisms, or “factories,” in the microbiome, while probiotics add the factories that make beneficial metabolites. “Postbiotics contain those beneficial metabolites themselves—the goods made by the microbial factories,” Green explained.
Put simply: “When beneficial bacteria (probiotics) ferment fiber (prebiotics) in the lower colon, they excrete beneficial compounds called postbiotic metabolites,” Matthew Olesiak, M.D., chief medical director, SANESolution, said. “So, postbiotics are essentially pre- and probiotics’ ‘waste’ products.”
Rachel Adams joined Informa’s Health & Nutrition Network in 2013. Her career in the natural products industry started with a food and beverage focus before transitioning into her role as managing editor of Natural Products INSIDER, where she covered the dietary supplement industry. Adams left Informa Markets in 2019.
1 Fuentes-Zaragoza E et al. “Resistant starch as prebiotic: A review.” Starch. 2011;63(7):406-415.
2 Canani RB. “Potential beneficial effects of butyrate in intestinal and extraintestinal diseases.” World J Gastroenterol. 2011;17(12):1519-1528.
3 Lupton JR. “Microbial degradation products influence colon cancer risk: the butyrate controversy.” J Nutr. 2004;134(2):479-482.
4. Fu X et al. “Nondigestible carbohydrates, butyrate, and butyrate-producing bacteria.” Crit Rev Food Sci Nutr. 2019;59(sup1):S130-S152.