Good Gut Feelings

Gut health or digestive health, however you refer to it, one thing is for certain: consumers are interested in it. They’re learning more about the relationship between nutrition, gut health, and concerns like immunity, brain health, mood, and overall wellness. Preliminary research is even looking at how nutrition can modulate the link between gut microbiota and chronic painful conditions (Lu et al. 2023).

“From a consumer point of view, we’re seeing an increased understanding of the links between digestive health, the gut microbiome, and better health,” says Denisse Colindres, manager, nutritional communication, North America, BENEO. “In fact, well over half of global consumers say that they regularly look for products that improve digestive health.”

While terms like digestive health, gut, and microbiome are becoming more commonplace, there is still much to be studied and defined when it comes to gut health. For example, what is a healthy gut?

“For the definition of a healthy gut microbiota, the [jury] is still out on that,” says Hannah Holscher, director of the Nutrition and Human Microbiome Laboratory and associate professor of nutrition, with the University of Illinois Urbana-Champaign. “One of the markers in adults may be greater diversity: more types of microbes and a more robust ecosystem.”

Although a diverse gut microbiota has been linked to healthy dietary patterns and possible lower risk of certain diseases and infections, current dietary guidelines don’t include nutrient recommendations for gut microbiota. Holscher thinks that could change in the future. Her laboratory recently published a study demonstrating that adults with greater compliance to the Dietary Guidelines (a diet rich in fruits, vegetables, and fiber) demonstrated higher diversity in their fecal microbiota and greater abundance of bacteria capable of metabolizing complex carbohydrates (Baldeon et al. 2023).

Holscher suggests that following the U.S. Department of Agriculture’s MyPlate (i.e., the plate graphic showing different food groups as a reminder of what—and how much—people should put on their plates to eat healthy) and consuming nutritious whole foods are good for a healthy gut. Recent research highlights specific whole foods and their beneficial effect on the gut microbiota, including:

Almonds. Creedon et al. (2022) investigated how gut microbes break down almonds to produce butyrate, a short-chain fatty acid that is associated with several health benefits, including nutrient absorption. Results of the four-week study showed that participants who consumed about two servings of almonds a day experienced small but significant differences in stool frequency, as well as significant increases in butyrate in the colon, suggesting positive changes to the functionality of gut microbiota.

Walnuts. In a paper published earlier this year, researchers reviewed the evidence from 33 studies that investigated the benefits of walnuts in relation to inflammation and overall disease risk (Fan et al. 2023). They suggested that many of the beneficial properties of walnuts associated with anti-inflammatory effects are linked to ellagitannins, or polyphenols, found in walnuts, which are ultimately metabolized by gut microbiota to bioactive, anti-inflammatory urolithins that may help enhance cellular health.

Avocados. Avocados are rich in dietary fiber and monounsaturated fatty acids. These popular fruits were recently evaluated in terms of the impact of avocado consumption on the gastrointestinal microbiota and microbial metabolites (Thompson et al. 2021). Those who consumed avocados once daily for 12 weeks had a greater abundance of bacteria capable of fiber fermentation, a greater microbial diversity, and a reduction of bile acids.

Fermented Foods. The International Scientific Association for Probiotics and Prebiotics (ISAPP) defines fermented foods as “foods made through desired microbial growth and enzymatic conversions of food components.” Some of the bacteria in fermented foods are associated with digestive health. “Fermented foods [such as] yogurt, kimchi, kombucha, tea, and pickled vegetables have consistently been listed in the top 10 superfoods in the Today’s Dietitian annual survey for the last several years. We see them blooming in the market,” notes Holscher. Holscher adds that nutrients in the food matrix of fermented foods can often be more bioavailable. For example, isoflavones in soy can be more bioavailable in fermented foods like tempeh and tofu.

Good-for-the-Gut Ingredients

In addition to whole foods, research and attention also is focused on ingredients that can beneficially affect the gut microbiota. This year, Health and Happiness Group and Arla Foods Ingredients combined with APC Microbiome Ireland to collaborate on a research project focused on diet and early-life cognitive development. The one-year project will aim to understand the role of specific milk-based ingredients in the infant microbiome and reduce the negative impact of stress on early-life cognitive development.

Human milk oligosaccharides (HMOs) are another ingredient big in the microbiome space, adds Holscher. HMOs are natural prebiotics found in significant concentrations in human breast milk. They help promote a healthy and balanced infant gut microbiome.

Prebiotics. “With consumers’ growing interest in prebiotics and the gut microbiome, and manufacturers wanting to tap into that trend, we are now also seeing an increasing number of substances with prebiotic claims on the market,” Colindres explains. Nagy et al. (2022) conducted a systematic literature review with meta-analyses and demonstrated that chicory root fiber intake (starting at 3 g/day) promotes significant growth of Bifidobacteria in the gut microbiome in all age groups and improves bowel function parameters. It is the first study of this kind, based on randomized control trials, that has investigated the effect of inulin-type fructans derived from chicory root on Bifidobacteria abundance in gut microbiota and health-related outcomes.

A newer study demonstrated that prebiotic chicory root fibers supported the selective growth of Bifidobacteria in the human gut, no matter for which food application or in which food matrix they were used (Jackson et al. 2023). This is the first time that the effects of chicory root fiber in different food applications have been included within one study design, enabling their direct comparison. The foods reflected a wide range of matrices, such as baked, semi-solid, and liquid.

An upcycled soluble carrot fiber (BeniCaros, NutriLeads BV) has shown prebiotic activities. In a study with 24 healthy adults, it was demonstrated that consumption of the carrot-derived rhamnogalacturonan I (cRG-I) created a consistent gut microbiota composition and increased metabolite production (Van den Abbeele et al. 2023). The study also provided evidence that BeniCaros significantly enhanced the production of short-chain fatty acids (acetate, propionate, and butyrate).

Postbiotics. Postbiotics are increasing in notoriety for gut health. ISAPP defines a postbiotic as “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host.” Cargill offers a whole food fermentate, EpiCor, clinically shown to support immune and gut health. It is made through a specialized fermentation process that creates a unique fingerprint of metabolites including proteins, peptides, antioxidants, polyphenols, organic acids, nucleotides, polysaccharides (1-3 1-6, beta glucans), and mannans. The postbiotic has been shown to help support the immune system and positively modulate the gut microbiome.

Probiotics. Probiotics are widely known and accepted for their role in gut health. Not only do they help manage various gastrointestinal issues, but they also can beneficially affect immune health, eczema, and upper respiratory infections. Probiotics may prove to be a good fit in the increasingly popular personalized nutrition market. Because different strains affect health in various ways, food manufacturers and consumers will be paying more attention to the supporting science and studies for particular probiotics and their specific health benefits.

It will be interesting to watch the gut health market evolve as research continues to discover and understand the relationship between nutrition, gut, and overall health.ft